Chilled Beam Application Guidebook - Biblioteka | KTU · 2020. 10. 19. · CHILLED BEAM SYSTEM...

Chilled Beam Application Guidebook

Maija Virta (ed.)David Butler

Jonas GräslundJaap Hogeling

Erik Lund KristiansenMika Reinikainen

Gunnar Svensson

rehvaFederation of European Heating and Air-conditioning Associations

GUIDEBOOK NO 5

Single user license only, copying and networking prohibited. All rights reserved by REHVA.

.

.

Chilled Beam Application Guidebook

Maija Virta (ed.) David Butler

Jonas Gräslund Jaap Hogeling

Erik Lund Kristiansen Mika Reinikainen

Gunnar Svensson


.

.

DISCLAIMER This Guidebook is the result of the efforts of REHVA volunteers. It has been written with care, using the best available information and the soundest judgment possible. REHVA and the REHVA volunteers, who contributed to this Guidebook, make no rep-resentation or warranty, express or implied, concerning the completeness, accuracy, or applicability of the information contained in the Guidebook. No liability of any kind shall be assumed by REHVA or the authors of this Guidebook as a result of reliance on any information contained in this document. The user shall assume the entire risk of the use of any and all information in this Guidebook. ----------------------------------------------------------------------------------------------------------- Copyright © 2004 by REHVA, Federation of European Heating and Air–conditioning Associations Second edition 2007 All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronically or mechanical, including photocopy recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to REHVA, P.O. Box 82, 1200 Brussels e–mail: [email protected] ISBN 2-9600468-3-8 Printed in Finland, Forssan Kirjapaino Oy, Forssa


.

iii

List of contents

Terminology, Symbols and Units ..............................................................................vii 1. CHILLED BEAM COOLING AND HEATING IN A NUTSHELL.................1 2. THEORETICAL BACKGROUND .....................................................................3

2.1 Heat Transfer...................................................................................................3 2.1.1 Radiation ...........................................................................................3 2.1.2 Convection ........................................................................................3 2.1.3 Evaporation .......................................................................................3

2.2 Heat Transfer Efficiency in Chilled Beams .....................................................4 2.3 Room Control ..................................................................................................5

3. ROOM AIR CONDITIONING SYSTEM SELECTION ...................................6 3.1 Overview of Different Room Units ................................................................6 3.2 Conditions for Chilled Beam Applications ......................................................7 3.3 Life Cycle Cost (LCC) ....................................................................................7

4. CREATING GOOD INDOOR CLIMATE WITH CHILLED BEAMS......... 10 4.1 Types of Chilled Beam Systems .................................................................... 10

4.1.1 Passive Chilled Beams....................................................................10 4.1.2 Active Chilled Beams.......................................................................11 4.1.3 Perimeter Passive Chilled Beams....................................................11 4.1.4 Integrated Service Beams ...............................................................12

4.2 Comfortable Indoor Climate with Chilled Beams .......................................... 12 4.3 Room Construction Design Requirements ..................................................... 15 4.4 Positioning of chilled beams.......................................................................... 17

4.4.1 Positioning of passive chilled beams ...............................................17 4.4.2 Positioning of perimeter chilled beams ............................................17 4.4.3 Positioning of active chilled beam....................................................18

4.5 Demonstration of Indoor Climate Conditions ................................................19 5. CHILLED BEAM SYSTEM DESIGN .............................................................. 21

5.1 Cooling with Active Chilled Beams .............................................................. 21 5.2 Heating with Active Chilled Beams............................................................... 24 5.3 Active Chilled Beams in Hot and Humid Climates........................................ 25 5.4 Prevention of Condensation........................................................................... 26 5.5 Air and Water Distribution Systems .............................................................. 27

5.5.1 Distribution Pipe Work .....................................................................28 5.5.2 Chiller Plant and Buffer Vessel ........................................................29 5.5.3 Ductwork and Air Handling Unit .......................................................30

5.6 Use of Free Cooling and Sustainable Heat Sources ....................................... 31 5.7 Room Controls .............................................................................................. 31 5.8 Design Methodology for Chilled Beam System............................................. 32


.

iv

6. PRODUCT SELECTION................................................................................... 34 7. INSTALLATION AND COMMISSIONING.................................................... 37

7.1 Installation..................................................................................................... 37 7.2 Flushing......................................................................................................... 38 7.3 Filling-up and venting the system.................................................................. 38 7.4 Commissioning.............................................................................................. 38

8. RUNNING OF CHILLED BEAM SYSTEM .................................................... 41 8.1 Maintenance and Replacement ...................................................................... 41 8.2 Essential Issues in Beam Operation ............................................................... 41

9. CASE STUDIES ................................................................................................. 43 9.1 A Case of Office Building in United Kingdom.............................................. 43 9.2 A case of Office Building in France .............................................................. 44 9.3 A case of Office Building in Sweden............................................................. 45 9.4 A Case of Office Building in Belgium with High Performance Values ......... 46 9.5 A Case of Office Building in Finland with Passive Chilled Beams ............... 47

10. REFERENCES ................................................................................................... 48


.

v

Foreword REHVA is a 40-year-old organisation of European professionals in the field of building services (heating, ventilating and air-conditioning). REHVA represents more than 100,000 experts from 30 Euro-pean countries. REHVA´s main activity is to develop and disseminate economical, energy efficient and healthy technology for the mechanical services of buildings. The work is super-vised by the board of directors. Each member of the board is responsible for work in a specific area of REHVA activi-ties. REHVA Guidebook projects are coordi-nated by the Technical Committee of REHVA. The objectives of this work are: Initiate work for technical guidebooks

in the area of building services Establish task forces for such

guidebooks Develop distribution of REHVA

Guidebooks to members and other professionals

Supervise the quality of REHVA Guidebooks

Several task forces are currently working towards REHVA Guidebooks such as: commissioning of HVAC systems for good energy efficiency and indoor cli-

mate, control of exposure to environ-mental tobacco smoke with ventilation, criteria of clean ventilation systems, low temperature heating systems, indoor envi-ronment and productivity. The topic of the guidebook on chilled beam cooling is extremely important with respect to indoor environment. This rela-tively new technology has rapidly spread all over the Europe. Its advantages are in low noise generation, low room velocities and flexibility. High temperature level of cooling media also improves the energy efficiency of the mechanical cooling and allows longer periods of free cooling. The Guidebook presents the principles of chilled beam cooling and illustrates its practical applications. The guidebook on chilled beam cooling is written by a working group of highly qualified international experts under the leadership of Mrs Maija Virta from Finland. The work is done on a voluntary basis with no commercial interest. The document is approved by the REHVA board. The board would like to express its sincere gratitude to the working group for their invaluable work. Olli Seppänen President Elect of REHVA and Chairman of the technical committee


.

vi

Member countries of REHVA Belgium Greece Romania Bosnia and Herzegovina Hungary Russia Bulgaria Ireland Serbia and Montenegro Croatia Italy Slovakia Czech Republic Latvia Slovenia Denmark Lithuania Spain Estonia The Netherlands Sweden Finland Norway Switzerland France Poland Turkey Germany Portugal United Kingdom

Work Group This guidebook has been developed in a work-group consisting of the following experts: David Butler, Principal Consultant, BRE, Watford, United Kingdom Jonas Gräslund, Technical Director, Skanska Fastigheter Stockholm AB, Sweden Jaap Hogeling, Director, ISSO, Rotterdam, the Netherlands Erik Lund Kristiansen, Marketing Engineer, Danfoss A/S, Denmark Mika Reinikainen, Director, Olof Granlund Oy, Helsinki, Finland Gunnar Svensson, Export Director, Swegon AB, Stockholm, Sweden Maija Virta, M.Sc., Development Director, Halton Oy, Kausala, Finland

Reviewers The following persons have reviewed the book and made valuable suggestions for improvements: Francis Allard, France Derrick Braham, CIBSE

– Chartered Institution of Building Services Engineers, United Kingdom Peter Novak, Energotech d.o.o. Slovenia Michael Schmidt, Germany Olli Seppänen, Professor, Helsinki University of Technology, Finland Bjarne W. Olesen, DTU, Denmark

Acknowledgements The workgroup wishes to thank the contribution of Mrs. Verity Braham for checking the grammar and spelling and Mr. Harri Itkonen for his help with finalising this book.


.

vii

Terminology, Symbols and Units Terms and definitions

The terms and definitions are based on the CEN standard of Chilled Beams, testing and rating of active chilled beams. [12, 13] Additional definitions are mainly from an ISSO publication of Climatic Ceilings and Chilled Beams; Applications of Low Temperature Heating and High Temperature Cooling [1].

Active (Ventilated) Chilled Beam A convector with integrated air supply where primary air, induced air or primary air plus induced air passing through the cooling coil(s). The cooling medium in the coil is water. The beam is normally mounted under the ceiling. Chilled Beam A cooled element or cooling coil situated in, above or under a ceiling which cools con-vectively using natural or induced air flows. The cooling medium is usually water. Chilled Ceiling (Radiant Ceiling) Ceiling panels that are made up of elements that connect together and cool primarily through radiation. The cooling medium is usually water. Closed Chilled Beam An active chilled beam where there is an integrated secondary air path directly from the room space. Closed chilled beams are mainly situated within a suspended ceil-ing. The cooling medium is usually water. Dew Point The temperature at which the water vapour present in the air condenses. Draught Unwanted local cooling of the body caused by air movement.

Draught Rating (DR-value) The percentage of people predicted to be dissatisfied due to draught. Effective Length The length of the cooling section of a chilled beam. Induced Airflow The secondary airflow from the room induced into the chilled beam by the primary air. Induction Rate The total volume of air displaced by in-duction, divided by the volume of primary air supplied. Infiltration The transport of air through leakage paths in the envelope of a building, resulting from pressure (e.g. wind) and temperature differences. Mixed Airflow Rate The total airflow rate supplied from the beam to the space (mixture of primary air and induced air) Mean Radiant Temperature The theoretical uniform temperature of a room in which the radiant exchange be-tween the human body and its environ-ment is the same as the radiant exchange in the actual location.


.

viii

Nominal Cooling Capacity The cooling capacity calculated from the curve of best fit for the nominal cooling water flow rate at the nominal temperature difference. Nominal Cooling Water Flow Rate The flow rate that gives a cooling water temperature rise of 2 ± 0.2K at the nomi-nal temperature difference of 8K. Nominal Temperature Difference 8 K temperature difference between the reference air temperature and the mean cooling water temperature. Open Chilled Beam An active chilled beam where secondary air is taken in into the top of the beam. Open chilled beams are mainly used with-out a suspended ceiling. Operative Temperature Uniform temperature of an imaginary black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the ac-tual non-uniform environment.

Passive Chilled Beam (Static Beam) The cooled element or cooling coil fixed in, above or under a ceiling fitted with a cooling coil that cools mainly convectively using natural airflows. The cooling me-dium is usually water. Primary Airflow Rate Conditioned and dehumidified outdoor air supplied to the chilled beam through a duct from the air handling unit. Reference Air Temperature Average of the induced air temperature on the inlet side of a chilled beam. Room Air Temperature The average of air temperatures measured at 1.1m high, positioned out of the main air current from the chilled beam. Total Length The total installed length of the cooling section of a chilled beam, including casing. Turbulence Intensity The ratio of the standard deviation of the air velocity to the mean air velocity. Used to measure variations in air velocity.

Symbols and Units

SYMBOL QUANTITY UNIT cp Specific heat capacity, cp = 4.187 kJ/(kg,K) (water), cp = 1.005 kJ/(kg,K) (air) kJ/(kg,K) L Active length of chilled beam m Lt Total length of a chilled beam, including casing m P Total cooling capacity, P = cp·qm·(θw2 − θw1) W PL Specific cooling capacity of a chilled beam, relative to active length L W/m PN Nominal cooling capacity at ΔθN = 8K W PLN Nominal specific cooling capacity at ΔθN = 8K W/m qw Water flow rate l/s qm Water mass flow rate (qm = ρw · qw) kg/s ρw Density of water (1000 kg/m3) kg/m3 θa Room air temperature °C θr Reference air temperature = induced air temperature °C θp Primary air temperature °C Δθ Temperature difference, Δθ = θr − θw K ΔθN Nominal temperature difference (= 8K) K θw1 Water inlet temperature °C θw2 Water outlet temperature °C θw Mean water temperature, θw = 0.5·(θw1 + θw2) °C qp Primary air flow rate m³/s p Primary air temperature °C ρp Density of primary air (1.20 kg/m3, θ = 21°C) kg/m3


1

1. CHILLED BEAM COOLING AND HEATING IN A NUTSHELL

Principles Chilled beam systems are primarily used for cooling and ventilating spaces, where good indoor environmental quality and individual space control are appreciated. Chilled beam systems are dedicated out-door air systems to be applied primarily in spaces where internal humidity loads are moderate. They can also be used for heating. Active chilled beams are connected to both the ventilation supply air ductwork, and the chilled water system. When de-sired, hot water can be used in this system for heating. The main air-handling unit supplies primary air into the various rooms through the chilled beam. Primary air supply induces room air to be recircu-lated through the heat exchanger of the chilled beam. In order to cool or heat the room either cold (14−18°C) or warm (30−45°C) water is cycled through the heat exchanger. Recirculated room air and the primary air are mixed prior to diffusion in the space. Room temperature is controlled by the water flow rate through the heat exchanger.

