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Building energymanagement systems
SPECIALIST SERVICES, FUELS AND MECHANICAL
DEFENCE ESTATESMINISTRY OF DEFENCELONDON: The Stationery Office
January 2001
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Crown Copyright 2001
Published with the permission of the Ministry of Defenceon behalf of the Controller of Her Majesty's Stationery Office
Applications for reproduction should be made to
The Copyright Unit,Her Majesty's Stationery Office,St. Clements House,2-16 Colegate,Norwich NR3 1BQ
ISBN 0 11 772934 5
First Published 2001
Printed in the United Kingdom for the Stationary Office
TJ 3543 C1 O 05/01
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Foreword
This Guide has been produced by Defence Estates (DE), Central Business Unit,
Specialist Services, under the patronage of the Defence Utilities Working Group.
The purpose of this Guide is to provide assistance to Project Sponsors, Property
Managers, specifiers, designers, energy managers and operators in the
procurement, use and maintenance of Building Energy Management Systems(BEMS). Due to the wide potential readership, a chart has been prepared
overleaf showing topics likely to be of specific interest to particular readership
groups.
Whilst this Guide was commissioned by the DE for use on Ministry of Defence
(MOD) contracts, it is acknowledged that it could be usefully applied to other
contracts. DE commends the use of this document by other Government
Departments. It may also be used by non-government organisations. However, no
warranty is given as to the accuracy of the content of this Guide, or its fitness for
any purpose.
When this Guide is used in connection with a Defence contract then it shall be
read in conjunction with further documents setting out particular contractualrequirements.
This Guide has been compiled for the use of the Crown, its technical advisors
and contractors in execution of contracts for the Crown. The Crown hereby
excludes all liability (other than liability for death or personal injury)
whatsoever and howsoever arising (including, but without limitation, negligence
on the part of the Crown, its servants or agents) for any loss or damage however
caused where the Guide is used for any other purpose.
January 2001 iii
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The following table provides guidance to the reader on which sections of the
Guide are most likely to be of particular relevance to each type of reader:
Executive Summary
1 Introduction
2 Feasibility, design,procurement
3 Installation, commissioningperformance testing
4 BEMS operation
5 BEMS maintenance
6 Energy monitoring
and targeting
Analysis of requirements
Tender summary
Energy consumption
benchmarks
Glossary of Terms
Bibliography
Very significant
General interest
Background information
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Acknowledgements
This Guide has been compiled by consulting engineers Ove Arup & Partners.
The authors would like to record their gratitude to the staff at the following
seven sites within the MOD Estate for their time and co-operation in
researching the study:
R N Ensleigh, Bath
RNAS Yeovilton
RAF Brampton
RAC Centre Bovington, Wareham
RSS Blandford
RAF Coningsby
Defence Procurement Executive, Abbey Wood, Bristol
Gratitude is also extended to the Building Services Research and Information
Association (BSRIA) whose published guidance has been used in the production
of this document.
CONTACT FOR QUERIES
Specialist Services
Defence Estates
Blakemore Drive
Sutton Coldfield
West Midlands B75 7RLTel No: 0121 311 2294
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Abbreviations
Building Energy Management System
Building Management System
Building Services Research and Information Association
Chartered Institution of Building Services Engineers
Central Processing Unit
Direct Digital Control
Defence Estates (Formerly Defence Estates Organisation)
Defence Estates Organisation
Establishment Works Consultant
Heating, Ventilation and Air Conditioning
Heating and Ventilating Contractors Association
Information Technology
Monitoring and Targeting
Original Equipment Manufacturer
Personal Computer
Private Finance Initiative
Planned Preventive Maintenance
Public Private Partnership
Structured Cabling System
Variable Air Volume
January 2001 vii
BEMS
BMS
BSRIA
CIBSE
CPU
DDC
DE
DEO
EWC
HVAC
HVCA
IT
M&T
OEM
PC
PFI
PPM
PPP
scs
VAV
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Contents
Section 1
1.1
1.2
1.3
1.4
1.5
1.6
Section 2
2.1
2.2
2.3
2.4
2.5
2.6
2.6.1
2.6.2
2.6.3
2.7
2.8
2.9
2.10
2.11
Section 3
3.1
3.2
3.3
FOREWORD
ACKNOWLEDGEMENTS
ABBREVIATIONS
CONTENTS
EXECUTIVE SUMMARY
INTRODUCTION
AIMS AND OBJECTIVES
TERMINOLOGY
WHAT IS A BEMS?
HISTORY
ADVANTAGES AND DISADVANTAGES
OPTIONS AND FUTURE DEVELOPMENTS
FEASIBILITY, DESIGN AND PROCUREMENT
GENERALFINANCIAL APPRAISAL
INDICATIVE COSTS
JUSTIFICATION
FEASIBILITY
DESIGN AND SPECIFICATION
Design
Specification
Types of Specification
PROCUREMENT
COMMUNICATIONS
SOFTWARE
STANDARDS AND REGULATIONS
COPYRIGHT
INSTALLATION, COMMISSIONING, PERFORMANCE TESTING
INSTALLATION
COMMISSIONING
DRAWINGS AND DOCUMENTATION
iii
V
vii
ix
xi
1
1
1
2
4
6
7
9
99
10
10
13
13
13
14
14
15
16
17
17
18
19
19
20
22
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Contents
Section 4
4.1
4.1.1
4.1.2
4.2
4.3
4.4
4.5
Section 5
5.1
5.2
5.3
5.3.1
5.45.5
Section 6
6.1
6.2
6.3
BEMS OPERATION
OPTIONS FOR MANAGING BEMS
Examples of the functions of staff who operate and manage BEMS
Other Options
OUTLINE SPECIFICATION FOR LEVELS OF BEMS OPERATOR
TRAINING
COSTS OF OPERATING BEMS
UPGRADING AND REFUBISHMENT OF BEMS
BEMS MAINTENANCE
PREAMBLE
MAINTENANCE COSTS
CONTRACT ARRANGEMENTS
Operating and Maintenance Documentation
SPARES AND CONSUMABLESRECOMMISSIONING
ENERGY MONITORING AND TARGETING
REVIEW AND RELATIONSHIP WITH BEMS
ADVANTAGES AND POTENTIAL COST SAVINGS
COST IMPLICATIONS
ANNEX A - TYPICAL COSTS AND SAVINGS ASSOCIATED WITH BEMS
ANNEX B - ANALYSIS OF REQUIREMENTS
ANNEX C - TENDER SUMMARY
ANNEX D - ENERGY CONSUMPTION BENCHMARKINGFOR MOD BUILDINGS
GLOSSARY OF TERMS ASSOCIATED WITH BEMS
BIBLIOGRAPHY
23
23
24
25
25
27
27
27
29
29
29
29
30
3031
33
33
34
35
37
39
43
45
47
49
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Executive Summary
A Building Energy Management System (BEMS) is a computer based centralised
system that helps to manage, control and monitor particular engineering
services within a building or group of buildings. Use of a BEMS can limit energy
costs and labour requirements by improving plant efficiency and effectiveness. It
can also provide a more comfortable environment for the building occupants and
act as a focal point for alarms.
