Energy Performance Studies for HVAC System in Museum

i

ABSTRACT

Hong Kong has seen a sharp rise in energy consumption in the years lately, along with the

economic and population growth, and the expansion of the building stock associated with the

said, specifically the use of electricity in residential and commercial buildings. It is clearly

evident that the electricity consumption in residential and commercial buildings increased

rapidly in the last decade, particularly in the commercial building sector. On account of the

significance of the background, the objectives of this research study are (i) Discussing the

effectiveness / efficiency of the HVAC System that is currently used in the Museum, (ii)

Evaluating the significance of the energy performances with respect to HVAC System at the

Museum, and (iii) Suggesting energy saving design / method with respect to this HVAC System

in the Museum that is feasible. By way of using a combination of research methods inolving

qualitative explloratory study, observational study, and qualitative analysis the research

objectives are effectively addressed and the outcomes of the study are presented in this report

including the design / methods proposed for energy efficient HVAC system.

ii

ACKNOWLEDGMENTS

f

iii

TABLE OF CONTENTS

ABSTRACT ii

ACKNOWLEDGEMENTS iii

NOMENCLATURE v

LIST OF FIGURES vi

LIST OF TABLES vii

1. INTRODUCTION 1

1.1. RESEARCH BACKGROUND 1

1.2. RESEARCH OBJECTIVES 3

2. LITERATURE REVIEW 3

3. RESEARCH METHODOLOGY 14

4. RESULTS & DISCUSSIONS 15

5. CONCLUSIONS / RECOMMENDATIONS FOR FUTURE STUDIES 22

5.1. CONCLUSION 22

5.2. RECOMMENDATIONS FOR FUTURE STUDIES 23

REFERENCES 24

APPENDIX I – PROPOSED DESIGN 26

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NOMENCLATURE

BSRIA Building Services Research and Information Association

CC Chilled Ceiling

CSD Constant Speed Drives

DCS District Cooling System

DDC Direct Digital Control

DV Displacement Ventilation

FCU Fan Coil Unit

M & V Measurement and Verification

VAV Variable Air Volume

VRF Variable Refrigerant Flow

VRV Variable Refrigerant Volume

VSD Variable Speed Drives

v

LIST OF FIGURES

1. Figure 1 – Consumption of Electricity across Hong Kong 2

2. Figure 2 – Commercial Building Energy Consumption Breakup

for Hong Kong 2

vi

LIST OF TABLES

1. Table 1 – Energy Savings Scheme 18

vii

1. INTRODUCTION

1.1. RESEARCH BACKGROUND

Hong Kong SAR is also known as the international service center and financial trading

in the world. Its economy has ascended swiftly, especially in the last two decades. Hong

Kong has seen a sharp rise in energy consumption in the years lately, along with the

economic and population growth, and the expansion of the building stock associated

with the said, specifically the use of electricity in residential and commercial buildings

(Wu et al 2014; Li et al 2013; Chua et al 2013). It is clearly evident that the electricity

consumption in residential and commercial buildings increased rapidly in the last

decade, particularly in the commercial building sector (Wu et al 2014; Li et al 2013;

Chua et al 2013). Electricity consumption spiked from 54789 terajoules in 1994 to

86670 tera joule in 2004, in the commercial sector – a sharp increase of 58.2 per cent

(Wu et al 2014; Li et al 2013; Chua et al 2013). This goes hand in hand with an average

rate of growth of 5.8 per cent per year (Wu et al 2014; Li et al 2013; Chua et al 2013).

Interesting to note would be that electricity consumption in commercial buildings

counted for 61.4 per cent of the aggregate electricity usage in the city of Hong Kong

(Wu et al 2014; Li et al 2013; Chua et al 2013).