Passive chilled beams comprise a heat exchanger for cooling, and when desired for heating. The operation is based on natural convection. The primary air is supplied to the space using separate dif-fusers either in the ceiling or wall, or al-ternatively through the raised floor. Best suited for: The chilled beam system provides excel-lent thermal comfort, energy conservation and efficient use of space due to high heat capacity of water used as heat transfer medium. The system operation is simple and trouble-free with minimum mainte-nance requirements. The beam system design complements the flexible use of available space, whilst the high tempera-ture cooling and low temperature heating maximise the opportunity for free cooling and heating. Typical applications for beam systems are: Cellular and open plans offices Hotel rooms Hospital wards Retail shops Bank halls

Figure 1.1 Operation principle of closed active, open active and passive chilled beams. In active chilled beams the primary air supply induces room air through heat exchanger where as in passive chilled beam the operation is based on natural convection.

Closed active chilled beam Open active chilled beam Passive chilled beam


REHVA Chilled Beam Application Guidebook

2

Due to dry cooling operation the beam system is used where the internal humidity loads are moderate, the primary air is de-humidified and any infiltration through the building envelope is limited and controll-ed. Active chilled beams provide an option to integrate lighting and other building services with the air conditioning units. Less suited for: Spaces in which high ventilation rates are required, (i.e. where heat loads and con-taminant loads from occupants are con-current) such as conference areas, meet-ing rooms and classrooms, and where all-air systems are more practical. Demand based variable airflow systems (VAV) are recommended if heat and contaminant loads vary strongly all the time. In spaces, where internal humidity loads are high, or increased risk of infiltration exists e.g. through open doors, all-air sys-

tems or wet operating cooling systems (e.g. fan coils) are recommended. Operating range: The active chilled beam system can be used when the total sensible cooling (air + water) requirement is under 120 W/floor-m² in comfort conditions. The optimum operating range, when good thermal comfort in sedentary type occu-pations is required, is 60−80 W/floor-m². The active chilled beam system is typi-cally a dedicated outdoor air system, where primary airflow rates are between 1.5 – 3 l/s,floor-m². Passive chilled beams can be used when total sensible cooling requirement is 40 − 80 W/floor-m². Higher cooling requirements can be met, where optimal thermal comfort is not re-quired or where the occupancy type is not sedentary (for example in copying rooms, computer rooms etc.).

Figure 1.2 Examples of active and passive chilled beam installations.


3

2. THEORETICAL BACKGROUND 2.1 Heat Transfer

An individual’s heat exchange with the surroundings primarily occurs in three ways, these are: heat emission through radiation to

surrounding areas or to free space heat emission through convection

to the surrounding air heat emission through

the evaporation of fluid. A fourth form of heat exchange can also occur through conduction to fixed or floating objects in direct contact with the body. However, in normal cases this is so small it is negligible. 2.1.1 Radiation Radiant heat is constantly emitted from warmer to colder surfaces and increases with the temperature difference between them. The radiant heat exchange is primar-ily dependent on the following factors: the size and location of the surfaces and

the view factor in relation to each other the temperatures of

the individual surfaces the character of the surfaces, which

determines the emission and absorption factors, i.e. the ability to emit and absorb radiant heat.

As the room surfaces and conventional heaters have relatively low temperatures, an individual’s heat transfer with sur-rounding surfaces takes place in the form of long wave, low temperature radiation.

The structure and colour of the surfaces have virtually no significance for low temperature radiation as regards its ca-pacity to emit and absorb thermal radia-tion, with the exception of untreated metal surfaces. Examples of sources of low temperature radiation are panel radia-tors as well as ceiling and floor heating/ cooling systems. 2.1.2 Convection If a surface is warmer than the room air it emits heat to the room air. In the same way, the room air emits heat to a surface that is colder than the room air. This form of heat transfer is called convection, and is divided into: Natural convection Forced convection

Natural convection is obtained through the density differences of the air in the different layers, which are created by the temperature differences between the air and the objects against or around which the air flows. Forced convection is heat transfer in a fluid due to motion induced by mechani-cal means such as a fan. 2.1.3 Evaporation Evaporation heat is expended when a liq-uid changes to a gas state. When a person perspires this latent heat is transferred by the body surface, which then cools. Heat transfer through evaporation and convec-tion also takes place during breathing.



4

Figure 2.1 Radiant heat transfer occurs between all surfaces of differing temperatures.

Convection occurs when air moves along a surface. Natural convection is obtained through the density differences of air, and forced convection e.g. fans.

Heat emissions due to evaporation are de-pendent on the room air temperature but also on the absolute humidity of the room air. At average temperatures between ap-proximately 18°C to 25°C with normal relative humidity 20−50% this effect is small for sedentary persons. If the humid-ity level rises to 60% RH and above, the skin surface becomes clammy and evapo-ration is difficult. 2.2 Heat Transfer Efficiency in

Chilled Beams

Heat transfer within chilled beam occurs primarily by convection via the heat ex-changer. The heat exchanger is typically a coil with copper pipes and aluminium fins con-nected to the cooling / heating water sys-tems. In active chilled beams heat transfer is enhanced by forced convection gener-ated by high induction effect of primary air supply. The heat transfer in the ex-changer depends on several variables. Water mass flow rate is selected to achieve a desired outlet water tempera-ture for a given inlet water temperature and to ensure efficient heat transfer by maintaining turbulent flow conditions with sufficient water flow velocity.

Specific conductance of the heat ex-changer depends on coil and pipe dimen-sions and coil width. Convective heat transfer properties de-pend on primary airflow and induction airflow rates. Induction rate depends on the type and number of supply air nozzles. Inlet water and room temperatures af-fect the mean temperature difference be-tween the air and the water in the heat exchanger. Water is a much more efficient heat car-rier than air. Therefore high airflow rate and consequently large duct work are needed to provide the same cooling effect as water. The specific heat capacity per kg of water is 4.2 times higher than the specific heat capacity of air.

100%80%60%40%20%

0%

0.02

0.010

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

0.15

P L (W

)

qm (kg/s) Figure 2.2 The specific heat transfer of a chilled beam. Water flow rate (qm) should be turbulent to ensure effective heat transfer (PL) but after a certain point any increase of water flow rate does not improve the heat transfer.


2. THEORETICAL BACKGROUND

5

The water flow rate inside the pipe should be high enough to ensure a turbulent flow in design conditions. The heat transfer is significantly more effective in turbulent flow than in laminar flow. However the chilled beam heat exchanger has an opti-mum specific capacity above which higher water velocity does not increase the cooling output. Table 2.1 Minimum water flow rate with dif-ferent pipe diameters to ensure fully turbulent flow.

Outside diameter

(mm)

Water velocity

(m/s)

Minimum water flow rate

(kg/s)

10 0.28 0.016

12 0.23 0.018

15 0.18 0.024

18 0.15 0.030

22 0.12 0.038

2.3 Room Control The objective of room control is to mini-mize the difference between the ac-tual/controlled room temperature and the end-user defined set point temperature. There are two basic types of controllers used with chilled beam cooling system: self-acting controllers and electronic con-trollers. There are different solutions for control-ling room temperature in chilled beam installations: On/off time proportional on/off proportional (P) proportional-integrating (PI)

The on/off controller has two stages: “on” (valve fully open – full flow of water) or “off” (valve fully closed – no water flow). An on/off actuator takes 3−5 min-utes to open and close the valve, and therefore provides reasonable stability in the room temperature. The proportional (P) controller is modu-lating the position of the valve and the water flow continuously. The P-controller is associated with a proportional band (P-band), typically 1−3°C – which represents the deviation from the temperature set point that produces 100 % control signal (valve fully open). The P-controller en-sures a stable control and continuous wa-ter flow. P-controller does not eliminate the offset from the set point. The PI-controller is a proportional con-troller with an integrating-function that increases the gain and eliminates the off-set from the set point temperature over time. However, in the cooling season when cooling is only required for part of the day, there is actually little or no dif-ference between P- and PI-control.

Figure 2.3 Room temperature controls can be integrated inside the chilled beam or more typi-cally installed on the wall.


6

3. ROOM AIR CONDITIONING SYSTEM SELECTION

PROPERTIES OF CHILLED BEAM SYSTEM Low life cycle costs:

Low maintenance cost Good energy efficiency Free cooling possible in cold and temperate climate

Hygienic system

No filters to be changed or cleaning of drain pans for condensate Easy cleaning of coils and surfaces, only once in every 5 years

Chilled beams operate with a dry cooling coil

No condensate collection system Primary air should be dehumidified in the air handling unit and/or Control of water temperatures is needed to avoid condensation

Building conditions when chilled beams are used:

Cooling demand in the space is less than 80 W/floor-m² (max 120) Heating demand less than 40 W/floor-m² Limited infiltration through building envelope Special attention to the building management system if windows are

openable

3.1 Overview of Different

Room Units

There are a variety of air conditioning systems (air-water systems), where water is used as the heat transfer medium for cooling. The most common room air con-ditioning units and arrangements in these systems are: Fan coil unit High pressure induction unit (floor or

ceiling mounted) Climatic ceilings • Chilled ceilings

- Ceiling panels - Plastic pipes covered with plaster

• Chilled beams - Active chilled beams (open and

closed) - Passive chilled beams - Integrated service beams (active

or passive beam)

Different systems have different proper-ties with respect to thermal and acoustic performance, operation, maintenance and investments. The chilled beam system promotes excel-lent thermal comfort, energy conservation and efficient use of space due to the high heat capacity of water used as the heat transfer medium. The operation principle of the system is simple and trouble-free, because the chilled beam system does not use fans which consume energy and may break down. In active chilled beam sys-tems ventilation is integrated in the room units and no separate equipment for room air distribution is needed. Maintenance requirements are minimal because there are no filters to be changed or any condensate collection system to be cleaned annually. It is recommended that



7

the beam system is vacuum-cleaned every 3 − 5 years, and the control system opera-tion checked at the same time. Beam system design complements the flexible use of the available space, whilst the high temperature cooling and low temperature heating maximise the oppor-tunity for free cooling and heating. The final selection between systems depends on the design of the building, its spaces and their use, as well as the desired qual-ity level of indoor climate conditions and life cycle cost.

3.2 Conditions for Chilled Beam Applications

The operation of all climatic ceiling ap-plications (chilled beams and ceilings) is based on dry-cooling operation and typi-cally the units or arrangements do not include any condensate collection system. This means that temperature of heat trans-fer surfaces has to be higher than the dew point temperature of the room air. For this reason the humidity in these build-ings has to be controlled. In most cases this means, that the outdoor air has to be dehumidified by being cooled in the cen-tral air-handling unit. The building envelope should meet the best National Standard of Air tightness to limit the infiltration through the building envelope. If openable windows are used, then special attention should be paid to the control system of the water temperature to avoid condensation on the chilled beam. Chilled beams have a limited cooling ca-pacity when high thermal comfort re-quirements of spaces are set. Conse-quently all fenestration should be provid-

ed with efficient solar shading to limit the total room cooling demand to less than 80 (max 120) W/floor-m², particularly on the south façade spaces.

3.3 Life Cycle Cost (LCC) When making a decision between the dif-ferent systems, the life cycle cost analysis should be performed. Even though the investment cost presents about 80% of the overall life cycle cost with a life cycle of 15 years and respectively 50% with a life cycle of 50 years; the saving potential in energy, replacement and maintenance costs is still significant. It is difficult to give any general values of life cycle cost for different systems, as the result of LCC is very much dependent on the design of the building, climatic conditions etc. For this reason it is recommended to make a life cycle cost analysis of each building individually. The investment cost of the chilled beam system is influenced by the flexibility of the space. When beams are installed lengthwise in the room, the typical chilled beam installation is one beam in every second or third module. This means the minimum flexibility of about 0.9 m. When beams are installed crosswise the individual beam can be as short as 0.6m, and in consequence only has minimum flexibility. However such short lengths raise the investment cost due to the in-creased number of duct and pipe connec-tions, as well as valves and control damp-ers. This is why it is more cost-effective to install either longer beams, or use a mix-ture of shorter and longer beams e.g. alter-nating beam length equal to width of one space module and two space modules.



8

Figure 3.1 In lengthwise (left) installation there are often less pipe and duct connections with same module division, because there is only one beam in every second or third module, while in cross-wise installation (right) there is typically one beam per module. The smaller the module division is, the more expensive the beam installation is.

The installation time of a chilled beam is about 1 hour. Transportation costs are often included in the purchase price, but if not, 5 to 20% can be added depending on the distance between the building site and the manufacturing works. Estimating energy, maintenance and re-placement costs is laborious. Energy costs include typically heating and electric en-ergy costs. Annual energy consumption and energy price increases should be taken into account as well as the interest rate and calculation period. The energy consumption should be calculated with a dynamic energy simulation program. Chilled beams and chilled ceilings require only minimum maintenance. The finned coil of the beam should be vacuum-cleaned every 3−5 years and the operation of room controls should also be checked at the same time. When replacement costs are calculated, a maintenance period of 20 years can be used for beams, and 10 years for controls

(wax bulb actuators may need replace-ment earlier). Life cycle costs depend on local condi-tions and are project specific, and highly dependant on which cost items have been included in the analysis. Accordingly the cost difference between the different sys-tems is more significant and more reliable than the absolute cost level. Use of chilled ceilings and beams has a positive effect on the energy consumption of buildings. Since water is primarily used as an energy carrier instead of air, the sys-tem is using energy efficiently. Since wa-ter is the primary energy carrier, the sys-tem is more energy efficient than an all air system. Additionally it is possible to fur-ther improve the overall efficiency by us-ing higher cooling water temperatures and lower heating water temperatures than are used in air based systems. Even sustain-able energy sources (waste heat, ground heat etc.) and free cooling can be utilized in order to improve the energy perform-ance of the building.