BEMS have evolved from being a simple supervisory control tool to a totally
integrated computerised control and monitoring system.
Some advantages that a BEMS can provide are:
simple operation with routine and repetitive functions programmed for
automatic response
flexible time scheduling of plant and heating to meet site changes such as
holidays, training exercises and operational requirements
remote switching of plant and adjustment of set points
faster and better response to occupant needs
reduced energy costs through centralised control, monitoring and energy
management programmes
ability to cycle/control site electrical demands
better management through automatic alarm reporting, historical records
and maintenance programmes
graphical representation of plant operating conditions
improved operation through integration of sub-systems (eg. lighting and
access)
improved plant performance and life expectancyreal time collection and recording of data for improved analysis of
equipment or energy uses.
To obtain a successful BEMS installation:
provision needs to be made for ongoing operation and maintenance
operators must be skilled and fully trained on the use and operation of
BEMS
existing plant (when being overlaid with a new BEMS) must be capable of
performing its required functions
the system needs to be correctly specified, installed, commissioned andoperated.
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the functions of a BEMS
how to justify a BEMS
information required for a feasibility assessment
design and specification aspects
guidance on procurement
pointers for satisfactory installation and commissioning
the importance of record documentation
the need for ongoing operation and maintenance
the key role played by trained personnel.
xii January 2001
This Guide sets out:
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1 Introduction
1.2 TERMINOLOGY
BEMS is a generic term used to describe computer-based control systems for
engineering and building services such as air conditioning, lighting, access,
security, monitoring etc. Other titles used for such equipment are Building
Management System (BMS) and Energy Management System (EMS). The term
BEMS has been identified as the normal acronym for such systems and adoptedthroughout this Guide. Other terms are synonymous with this.
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provide a history of BEMS
list their advantages and disadvantages
address how to justify the application of BEMS
assess feasibility at a specific location
identify requirements for installation, testing and commissioning
explain the importance of operation and maintenance
demonstrate their potential for energy monitoring and targeting.
It provides background information, particularly for those who have little
detailed knowledge of such systems.
Further guidance is given in Specification 47 - Building Energy Management
Systems, due to be published in 2001.
This Guide is intended to:
selection
design
installation
testing
commissioning
use
maintenance.
1.1 AIMS AND OBJECTIVES
The principal purpose of this Guide is to provide a single source of information
regarding BEMS for those involved with:
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Section 1Introduction
1.3 WHAT IS A BEMS?
A BEMS is a computer-based system that helps to manage, control and monitor
building engineering services within a single building or a group of buildings.
Such a system, when properly designed, installed, commissioned and operated
will significantly improve the operational efficiency of the engineering
installation and its cost effectiveness in terms of labour and energy costs. It can
also help to provide a more comfortable environment for the building occupants.
A BEMS typically has at least one principal operator position (or central
station), connected via a communication network to remote outstations (or
controllers), which can function independently and provide local control to the
plant to which they are connected. They can also collect and respond to data
from the central station or other outstations. The central station is a user
interface at which various functions can be available depending on the client's
requirements. It may be located remotely eg. at a headquarters building or works
department.
Figure 1 demonstrates the components of a BEMS.
Figure 1Components of a BEMS
BEMS Central Station(Personal Computer)
Other OperatorInterface
Remote OperatorInterface
SITE DATA NETWORK
Controllers Hanger Group HQAccommodationBlock
Unitary controllersserving dedicated plant
Roomchillerunit
VAVterminal- box
AHU Standbygenerator
Heating pipework
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Figure 2 illustrates how the BEMS controller functions.
Figure 2Example of BEMS inoperation
Temperaturesensor
Humiditysensor
Velocitysensor
Sensorinputs
Time schedules(contained withinthe controller)
Elements of building engineering services with potential for control or
monitoring by a BEMS are:
heating
ventilation
air conditioning
domestic hot and cold water
lighting
electrical supply/distribution
electrical standby services
energy consumption (ie. reading electricity, gas, water meters)
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There is no reason, however, why any system needing to be monitored remotely
could not be integrated into a BEMS to provide a central focus point.
Most current generation BEMS provide the management interface at the central
station through a personal computer (PC). The operating system for the centralstation is likely to be Microsoft Windows, since this has become an industry
leader. The component structure below the central station comprises a
communication network, local controllers and field devices (eg. sensors, actuators
and meters). Different suppliers use different communication protocols to
transfer data, and within different generations of equipment from a single
supplier there may be variations in communication standards. Where different
suppliers equipment exist, or different generations of the same supplier, it may
be possible to integrate the control components, but due to different
communication standards and operating criteria this may not be a
straightforward process. As this integration can be expensive, costs should be
compared to replacement with directly compatible equipment.