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Figure 1 – Consumption of Electricity across Hong Kong (Wu et al 2014; Li et al

2013; Chua et al 2013)

Figure 2 – Commercial Building Energy Consumption Breakup for Hong Kong

(Wu et al 2014; Li et al 2013; Chua et al 2013)

The advancing demand for electricity in the coming years will be critical both

environmentally and economically. As a reaction to the increasing concerns about the

usage of energy and its effects on the environment, there are measures that need to be

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taken immediately (Wu et al 2014; Li et al 2013; Chua et al 2013). Since more than half

of the electricity supply in Hong Kong is used up by the commercial sector, and as we

know HVAC is the largest client of such buildings (amounting to 40 per cent – 60 per

cent of the total electrical demand in commercial buildings) especially the share that is

used for HVAC helps in boosting the efficiency of power meant for consumption is an

important step to take in Hong Kong for sustainable growth and protection of the

environment (Wu et al 2014; Li et al 2013; Chua et al 2013).

1.2. RESEARCH OBJECTIVES

On account of the significance of the background presented and in endeavouring to

determine effective designs for energy efficient operation of HVAC systems, the

objective of thus research study can be stated as follows,

i. Discussing the effectiveness / efficiency of the HVAC System that is currently

used in the Museum.

ii. Evaluating the significance of the energy performances with respect to HVAC

System at the Museum.

iii. Suggesting energy saving design / method with respect to this HVAC System in

the Museum that is feasible.

2. LITERATURE REVIEW

The procedure of energy efficiency in buildings should be integrated into the design process

during the erection of the building itself, followed by considering high thermal performance

construction materials and adding energy-saving design features (Chan & Chow 2013; Janis

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& Tao 2013; Chua et al 2013). The construction and design features are generally hard to

modify or replace in buildings that already exist (Chan & Chow 2013; Janis & Tao 2013;

Chua et al 2013). Nevertheless, one can simply renovate external shading of windows and

multiple glazing as it is a better and cheaper practice to stop heat from penetrating a building

through windows rather than fitting a new cooling system (Chan & Chow 2013; Janis & Tao

2013; Chua et al 2013).

Each HVAC system has a general rule, the more you pay the more you get. The potential to

be effective depending on the level of control attributes integrated into the system (Chan &

Chow 2013; Janis & Tao 2013; Chua et al 2013).

All-air systems: A key advantage of the ‘all-air’ cooling systems is their cost-effectiveness -

they can induct fresh outdoor air when the indoor temperature is too low and requires cooling

off (Chan & Chow 2013; Janis & Tao 2013; Chua et al 2013). This ‘economy cooling’

procedure minimizes the use of the refrigeration appliances, saving cost and energy up to 15

per cent in most cases (Chan & Chow 2013; Janis & Tao 2013; Chua et al 2013). Some

central plants have been installed without this simple feature and in most cases, a fitting

renovation can be done (Chan & Chow 2013; Janis & Tao 2013; Chua et al 2013).

Letting the supply of air temperature rise as the requirement for cooling reduces is another

inexpensive property of an all-air system. Other systems may not have this advantage of

control (Chan & Chow 2013; Janis & Tao 2013; Chua et al 2013).

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The air quantities during the heating mode are small in the electric terminal reheaters of the

VAV systems, as with the expensive CAV systems (Chan & Chow 2013; Janis & Tao 2013;

Chua et al 2013). Boilers producing heat through hot water or steam or could be considered,

if heating requirements are large. VAV systems need a little higher quality of engineering

design than VRV systems (Chan & Chow 2013; Janis & Tao 2013; Chua et al 2013).

All water systems: These systems require chilled distributed water as the chief method of

removing heat from a building. As with the air system, the chilled water temperature can be

set to increase as per the building cooling requirement (Yu et al 2016; Yeung et al 2015;

Afram & Janabi Sharifi 2014).

All-water systems can generally convert from chilled water in the distribution tubes to hot

water whenever they required heating (Yu et al 2016; Yeung et al 2015; Afram & Janabi

Sharifi 2014). Nevertheless, often the cold air in the room terminals is also heated again

electrically, specifically during upcoming winters VRF or VRV (Refrigerant-based energy

distribution) (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014): In this case, an

irregular quantity of refrigerant is pushed from external units into air distribution units inside

the interiors. These systems do not have the capacity for modifying the fluid temperature or

ambient air cooling, but some particular options do have a mechanism that transmits hot air

ejected from one part of a building to another part that requires heating. But this feature has

no value if the entire building requires cooling or heating simultaneously (Yu et al 2016;

Yeung et al 2015; Afram & Janabi Sharifi 2014).