9

Figure 3.2 Example of different costs in a Scandinavian office building, where chilled beams are used for cooling in the office spaces, and all-air system in other spaces. [5]

The following investment costs (includ-ing purchase price, installation and trans-portation costs) should be taken into ac-count in life cycle cost calculations. Building Automation • Building automation and room con-

trol equipment Ventilation and Air Conditioning • Air handling units, fans, and ductwork • Room equipment, chilled beams, fan

coils, VAV units, re-heat coils Cooling and heating • Water cooling equipment • Central heating units

Piping and plumbing • Cooling pipe work • Heating pipe work and radiators • Condensate collection systems

(drain pans and drains) Electricity consumption and

power demand • HVAC electricity components

(fans, chiller, pumps etc.) Extra building costs • Suspended ceiling and raised floor

Reservations for modifications during the building process (%).

Fan coil in 300 rooms, 20-year life cycle: Filter change: €25/filter twice a year € 300.000 15 min to replace @ €20/hr € 60.000 Cleaning of condensation system: 3 times/year @ 15 min € 90.000 Motor replacement: €200/motor € 60.000 2 h work @ €20/hr € 12.000 Fan coil replacement: € 1000/ unit € 150.000 Total € 672.000 Chilled beam in 300 rooms, 20-year life cycle: Cleaning of chilled beam: once in every 5 years á 15 min @ €20/hr € 6.000 Difference in maintenance and replacement costs € 666.000

Figure 3.3 Example of maintenance and replacement costs of a fan coil system and chilled beam system.

Share of different life cycle costs over 15 years

Maintenance Investment Energy

Share of different investment costs

Building automation Electricity Plumbing Cooling Equipments Beams Ventilation and air conditioning


10

4. CREATING GOOD INDOOR CLIMATE WITH CHILLED BEAMS

PRACTICAL GUIDELINES

− Comfortable indoor environment can be achieved when: Cooling capacity of active chilled beams is typically 250 W/m

(max 350 W/m) and passive chilled beams 150 W/m (max 250 W/m) to avoid draughts in the occupied zone

Highly insulated airtight windows with effective solar shading are used Window draught (radiation and downward air movement) in cold seasons

is eliminated Heating capacity of active beams is typically150 W/m to create sufficient

mixing between the supply air from the beam and the room air Operation is designed taking into account the conditions during seasons

(winter, summer, intermediate season) An efficient control system is used Chilled beams are installed and placed correctly in the space.

− Be aware of increased risk of draught if cold air from chilled beams is supplied

towards the cold window surface or directly down to the occupied zone.

− Chilled beams installed above the door can create draught problems if the internal loads near the window are strong enough to bend the air jet from the beam to the occupied zone.

− Passive and open active chilled beams installed in the suspended ceiling

always require sufficiently large openings in the ceiling for the induced room air path.

− When demonstrating the operation of chilled beams with full-scale mock-ups

or computational fluid dynamics (CFD) simulations, the input parameters should be adequately defined, especially the boundary conditions of beam when using CFD.

4.1 Types of Chilled Beam

Systems

4.1.1 Passive Chilled Beams Heat transfer from passive beams occurs mainly by natural convection with a minor part by radiation. Warm room air in con-tact with the cooled surface of the heat exchanger flows downwards through the beam into the room. Passive chilled beams are not connected to the ventilation system and can be positioned fully exposed, re-cessed within a suspended ceiling or above

a perforated ceiling. Supply air can be in-troduced either from high or low level.

Figure 4.1 Operation principle of a passive chilled beam is mainly based on natural con-vection.



11

Ventilation air supply (outdoor air) ar-rangements need to be designed carefully in order not to interfere with the operation of passive chilled beam. When the air is supplied using ceiling diffusers, the air jet should not obstruct the convective flow of passive chilled beam. In some cases where this could be exploited to prevent downdraught from a beam, the reduction in capacity of the chilled beam should be taken into account (e.g. in full scale mock-up). Passive chilled beams can also be used with under floor supply or with sidewall displacement terminals. This arrangement typically creates a good mixed flow sys-tem, where the convective down flow from passive chilled beams mixes with the low velocity air supply. Room air quality can be improved using high supply airflow rates. However, the size and number of diffusers should be selected so that the air velocities in the occupied zone are low.

4.1.2 Active Chilled Beams Active chilled beams combine the supply of ventilation air (outdoor air) and cool-ing in order to enable effective heat trans-fer due to forced convection, and ensure good air distribution also at high cooling capacity levels. Primary air is supplied into the space via a supply air plenum through nozzles along its length. The supply air jet induces room air through the heat exchanger. The mixture of outdoor air and induced room air is supplied into the room through the longitudinal slots along both sides of the beam. Depending on re-quirements, available space and beam

positioning, it is possible to supply air in one or two opposite directions. An active chilled beam can be either open or closed with an integral induced air path. In closed chilled beams induced room air flows directly through the heat exchanger so that is not circulated via the suspended ceiling.

65 l/s18.5°C

50 l/s24°C

15 l/s18°C

65 l/s18.5°C

15 l/s18°C

50 l/s24°C

Figure 4.2 Active chilled beam operation is based on induction of room air through the cooling coil. The induction rate varies between 1:3 and 1:5 depending on the design.

4.1.3 Perimeter Passive Chilled Beams Perimeter passive chilled beams are in-stalled close to glazed façades or win-dows, and are designed to offset solar gains in the perimeter zone and minimise the depth of the zone of high cooling de-mand. They minimise the disruptive ef-fect that solar gains can have on air tem-perature and air circulation away from the perimeter, which is especially important where displacement ventilation and/or chilled ceilings are used. A further advan-tage of locating chilled beams in the



12

perimeter is that any warm plume rising from the window or blind enhances the air-water temperature difference in the chilled beam and this raises its cooling performance. [7]

Lighting heat extracted in exhaust

Chilled ceiling panels

Displacement ventilation

Chilled beam

Figure 4.3 An example of a perimeter chilled beam installation. It can be used with different kind of climatic ceilings as in this illustration, with chilled ceiling panels and under floor sup-ply but also with active or passive chilled beams.

4.1.4 Integrated Service Beams Traditional chilled beam installations have chilled beams as the ventilation, cooling and heating solution, but an inte-grated service beam concept proposes an all-in-one solution for all ceiling mounted room technical services like down and/or up lights, exhaust, sprinklers, PA/VA speakers, PIR sensors, smoke detectors, power and IT cabling and connections. The integrated service beam concept is suitable for both active and passive beams for both flush and exposed mounted in-stallations. The service beam is an integration of aes-thetics and economics. Pre-assembly of all desired services at the factory in-creases installation speed and quality

while reducing costs. Single source re-sponsibility lowers risk and reduces the need for co-ordination. In addition, the space achieves architectural finish when fewer separate pieces of equipment are fixed to ceiling and walls. Often available room height is increased, as no suspended ceiling is needed.

Figure 4.4 Different room services can be inte-grated into the chilled beam at the factory.

4.2 Comfortable Indoor Climate with Chilled Beams

Indoor climate target values should be taken into account, when defining design values for chilled beam systems. Specific cooling capacity and primary airflow rate should be limited to the range where proper operation conditions and comfort-able thermal conditions can be ensured



13

e.g. by avoiding too high air velocities in the occupied zone. The higher the spe-cific cooling output, the higher the induc-tion rate (typically 1:3−1:5) and therefore the risk of draught is increased with high linear cooling capacities. To ensure comfortable conditions in spaces, it is recommended that the building is de-signed so that heat loads can be maintained below 80 (max 120) W/floor-m².

The required cooling capacity should always be calculated using dynamic simulation software taking into account the simultane-ous heat loads as well as the transient heat transfer effects of the thermal mass of the construction. Unnecessary over-sizing of the system increases the investment costs. The intentional over-sizing for future flexibility is realised by paying attention to the sizing of water flow rates and ensuring the stable room temperature control.

Table 4.1 The following values can be used as a guideline the interdependency between the maxi-mum cooling output of the chilled beam system and the supply airflow rate. Actual values need to be checked case by case using the data of selected beam type and model.

Airflow Rate ( l/s,m²)

Cooling Capacity (W/m²)

1.5 … 70 2 … 90 3 … 120

Table 4.2 Recommended indoor climate target values. These values are based on good indoor climate level of international standards and recommendations like EN ISO 7730 and CEN report 1752, noticing some limitations of chilled beam system.

Summer Winter Comfort

PMV -0.5…+0.5 -0.5…+0.5 Temperature

Operative room air temperature 24.5 ± 1.5°C 22 ± 2°C Vertical air temperature difference (0,1…1,1 m) < 3°C < 3°C Radiant temperature asymmetry of windows < 23°C < 10°C Radiant temperature asymmetry of ceiling < 14°C < 5°C Floor surface temperature 19…26°C 19…26°C

Air Quality Outdoor air requirement per floor area 1.5…3 l/s,m² 1.5…3 l/s,m² Outdoor air requirement per person 8…20 l/s,person 8…20 l/s,person

Air Velocity Draught rating (DR) < 15% < 15% Average air velocity in the occupied zone (PMV=0) 0.18 m/s 0.15 m/s Maximum air velocity in the occupied zone 0.23 m/s 0.18 m/s

Air Humidity Relative humidity 30…55% 25…40%

Acoustics Sound level requirement NR15-NR30 NR15-NR30



14

Figure 4.5 The design cooling capacity of chilled beam should be defined based on hourly solar, occupancy, light and equipment loads. The cooling demand can be calculated by taking into ac-count the thermal mass of constructions and, when desired, the night ventilation.

Satisfactory heating operation of active chilled beams is by selecting units with low specific capacity so that the warm mixed airflow mixes well with the room air. High supply air temperature and high specific heating capacity decrease the ven-tilation efficiency and increase the tem-perature difference between the floor and ceiling. Cold and extensive window sur-face increases the risk of stratification. Attention should be paid to the fabric, and size of the fenestration to keep the heat losses moderate and surface temperatures close to the room air temperature. If possible the chilled beam arrangement should be designed to allow for future layout changes within the space. This will apply to speculative office buildings, owner-occupier developments and refur-bishments. Chilled beams may be se-

lected to allow for higher primary airflow and water flow rates to compensate po-tential increases in heat loads within the space. The beam design and arrangement can allow for both future partitioning re-quirements and the modular design of the space. Since both active and passive chilled beam operation is sensitive to internal conditions, design parameters should be considered not only for summer and win-ter conditions but also for intermediate seasons, when the system is often operat-ing in cooling mode due to high internal and external heat loads, although the ex-ternal weather conditions are closer to winter conditions. This is especially im-portant when the airflow from the active chilled beam is directed towards the cold window surface.



15

Table 4.3 Recommended design values for chilled beam system. Cooling Heating

Cooling and Heating Optimum heat loads / losses 60…80 W/floor-m² 25…35 W/floor-m² Maximum heat loads / losses < 120 W/floor-m² < 50 W/floor-m² Specific capacity of passive beam above occupied zone < 150 W/m − Specific capacity of passive beam outside occupied zone < 250 W/m − Specific capacity of active beams (highest class of indoor climate) < 250 W/m < 150 W/m Specific capacity of active beams (medium class of indoor climate) < 350 W/m < 150 W/m

Supply air Specific primary air flow rate of active beam 5…15 l/s,m 5…15 l/s,m Supply air temperature 18…20°C 19…21°C Pressure drop of active beam 30…120 Pa 30…120 Pa

Room air Reference air temperature (air into the beam): active beam Room air temp. Room air temp. + 0…2°C Reference air temperature (air into the beam): passive beam Room air temp. + 0…2°C −

Inlet water Water flow rate with pipe size of 15 mm (turbulent flow) > 0.03…0.10 kg/s > 0.03…0.10 kg/s Water flow rate with pipe size of 10 mm (turbulent flow) > 0.015…0.04 kg/s > 0.015…0.04 kg/s Inlet water temperature 14…18°C 30…45°C Pressure drop 0.5…15 kPa 0.5…15 kPa

The successful operation of passive beams is dependent on the correct positioning of the beam with respect to the internal heat loads. If the loads are located right under the beam, the convective flow of the heat loads may obstruct the natural convection through the coil. On the other hand the correct positioning may slightly improve the performance of passive chilled beams. A chilled beam system (mainly passive beams) can also be partly designed as a self-regulating system without a room con-troller. The water inlet and outlet tempera-tures (typically 19/22°C) are selected close to the minimum room air temperature. This ensures that with minimum heat load level the room is not becoming too cold. Once the heat loads start to increase, the room air temperature rises. As the tem-perature difference between the ambient

room air and inlet water increases the cooling outlet of the passive beam is also increased. The system operation is reliable and the room temperature is kept within the desired range. To avoid heating and cooling at the same time this solution should be combined with free cooling by air handling unit heat recovery. 4.3 Room Construction Design

Requirements

When installing open active chilled beams or passive chilled beams into a suspended ceiling, a minimum clearance between the top of the beam and soffit should be pro-vided for a sufficient return air path. Shadow gaps, dummy beam sections and transfer grilles are recommended for return air path arrangements. The return air path



16

should be placed at the unit’s short side if possible. The net free area of return air path should be at least 0.1m² per linear active chilled beam meter and a minimum 50% of the surface area of passive beams. Secondary air recirculation into the ceiling void only through the air handling light fittings is not recommended due to the higher air pressure drop incurred.

Figure 4.6 A minimum clearance between the top of the passive chilled beam and soffit should be provided for a sufficient return air path.

The selection of windows critically af-fects the indoor climate conditions. The heat transmission coefficient of win-dow should be sufficiently low to ensure that during the winter the internal window surface is warm enough to avoid direct radiation between the window and the

occupants, as well as to prevent any down draught from the internal window surface. Whenever chilled beams are used for heating with extensive glass facades, spe-cial attention should be paid to window construction. There are several options to increase the surface temperature of win-dow and minimise the draught created by the window. As long as the window internal surface temperature is high enough (at least 14°C) the risk of draught is small. In practice this means that the average U-value of window (frame and glass areas) should be around 1.2 W/m²K. A radiant panel or passive chilled beam above the window cannot measurably increase the surface temperature of win-dow. However it lowers the radiant tem-perature asymmetry near window, and because air is warmer above the window, the air temperature underneath the win-dow is also higher and thereby reduces the draught.