CIBSE note in their Energy Efficiency in Buildings Guide (published in 1998),
that energy savings of between 10% and 20% can be achieved through the use of
a BEMS, compared with independent controllers for each system, though
opportunities for savings of this size will not always be available.
1.4 HISTORY
The development and processing power of computers, and in particular
microprocessors, has enabled a steady growth since the late 1960s from separate,
independent and dedicated control equipment to increasing degrees of
automation, control and communication. One driving force was to reduce theamount of cabling by the use of data networks.
Early systems were structured around a central computer called the 'head end'
or 'front end' which contained the processing capability, linked by fixed wiring to
each sensor or actuator device (eg. a room thermostat or a motorised valve).
Although the processing capability was limited, only providing start/stop control
and system monitoring, a central facility became available where all control and
performance information could be accessed such as alarms, room temperatures
and on-off switching times. This reduced the need for frequent site visits and
hence offered more efficient use of maintenance operatives.
Because the central processor carried out all the functions, the system capabilitywas limited by the available capacity. Such systems were generally very
inflexible and not user friendly.
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electrical maximum demand
security/access equipment
fire detection/alarm systems
vertical transportation
specialist equipment (eg. standby facilities, smoke control and fume
cupboards etc.)
catering services (eg. ventilation, electricity and water usage)
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Section 1 Introduction
The next development was the introduction of direct digital control (DDC) and
the reduction of the dependence on the central computer by distributing the
computing power round the building or estate within local microprocessors, each
with a limited input/output capacity. This style of system became known as
'distributed intelligence'. System design and operational requirements
determined the need for a central computer. This was not essential because thesystem 'intelligence' was provided by the outstations. Provision of a
communication network to link the outstations and allow data to be passed
between them promoted the stand-alone outstations to a BEMS.
Use of BEMS for control and monitoring of building services significantly
increased over the decade from 1980. Interest increased also in the potential to
link Heating, Ventilation and Air Conditioning (HVAC) equipment controls using
BEMS for at least alarm monitoring from other stand alone systems such as
lighting, lifts, fire and security and providing a single point for alarms to be
registered.
As computer processing power increased and costs reduced, the capabilities and
applications of BEMS grew, though on occasions the installations became
difficult to manage. Installation standards were not always followed,
commissioning became difficult and not always effective, which resulted in
systems that failed to achieve their original expectations.
Building owners and operators became disenchanted with "automated systems"
which failed to deliver the promised solution. However, they accepted that if the
systems could be simplified, designed properly, installed correctly and fully
commissioned, they would be a useful tool for running properties.
As microprocessor technology developed, stand-alone controllers becameoperated alone or linked through a communication network to other controllers
and a central point of information access. Such units, where they serve terminal
units such as fan coil units or Variable Air Volume (VAV) boxes have become
known as unitary controllers. Plant manufacturers or Original Equipment
Manufacturers (OEMs), purchase unitary controllers and fit them to their own
products. These can provide an opportunity for later integration into a BEMS
through a communication network. Computer power has now become fully
distributed, with the central computer becoming the 'host' for loading
programmes, interrogating performance and recovering data. Systems have also
become more user friendly and easier to programme.
Figure 3Summary of changes inBEMS technology
BEMS with outstations
1970 1980 1990 2000
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1.5 ADVANTAGES AND DISADVANTAGES
The use of a BEMS provides an integrated computer based facility for the
control and monitoring of the building engineering services.
Advantages are:
routine and repetitive functions are programmed and responded to
automatically (eg. daily on and off times, holiday scheduling, operational
programming for different buildings, periodic testing of standby plant)
relatively simple operation for trained users (eg. access to detailed
information such as room temperatures to monitor plant performance;
modifying operating times to match changes to building use)
quick response to occupant complaints about environmental conditions
(the sensitivity of BEMS can highlight potential problems and allow
adjustments to be made before occupants initiate complaints)
reduced energy consumption and hence costs by central monitoring and
control (savings may be up to 10% by constant fine tuning to match
occupational needs)
ability to cycle or control site electrical demand
improved management information such as historical records, alarm logs
and hours run can demonstrate that environmental criteria have been
achieved; alarms have been actioned and plant maintenance can be more
precisely managed
graphical representation of plant operating conditions and internal
environment, providing quick and simple understanding of the
information presented
integration of system control and operation through software links
(allowing increased opportunities for fine-tuning of controls to the
particular application)
improved plant performance and life expectancy (eg. by establishing key
operating criteria and monitoring performance efficiency).
Disadvantages that can apply include:
any BEMS installation will have costs associated with it. These will not
only be the initial design and installation, but also the subsequent
operation and maintenance (see para 2.1)
possible disruption to normal plant operation during BEMS installation
need for a skilled operator to ensure maximum use is made of the system
the effective potential of a BEMS can be very sensitive to proper
specification, full consideration of condition and ability of plant to be
controlled, commissioning by a skilled BEMS specialist and continued
maintenance
difficulty in integrating with existing equipment especially regardingcommunication protocol or the need for new controls or sensors to allow
integration
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requires commitment at all levels throughout its operational life to
maintain maximum effectiveness
unless carefully chosen, certain aspects of BEMS can become obsolete
relatively quickly
unless correctly specified, installed, maintained and operated BEMS canincrease costs and environmental impacts.
1.6 OPTIONS AND FUTURE DEVELOPMENTS
The processing power of electronic equipment being used within a BEMS means
that any system needing to be controlled or remotely monitored could be
accommodated, providing the cost of the initial installation and ongoing
operation and maintenance can be justified.
Greater integration between different systems such as lighting, fire alarms,
security and BEMS is likely to develop as the full capabilities become
recognised. The links at present tend to be for monitoring and alarm reporting.As users investigate different options and the potential of the full equipment,
greater confidence will be developed.
Whilst communication standards do exist, different suppliers and manufacturers
still have their own for their respective systems. As clients begin to demand
system integration to allow data from different components and systems to be
viewed and managed centrally, and control functions to be enhanced by sharing
data, greater flexibility will be achieved. The components of BEMS from different
suppliers are expected to become more compatible.