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Another advantage of the VRF/VRV is that a lot of the systems have compressors with

changeable speed drives (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

Meaning if the requirement for cooling or heating reduces, the compressor power can be

decreased as well (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

It is advantageous to identify VRV/VRF systems to be of the heat pump kind in order to

supply heating during winters (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi

2014). Such systems are able to function alternatively, removing heat from the outdoors and

transmitting it into indoor spaces (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi

2014). This is many times higher cost effective than direct electric heat.

All HVAC systems are fitted with external parts (cooling towers or condensers) which have

fans that eliminate the heat extracted from the indoor spaces (Yu et al 2016; Yeung et al

2015; Afram & Janabi Sharifi 2014). The systems would gain from maintaining the head

pressure (or ‘refrigerant temperature’) as low as possible. This is simply achieved by pushing

a lot of volume of air as reasonable through either the cooling tower or the condenser (Yu et

al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

Steadily growing data suggests that a lot of energy savings emerge from suitable behavior

and management, more than a technical fix (Yu et al 2016; Yeung et al 2015; Afram &

Janabi Sharifi 2014). Easy building management behavior, such as switching power off when

not required, can reduce the load on the HVAC system quite substantially (Yu et al 2016;

Yeung et al 2015; Afram & Janabi Sharifi 2014).

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A neglected feature in all air conditioning systems is the maintenance of systems as the

awareness of the result of good maintenance on performance has grown only recently (Yu et

al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014). Clean heat exchanger surfaces and

clean filters and have a remarkable influence not only on energy saving but also on

performance (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

In addition to introducing a culture and habit of energy efficiency amongst the building users

and residents, other early responsibilities for an energy manager could be to assess the

existing system, undertaking efficiency interventions stated in the Building Energy

Manager’s Checklist and clearly understanding and defining the performance of the system.

(Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014) It has been proved that it is

very advantageous to establish guidelines against which to observe the performance of

HVAC (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

Certain maintenance and management tasks may fall outside the duty of many energy

managers (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014). It is strongly

suggested that independent energy counselors are hired to compute the specific opportunities

and tackle the assessment (Yu et al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

Please note that the counselors should be selected from the ones that can exhibit a systems

approach, more than someone with experience and skill focused on a particular aspect (Yu et

al 2016; Yeung et al 2015; Afram & Janabi Sharifi 2014).

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The term HVAC is commonly used in association with commercial buildings (Tse et al 2016;

Wong & Lau 2013; Huang et al 2015). HVAC systems contain filtration and whenever

required by the climate - dehumidification and humidification and as well as cooling and

heating the space (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). Nevertheless,

energy-efficient homes in weather with periodic heating are nearly airtight, so in combination

with the cooling and/or heating system, automatic ventilation has to be fitted during seasons

when windows will be shut (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

In the simplest of HVAC systems, cooling or heating is arranged by circling around a fixed

amount of air at a reasonably cold or warm temperature to preserve the chosen room

temperature (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). The rate at which air is

circulated is generally much higher than required for ventilation to eliminate contaminants.

In the cooling season, the air is supplied at the coldest climate required and heated again as

needed just before entering other zones (Tse et al 2016; Wong & Lau 2013; Huang et al

2015). There other changes in the design of HVAC systems that can garner huge savings in

the energy consumption for cooling, ventilation, and heating (Tse et al 2016; Wong & Lau

2013; Huang et al 2015). They are (i) making use of heat exchangers to restore coldness or

heat from ventilated exhaust air (Tse et al 2016; Wong & Lau 2013; Huang et al 2015); (ii)

segregating the ventilation from the cooling and heating functions by using hot or chilled

water for climate control and circulating only the amount of air required for ventilation (Tse

et al 2016; Wong & Lau 2013; Huang et al 2015); (iii) splitting dehumidification from

cooling activities through the usage of dry dehumidification (Tse et al 2016; Wong & Lau