Table 4.4 Air velocity underneath the window created by cold window surfaces. However in a typical office application the air velocity underneath the window is not important, but it should be studied in the occupied zone 1 meter from the window.

Troom (°C) Toutdoor (°C) U-value (W/m²K) Window height (m) Tsurface (°C) V (m/s) 21 −20 1 1.5 14.9 0.22 21 −20 1 2 14.9 0.24 21 −20 1.5 1.5 11.8 0.26 21 −20 1.5 2 11.8 0.31 21 −5 1 1.5 17.1 0.18 21 −5 1 2 17.1 0.2 21 −5 1.5 1.5 15.2 0.21 21 −5 1.5 2 15.2 0.23 21 −5 2 1.5 13.2 0.24 21 −5 2 2 13.2 0.27



17

A warm radiator underneath the window prevents down draught. It is also impor-tant to remember that there should be no obstacles close to the window (table at least 100 mm from window). Heating strips (electrical) underneath the window or heated window glass can also be used. There are also other constructional tech-niques to reduce down draught from a window. It can be divided to several sec-tions when turbulence between each win-dow sector decreases the velocity under-neath. Obstacles like cable chases have the same effect. 4.4 Positioning of chilled beams

4.4.1 Positioning of passive chilled beams Passive beams should not be installed directly above fixed working positions, because the velocity created by natural convection is highest underneath the beam. If the beam is situated above the window or above other high convective heat loads, the possible reduction of cool-ing output should be taken into account.

Figure 4.7 Passive beams should always be positioned outside of occupied zone.

The risk of draught can be minimised by positioning the passive beam above the perforated ceiling, in which case the per-forations in the ceiling should be large enough (approximately 50% free area) to

ensure proper cooling output, but on the other hand small enough to avoid down draught directly from beam. 4.4.2 Positioning of perimeter chilled

beams The performance of perimeter chilled beams has been shown to be very sensi-tive to the design and configuration of the perimeter area including suspended ceil-ings and window blinds. In practice this has often led to poor performance and conflict with architectural and aesthetic requirements. The following guidelines should mini-mise the negative impact of interaction of thermal plumes and building construction and ceiling elements. Internal roller blinds are more effective at guiding the thermal plumes from solar gains to perimeter chilled beams than slatted horizontal blinds. If the blind is not installed in a box then the gap be-tween the top of the blind and the under-side of the building frame should be as small as possible. The installation of ceiling tiles below chilled beams restricts the free flow of air into and out of the ceiling void and there-fore through the chilled beams. Ceiling tiles should therefore have at least 50% free area and hole size maximised (for example 10 mm diameter). Ideally no ceiling tiles should be fitted or louvered tiles should be used below perimeter chilled beams. Lowering the chilled beams and ceiling relative to the underside of the building perimeter frame results in more of the thermal plume being captured and



18

directed into the ceiling void. This pro-vides both increased cooling performance and improved thermal comfort. [7] 4.4.3 Positioning of active chilled beam The recommended location of active beams is above work places, because ve-locity is lowest precisely underneath the beam (if the throw pattern of the beam is horizontal). If the beam is positioned near the wall, the asymmetrical / unidirec-tional throw pattern is recommended. The lowest velocity conditions for all sea-sons can be created, when chilled beams are installed lengthwise in the space. This normally ensures the use of longer beams, which means lower cooling capacity re-quirement per linear meter. Lengthwise installation is also beneficial in intermediate seasons, when window surface is still cold but due to internal loads cooling is required in the space. In the crosswise installation the cool supply air is discharged towards the cold window surface increasing the velocity underneath the window. The beam installation above the door is sensitive to internal convection flows if the supply air is discharged towards the window. Due to the long distance from the beam to the opposite wall, the supply air jet may be interfered by uprising con-vective flows from heat loads and de-flected directly into the occupied zone. When active beams discharge downwards e.g. from above the door, the distance from the beam to the occupied zone must be long enough to avoid high velocity close to the floor in the occupied zone.

This positioning is acceptable only when it is agreed to limit the occupied zone.

Figure 4.8 Active beams should be positioned above the work place in the space to ensure the lowest air velocities in all seasonal condi-tions.

Figure 4.9 Room air velocities in the interme-diate season with the same beam installed ei-ther crosswise or lengthwise in the room. [11]



19

Figure 4.10 Possible risk of room loads influ-encing the throw pattern of the beam. In the top picture there is no internal load in the space and in the bottom picture the room is occupied and the window surface is warm. [11]

4.5 Demonstration of Indoor Climate Conditions

When chilled beams are used within the normal operation range and in normal installation positions, any special demon-strations of operation is not necessarily needed. But if the operational parameters of a chilled beam are close to or beyond the recommended limits, and if the posi-tioning of the beam is critical, it is rec-ommended to demonstrate the operation of the product in the specified design conditions. There are two options to demonstrate the operation: full-scale mock-up tests and Computational Fluid Dynamics (CFD) simulations. CFD-simulation equations

describing physical phenomena are solved numerically. Both options are ca-pable of demonstrating the velocities and temperatures in the space in steady-state conditions, as long as the input parame-ters are correct. If there is no real boundary data of chilled beam available (given by a manufac-turer), the mock-up then gives more reli-able information. It is critical to model the internal condi-tions and external solar loads as naturally as possible. A chilled beam system is sen-sitive to convective flows and for this reason the ratio of convective and radiant heat transfer should be correct when demonstrating the process in the space. The surface temperature and area of each mock-up of heat sources should be at the correct level. For the same reason the po-sitioning of all the loads should be identi-cal to an actual case. Using the even dis-tribution of loads inside the space, or transferring all the loads through the wall construction (as in a standard capacity measurement), the velocity and tempera-ture values measured in the occupied zone are unrealistic. In CFD simulations the critical issue is the boundary conditions of selected beam. This is why whenever CFD simulations are used; the product boundary conditions specified by the manufacturer should be used. The difference between simulated and actual velocity and temperature val-ues can be remarkable if using generic product model.



20

Figure 4.11 Example of full-scale mock-up, where internal loads are simulated with dummies giving the correct ratio of convective and radiant load. Window wall and floor close to window is heated to give external loads to the space. Air movements are visualized with smoke.

When ordering a full-scale mock-up or CFD demonstrations the following items should be specified: Target of the test

(what problems need to be solved) Sizes of the space

(length, width, height) Window construction

(type, width, height and heat transmission coefficient, solar shading)

External temperatures (summer / winter)

Furniture and ceiling lay-out Specification of internal loads

(also positioning)

Specification of solar gain through the window (surface temperatures of walls and floor)

Tested products, locations and manufacturer

Details of different test cases: • Room air temperature • Supply air temperature and airflow rate • Water inlet temperature and water

flow rate Velocity and temperature measurement

grid and heights e.g. 0.1 m, 0.6 m, 1.1 m, 1.4 m and 1.8 m (measurement points to find maximum velocity need to be defined e.g. by smoke during the test).


21

5. CHILLED BEAM SYSTEM DESIGN

PRACTICAL GUIDELINES − Design the chilled beam system based on real cooling requirements.

Overdesign of the system makes it more expensive and decreases comfort.

− Primary air should be dehumidified in most cases and the airflow rate must be high enough to absorb the humidity generated in the space and fulfil the hygienic needs (1.5 – 3 l/s,floor-m²) (5−15 l/s,beam-m). Very high primary airflow rates increase the risk of draughts in the occupied zone.

− Try to use only a few different type of beams (type, length, nozzle size etc.) in

order to make the tendering process, logistics on the construction site and maintenance of building easier.

− Oversizing of heating system may prevent the proper operation of chilled

beams used as a heating unit. Use as low an inlet water temperature as possible (max 45°C)

− Chilled beam systems can be used also in a hot and humid climate, as long as

infiltration is controlled, primary air volume is high enough and morning start-up is in control.

− Condensation must be prevented in chilled beam systems by:

Sufficiently high inlet water temperature (14°C or higher) Dehumidification of primary air (especially when the outdoor air

temperature is above 22°C) Insulating valves and pipes Using condensation sensors on the pipe surface Raising the chilled water temperature or switching off valves locally if there

is an increased risk of condensation

− Distribution pipework dimensions are larger due to dry cooling system operation (low temperature drop across the coil 2 – 4°C)

− Typical room air temperature control is time proportional on-off control with

2-way valves.

− Chilled beam system increases the opportunities to use free cooling and sustainable heat sources.

5.1 Cooling with Active Chilled

Beams

Having defined the design room tempera-ture (normally between 23−26°C in the summer) and established the external de-sign ambient conditions, external sensible

heat loads together with internal gains can be calculated. The thermal capacity of the construction should be taken into account in cooling load calculations by using dynamic simulation software. The difference of external heat loads through windows based on dynamic simulation in



22

different geographical locations in Europe, is smaller than those generally used in design practice. Overdesign of the system increases the installation cost, and even if the thermal comfort criteria is fulfilled, the percent-age of satisfied occupants is reduced due to increased air velocities in the occupied

zone. The use of protection against exces-sive solar gain is therefore highly recom-mended (special glass, different types of shading etc). The chilled beam system primary airflow rate is defined to satisfy comfort condi-tions, minimum ventilation requirement and internal humidity level.

Figure 5.1 The chilled beam system creates comfortable air velocity and temperature conditions in the space when the overall building and chilled beam system is designed correctly.

Figure 5.2 A study shows the cooling load using different window types and directions in three dif-ferent geographical areas in Europe. According to this study the difference in the cooling load in different areas is 10−18% depending on the case and the maximum cooling load is 110 W/m²,floor.

50

60

70

80

90

100

110

120

2xCl

ear,

No

blin

ds

,

West South East Window type and direction

Cool

ing

requ

ired

[W/m

² floor

]

HelsinkiParis Rome

2xCl

ear,

Blind

s 50%

2xCl

ear,

No

blin

ds

2xCl

ear,

Blind

s 50%

2xCl

ear,

No

blin

ds

2xCl

ear,

Blind

s 50%

Low-

emis.

, An

tis.g

reen

Low-

emis.

, An

tis.g

reen

Low-

emis.

, An

tis.g

reen



23

The required ventilation rate in a typical of-fice space is 1.5 − 3 l/s,m² (6 – 12 m3/h,m²). In order to keep humidity levels within the design parameters the primary air handling unit normally requires the facility to de-humidify the supply air. The primary air-flow rate should also be high enough to absorb the humidity generated inside the space. Chilled beam systems normally use a constant air flow and operate with a pri-mary supply air temperature reset by the season (summer: 18 − 20°C and winter: 19 − 21°C). Lower supply air tempera-tures can be used if the room system (beam or other heating element) has the capacity to also heat the cold supply air in order to avoid too cold room air tempera-ture. When the specific length (of the heat ex-changer) of the chilled beam and the pri-mary air flow rate are defined, it is impor-tant to note that each beam has a mini-mum operating airflow rate to keep the minimum pressure inside the beam cham-ber, as well as to ensure effective heat transfer of the cooling coil and to guaran-tee the operation of air diffusion. On the other hand the primary airflow rate should not be too high in order to avoid excessive induced air flow which can cause draughts in the occupied zone. The typical airflow rate of an active chilled beam is 5 l/s,m – 15 l/s,m. Chilled beams are selected with inlet and outlet water temperature differences of typically 2 − 4°C. Water flow rates and connection method (chilled beams con-nected in parallel or series) should also be considered. As the chilled beam system is designed to provide sensible cooling

only, the inlet water temperature must be selected to avoid condensation. The inlet water temperature (normally no lower than 14°C) must be selected so that the surface temperature of the cooling water inlet pipe is above the dew point tempera-ture of the room air. The cooling water inlet temperature and water flow rate are selected so that an adequate temperature difference between the mean water temperature and room temperature (Dq = 6 – 10°C) and the re-quired cooling capacity can be achieved. Cooling water mass flow rate is selected so that the flow is turbulent in the normal operating situation, typically 0.025 – 0.10 kg/s for a ø15 mm pipe. Beams can be connected in parallel or series. Parallel connection is normally used, but for short-length or low-capacity chilled beams, series connection may also be used. To suit architectural requirements the length of the beam casing can be selected longer than the actual capacity requires (e.g. as long as the room). In this case the actual heat exchanger section is sized ac-cording to the required cooling load, after deducting the cooling effect of the pri-mary air supply. However it is always beneficial to select as few different types and lengths of beam as possible in each floor or building. It simplifies both the tendering process and the logistics on the building site. In the case of large cold windows, the simultaneous operation of both the beam cooling and the under window heating system is recommended. This avoids cold draughts from the window, and compen-



24

sates the internal heat loads with cooling. This increases the operative temperature and ensures the comfort of the occupants. The energy wasted from the heating ele-ments is recovered by the heat recovery system of the air-handling unit.

5.2 Heating with Active Chilled Beams

The design of the heating system begins by defining the required heating capacity. In traditional heating systems the design is often based on high safety margins when heat losses are calculated. When a chilled beam system is used for heating, proper system operation cannot be achieved by oversizing the heating sys-tem. In a new office building 30 –45W/m²,floor of heating capacity is typi-cally enough. If the heating inlet water temperature of a chilled beam is higher than 40 – 45°C (linear output of an active beam is higher than 140 − 160 W/m) in a typical installa-tion, secondary air is often too warm to mix properly with the room air. The rela-tively low temperature gradient in the space raises the air temperature near the floor thus maintaining comfortable ther-mal conditions, as well as ensuring the energy efficiency of the system (by de-creasing the short circuit and thus the ex-haust air temperature). The mixing is also dependent on the win-dow size and surface temperature. The higher and colder the window, the colder the air falling down to the floor, and the temperature gradient between secondary air and room air becomes higher. For this reason using beams for heating is recom-mended when the heat transmission of the windows is moderate (e.g. surface tem-

perature is higher than 14°C and height is not more than 1.5 m).