Unitary controllers are likely to become standard items of plant and equipment.
This may also influence the move towards communication standards, as greater
integration between suppliers equipment will be required. Unitary controllerscan provide programmable memories for field devices such as temperature
sensors or valve actuators, allowing them to be programmed and commissioned
before delivery to site. On-site commissioning will, however, always be required.
The costs of outstations and central stations will be influenced by the continuous
developments of IT equipment, with the expectation that greater processing
capability will be obtained for less cost. The cost element of a BEMS taken up
with the installation of the communication network may be reduced where an IT
network is available. Alternatively, the use of radio communications for both
internal and external links has considerable potential to grow and develop,
particularly between field devices and their associated outstations. Overall costs
of BEMS are unlikely to reduce. Whilst some components such as electronicequipment may become cheaper, other hardware costs and the system design and
engineering will continue to be the major proportion of the price and not provide
opportunities for savings.
As the volume of data increases, the levels of management information will rise.
Exception reporting, to show potential problem areas with likely causes and
possible solutions, may be developed to enable full use to be made of the
available information.
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2 Feasibility, design and
procurement
GENERAL
This section helps to identify the factors for choosing a BEMS and provides
guidance in establishing the feasibility and requirements for a BEMS. The most
common reasons for considering the use of BEMS are:
for new builds where costs are comparable to other forms of control
to replace existing old or failing controls where the difference in costs are
outweighed by the benefits provided by the BEMS
to improve the system where the benefits outweigh the costs
where there is a need for stringent control and monitoring levels of
building services.
2.2 FINANCIAL APPRAISAL
A key factor in building a business case for a BEMS will be a financial appraisal
over the proposed life of the system. Annex A is a simple table to help provide
initial indications of the likely costs and savings associated with BEMS. MOD
Guidance and Policy for carrying out full financial appraisals is given in:
JSP 414 Part 4 Chapter 16 Investment Appraisal and Post Project
Evaluation
DEO (Works) 1996 DEO Technical Bulletin 96/04 - Through Life Costing
DEO (Works) 1996 DEO Technical Bulletin 96/03 - Value Engineering
MOD Guide to Investment Appraisal and Evaluation.
Further guidance is also given in:
Appraisal and Evaluation in Central Government (Treasury Guidance
1997)
Appropriate local guidelines should also be followed.
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2.3 INDICATIVE COSTS
As general background information, three generic types of installation are
considered with outline cost information based on Quarter One year 2000. These
are not intended to be used for budget purposes, only to provide outline guidance
of the order of costs for the different types of properties. The particularrequirements for a specific location may result in significant variations from
these figures.
Total installed
cost of BEMS
(new greenfield
site)*
Property Type One
Very large major site with numerous buildings and facilities 300,000
eg. Naval Dockyard; RAF Operational Site
Total utilities cost per annum (electricity, oil, gas, water)
1 million.
Property Type Two
Medium to large 75,000
eg. Large single building or complex of buildings
Total utilities cost per annum
200,000.
Property Type Three
Small to medium single building or small complex of 30,000
buildings
Total utilities cost per annum
(electricity, oil, gas, water)50,000
* Installation in existing buildings will require an increase of
10% to allow for additional design and installation costs.
2.4 JUSTIFICATION
All building services need controls. BEMS can be cheaper than individual
controls, particularly for new buildings where they can be justified on first costs
for almost all types of buildings. For refurbishment or replacement situations,
first costs alone may not indicate that a BEMS is appropriate. Whole life costs
should also be investigated when system flexibility, monitoring and centralcontrol capability can be taken into account. Upgrading costs will need to be
compared with potential energy savings.
CIBSE indicate energy cost savings between 10% and 20% by use of BEMS in
their 1998 Energy Efficiency in Buildings Guide. As a rule of thumb, a retrofit
BEMS can yield a 10% direct fuel cost saving against a reasonably well
maintained conventional control system when properly designed, installed and
commissioned.
The benefits of using a BEMS are the flexibility of the controls available,
communications capability (particularly for operational data between plant and
system) and overall performance monitoring.
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A BEMS can provide three key advantages over stand alone control:
provision of management information
remote operation, interrogation and alarm monitoring
greater flexibility and range of control strategies.
BEMS will not compensate for fundamentally inefficient buildings and plant.
Benefits of a BEMS can include:
improved environmental (eg. temperature) and time control from central
location
rapid communication (system monitoring, operation and control) with
remote sites, without physical visits
improved comfort for building occupants
automatic fault reporting at central location (with predetermined levels of
action)
monitoring and targeting of energy consumption
allows easy trial and monitoring of building response characteristics and
related energy saving proposals such as lunch time set back of heating.
graphical representation of plant performance and environmental
conditions.
Examples of specific capabilities of BEMS are:
scheduling plant start / stop times
fuel consumption recording / energy metering
plant sequencing / optimisation
filter condition monitoring
electrical maximum demand limiting
lift monitoring
lighting control
hours run recording and trend logging
security management
alarm handling
'at a glance' information presentation.
Whilst these are also available using stand-alone controls, integration into a
BEMS provides the opportunity for achieving the greatest savings and operating
efficiency.
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In addition to the technical capabilities listed above, BEMS can provide the
opportunity for improved financial control, for example, by billing sub-tenants
where suitable metering is provided. Close monitoring of occupancy times and
adjusting BEMS settings can produce energy savings. Reduced maintenance
attendance by scheduling work on an hours run basis can lead to manpower
savings.
Before purchasing such a system, it is important to consider what the controls
are intended to do and how they will achieve this.
To provide a framework for this, Annex B - Analysis of Requirements provides a
series of questions to help analyse requirements at a specific location, including
a pro forma to identify which plant and services are to be covered by the BEMS.
The particular plant or system will generally determine the type of control
required. Each control requirement should be considered separately and the
details listed. It is important to avoid an over specified or unnecessarily complex
control system for the particular application. Advice on what is necessary and
appropriate, and help on completion of the check list can be obtained from the
Establishment Works Consultant (EWC) through the Property Manager or
through the Establishment Energy Focal Point.