2013; Huang et al 2015); (iv) making use of variable-air-volume systems to diminish

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simultaneous cooling and heating of air; (v) reducing pump and fan energy usage by

regulating rotation speed (Tse et al 2016; Wong & Lau 2013; Huang et al 2015); (vi)

applying a requirement-controlled ventilation system in which ventilation current changes

with different building occupancy and that alone can save 20 per cent to 30 per cent of gross

HVAC energy use (Tse et al 2016; Wong & Lau 2013; Huang et al 2015); (vii) allowing the

temperature maintained by the HVAC system to vary seasonally with outdoor conditions

(Tse et al 2016; Wong & Lau 2013; Huang et al 2015), and (viii) justly allocating all

components; (substantial evidence shows that the humidity and temperature set-points

generally found in air-conditioned buildings are substantially lower than needed, while

computer simulations by various examinations signify that raising the thermostat by 2 degree

Celsius to 4 degree Celsius will decrease yearly cooling energy consumption by more than

one-third for a typical office building in Zurich, and by about half if the thermostat setting is

raised from 23 degree Celsius to 27 degree Celsius air conditioning during nights in the

bedrooms in apartments in Hong Kong (Tse et al 2016; Wong & Lau 2013; Huang et al

2015).

More savings can be garnered in ‘mixed-mode’ type of buildings, where natural ventilation is

used whenever possible, utilizing a large range of comfort identified with windows that can

be opened, and automated cooling is used only when required during cycles of high building

occupancy or very warm weather (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

The following details illustrate two substitutes to regular HVAC systems in commercial

buildings that can together decrease the HVAC system energy usage by 30 per cent to 75 per

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cent. These savings are on top of savings resulting from decreasing cooling and heating loads

(Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

Radiant chilled-ceiling cooling

A room may be chilled by chilling a large portion of the ceiling by circling water through

lightweight panels or tubes. Since at least the mid-1970s, chilled ceiling (“CC”) cooling has

been in use in Europe (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). 10 per cent of

retrofitted buildings used CC cooling in Germany of the 1990s, Substantial energy savings

emerge because of the better impact of water than air in transmitting heat and because the

cold water is provided at 16 degree Celsius to 20 degree Celsius rather than at 5 degree

Celsius to 7 degree Celsius (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). This

process lets a higher chiller COP when the chiller functions, but also lets higher usage of

‘water-side free cooling,’ in which the chiller is sidestepped completely and water from the

cooling tower is used precisely for space cooling (Tse et al 2016; Wong & Lau 2013; Huang

et al 2015). For example, only a cooling tower could directly meet the cooling conditions 97

per cent of the time in Ireland and Dublin and in Milan (Italy) if the chilled water is supplied

at 18 degree Celsius only 67 per cent of the time (Tse et al 2016; Wong & Lau 2013; Huang

et al 2015).

Displacement ventilation

Typical ventilation depends on crude mixing to blend ventilation air with room air (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). A better system is called ‘displacement

ventilation’ (“DV”) in which air is entered at little speed via many circulators within the floor

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or alongside of a room and is heated by sources (plug-in equipment, lights, occupants) of

indoor heat as it increases to the ceiling of the room, replacing the air already inside (Tse et

al 2016; Wong & Lau 2013; Huang et al 2015). The thermodynamic benefit of shift

ventilation is that the air temperature supply is substantially larger for similar comfort

conditions (about 18oC vs. with about 13oC in a typical mixing ventilation system). It also

allows substantially lower airflow (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

DV was initially used in northern Europe; by 1989 it had occupied 25 per cent for new office

buildings and 50 per cent of the Scandinavian market for new industrial buildings (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). The building industry of North America has

been much gradual to adapt to DV; towards to the end of the 90s lesser than 5 per cent of

newly constructed buildings used under-floor air channeling systems (Tse et al 2016; Wong

& Lau 2013; Huang et al 2015). Basically, DV can decrease energy usage for ventilation and

cool depending on the climate, by about 30 per cent to 60 per cent (Tse et al 2016; Wong &

Lau 2013; Huang et al 2015),

Central chiller plant

One of the most energy intensive items of equipment in a building is the chiller. A powerful

central chiller fitting can substantially add to the total energy saving of the building (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). Commercial chillers can either be water cooled

or air cooled. In air cooled chillers, short-circuiting hot released air towards the shabby

function of the chillers, which will considerably impact the energy production of an air

conditioning system (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). Air cooled

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chillers must be located on an open roof whenever possible, to avoid short-circuiting (Tse et

al 2016; Wong & Lau 2013; Huang et al 2015).