Figure 5.3 Temperature gradient in the space with different inlet water temperatures.

Inlet w ater 36 O C

28°C

24°C

Inlet w ater 55°C

38°C

26°C

Figure 5.4 IR Measurements of a closed beam during heating mode with two different inlet water temperatures made by KTH in Sweden.

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 Temperature difference dT (C)

Room

hei

ght (

m)

40 deg.C 60 deg.C 74 deg.C

3



25

The heating capacity of active beams is dependent on the primary airflow rate. This is why ventilation must be operating when heating is required. The heating of static beams is based on the mixing effect of primary air supply and cold window surface, partly because the warmer upper part of the space is ra-diating to other surfaces and warming them up. The temperature gradient between the cold floor and the warm ceiling is slightly mixed by the cold window but is still relatively high in early morning. There-fore the ventilation needs to be started early enough to ensure that the warm room air near the ceiling is mixed well before space is occupied. Sometimes it is necessary to close the warm water circu-lation of the beam system to increase the mixing of room air at start up.

When an office room is occupied the in-ternal heat sources normally reduce the required heating output and the tempera-ture gradient stays at an acceptable level. 5.3 Active Chilled Beams in Hot

and Humid Climates

In a hot and humid climate, it is important to control the relative humidity concur-rently with the temperature. Decreasing the indoor air temperature and humidity could improve the perceived air quality signifi-cantly. The results have shown that the ac-ceptability of indoor climate increases line-arly with decreasing enthalpy of air. The use of a chilled beam system in a hot and humid climate has been studied using the case-study approach [14]. Field meas-urements were conducted in two rooms of an office building, located in Singapore, served by a ventilated chilled beam system.

10,0

12,0

14,0

16,0

18,0

20,0

22,0

24,0

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00

27 of March

tem

pera

ture

(o C)

Beam Water InletTemperature

Beam Water OutletTemperature

Room AirTemperature

Dew PointTemperautre

Off-Coil Temperature (AHU)

Figure 5.5 Case study measurement results of an office room during 24 hours in Singapore. With these set points, the objective was to prevent condensation in the beam unit and to achieve dry cooling. The humidity level was high because the supply airflow rate was much lower (39%) than the design specification due to undersized fan capacity. It should be noted that the humidity level was not significantly increased during the night. During the nighttime the dew point was only 1OC higher than the daytime value. [14]



26

Based on the measurements, it is possible to prevent the condensation in the beam system and achieve dry cooling. But only if the infiltration is minimized, the supply airflow rate is sufficient to extract humid-ity caused by people, and the control sys-tem has correctly designed and commis-sioned. Consequently night ventilation is not recommended and the exhaust fans must also be stopped during the night time. The most critical time to reach dry cool-ing is to maintain the required humidity level during the morning start-up period. Condensation can be prevented by start-ing dry air ventilation about 30 minutes before the water-based cooling by adjust-ing the operating hours of the fans and the chilled water pump of the beam sys-tem. The target temperature and humidity lev-els are the starting point for the system design. Typically, the target for the room temperature is 23−24°C and 60−65% for the relative humidity. 5.4 Prevention of Condensation

Cooled beam systems must be designed to ensure that there is no risk of conden-sation. This means selecting an inlet wa-ter temperature higher than the dew point temperature. The inlet water temperature must be reset accordingly, if the internal humidity levels are affected by external influences. Dehumidification of the primary supply air by the main air handling unit plant is

used to control humidity levels and avoid condensation. In order to ensure dehumidification the supply air during periods of high outdoor temperatures and high relative humidity, the cooling coil of the air handling unit should be sized adequately to meet the total cooling demand including both sen-sible and latent heat load. The supply air water content should be so low that the ventilation airflow compensates for the internal humidity loads, in practice the room air dew point temperature is lower or equal to the inlet temperature of chilled water in the chilled beam system. As moisture will most likely first appear on the valves it is good practice to insulate the valves and connecting pipe work lead-ing to the heat exchanger. The system can be further safeguarded with condensation sensors mounted on the surface of the connecting pipe work. If condensation is detected then either the inlet water tem-perature is raised, the beam cooling water circulation pumps are switched off, or con-trol valves are switched off locally. How-ever in the case of a building with openable windows individual contact sen-sors can be applied to the windows to shut off the cooling water supply to that area. Studies have shown that the inlet water temperature can be slightly lower than the dew point of the space before the conden-sation occurs on the pipe surface and even lower (-1.5°C) before the water droplets start to form. This difference is recommended as a safety margin for un-expected humidity loads.



27

Outdoor air e.g.in Scandinavia

Inlet water to beams

Room air

Supply air

Water temperature in cooling coil

Figure 5.6 Dehumidification process of primary air presented in psychometric chart.

5.5 Air and Water Distribution

Systems

A typical active chilled beam system for cooling is presented in the schematic dia-gram (Figure 5.7). The chilled water cir-cuit for the chilled beams is connected to the primary chilled water system via a buffer vessel. Chilled water is continu-ously circulated the system using a 3-way mixing valve for flow water temperature control. The water inlet temperature of

the chilled beams (14–18°C) is generally significantly higher than the supply water temperature of the air handling unit's cooling coil for dehumidification of the primary supply air (7−9°C). If chilled beams are also used for heating, the system has two separate water cir-cuits, a low temperature (35−40°C) cir-cuit for the chilled beams and high tem-perature circuit for the air handling unit’s heating coil.



28

Air handling unit

Chiller

Buffer vessel

District heating

Thermostatic valve + water radiator

Active chilled beam

Figure 5.7 An example schematic diagram of an active chilled beam system typically used in Scan-dinavia, where one chiller is providing cooling water both for the air handling unit (7°C) and the chilled beams (15°C).

5.5.1 Distribution Pipe Work Due to lower temperature difference be-tween flow water and room air (8−10°C) in a dry cooling system, the water flow rates are higher and the pipe sizes in the distribution pipe work are larger. Distri-bution pipe work is typically sized to a pressure drop of 50−100 Pa/m in order to enable balancing the pipe work using small pressure drops in the balancing valves to avoid noise generation. The maximum recommended pressure for the distribution system is 35 kPa compris-

ing 10 kPa pressure drop in the coil of the chilled beam, 10 kPa for the control valves and 10 kPa for the pipe work. By using the final pressure drop over beam coil and beam valve / balancing valve, the balancing by the balancing valves in the shaft for each floor could be excluded. Copper, steel or plastic pipes can all be used. Pipes should be insulated to save energy and avoid condensation. If the inlet water temperature is constantly kept above the dew point temperature, no va-pour barrier in the insulation is needed.



29

Due to the lower heat transmission proper-ties, plastic pipes may be used without insulation taking care that the flow water temperature is kept at a sufficiently high level. The main pipes should be installed at a higher level than the chilled beams to en-able the venting of the pipe work e.g. us-ing automatic venting valves. When using 2-way control valves for the water flow control of the chilled beams, the pressure control with constant pres-sure regulators should be used to avoid the risk of water borne noise. With vari-able speed pumps also pumping energy is conserved. Alternatively, the pressure difference can also be regulated by mounting a by-pass connection equipped with a balancing valve or pressure reduction valve at the end of each branch.

The flow water temperature is controlled according to the dew point of room or exhaust air. The operation of mixing valve group is essential for condensation prevention. Either 2-way valve with a bypass or 3- way valve is used. 5.5.2 Chiller Plant and Buffer Vessel In chilled beam systems it is possible to benefit from the high coefficient of per-formance (COP) of the chiller plant at the elevated flow water temperatures. This can reduce the chiller plant size and run-ning costs. Cooling is also needed in wintertime, and for this reason the chiller must be sup-plied with winter operation equipment. The chilled water circuit is connected to the primary chilled water circuit via a buffer vessel. This buffer vessel mini-mises the frequency of stop/start opera-tions of the chiller plant.

14 – 19°C

15 … °C

AHU

Beams

7 – 14°C

TE TC

TE ME

14 – 19°C

15 … °C

AHU

Beams

7 – 14°C

TE TC

TE ME

Figure 5.8 Mixing valve group prevents too cold water circulating in the chilled beam system.



30

Figure 5.9 The efficiency of the compressor can be increased by using a dry cooling system (inlet water 14°C instead of 7°C).

5.5.3 Ductwork and Air Handling Unit Due to constant airflow and full outdoor air system the duct dimensions are small. The ductwork is proportionally balanced, but also constant pressure controlled ductwork zones are use for two reasons: 1. variable flow applications are incor-

porated in the zones 2. effective implementation of airflow

adjustment within the zone.

However dehumidification of the supply air is needed in the cooling coil of air handling unit. When chilled beam duct branches are symmetric and the main ducts are large with low pressure losses (1 − 2 Pa/m), in-dividual balancing dampers are not neces-sarily required. This is beneficial not only in operation (e.g. noise generation and fan



31

energy) but also in both installation and commissioning. If symmetrical duct de-sign is not possible, similar benefits can be achieved by designing constant pressure ductworks.

Figure 5.10 Example of traditional and self-adjusting ductwork.

5.6 Use of Free Cooling and Sustainable Heat Sources

A higher chilled water temperature is used in active chilled beam systems com-pared to other systems (e.g. fan coil sys-tems). This provides the opportunity to use various sources of free cooling such as outdoor air or ground water heat sinks. Free cooling reduces the need for addi-tional mechanical cooling and will reduce operating costs. During the summer sea-son however, a mechanical cooling sys-tem will be required. Chilled beams can be designed and se-lected to use higher operating tempera-tures than typical fan coil systems (14−18°C Vs 6−12°C), increasing the available free-cooling period. On the other hand due to small inlet-outlet tem-perature difference pumping energy costs are higher than in fan coil systems.

There are several options for utilising the cold outdoor air. For example, the chilled water from the buffer vessel can be circu-lated through the cooling coil of the air-handling unit during free-cooling opera-tion and heat is transmitted from the chilled water to the supply air. Other al-ternatives are dry air coolers, cooling towers or ground cold energy storages. Since the chilled beam system is a low temperature (30−45°C) heating system, sustainable heat sources are easier to use than with traditional heating systems; and higher efficiency of the heating boiler is achieved. A heat pump system is particu-larly suitable for heat generation due to its high efficiency at the low temperature levels. If either free cooling or sustainable heat sources are considered, the requirements of the systems mentioned earlier, need to be taken into account when selecting the inlet and outlet water temperature differ-ences. 5.7 Room Controls

Very basic controls can be used with chilled beam systems, because of the long reaction time of chilled beam. This is due to the large coil size and low air velocity through the coil, compared to the other air-water systems like fan coils. The control principle can be on−off, time proportional on−off or modulating. The selection of the control system is depend-ent on the system design. In most cases all the above mentioned control principles provide reliable operation of the system. In cases where the difference between the



32

design and normal operating conditions is large (e.g. the design is based on a much higher heat load level than the existing load), time proportional on−off or modu-lating controls are recommended. The room air temperature is maintained by regulating the water flow rate with a 2-way valve in order to minimise pump-ing costs.

Figure 5.11 Typical room air temperature con-trol with a chilled beam system.

The valves should be made of corrosion-resistant brass, specially designed for chilled water applications. The risk of condensation should be pre-vented when using chilled ceiling sys-tems, because chilled panels and beams are not equipped with either a drain tray or condensate evacuation. There are dif-ferent methods for condensation preven-tion, refer to the chapter 5.4 Prevention of Condensation. Additionally a dew-point alarm in high-risk areas is recommended. The electronic dew-point alarm is equipped with a sen-

sor that registers if condensation forms on the flow pipe to the chilled beam. When the sensor registers condensation on the flow pipe, the electronic dew-point alarm is activated. In the alarm mode, the two potential-free relays are activated. The relay outputs can be used to shut off the valve and/or to send a signal to an alarm system or BMS system that condensation is appearing in the room or zone. 5.8 Design Methodology for

Chilled Beam System

The design of chilled beam systems is twofold: the determination of the design

conditions of the space the selection of the type and length of

the chilled beam and definition of other related design parameters.

The first is related to the specific space where beams are used. However, the op-timum operation of chilled beam system sets some limitations to the space design. For this reason the design of the space and selection of the beam is often an it-erative design process where input values are optimised to meet both the comfort conditions as well as the optimum re-quirements of the product operation. The room control system is selected after the beam selection to ensure the selected indoor climate parameters and the energy efficiency of system. After that the critical points of water and air distribution, the chilled beam system operation is checked as well as the management principles of the building management system.