The larger the number of systems or plant items listed for the project, and the
larger the number of control or monitoring requirements, then the greater is the
likelihood for a BEMS to be the appropriate choice for controlling the building
services.
For an existing installation, a list of questions to consider is given below:
is there an operational requirement for central monitoring or control?
do the existing controls meet current good practice? (eg. time control,weather compensation, optimum start/stop)
can the existing control be adequately operated and maintained?
does energy use compare well with published guidelines? (see Annex D -
Energy consumption benchmarks for existing MOD buildings)
is there a need to attribute responsibility for utilities to specific users?
(eg. billing of non-entitled users and resource accounting)
are consumption records needed for tariff/consumption profile analysis?
is there an opportunity to integrate control of different engineeringservices?
has the building function changed?
have good housekeeping measures to reduce energy consumption been
carried out.
are the building occupants satisfied with their environment?
These questions are included in Annex B - Analysis of Requirements
Once a decision in principle has been taken to consider a BEMS, the full
potential benefits and costs of achieving them need to be examined.
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2.5 FEASIBILITY
BEMS are becoming the norm in many larger new buildings, as their first cost is
similar to stand alone controllers.
In existing buildings, assessing the feasibility of a BEMS can be more difficult.
Where existing stand alone control equipment is available, the suitability,practicality and cost of retaining and incorporating components of it into a larger
BEMS needs to be assessed.
The following considerations are aimed at existing buildings, but could also be
applied to new buildings.
Zoning of Building Services
Are these adequate for energy efficient operation and match current
and proposed occupant requirements?
Primary Plant
Does this have stand alone control, could it be linked with a BEMS?
Existing stand alone controls
Are they still supported by manufacturers? Can they be
economically integrated into a new BEMS? Control equipment
installed in the late 80s, early 90s or earlier may have limited
functions available and be difficult to reprogramme.
Existing BEMS
Is there an existing BEMS available that could be used?
2.6 DESIGN AND SPECIFICATION
2.6.1 Design
A BEMS is a powerful tool that allows building owners, operators, and managers
to understand the function and control the operation of engineering plant and
services for which they have responsibility. It is important to note that however
a BEMS is designed or specified it can only control within the limits and
accuracy of the equipment to which it is connected.
There are a wide variety of systems available that can provide control or simply
monitor the status of plant. A purchaser needs to be clear and unambiguous
about the plant and equipment to be served by the BEMS and the degree of
control required.
The extent and method of design will depend on the size and complexity of the
installation and its controls, the technical competence of the client and any
relationship which exists with a preferred supplier.
Where the BEMS is being overlaid on existing plant and equipment, control
devices such as sensors and actuators may not be compatible or suitable for
connection to the BEMS. Allowance for this will need to be included in the costs
of the work.
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Section 2Feasibility, design and procurement
Control of different engineering systems such as HVAC, lighting, major plant
items such as chillers, and life safety (eg. fire) has traditionally been kept
independent. BEMS can provide opportunities for a degree of integration, but
this is likely to be limited to alarm monitoring or sequence initiation. The extent
of integration will be governed by the risks involved. Plant that is safety critical,
has military operational implications or operates under its own dedicated controlsystem may not be appropriate for integration.
2.6.2 Specification
The objectives of a specification are to:
14 January 2001
provide a firm basis tor a tender
identify required performance criteria
minimise misunderstanding
define responsibilities
provide like for like comparisons between different proposals.
The specification provides basic information together with exact functional
requirements, where appropriate, for the specific application. Further detailed
guidance regarding this is provided in Specification 47 - Building Energy
Management Systems to be published in 2001.
The initial step when preparing a specification is to define the building
management strategy from which a specification can be developed. To achieve
maximum benefit the strategy must take account of the function of each building
and the existing or proposed operation and maintenance manpower availability.
For large, complex applications it may be appropriate to appoint a professional
advisor for this role. Advice on this can be obtained from the EWC through the
Property Manager, or through the Establishment Energy Focal Point.
2.6.3 Types of Specif ication
Two generic types of specification can be identified:
Performance
Functional
states how the system will operate in strategic terms, with an
outline description of what is to be controlled and monitored.
gives detailed requirements for the system, including control
and monitoring strategies and the devices included, such as
controllers, sensors and actuators.
Both types of specification should describe the features to be provided, standards
to be met including materials and workmanship, testing and commissioning
requirements, training to be carried out and guarantees to be provided.
The type of specification will be dictated by the particular application and
intended procurement strategy. Where a specialist controls contractor is to be
used and competence has been demonstrated and proved on similar work, a
performance specification may suffice. The same type of specification may also be
appropriate for buildings with relatively simple engineering services and no need
for elaborate control. However, where a building has complex plant such as full
air conditioning, or where environmental conditions have to be closely controlled
within strict limits and there are considerable inter-relationships between the
control sequences, a functional specification will be required to ensure the
client's requirements are fully defined and able to be interpreted by the supplier
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and installer. Care must be taken to ensure BEMS equipment is compatible with
all systems and its operation does not allow plant to operate outside
manufactures parameters, normal duty ranges or operational limits.
In 1998 The Building Services Research and Information Association (BSRIA)
published a Library of Control Strategies (Application Guide AG7/98) as a
reference document for when the controls are being developed, specified and
configured. The strategies can be used when specifying control systems as an
independent source of control solutions. The provision of this Library does not
remove the onus from designers to ensure that an appropriate working solution
is produced.
To create a specification for a particular installation from the strategies within
AG7/98 the designer needs to:
decide which 'plant functions' are required to make up the whole system
decide for each plant function which of the available plant modulesoptions is to be used
forstrategieswhichofferalternativesoroptions, decide whichare
required in the specific application.