Most of the retail outlets in Hong Kong are situated on the dais of an extensive development.

Due to constraints in planning, air cooled chillers may not be planted on an open roof (Tse et

al 2016; Wong & Lau 2013; Huang et al 2015). Hence, indoor air cool chillers may be

unavoidable (Tse et al 2016; Wong & Lau 2013; Huang et al 2015). In such case, exhaust

louvers and air absorption must be appropriately organized to avert air short-circuiting. The

suggested remedies are the following:

Equip intake louvers facing southeast to reduce short-circuiting due to the current

direction of the wind in summer (Tse et al 2016; Wong & Lau 2013; Huang et al

2015).

Equip louvers with dissimilar building orientations (Tse et al 2016; Wong & Lau

2013; Huang et al 2015).

Appropriate separation between exhaust and intake (Tse et al 2016; Wong & Lau

2013; Huang et al 2015).

Air conditioning system cooled by water (“WACS”) uses 35 per cent less energy as opposed

to an air-cooled chiller system (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

Despite the installation expense of water cooled system being a little more than an air cooled

system, the accrual period is expected to be say, 2 to 3 years (Tse et al 2016; Wong & Lau

2013; Huang et al 2015). WACS should be installed in shopping malls to enhance the

comprehensive energy production of the air conditioning system (Tse et al 2016; Wong &

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Lau 2013; Huang et al 2015). The position of the chiller plant should also be examined to

reduce and structurally borne and the airborne noise inconvenience to residents and the

neighborhood (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

Chilled water circulating system

Water pumps are used to circulate chilled water to air-conditioning equipment (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). Variable speed pumps must be used which are

proficient in varying the flow of cold water in reaction to the switch in building cooling load.

Energy utilized by both the chiller and the pump can be saved (Tse et al 2016; Wong & Lau

2013; Huang et al 2015).

The on/off control valve for the fan coil unit (“FCU”) must be the “Normally Closed” kind to

allow the saving of pump energy when the FCU is not in use, for retail tenants (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). As the tenants’ functional hours may be

dissimilar based on the nature of their work, it is favorable to fit single motorized on/off

valves in each shop to allow the A/C supply to be closed off on its own (Tse et al 2016;

Wong & Lau 2013; Huang et al 2015). The valve should be controlled by the building

management system (BMS) to suit the different needs of different tenants (Tse et al 2016;

Wong & Lau 2013; Huang et al 2015).

In addition to motorized control valves for the anchor shops to facilitate energy management,

energy meters should be fitted as well (Tse et al 2016; Wong & Lau 2013; Huang et al 2015).

To offer incentives for residents/tenants to save on power and energy, it is also suggested to

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expense the A/C cost by confirmed demand rather than based on the rentable area (Tse et al

2016; Wong & Lau 2013; Huang et al 2015). Piping accessories, such as strainers, isolation

valves, etc., must be reduced to decrease the energy loss (Tse et al 2016; Wong & Lau 2013;

Huang et al 2015).

3. RESEARCH METHODOLOGY

The overall approach for the study in terms of strategy / tools / methodologies used for the

purposes of data collection and data analysis are as follows,

Data Collection: Secondary Data

o Qualitative exploratory research was undertaken to collate various conceptual,

technical and industry specific aspects relating to HVAC systems, scope for

energy efficiency enhancements, Hong Kong specific case reviews, etc. by

way of review of literature sourced from various resources like text books,

publications, reports, academic journals / studies, etc. (Matthews & Ross

2014; Yanow & Schwartz Shea 2015; Vaishnavi & Kuechler 2015).

o Observational research study at the proposed museum site collect the various

details concerning the prevailing HVAC System and affiliated effectiveness /

efficiency parameters at the Museum as well as energy performance details /

potential scope for the HVAC System at the Museum (Matthews & Ross

2014; Yanow & Schwartz Shea 2015; Vaishnavi & Kuechler 2015).