Balancing + shut off valve

Room thermostat/controller

Control valve

Shut off valve



33

Selection of chilled beam type, length and design parameters

Determination of space design parametersSelection of thermal environment level• Room air temperature / summer qa = 23…26 OC• Room air temperature / winter qa = 20…22 OC

Selection of thermal environment level• Room air temperature / summer qa = 23…26 OC• Room air temperature / winter qa = 20…22 OC

Calculation of required cooling and heating capacity• Heat loads: (dynamic energy simulations and internal loads): P < 80 (max 120) W/m2

• Heat losses P < 45 W/m2,floor • Check comfort conditions (draught from windows and asymmetric radiation)• Cooling effect of primary air:

Pa = cp· ρw · qp · (qp – qa) = 1,005 kJ/(kg,K) · 1,20 kg/m3 · qp · (qp – qa)

Calculation of required cooling and heating capacity• Heat loads: (dynamic energy simulations and internal loads): P < 80 (max 120) W/m2

• Heat losses P < 45 W/m2,floor • Check comfort conditions (draught from windows and asymmetric radiation)• Cooling effect of primary air:

Pa = cp· ρw · qp · (qp – qa) = 1,005 kJ/(kg,K) · 1,20 kg/m3 · qp · (qp – qa)

Selection of the indoor air quality level and air flow rate• Fresh air flow requirement qp = 1.5…3 l/s,m2 and/or 10…15 l/s,person• Calculate infiltration through external wall based on pressure / temperature difference• Select relative humidity level in the space Rh = 30…50%• Primary air off-coil temperature

• Temperate climate qp = 14…15 OC (air moisture content 9…10 g/kg)• Hot and humid climate qp = 12…13 OC (air moisture content 8…8,5 g/kg)

• Check humidity balance based on infiltration, air moisture content and internal loads

Selection of the indoor air quality level and air flow rate• Fresh air flow requirement qp = 1.5…3 l/s,m2 and/or 10…15 l/s,person• Calculate infiltration through external wall based on pressure / temperature difference• Select relative humidity level in the space Rh = 30…50%• Primary air off-coil temperature

• Temperate climate qp = 14…15 OC (air moisture content 9…10 g/kg)• Hot and humid climate qp = 12…13 OC (air moisture content 8…8,5 g/kg)

• Check humidity balance based on infiltration, air moisture content and internal loads

Selection of chilled beam type• active beam (exposed or integrated into ceiling)• passive beam + air diffuser (ceiling / wall / floor)

Selection of chilled beam type• active beam (exposed or integrated into ceiling)• passive beam + air diffuser (ceiling / wall / floor)

Selection of inlet water temperature (avoid condensation)• Temperate climate qw1 = 14…16 OC• Hot and humid climate qw1 = 17…18 OC

Selection of inlet water temperature (avoid condensation)• Temperate climate qw1 = 14…16 OC• Hot and humid climate qw1 = 17…18 OC

Select total and active length of beam• Specific cooling capacity of active beam PL = 250 (max. 350) W/m• Specific heating capacity of active beam PL = max. 150 W/m• Specific primary airflow rate of active beam 5…15 l/s,m (dependent on model)

Select total and active length of beam• Specific cooling capacity of active beam PL = 250 (max. 350) W/m• Specific heating capacity of active beam PL = max. 150 W/m• Specific primary airflow rate of active beam 5…15 l/s,m (dependent on model)

Selection of water temperature difference and/or water flow rate• Temperature difference Δθw = qw2 - qw1 = 2 - 4 °C• Water flow rate (securing turbulent flow inside the pipe)

• qw = 0.03…0.10 kg/s (15 mm pipe)• qw = 0.02…0.08 kg/s (12 mm pipe)• qw = 0.01…0.05 kg/s (10 mm pipe)

Selection of water temperature difference and/or water flow rate• Temperature difference Δθw = qw2 - qw1 = 2 - 4 °C• Water flow rate (securing turbulent flow inside the pipe)

• qw = 0.03…0.10 kg/s (15 mm pipe)• qw = 0.02…0.08 kg/s (12 mm pipe)• qw = 0.01…0.05 kg/s (10 mm pipe)

Noise level and system pressure loss calculationNoise level and system pressure loss calculation

Adjustment of building design parameters• Decrease external loads/ losses by better solar shading and improved window type• Improve the window and external wall structure to decrease infiltration

Adjustment of building design parameters• Decrease external loads/ losses by better solar shading and improved window type• Improve the window and external wall structure to decrease infiltration

Design of room controls, water and air distribution systems and BMS

Selection of room controls• room air temperature is controlled by modulating water flow rate• two port valves with time proportional on-off or modular control• constant air flow rate with possible stand by mode when not occupied

Selection of room controls• room air temperature is controlled by modulating water flow rate• two port valves with time proportional on-off or modular control• constant air flow rate with possible stand by mode when not occupied

Air and water distribution system• dehumidification in air handling unit• three port mixing valve in cooling pipe to keep the inlet water temperature in design value• free cooling equipments in chiller / air handling unit

Air and water distribution system• dehumidification in air handling unit• three port mixing valve in cooling pipe to keep the inlet water temperature in design value• free cooling equipments in chiller / air handling unit

Building management system (BMS)• dew point compensation of inlet water temperature (summer)• outdoor temperature compensation of inlet water temperature (winter)

Building management system (BMS)• dew point compensation of inlet water temperature (summer)• outdoor temperature compensation of inlet water temperature (winter)

Figure 5.12 Design methodology of a chilled beam system.


34

6. PRODUCT SELECTION

PRACTICAL GUIDELINES − The cooling capacity of chilled beams is one of the major selection criteria.

However other criteria also need to be considered such as linear cooling capacity and airflow rate, air velocity profile etc.

− Technical data is comparable if it is measured using the same standards and presented using the same parameter values (e.g. reference air temperature and chamber pressure).

− Use closed beams in suspended ceiling installations and exposed models in all other installation to avoid problems with wrongly directed throw pattern.

− Pay attention also to accessories, ease of installation, and maintenance issues like cleanability of the coil and air plenum as well as access to the coil

There is large variety of chilled beams on the market, which makes the selection and comparison between product types and manufacturers difficult. There are some special technical details to be compared when making chilled beam selection. The cooling capacity of the chilled beam is a major selection criterion. The techni-cal data of different manufacturers are comparable if the cooling capacity meas-urements are made based on CEN stan-dards created for passive and active chilled beams. This new standard is mainly following the existing Scandina-vian Nordtest (NT VVS 078) and German DIN (4715) measurement standards. The acoustic data should be based on measurements according ISO standards (EN-ISO 3741 and EN-ISO 5135) as well as the airflow rate and pressure difference (EN-ISO 5167-1 and EN-ISO 5135). It is also important to compare the veloc-ity data in the occupied zone created by the active chilled beam. Each manufac-turer has a unit specific data for each chilled beam type, because the air veloci-ties are dependent on the construction of

the chilled beam, the dimensions and ge-ometry of the supply air slot as well as the induction ratio of the chilled beam.

V 2 (m

/s)

4 6 8 100.40

0.30

0.20

0.10

L2 (m)

0

6 l/s,m8

101214161820

2224

1.8 m2.7 m

0.1 m

0.5 m

BL

L1

V1

V2L2

V3

L3

Figure 6.1 Example of velocity data of active chilled beam. Three critical points should be studied. Normally, velocity V2 is the most critical.

If there is a need to change a specified beam model during the contracting phase, it is important to compare beams in simi-lar design conditions e.g. using the same room air temperature (adequate cool-ing/heating capacity), having the same linear cooling output and primary airflow rate (risk of draught).


6. PRODUCT SELECTION

35

Also the architectural features vary between different units. Some models can be used in exposed installation, but the capacity in the ceiling installation is reduced unless there are sufficient return air paths in the sus-pended ceiling. Respectively the beam models developed for ceiling installation may create high velocities to the occupied zone in free installation because they are unable to utilise the “coanda effect”.

Figure 6.2 There are two architecturally almost identical chilled beams. The chilled beam on the left does not perform well in exposed installation, whereas the throw pattern of the chilled beam on the right is directed correctly towards walls.

The types of materials used also vary be-tween different manufacturers and models. The most critical for chilled beam opera-tion is the type of material used and the dimensions of the finned coil. The pipe size affects the waterside pressure drop. The thickness of the fins affects the dura-bility of coil during installation and main-tenance (too thin fins bend more easily). The fin pitch has an influence on heat transfer and induction as well as the clean-ness of coil. Too small a fin pitch (≤ 3mm) collects more dust and is more difficult to clean. The typical distance between fins is approximately 5 mm in active chilled beams and 9 mm in passive chilled beams. In some models there is space inside the beam for valve and damper installation. The total length of the product is longer than the active length but the number of access doors into ceiling void can be reduced.

If chilled beams are connected to pipe work using flexible hoses, there are some special requirements. Air diffusion resis-tant hoses are recommended in order to avoid problems with oxygen in chilled water. It is also important that the pipe ends in chilled beam are circular to secure a tight connection between hose and pipe.

Figure 6.3 Examples of chilled beam models on the market.

CBC/B-100-3300-3000INPUT DATARoom air temperature Tr °C

Relative humidity of room air f %

Supply air flow rate qvs l/s

Supply air temperature Ts °C

Inlet water temperature Tw1 °C

Water flow rate qmw kg/s

Effective beam length l mm

Duct connection D mm

CALCULATED DATA 1Supply air capacity Pa W

Water capacity Pw W

Total capacity Pt W

Temperature difference dT °C

Outlet water temperature Tw2 °C

Sound pressure level (without damper) LpA dB

Total pressure drop (without damper) dptot Pa

Pressure drop of water flow dpw kPa

CALCULATED DATA 2Dew point temperature of room air Tdew °C

Supply air flow rate qvs l/s

Induced air flow rate qvi l/s

Air flow rate leaving the unit qvtot l/s

Temperature of air leaving the unit Ta °C

Supply air flow rate/radiator length qv'a l/(sm)

24.0

50

30.0

18.0

15.0

0.060

3000

100

215

769

984

7.5

18.1

28

87

4.0

12.9

10.0

30

98

128

17.6 Figure 6.4 Example of product selection of chilled beam.



36

A. TENDERING: Checklist B. CONTRACTING: Checklist 1. Capacity of chilled beam

Cooling capacity per meter Heating capacity per meter Supply airflow rate per meter Air chamber pressure Sound level Mock-up test results Test methods

CEN Nordtest / V-method DIN ISO Other tests

2. Comfort requirements

Air temperature Room air temperature Supply air temperature Temperature gradient in

space Air velocity

Maximum velocity Velocity in occupied zone Draught rating

Surface temperatures 3. Material

Casing design Material thickness Surface treatment Perforations Coil fin thickness and fin pitch Dimensions of pipe and duct

connections 4. Installations

Suspended ceiling integration Ceiling connections Hanging system Water and air connections Electric and other connections

5. Cleaning

Access to coil Removable bottom plate Access to air plenum

6. Control system

1. Checking of drawings Number of beams Installed cooling/heating capacity Airflow rates Locations of beams Total / active length Return air paths in the ceiling Obstacles in front of the chilled beam Pipe and duct connections Connections to lights, sprinkler,

speakers etc. 2. Installations

Slab system Suspended ceiling type Plenum height Distance to walls

C. COMMISSIONING: checklist 1. Visual inspection

Colour and gloss Perforation for return air Any protection / packaging left Nozzle configuration Access to coil / valves / damper Supply air slots direction? Surface finish

marks correct level

2. Inspection of plenum

Free airflow at open beams Return air openings Thermal insulations of valves and

pipes Pipe and duct connections Flexible hose connections Air vents

3. Function

Cooling / Heating capacity Airflow rate Air velocity in occupied zone Inlet water temperature Water flow rate Thermal comfort (ISO 7730) Sound level


37

7. INSTALLATION AND COMMISSIONING

PRACTICAL GUIDELINES

− When installing chilled beams ensure that the main pipes are at a higher level than the beams and there are no air pockets in the pipe work.

− Fit the pipe coupling with extra care to avoid bending the pipes and breaking

the heat exchanger’s welded joints. Beam pipes are small and relatively thin. − Ensure that there is access to the water valves and dampers after installation.

Remove the protective plastic covers from beam surfaces just before commissioning.

− If the balancing damper is too close upstream to the chilled beam, the airflow

inside the beam may be disturbed and the air supply is adversely affected. − Open all control and shut-off valves before filling the water pipes. Continuous

venting is necessary during filling. − Close the shut-off valves in each beam before flushing the main pipes to avoid

blocking the control valves. − Chamber pressure measurement is the most accurate method of measuring

the primary airflow rate of active chilled beam.

7.1 Installation

Chilled beams can be installed fully ex-posed, recessed within a suspended ceil-ing or positioned above a perforated or an open grid ceiling. For beams installed within or above a ceiling, suitable access must be provided for service and mainte-nance. With an open type of chilled beam a free area is required in the suspended ceiling for re-circulation of room air. As a guide, the minimum free area should be 30% of the beam front panel surface area. When a suspended ceiling is installed around an open or a closed beam, it should be in the same level or slightly higher than a beam

bottom to avoid collision of the supply air with the ceiling. Any other obstacles near the beam should be low enough or far enough away to make sure they are not disturbing the air jet. The main pipes are installed first. Pipes should be installed so, that they do not leave any “air pockets”, and a venting valve should always be installed at the highest point of the vertical main pipes in the shaft. All extra joints are a leakage risk. The direction of the supply air and water circuit connection directions must be se-lected according to the beam orientation. The beam can be fixed directly onto the



38

ceiling surface or hung with threaded drop rods. The recommended positioning for the mounting bracket is about L/4 measured from the end of the beam. The weight of the beam (10–20 kg/m) must be taken into account when beam installation and logistics in building site are planned. Beams can be connected to the main pipes either by using crimp, screw or sol-der connection, or with flexible hoses. The use air diffusion resistant hoses is recommended to prevent air from diffus-ing into the water pipe. When beams are connected to the pipe, extra attention should be paid to attaching the pipe cou-pling when using a spanner. The pipe wall is relatively thin and the whole pipe might bend and break the heat exchanger joints. Coupling rings should be used dur-ing the installation. The airflow balancing dampers are often installed just before the active beam. It is important to have a sufficient safety dis-tance between the damper and the beam, in order to avoid any disturbance of the beam operation. If the iris damper is situ-ated too close to the straight connected beam, there is a risk that the first nozzles will suck air into the plenum instead of blowing it out, thus creating a noise prob-lem. Chilled beams are often supplied with factory installed protective covers to both the heat exchanger and the inlet to the supply air plenum. Protective end caps should also be fitted to the heat exchanger pipes. These must be removed during the installation. Plastic film protecting sheet metal surfaces should be removed just before commissioning.