2.7 PROCUREMENT
A number of options are available. These include:
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direct purchase from a specialist supplier of controls equipment
direct purchase from a systems integrator (who obtains components such
as controls equipment from a specialist supplier and designs, installs and
commissions the system to meet the user's requirements)
use of a controls specialist to design the system, tender the work and
oversee installation and commissioning
produce in-house, an outline brief of requirements and tender the work
for purchase
produce in-house, an outline brief of requirements and tender for leasing
an installed BEMS (where such a leasing agreement is deemed
appropriate). The lease agreement may include upgrades to the BEMSover the stated period of the lease agreement.
incorporate the BEMS installation within a Private Finance Initiative
(PFI)/Public Private Partnership (PPP) arrangement.
lease the BEMS through the Facilities Management Contractor.
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2.8 COMMUNICATIONS
Two aspects of communications need to be considered:
1. The information being communicated.
Computers need precise, rigidly defined rules and protocols for successful
communication.
Typically, translation problems occur when trying to connect products
made by different manufacturers, or in some cases, different versions of
products made by the same manufacturer.
Traditionally, different systems such as lighting, HVAC and life safety (eg.
fire) have had separate, dedicated controls. Relevant specialists should
be fully consulted where safety critical systems are to be connected to a
BEMS.
Communication standards allow transfer and interpretation of data
between different parts of the BEMS and integration of equipment from
different suppliers. There is no single agreed communications standard,
at present, followed by all BEMS suppliers. Several exist and are being
used by different suppliers.
2. Physical communication system between all parts of the BEMS (eg. data
cabling).
The elements of a BEMS need to be linked together to transfer data
through a communication network. The most common method is data
cabling using shielded or unshielded twisted pair. Other options include
fibre optics, which can provide increased security, radio links, which may
be more appropriate when long distances (eg. across an operational RAFsite) are involved, mains borne signalling, where the electrical
distribution system is suitable and modem links to public or private
telephone networks.
Existing communication network cabling may be available, eg. redundant
voice systems, but will need to be checked and proved suitable before
inclusion into the project scheme. Dedicated voice networks using
modems, can provide a basic communication infrastructure, particularly
on extensive sites where buildings are spread over a large area. This
application can result in prolonged times for data transfer and problems
with data accuracy which may have implications if used for generating
energy bills.
Alternatively, an existing IT cabling system may be available. Office
accommodation in particular is increasingly likely to have a structured
cabling system providing an infrastructure on each floor, with a grid of
outlet connections allowing connection of IT equipment such as PC's and
printers. BEMS may be able to use this to link major components directly
together (eg. controllers and the central station). The cost of integrating a
BEMS with an IT structured cabling systems (SCS) will depend on how
much of the SCS is required.
Where it is proposed to use an existing or proposed general use cabling
system for a BEMS, application for this must be made in sufficient time
to ensure its availability when required. The continuing availability ofshared access to the system also needs to be confirmed.
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If the SCS is installed at the same time as the BEMS (eg. on a green field
development) it can be designed to accommodate the BEMS requirements
and installed by the SCS installer.
Other benefits of using the IT network are shared network maintenance
costs, access to a robust and industry recognised communication network
and an enhanced network security (faults detected and rectified more
quickly than normal BEMS network).
Use of an IT network is likely to be for the major data interconnections such as
between controllers and the central station. Use of a local BEMS network is
more likely to be cost effective for individual plant controllers.
Radio communications applied to BEMS are very limited but offer potential for
future growth. It has been successfully adopted on large MOD sites such as
operational RAF stations with considerable distances between buildings, to
reduce the need for cable links. The technology can be applied both internally
between field devices and associated outstations and externally over a campus
type environment for communications between remote buildings. Security of
radio communication systems may not be satisfactory for particular locations.
2.9 SOFTWARE
The software elements of a BEMS determine how the controls and monitoring
functions built into it will operate and communicate. This level of software may
be termed the 'firmware' since they can be fixed components of the system whose
operating parameters and characteristics are set up to match the specific
requirements. The BSRIA Library of Control Strategies provides a set of
standards. Individual suppliers may opt for particular ways to achieve each
strategy.
BEMS software imposed above the control strategies provides the monitoring
and reporting structure of the system, including how and what reports, alarms
and historical logs are generated.
Documentation for both the firmware and software is critical because it will
define how each controller and control parameter has been configured, how
information is stored and reports are generated.
Software protection in terms of licence agreements needs to be resolved at an
early stage of the project. Copies of the software should be held in secure
locations, ideally both on and off site.
2.10 STANDARDS AND REGULATIONS
BEMS installations must comply with all relevant statutory regulations. Other
guidance in terms of standards and codes of practice should also be noted.
Examples of these are British Standards Codes of Practice and MOD guidance.
The following is a general list of some areas that should be addressed when
installing a BEMS:
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a safe means of access for maintenance
all BEMS panels are secured to prevent unauthorised access
the central station and controllers are password protected to prevent
unauthorised access
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sufficient illumination is provided as required for user operation of BEMS
where they are situated in plant rooms. This may require additional task
lighting.
electrical installations comply with BS7671 1992 - Requirements for
Electrical Installations (IEE Wiring Regulations 16th Edition). Commonly
known as the Wiring Reg's
all equipment complies with the standards relating to electromagnetic
interference and is suitable for the particular application
workstations comply with the Health and Safety (Display Screen
Equipment) Regulations 1992
specific security needs for the particular application relating to hardware,
software, sensors and other electronic and IT equipment are followed.
2.11 COPYRIGHT
For a particular application, the detailed BEMS specification, software
configuration, operating parameters and reporting structures established for thespecific application will all be covered by MOD copyright and not, therefore,
available to others without authorised agreement.
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3 Installation, Commissioning,
Performance Testing
3.1 INSTALLATION
This is the process of translating the requirements set out in the specification
into a physically completed system (static completion). It requires labour,
materials, supervision, inspection, testing and documentation.
In a new installation the plant and equipment needing interconnection with the
BEMS should have suitable facilities already available. For existing plant and
equipment, where a new BEMS is being installed, there may be a need to replace
or refurbish existing control devices such as sensors, actuators and analogue
controls.