Data Analysis

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o A critical qualitative analysis of the various secondary data as detailed above

was undertaken to identify and develop key / relevant design considerations

for the proposed HVAC system at the Museum that is energy efficient

(Matthews & Ross 2014; Yanow & Schwartz Shea 2015; Vaishnavi &

Kuechler 2015).

o Based on the identified design considerations, a visual design proposal for the

HVAC system design at the Museum shall be undertaken and proposed

(Matthews & Ross 2014; Yanow & Schwartz Shea 2015; Vaishnavi &

Kuechler 2015).

4. RESULTS & DISCUSSIONS

Museum Site Review – Effectiveness / Efficiency of Prevailing HVAC Systems & Scope

for Energy Performance Enhancements

On the basis of the detailed review of the museum site by way of observational study it was

determined that the District cooling system (“DCS”) will be required for delivering the

chilled water needed at the M+ (site name) development, RDE as well as Parcel 34 / 36 - 38.

This DCS shall in addition offer AC based hot water for the M+ development. Closed loop

form of chilled water system of piping using reverse returns will be required for distributing

the chilled water towards the various substations at the M+ developments, RDE as well as

Parcel 34 / 36 - 38. This closed loop form of hot water based piping system will be required

for distributing the AC based hot water towards the various sub-stations of the M+

development.

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Three different set of the variable speed drives (“VSD”) based seawater form of cooled

chillers which are rated at value equivalent to 1100 TR (three duty) as well as one of the

constant speed drives (“CSD”) seawater form of cooled heat based recovery chiller that is

rated at value equivalent to 500 TR cooling and 1800 kilo Watt heating (one duty) by using

the centrifugal form of compressor being provided over the B2 / F DCS based Chiller Plant.

Overall capacities that will be installed shall equal to 3,800 TR. Further spaces will be

needed to be reserved with respect to (i) one of the VSD seawater based cooled chiller which

is rated at value equivalent to 1100 TR, (ii) one of the primary chilled form of water pump,

and (iii) one of the secondary form of chilled water based pump that shall be effectively

supplied / installed through others over to B2 / F DCS based Chiller Plant.

The distribution of the chilled water from that of DCS plant will work based on the principle

of primary secondary flows. Each of the chillers will be set up with the primary form of

chilled water based pump. This chilled water based pumps will be operated by way of time

leading the affiliated chillers as well as the cut out while the affiliated chiller is essentially

switched off. The chilled water pertaining to DCS loops will be distributed through

secondary fork of chilled water based pump towards the various sub-stations across the M+

developments, RDE as well as Parcel 34 / 36 - 38. Then distribution of AC based hot water

from that of the DCS plant will operate based on single loop using the principle of variable

flows. Two of the air-cooled based chillers each of which rated with 250 TR as well as four

units of the air source based heat pumps which are rated at value equal to 450 kilo Watt

located over the CSF 8 / F will be set up for the essential form of cooling backups for the

galleries as well as storage areas of CSF in the instances of the suspension of DCS. The

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domains backed up with the necessary cooling systems will relate to the relevant drawings.

There shall be a requirement for providing the sequencing pertaining to chillers for obtaining

the optimal performances. In addition, the overall controls pertaining to chiller plants will

essentially pave way for the interchanges concerning the operations amongst the DCS as well

as essential chiller. The acoustic treatments will be required, wherein necessary for meeting

the requirements of statutory operations for the purposes of reducing the noise nuisances in

lowering the floor suites as well as the closest sensitive receivers for noise. The overall

system of cooling demands will be computed by way of the PLC controller that is standalone

making use of the input data pertaining to flow rates of chilled water, supply / return of the

temperature concerning chilled water. This chilled water based plant will operate in

alignment with the controls of the DCICCS. Overall temperature will rise and tests will be

required across the facility with respect to Motor Control Centre.