7.2 Flushing

To minimize the dirt and facilitate flush-ing, it is important to close open ends of pipes during the installation work. Before starting the flushing it is important to close the shut-off valves of individual beams and flush the main pipes first. 7.3 Filling-up and venting the

system

To ensure easy venting, care should be taken that the main pipes are installed at a higher level than the beams. The horizon-tal pipes should be installed, rising slightly towards the venting points and there should be no high points to create “air pockets” to the system. Before filling up, all shut-off and control valves must be in the fully open position. The pumps should not be running during the filling-up (static filling). Continuous venting is necessary and it is recom-mended to have both manual and auto-matic venting systems installed. The pump should only be started when filling is complete. To remove all air from the system, the major part (>75%) of the sys-tem should be closed so that the water can circulate fast enough. When each section is full, it should be closed, and the same procedure repeated for the rest of the sys-tem. 7.4 Commissioning

The required air and water flow rates are adjusted during commissioning. The air-flow rates are typically adjusted with a blade or an iris damper.


7. INSTALLATION AND COMMISSIONING

39

The iris damper should be positioned far enough away from the beam to ensure the even flow inside the duct before a beam. This safety distance (>3D) is needed to avoid any performance failure. Measuring the airflow rate by using a chamber pressure measurement in the beam is recommended. This gives the most accurate measurement result due to the higher pressure level (50−150Pa). In other methods e.g. pitot-tube measure-ment the pressure level is much lower. The commissioning of the chilled and hot water circulation systems is carried out by balancing the water flow rates using

balancing valves and ensuring that all the shut-off valves are open. The chilled beam water flow rate is controlled by a control valve; which is typically an on-off or modulating valve. Balancing valves can be replaced with control valves with adjustable kv-value. Check the function with an IR-sensor di-rected towards the chilled beam supply air slot after maximum cooling capacity is set on the room controller. Temporarily lowering the chilled water set point to approximately 10°C during commission-ing will highlight any malfunction of sys-tem (too low water flow rate, shut off valves closed, etc.).

Figure 7.1 Connection of chilled water pipes after installing the beam in the ceiling.



40

Figure 7.2 Installation of an active chilled beam using flexible hoses in the water pipes and flexible duct in air side.


41

8. RUNNING OF CHILLED BEAM SYSTEM 8.1 Maintenance and

Replacement

The chilled beam system operation is sim-ple and trouble-free, with limited mainte-nance requirements. Although the mainte-nance of the beam system is minimal it is important to have easy access to the inside of the beam without disturbing the sus-pended ceiling. Access doors should allow access to the heat exchanger, supply air plenum and primary air ductwork for cleaning, service and maintenance. The heat exchanger should be vacuum cleaned once every 1−5 years depending on the use of space. The more dust gener-ated during use, the more often the need for cleaning. However, if for some reason either the beam surface or the finned coil becomes wet, it must be cleaned immediately. Dirt

adheres more easily to the wet surface of fins. When the coil is dry again the fin surface is often coated with dirt. When the coil is dry, the dust particles coming from the secondary air are so small that they pass through the finned coil. The air velocity through the coil is approximately 0.1 – 0.2 m/s. There are no moving parts apart from the control valve, so there are only minor re-placements needed during the life cycle. Beam systems do not include filters or condensation collection drains and pipes which require cleaning. 8.2 Essential Issues in Beam

Operation

It is important to train the operating per-sonnel to manage the beam system cor-rectly, especially when they have previ-ously been running wet systems.

Figure 8.1 Cleaning of chilled beam.



42

The following items are essential in beam operation: The chilled beam system is a dry-

cooling system and therefore the inlet water temperature must always be above the dew point temperature.

When condensation occurs, the water circulation in that area must be stopped, even before looking for the cause of the condensation.

If the room air has become too humid, the ventilation should be switched on, and after the building has been dehumidified, the water circulation can be restarted.

It is important that the dehumidification by the air-handling unit has been realised correctly and that the control operates properly.

The operation of the 3-way mixing valve should be checked regularly.

The solutions for typical complaints of end users are: Draught Firstly, check that the room air

temperature is not too low. Secondly, check that the airflow rate is

not too high or too low. Too high an airflow rate may create draught near the floor. Whereas, if the airflow rate is too low or too cold, the air jet may fall intentionally downwards, which may create draught at the neck level.

High room air temperature Check that water flow rate is not too low Check that the water flow temperature

is not too high If the heat loads in the space are

significantly higher than the capacity of the chilled beam the water flow rate could be increased. If this does not solve the problem, longer or additional units should be installed.

Figure 8.2 When the chilled beam system is well designed, installed and commissioned, and the maintenance of the system is continuous, the chilled beam system provides an excellent and pro-ductive working environment.


43

9. CASE STUDIES 9.1 A Case of Office Building in United Kingdom

Project Office Building in London Room Lay-out and Measurement Grid: Space, where chilled beams are used

Office room

Window internal surface temperature

30°C

Sensible internal heat loads

50 W/ m²,floor

External heat loads 30 W/ m²,floor Heat losses 25 W/ m²,floor Supply air properties 2.5l/s,floor-m², supply air

temperature in summer 16°C and winter 18°C

Room design parameters

Room air temperature in summer 24°C and winter 21°C

Flexibility Flexibility of 2.65 m, beams installed lengthwise in every module

Viewing window

Simulation window

INTERMEDIATE "B" BEAM PERIMETER BEAMBULKHEAD "A" BEAM

PERIMETER BEAMINTERMEDIATE "B" BEAMBULKHEAD "A" BEAM

Chilled beam selection

Exposed, open active service chilled beam, total length 5100 mm, effective length 4200 mm, cooling output 370W/m, heating output 120W/m, primary air volume 11l/s,m, cooling water flow rate 0.04kg/s and inlet water temperature of 14°C, heating water flow rate 0.01kg/s and inlet water temperature of 35°C

Measurement result: cooling

Height (m)

v (m/s)

T a (°C)

Turb. (%)

DR v (m/s)

Ta Turb. (%)

DR v (m/s)

Ta Turb. (%)

DR v (m/s)

Ta Turb. (%)

DR v (m/s)

T a Turb. (%)

DR

1.80 0.11 22.6 40 9 0.11 22.9 46 10 0.10 22.9 45 8 0.11 23.1 58 10 0.07 23.2 46 4 1.50 0.12 22.4 35 10 0.10 22.8 45 8 0.11 22.8 40 9 0.12 23.0 49 11 0.09 23.1 39 7 1.10 0.10 22.3 31 8 0.10 22.6 43 8 0.09 22.8 45 7 0.14 22.8 45 14 0.11 23.1 39 9 0.60 0.07 22.3 46 4 0.09 22.5 46 7 0.08 22.8 50 6 0.13 22.9 36 11 0.11 23.1 51 10 0.20 0.09 22.2 42 7 0.11 22.4 46 10 0.06 22.8 45 3 0.10 23.0 44 8 0.10 23.1 49 8 0.10 0.15 22.1 31 14 0.16 22.2 33 15 0.09 22.7 40 7 0.11 23.0 40 9 0.13 23.1 43 12

4 2 6810

(%) (°C) (°C) (°C) (°C) (%) (%) (%) (%)

Measurement result: heating

Height (m)

v T a Turb. DR v Ta Turb. DR v Ta Turb. DR v Ta Turb. DR v T a Turb. DR

1.80 0.04 21.7 52 - 0.08 21.7 33 6 0.08 21.7 42 6 0.08 21.4 35 6 0.07 21.2 44 5 1.50 0.03 21.5 50 - 0.07 21.5 52 5 0.08 21.5 44 6 0.09 21.4 41 8 0.08 21.2 39 6 1.10 0.03 21.2 46 - 0.04 21.2 79 - 0.03 21.2 43 - 0.10 21.3 34 9 0.08 21.2 34 6 0.60 0.02 20.6 32 - 0.02 20.6 27 - 0.02 20.6 33 - 0.06 20.8 53 3 0.07 20.9 59 5 0.20 0.02 20.4 30 - 0.02 20.3 20 - 0.03 20.2 36 - 0.06 20.2 40 3 0.11 20.5 37 11 0.10 0.02 20.3 28 - 0.02 20.1 28 - 0.03 19.9 35 - 0.05 19.6 32 - 0.09 19.9 34 8

4 2 6810

(m/s) (°C) (%) (m/s) (%) (m/s) (%) (m/s) (%) (m/s) (%) (%) (°C) (°C) (°C) (°C) (%) (%) (%) (%)



44

9.2 A case of Office Building in France

Project Office Building in Paris Room Lay-out and Measurement Grid: Space, where chilled beams are used

Office room


30°C


45 W/m²,floor

External heat loads 40 W/ m²,floor Heat losses 50 W/ m²,floor Supply air properties 2 l/s,floor-m², supply air



Room air temperature in summer 24°C and winter 21°C

Flexibility Flexibility of 1.5 m, beams installed lengthwise in every second module

1 2 3 4 5


600 mm wide, closed active chilled beam, total length 3000 mm, effective length 2700 mm, cooling output 400 W/m, heating output 270 W/m, primary air volume 9 l/s,m, cooling water flow rate 0.10 kg/s and inlet water temperature of 14°C, heating water flow rate 0.013 kg/s and inlet water temperature of 40°C

Measurement result: cooling with standard air diffusion.

Height (m) v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR 1.80 0.05 23.7 47 - 0.05 23.8 45 - 0.08 23.8 73 6 0.06 23.6 56 3 0.51 21.5 10 39 1.40 0.05 23.6 46 - 0.06 23.6 51 3 0.07 23.5 48 4 0.08 23.5 45 5 0.49 21.5 11 39 1.10 0.05 23.5 53 - 0.06 23.4 60 3 0.08 23.4 47 5 0.09 23.8 43 6 0.41 21.6 16 37 0.60 0.07 23.4 53 4 0.10 23.4 44 8 0.11 23.4 39 9 0.06 23.3 46 3 0.28 22.3 38 33 0.20 0.13 23.4 25 10 0.10 23.5 46 8 0.07 23.5 39 4 0.17 22.8 29 15 0.16 22.6 35 15 0.10 0.16 23.3 23 12 0.13 23.6 43 11 0.10 23.4 33 7 0.13 22.8 38 12 0.16 22.6 36 15

21 43 5


Measurement result: cooling with reduced induction in the right hand side of a beam (cooling capacity is reduced 11%)

Height (m) v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR 1.80 - 0.09 23.6 42 6 0.07 23.7 59 4 0.11 23.8 44 9 0.11 23.6 57 10 1.40 - 0.06 23.6 48 3 0.06 23.6 48 3 0.08 23.6 49 5 0.10 23.5 47 8 1.10 - 0.06 23.5 52 3 0.08 23.4 44 5 0.08 23.4 58 6 0.11 23.4 41 9 0.60 - 0.07 23.5 45 4 0.08 23.4 38 5 0.13 23.3 39 11 0.13 2.5 28 30 0.20 - 0.06 23.5 47 3 0.08 23.5 42 5 0.15 23.3 23 11 0.08 23.7 35 5 0.10 - 0.12 23.5 35 9 0.09 23.5 47 7 0.16 23.3 30 13 0.10 23.6 32 7

5 1 432


Measurement result: heating

Height (m) v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR v T a Turb. DR 1.80 0.40 22.3 11 29 0.10 22.0 37 8 0.09 21.4 54 8 0.09 21.8 31 7 0.13 22.3 31 11 1.40 0.23 21.4 46 31 0.12 21.7 30 11 0.04 20.7 53 - 0.05 20.9 33 - 0.07 22.0 45 5 1.10 0.10 20.1 56 11 0.05 19.8 46 - 0.03 19.7 39 - 0.03 20.0 59 - 0.03 19.8 36 - 0.60 0.03 18.8 22 - 0.03 18.8 34 - 0.02 18.7 46 - 0.02 18.9 23 - 0.02 18.5 24 - 0.20 0.05 18.4 24 - 0.05 18.0 27 - 0.03 18.0 36 - 0.02 18.3 31 - 0.02 18.0 35 - 0.10 0.04 18.2 29 - 0.06 17.6 20 3 0.04 17.6 28 - 0.03 17.9 33 - 0.02 17.5 26 -

1 2 3 4 5



9. CASE STUDIES

45

9.3 A case of Office Building in Sweden

Project Office Building in Stockholm Room Lay-out and Measurement Grid: Space, where chilled beams are used

Office room / meeting room with extra supply air diffuser


31.5°C


25 W/m²,floor

External heat loads 40 W/m²,floor Supply air properties 1.5 / 3.8 l/s,floor-m², supply air temperature in

summer 16°C Room design parameters

Room air temperature in summer 23°C

Flexibility Flexibility of 1.1 m, beams installed lengthwise in every second module

Chilled beam selection 600 mm wide, closed active chilled beam, total length 3000 mm, effective length 2700 mm, cooling output 240 W/m, primary air volume 6 l/s,m, cooling water flow rate 0.09 kg/s and inlet water temperature of 15°C, additional perforated diffuser in meeting room application

11 12 13 14

8 9 10

Measurement result: office space

Height (m) v

(m/s) T a (°C)

Turb. (%)

DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s) T a Turb.

(%) DR %

1.80 0.04 23.2 57 - 0.04 23.1 55 - 0.02 23.2 52 - 0.09 23.3 39 6 1.50 0.06 23.1 43 3 0.07 23.0 53 4 0.05 23.1 38 - 0.08 23.2 39 5 1.10 0.07 23.1 24 4 0.10 22.9 41 8 0.06 23.0 36 2 0.08 23.2 39 5 0.80 0.08 23.1 35 5 0.10 22.9 34 8 0.09 23.0 29 6 0.08 23.2 35 5 0.50 0.06 23.1 35 2 0.10 22.9 38 8 0.07 23.0 37 4 0.06 23.2 26 2 0.10 0.06 23.1 43 3 0.08 23.3 37 5 0.05 23.5 35 - 0.08 23.5 49 5

Height (m) v

(m/s) T a Turb.