Installation standards should be defined in the specification, including those for
data cabling, programming, testing, documentation and cable identification.
The installation of a BEMS can be critical to its effective and efficient
performance. It is advised that installation should only be carried out, or closely
managed, by specialist BEMS installers, or organisations who can demonstrate
their particular expertise in this field.
Safety and operational interlocks are likely to be included within the specific
control strategies. These need to be identified in schedule format and proved to
be working in a safe and correct manner. The BEMS would normally only
monitor the action of such interlocks, particularly for critical operations.
Tests to confirm an installation has been completed and approved to the
satisfaction of the Project Manager should include:
an audit of the cabling and hardware
demonstration of the physical and logical integrity of the system
demonstration of all the control actions
demonstration of all the sensor calibrations
demonstration of the system software
demonstration of the system graphics
all documentation including drawings and operating and maintenance
manuals have been provided.
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3.2 COMMISSIONING
Commissioning is the process of turning a physically completed system into a
fully operational working system that meets the designed requirements. Poor
commissioning is the most common cause of BEMS failing to meet the initial
performance expectations. This in turn can lead to unstable and underperforming plant. Suppliers can benefit from good commissioning since
subsequent warranty costs are likely to be less than for a poorly commissioned
installation.
A comprehensive specification supplemented with flow diagrams can form the
basis of the commissioning checklist and serve as a yardstick to test the BEMS
control strategies. It is beneficial to specify as much off-site testing as possible
(eg. control panels, application software and graphics) when conditions are more
suitable for testing and remedial work.
Once installed, the BEMS should be fully pre-commissioned as far as
possible,(eg. data cabling interconnections, validity of sensor readings, actuator
performance). All controls are likely to be needed in 'manual' operation duringfull commissioning of the engineering services. The BEMS can then be
integrated with the building services and finally commissioned and put into
operation. Adequate time needs to be allowed for this, as a guide 30 minutes for
each BEMS sensing point should be anticipated. Attendance will also be required
by other trades and this should be reflected in the tender figures as part of the
commissioning costs.
On sites where the BEMS is commissioned and handed over in stages, the
sensors in the earliest stages may have drifted from the calibration setting by
the time that later stages are commissioned.
Where the BEMS is being installed in an operational building, careful planningis needed to maintain all services so that they continue to function during the
commissioning process.
Whilst the initial commissioning will be carried out to the original design data, it
is likely that fine tuning of the system will be required over the first full year of
building occupation to fully meet the requirements of the building operator and
the occupants. It may be appropriate to include this in the original contract cost,
particularly for more complex installations. This will lead to greater savings as
the BEMS operation and performance parameters can be optimised. Liaison
between the building user/operator and the installation contractor during the
period of fine tuning is important to ensure a full understanding of how the
building is required to function.
BSRIA Application Handbook AH 2/92, Commissioning of BEMS, provides a code
of practice including detailed check lists. Other relevant publications are:
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Commissioning HVAC Systems - Divisions of Responsibilities.
The Commissioning of Air Systems in Buildings
The Commissioning of Water Systems in Buildings
A Procedure for Commissioning VAV Systems
Commissioning of VAV systems in buildings
Commissioning Code C Automatic Control
TM1/88
AG3/89.1
AG2/89.1
TM2/88
AG1/91
BSRIA
CIBSE
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Performance testing addresses the operation of the BEMS and the associated
plant. It is aimed at ensuring both are operating in an optimum manner in
terms of energy and internal environmental performance.
The BEMS operator should be trained to monitor the BEMS performance and to
note and respond to feedback from the building occupants.
Many BEMS receive little or no maintenance. Possibly this is because a BEMS is
perceived as microprocessor based and not requiring attention. A BEMS is more
than the central station or controllers. Sensors can go out of calibration,
actuators can fail to operate. Building use will change over time, needing set
points to be revised. Performance testing will detect changes to the BEMS level
of performance and faults due to incomplete commissioning.
Reasons for performance testing include:
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occupant complaints about the environment
energy performance is unsatisfactory
system neglect
little information may be available about the installed control regimes
BEMS performance is inadequate/not satisfactory
unsatisfactory environmental performance
significant change to energy consumption
to evaluate BEMS performance
repeated failures or alarms need to be investigated.
fits ofperformancetestingare:
improved occupant comfort
prevents complaints arising from occupants
energy savings
reduced false alarms
improved awareness of BEMS and control strategies
confidence in BEMS records.
BSRIA Application Guide AG2/94 - BEMS, Performance Testing, provides
guidance on a general performance audit and help in resolving particular BEMS
problems.
Guidance on energy consumption benchmarks for MOD buildings can be found
in the DETR Energy Conservation Guide 75 - Energy Use in Ministry of Defence
Establishments. A copy of the summary page giving the benchmark figures from
this document is given in Annex D.
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3.3 DRAWINGS AND DOCUMENTATION
Comprehensive and accurate record drawings and documentation are essential
for the satisfactory operation and maintenance of a BEMS. These should include:
BEMS Performance Specification
written description of plant and how it is controlled
control strategy, including diagrams
operating and maintenance manual
maintenance schedules
central station software manual
points list (all analogue and digital inputs and outputs)
flow diagram
specifications for sensors and actuators
schematic wiring diagrams for outstations, field devices and control panels
controls design specification
details of set points, alarm levels, time schedules, overload settings
commissioning data
plant diagrams showing locations of field devices
software back-up copies
emergency procedures
handover/acceptance documentation
log book - to record incidents, operational information and all changes
made to the system (para 5.3.1 gives more information about this).
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4 BEMS Operation
4.1 OPTIONS FOR MANAGING BEMS
To achieve the full benefit of a BEMS installation it will need to be monitored,
used and properly maintained rather than simply installed and ignored. The
man/machine interface of a BEMS provides ready access to plant operating data,
allows better understanding of the performance of the systems being controlled
and helps improve decision making. As such, this interface is a key element of
any BEMS.