Design Considerations for the HVAC Systems at the Museum

Air side system

An FCU system allows single small areas to function on their own to suit the cooling demand

and operation schedule (Hoyt et al 2015; Gang et al 2016; Gang et al 2015). Single FCU

control is suggested to facilitate better environmental control of zones without cooling too

much. In the meantime, FCUs should be turned off or set to function at a greater temperature

during the vacancy (Hoyt et al 2015; Gang et al 2016; Gang et al 2015). For large spaces

such as public areas and arcades in shopping malls, the central all-air system by using AHU

is suggested (Hoyt et al 2015; Gang et al 2016; Gang et al 2015). To reduce power usage by

the fans, the air distribution ductwork should be appropriately sized to prevent high air

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struggle. In the meantime, many energy saving attributes such as heat wheels, multi-speed

motors, free cooling, and desiccant dehumidifiers, should be examined whenever viable

(Hoyt et al 2015; Gang et al 2016; Gang et al 2015). A comparison of different energy saving

projects for an AHU is listed for your reference (Hoyt et al 2015; Gang et al 2016; Gang et al

2015).

Table 1 – Energy Savings Scheme (Hoyt et al 2015; Gang et al 2016; Gang et al 2015)

Energy efficient controls

An exact and precise automatic control system is relevant to saving energy. Common control

problems like system hunting and over-cooling will significantly impact the function of air

conditioning systems and lead towards energy waste (Hoyt et al 2015; Gang et al 2016; Gang

et al 2015).

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One usual problem in Hong Kong shopping malls is the over-cooling of space. This is

because of the loss of accuracy of sensing elements over time and also wrong settings on

thermostats (Hoyt et al 2015; Gang et al 2016; Gang et al 2015). Keeping in mind the issue,

the design of automatic control systems must incorporate the important maintenance

allocation to qualifying calibration of control systems every year (Hoyt et al 2015; Gang et al

2016; Gang et al 2015). Provisions, like tap points, thermometers, test holes, and pressure

gauges must be provided to facilitate confirmation of control settings (Hoyt et al 2015; Gang

et al 2016; Gang et al 2015).

These days, the technology of Direct Digital Control (“DDC”) system permits adjustment of

settings remotely via the central workstations (Hoyt et al 2015; Gang et al 2016; Gang et al

2015). To reduce the chances of wrong settings, it is suggested that shopping malls should

adapt to full DDC as the mechanical control system for air conditioning systems in planning

for future (Hoyt et al 2015; Gang et al 2016; Gang et al 2015). Through the DDC, yearly

maintenance will become much more feasible. Appropriate commissioning and testing

should be carried out on a regularly (Hoyt et al 2015; Gang et al 2016; Gang et al 2015).

Metering for the audit of energy

Adequate measurement and verification (“M&V”) machinery is important for carrying out

energy audits for retail areas in the future (Hoyt et al 2015; Gang et al 2016; Gang et al

2015). The chief aim of an energy audit is to recognize the pattern of demand so that an

energy management scheme can be executed (Hoyt et al 2015; Gang et al 2016; Gang et al

2015).

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With the broader implementation of DDC, the M&V machinery could also connect to the

DDC system so that trend logging of data becomes feasible (Hoyt et al 2015; Gang et al

2016; Gang et al 2015). Instances of the M&V machinery for air conditioning

implementation include (Hoyt et al 2015; Gang et al 2016; Gang et al 2015):

i. kWh meter

ii. Electromagnetic flow meter

iii. Temperature sensor

iv. Humidity sensor

v. Pressure sensor

Crucial air conditioning machinery, A/C pumps, air handling units and like chillers, must be

supplied with individual M&V machinery for energy management (Hoyt et al 2015; Gang et

al 2016; Gang et al 2015). If the budget is restricted, group metering could be reckoned as a

substitute. M&V machinery for chiller plant is especially crucial. Based on the Building

Services (Hoyt et al 2015; Gang et al 2016; Gang et al 2015) Research and Information

Association (“BSRIA”) Technical Notes, the monitoring apparatus must document the output

and input energy usage of each chiller so that the reduction rate can be deduced, and to warn

the facility management staff when to carry out maintenance (Hoyt et al 2015; Gang et al

2016; Gang et al 2015).