(%)DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s)

T a Turb. (%) DR

% 1.80 0.06 23.0 38 3 0.09 23.1 33 6 0.07 23.3 33 4 1.50 0.05 22.9 38 - 0.08 23.1 49 6 0.08 23.1 30 5 1.10 0.05 22.9 44 - 0.12 23.1 39 10 0.08 23.1 32 5 0.80 0.05 22.8 35 - 0.12 23.0 36 10 0.06 23.1 33 2 0.50 0.05 22.8 52 - 0.15 22.6 28 13 0.05 23.0 47 - 0.10 0.10 22.9 29 7 0.11 22.8 37 9 0.14 22.8 27 11

11 12 13 14

98 10

(°C) (°C) (°C)

(°C) (°C) (°C)

Measurement result: meeting room

Height (m) v

(m/s) T a (°C)

Turb. (%)

DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s) T a Turb.

(%) DR %

1.80 0.09 23.2 56 7 0.06 23.2 59 3 0.08 23.4 52 6 0.07 23.3 53 4 1.50 0.09 23.0 46 7 0.10 23.1 41 8 0.10 23.2 51 8 0.06 23.3 64 3 1.10 0.09 23.0 43 7 0.12 23.1 34 10 0.08 23.1 42 5 0.06 23.2 47 3 0.80 0.09 23.0 37 7 0.14 23.2 34 12 0.10 23.0 23 7 0.06 23.2 44 3 0.50 0.06 23.1 42 3 0.12 23.3 33 9 0.10 23.1 28 7 0.04 23.2 51 - 0.10 0.07 23.4 38 4 0.08 23.8 37 5 0.10 23.9 42 7 0.17 23.4 27 14

Height (m) v

(m/s) T a Turb. (%)

DR %

v (m/s)

T a Turb. (%)

DR %

v (m/s) T a Turb.

(%) DR %

1.80 0.05 23.1 52 - 0.09 23.2 31 6 0.08 23.3 35 5 1.50 0.05 23.0 48 - 0.08 23.1 45 6 0.06 23.2 37 2 1.10 0.06 22.9 58 3 0.08 23.2 51 6 0.06 23.3 43 3 0.80 0.07 22.7 57 5 0.09 23.0 46 7 0.05 23.3 42 - 0.50 0.08 22.8 57 6 0.10 22.7 41 8 0.05 23.1 54 - 0.10 0.14 23.5 28 11 0.10 23.0 29 7 0.13 22.9 34 11

98 10

11 12 13 14 (°C) (°C) (°C)

(°C) (°C) (°C)



46

9.4 A Case of Office Building in Belgium with High Performance Values

Project Office Building in Belgium Room Lay-out and Measurement Grid: Space, where chilled beams are used

Office room


38°C


35 W/m²,floor

External heat loads 65 W/m²,floor Heat losses 80 W/ m²,floor Supply air properties 3 l/s,floor-m², supply air



Room air temperature in summer 25°C and winter 21°C, relative humidity in summer under 50%,

Flexibility Flexibility of 1.5m, beams installed crosswise in every module

6 5 4 3 2 1


300mm wide, open active chilled beam, total length 1400mm, effective length 1200mm, cooling output 500 W/m, heating output 380W/m, primary air volume 15l/s,m, cooling water flow rate 0.10kg/s and inlet water temperature of 15°C, heating water flow rate 0.038kg/s and inlet water temperature of 55°C

Measurement result: cooling Height (m) v

(m/s) T a Turb.

(%) DR % v

(m/s)Ta Turb.

(%)DR %

v (m/s)

Ta Turb. (%) DR

%v

(m/s)Ta Turb.

(%)DR %

v (m/s)

Ta Turb. (%)

DR %

v (m/s)

T a Turb. (%) DR

% 2.00 0.34 24.2 25 29 0.10 24.7 34 6 0.13 24.8 24 8 0.13 25.0 31 9 0.18 25.0 42 15 0.08 25.7 45 4 1.70 0.25 24.3 36 23 0.09 24.6 29 5 0.13 24.7 35 9 0.12 24.9 33 8 0.16 25.1 35 12 0.09 25.6 54 6 1.40 0.20 24.4 37 17 0.06 24.5 52 2 0.08 24.6 52 5 0.11 24.9 31 7 0.15 25.2 42 12 0.09 25.6 52 6 1.10 0.15 24.4 45 13 0.07 24.5 67 4 0.07 24.5 57 4 0.10 24.8 45 7 0.12 25.1 48 9 0.09 25.4 66 6 0.60 0.08 24.5 59 5 0.14 24.4 41 11 0.11 24.5 49 9 0.08 24.9 41 5 0.13 25.1 43 10 0.09 25.2 58 6 0.10 0.22 24.3 20 15 0.25 24.3 21 18 0.11 24.6 54 9 0.04 25.3 59 - 0.08 25.1 35 4 0.11 25.1 54 8

6 531 42

(°C)(°C) (°C) (°C)(°C) (°C)

Measurement result: heating Height (m)

v (m /s)

T a Turb. (% ) DR

%v

(m /s)T a Turb.

(%)DR %

v (m/s)

T a Turb. (% )

DR %

v (m /s)

T a Turb. (%)

DR %

v (m/s)

T a Turb. (% ) DR

% 2.00 0.15 22.8 28 13 0.07 22.6 45 4 0.07 22.6 48 4 0.03 22.7 44 - 0.06 22.3 48 3 1.70 0.09 22.5 42 7 0.05 22.4 58 - 0.03 22.2 42 - 0.03 22.2 41 - 0.05 22.0 47 - 1.40 0.12 22.4 44 11 0.04 22.2 34 - 0.02 21.9 36 - 0.02 21.8 30 - 0.03 21.8 34 - 1.10 0.12 21.9 37 11 0.04 21.6 32 - 0.02 21.5 39 - 0.02 21.5 25 - 0.04 21.4 30 - 0.60 0.04 21.1 18 - 0.03 20.9 23 - 0.03 21.0 19 - 0.03 21.1 25 - 0.02 21.0 19 - 0.10 0.03 20.6 19 - 0.02 20.5 29 - 0.02 20.5 16 - 0.02 20.2 24 - 0.03 20.1 35 -

431 2 5

(°C) (°C) (°C) (°C) (°C)


9. CASE STUDIES

47

9.5 A Case of Office Building in Finland with Passive Chilled Beams

Project Office Building in Helsinki Room Lay-out and Measurement Grid: Space, where chilled beams are used

Office room


26.5°C


35 W/m²,floor

External heat loads 15 W/m²,floor Supply air properties 2 l/s,floor-m², supply air temperature in

summer 18°C Room design parameters

Room air temperature in summer 26°C

Flexibility Flexibility of 2.8 m, beams installed crosswise above door

Chilled beam selection 300 mm wide, passive chilled beam, total length 2400 mm, effective length 2200 mm, cooling output 190 W/m, cooling water flow rate 0.03 kg/s and inlet water temperature of 15°C

Measurement result: cooling

Height (m )

v (m /s )

T a Tu rb . (% )

D R %

v (m /s )

T a Turb . (% )

D R %

1 .80 0 .05 26 .0 63 0 0 .10 26 .1 19 5 1 .50 0 .06 26 .1 51 2 0 .02 26 .4 31 - 1 .10 0 .09 25 .9 37 5 0 .12 26 .1 19 6 0 .80 0 .12 25 .8 25 6 0 .12 26 .2 24 6 0 .50 0 .09 25 .7 33 5 0 .08 25 .6 42 4

Height (m )

v (m /s )

T a

(°C )Turb .

(% )D R %

v (m /s )

T a Tu rb . (% )

D R %

v (m /s )

T a Turb . (% )

D R %

1 .80 0 .07 26 .2 49 3 0 .14 26 .1 26 8 0 .11 26 .0 28 6 1 .50 0 .10 26 .2 45 6 0 .10 26 .3 22 5 0 .08 26 .3 45 4 1 .10 0 .15 25 .9 23 8 0 .09 26 .1 19 4 0 .05 26 .0 51 - 0 .80 0 .15 25 .7 25 9 0 .07 26 .2 28 3 0 .08 26 .1 41 4 0 .50 0 .24 25 .4 19 15 0 .14 25 .5 24 8 0 .12 25 .7 21 7

Heigh (m )

v (m /s )

T a Tu rb . (% )

D R %

v (m /s )

T a Tu rb . (% )

D R %

v (m /s )

T a Turb . (% )

D R %

1 .80 0 .07 26 .1 50 3 0 .06 26 .3 36 2 0 .13 26 .0 31 7 1 .50 0 .09 26 .1 37 5 0 .05 26 .4 33 - 0 .07 26 .3 60 3 1 .10 0 .09 25 .8 42 5 0 .05 26 .1 44 - 0 .08 26 .0 36 4 0 .80 0 .11 25 .6 36 7 0 .05 26 .2 42 - 0 .11 26 .0 40 6 0 .50 0 .26 25 .1 21 18 0 .12 25 .3 26 7 0 .17 25 .5 16 10

Heigh t (m )

v (m /s )

T a

( o C )Turb .

(% )D R %

v (m /s )

T a

( o C )Turb .

(% )D R %

v (m /s )

T a ( o C )

Turb . (% )

D R %

1 .80 0 .07 26 .0 40 2 0 .05 25 .9 36 - 0 .17 25 .9 23 10 1 .50 0 .04 26 .2 46 - 0 .03 26 .1 62 - 0 .12 26 .0 32 7 1 .10 0 .06 25 .8 39 2 0 .07 25 .8 53 3 0 .08 25 .8 47 5 0 .80 0 .08 25 .6 34 4 0 .11 25 .9 69 8 0 .06 26 .0 50 2 0 .50 0 .23 24 .8 21 16 0 .27 25 .0 16 16 0 .19 25 .5 14 11

11

3 6 10

4 7

2 5

1 8

9

(°C )

(°C ) (°C )

(°C )

(°C ) (°C ) (°C )


48

10. REFERENCES [1] ISSO (2001), Climatic Ceilings and Chilled Beams; Applications of Low Temperature

heating and High Temperature Cooling, Thermic Project no. DIS/1522/97/FR, New solutions in Energy Utilisation, European Commission

[2] ISSO (2001), Climatic Ceilings; Technical Note: Design Calculations, New solutions in

Energy Utilisation, European Commission [3] CEN Report 1752; Ventilation for Buildings – Design criteria for the indoor environment [4] Directive of the European Parliament and of the Council on the

energy performance of the buildings [5] Halton Oy, Cooled Beam System, Design Guide, 2000 [6] Laine T, Kosonen R, Horttanainen, P, Laitinen A. LCC comparison of

air-conditioning systems. Indoor Air 99. Edinbugh, Scotland 8-13.8. 1999. The 8th International Conference on Indoor Air Quality and Climate. pp. 602-603

[7] Butler D, Swainson M. Perimeter Chilled Beams BRE Information Paper IP 11/04

September 2004. BRE, Watford, UL. [8] Stifab Farex system guide [10] Skanska Internal Case Studies [11] Halton Oy laboratory measurement reports [12] EN 14518 Ventilation for buildings - Chilled beams

- Testing and rating of passive chilled beams [13] prEN 15116 Ventilation in buildings - Chilled beams

- Testing and rating of active chilled beams [14] Kosonen R, Tan F. A Feasibility Study of a Ventilated Beam System in the

Hot and Humid Climate: A Case-Study Approach. 2003 (not published). [15] ASHRAE. Pocket Guide for Air Conditioning, Heating, ventilation and

Refrigeration (SI units) American Society of Heating, Refrigerating and Air-Conditioning Engineers, INC, Atlanta, GA, USA 1997.

[16] Fanger PO. Thermal comfort, McGraw-Hill Book Company 1972. [17] Kosonen, R., Horttanainen, P, Dunlop, G. Integration of heating mode into

ventilated cooled beam. Proceedings of Roomvent 2000.



49



50


REHVA Guidebooks:No 1 Displacement Ventilation in Non-industrial PremisesNo 2 Ventilation EffectivenessNo 3 Electrostatic Precipitators for Industrial ApplicationsNo 4 Ventilation and SmokingNo 5 Chilled Beam CoolingNo 6 Indoor Climate and Productivity in OfficesNo 7 Low Temperature Heating And High Temperature CoolingNo 8 Cleanliness of Ventilation SystemsNo 9 Hygiene Requirement for Ventilation and Air-conditioningNo 10 Computational Fluid Dynamics in Ventilation DesignNo 11 Air Filtration in HVAC SystemsNo 12 Solar Shading – How to integrate solar shading in sustainable buildingsNo 13 Indoor Environment and Energy Efficiency in Schools – Part 1 PrinciplesNo 14 Indoor Climate Quality AssessmentNo 15 Energy Efficient Heating and Ventilation of Large Halls

REHVA Reports:No 1 REHVA Workshops at Clima 2005 - LausanneNo 2 REHVA Workshops at Clima 2007 - HelsinkiNo 3 REHVA Workshops at Clima 2010 - Antalya

rehvaFederation of European Heating, Ventilation and Air-conditioning Associations

REHVA OfficeWashington Street 40, 1050 Brussels – BelgiumTel: +32-2-5141171 Fax: +32-2-5129062Orders: www.rehva.eu [email protected]


Chilled Beam Application Guidebook - Biblioteka | KTU · 2020. 10. 19. · CHILLED BEAM SYSTEM...

Documents

Transcript of Chilled Beam Application Guidebook - Biblioteka | KTU · 2020. 10. 19. · CHILLED BEAM SYSTEM...