Other design considerations

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To avoid big equipment, suitable indoor and outdoor air conditioning criteria should be

embraced in the selection of machinery and system design (Hoyt et al 2015; Gang et al 2016;

Gang et al 2015). For outdoor design criteria, these are ready made available in the

international design guides like the ASHRAE handbook, the BEC, and the Hong Kong

Observatory (Hoyt et al 2015; Gang et al 2016; Gang et al 2015).

The aim is to continue human comfort under the activities level, for indoor criteria in

shopping malls. There are guidelines and international standards available, like the AHSRAE

Standard 55 and designers can consult these suggestions to find out appropriate indoor

criteria without over-cooling (Hoyt et al 2015; Gang et al 2016; Gang et al 2015).

To reduce the fan energy against loss of friction, duct routes, and air conditioning tubes

should be rearranged based on the minuscule horizontal distance, and must be self-balancing

to evade excessive pumping energy. Standard fitting should be used whenever possible (Hoyt

et al 2015; Gang et al 2016; Gang et al 2015). The central air conditioning machinery should

be found close to the load center to reduce the length of the distribution tube/duct, along with

energy usage (Hoyt et al 2015; Gang et al 2016; Gang et al 2015).

In the general comprehensive planning of shops with same businesses and trading hours and

shopping malls should be classified together and if possible to enable energy management

(Hoyt et al 2015; Gang et al 2016; Gang et al 2015). For instance, the cold water provision

for a whole zone could be closed off post business hours to save cooling and pumping energy

(Hoyt et al 2015; Gang et al 2016; Gang et al 2015). Moreover, the zone AHU serving the

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public space linked to the cluster of shops can be re-organized to decrease the fan speed or to

increase the temperature setting to save cooling energy and fan power (Hoyt et al 2015; Gang

et al 2016; Gang et al 2015).

Design / Methodology Proposal

Please refer Appendix 1 for the energy efficient HVAC system design for the museum.

5. CONCLUSIONS / RECOMMENDATIONS FOR FUTURE STUDIES

5.1. CONCLUSION

On the basis of this undertaken study, the overall data analysis, results of the study and

assessment of the results indicate clear addressing of the research objectives of this study

and the same is summarized as follows,

i. Discussing the effectiveness / efficiency of the HVAC System that is currently

used in the Museum.

On the basis of the comprehensive observational study at the museum site, an

elaborate and critical identification / assessment of the effectiveness / efficiency

of the HVAC System that is currently used in the Museum was presented in the

earlier section. The same presented scope for various enhancements in terms of

design / methods to improve the levels of effectiveness / efficiency of the HVAC

System at the Museum

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ii. Evaluating the significance of the energy performances with respect to HVAC

System at the Museum.

On the basis of the comprehensive qualitative exploratory study and the

observational study at the museum site, an elaborate and critical identification /

assessment of the significance of the energy performances with respect to HVAC

System at the Museum was presented in the earlier section. The same presented

scope for various enhancements in terms of design / methods to improve the

levels of energy performances of the HVAC System at the Museum

iii. Suggesting energy saving design / method with respect to this HVAC System in

the Museum that is feasible.

On the basis of the detailed analysis undertaken in terms of the site review,

energy performance needs, assessment of design consideration various design /

methodology are proposed for the museum and presented in Appendix 1.

5.2. RECOMMENDATIONS FOR FUTURE STUDIES

At the outset, this study was effective in developing an effective design / methodology

for the HVAC system that is effective and energy efficient and adequately meets the

research objectives identified as part of the study. However, even if the study is

successful given the overall project scope and identified objectives, the outcome of the

study can be foundation for future studies to design and develop similar energy

efficiency performance improvements for various other commercial building types.

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APPENDIX I – PROPOSED DESIGN

Design Plan I

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Design Plan II

Design Plan III

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Design Plan IV

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Design Plan V

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