Due to the complexities of modern BEMS systems a common problem is
identifying just who is responsible for what and in what context. To help
eliminate this it is recommended that this is agreed and documented at the
design stage, include operation, access, maintenance and communication
responsibilities.
It is essential that all personnel authorised to access or use a BEMS are
adequately trained to ensure safe and efficient operation of the system. Where
personnel have the ability to control or effect equipment or plant controlled bythe BEMS, they must be competent to do so. Risk Assessments and Safety
Method Statements should be produced and used to ensure safe and correct
operation and use of the BEMS. Individuals with the appropriate authority
should be able to demonstrate their understanding of the areas within the
BEMS to which they have access, and any implications their actions may have
relating to the Health and Safety of both themselves and others.
Authorisation for access to the BEMS or plant rooms in which they may be sited,
especially where plant/equipment settings and controls are involved, should be
approved through the Property Manager and managed throughout by the
Authorised Person. In turn the Property Manager should confirm with the
Establishment Works Consultant (EWC) and Works Services Manager (WSM), or
relevant service provider, that the individual requesting use/control of the BEMS
is deemed competent for their specific requirements. The EWC and WSM should
also be able to confirm if there are any other implications regarding existing
maintenance and operation contracts.
It would be beneficial for the main operators of BEMS to be longer term
personnel who have a good understanding of the site and any necessary
conditions or concerns. Where this is not appropriate/possible operators can help
by keeping records to pass on. Each new operator should receive full training for
the system.
Having regard to the above, Site Energy Managers would typically be included
in those with access to BEMS at the highest level. This will help ensure
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maximum benefit from the BEMS in terms of energy management, efficiency
and savings. Potential overlap between Site Energy Managers and the WSM
must be discussed and agreed at the earliest stage in the BEMS design. This
may, for example, lead to siting of BEMS controllers out of plant rooms to
facilitate safe access by the Site Energy Manager.
4.1.1 Examples of the functions of staff who operate and manage BEMS
The hours noted overleaf are illustrative only and will depend on the particular
site and application. Hours do not include for energy Monitoring and Targeting
(M&T), or interpretation of consumption information. A BEMS is a tool to aid
the staff listed overleaf. As such, the installation and use of a BEMS, within the
roles described, should represent savings in human resources, not demands on
them. This is based on the principle that the BEMS should allow existing tasks
to be done in less time. In addition, the improved quality and quantity of
information and rapid and flexible control of plant will allow much greater
effectiveness of these tasks.Site Energy Manager
The typical emphasis of this role regarding BEMS is on improved energy
efficiency and management. Typical BEMS use for this role is seven
hours per week. The role may typically include an understanding of how
the engineering plant functions and be aware of the complexities,
capabilities and design philosophy of the BEMS. The post holder 's
functions could include regular checking of plant performance and
environmental conditions, adjustment of environmental conditions to
meet changes in weather, occupancy or usage and bringing any other
areas of concern to the attention of the Property Manager. The level of
potential achieved from the BEMS in this role will strongly depend on thelevel of training, understanding, experience and delegated authority to
take necessary action.
Site Maintenance Staff/Consultants (Other Service Providers)
The typical emphasis of this role regarding BEMS is on maintenance and
operation of the site infrastructure, without necessarily having any
specific direction on energy management. Typical BEMS use for this role
is three hours per week. The principle use of the BEMS in this role is to
confirm plant is operating correctly, identify and respond to plant failure
alarms and use information for proactive maintenance management. In
many cases, it will also include operation of plant and equipment. This
role requires detailed understanding of how the engineering plantfunctions and all aspects of the BEMS.
Energy Warden (or Building Custodian)
This is often a supporting role to the Site Energy Manager or Property
Manager, normally associated with a single building or small group of
buildings. Typical BEMS use for this role is up to two hours per week.
The role requires ready access to information from the BEMS such as
time / environmental settings and actual conditions for the relevant
area(s). Any anomalies can then be manually verified or investigated as
required and recommendations made or action taken using local
knowledge. A basic understanding of the relevant functions and
capabilities of the BEMS would be beneficial. This role does not normallyhave authority for any control function but may have access for limited
adjustment to environmental set points.
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Property Manager/EWC (Management)
This role primarily requires access to information from the BEMS to aid
in the management role or provide clear and rapid understanding of
relevant systems through the schematics. Use is dependent on
requirement. Typical BEMS use would be up to one hour a week. Only a
basic understanding of the plant or BEMS function or capability is
required. This role would not normally access the control functions. Full
understanding of plant or BEMS functions or access to the control
functions would be achieved through the Site Energy Manager, WSM or
EWC, as required.
4.1.2 Other Options
A Bureau Service could be used to provide 24 hour monitoring of BEMS alarms
remote from the site. There may be scope for this function to be provided by the
site security organisation when the main tenance contractor is not in attendance.
Instructions on how to respond to each alarm type or priority level would need tobe established along with contact details for unexpected situations. Maintenance
contractors and other commercial organisations often provide such a facility, at a
cost, if required.
A more effective use of a Bureau Service would be to audit the BEMS
performance, rather than only provide a reactive alarm monitoring function.
This would require the Bureau Service to have skilled and experienced staff who
could interrogate the BEMS, interpret the results and monitor that appropriate
action had been taken. As such, this role would not be suitable for site security
staff.
Use of a Bureau Service would need to be considered in relation to the existing
contractual arrangements to determine whether scope is available for this.
Another option would be to use the enthusiasm and expertise of existing Site
Energy Managers by extending their role and responsibility across a number of
sites. Dependent on site sizes, one Site Energy Manager could potentially have
responsibility for several sites if linked through a suitable communication
network. The BEMS at each location would provide local control and reporting.
The Site Energy Manager would interpret the data and, from intimate
knowledge of the sites, be able to initiate the appropriate action. This role
would be further enhanced by access to a comprehensive energy M&T system.
4.2 OUTLINE SPECIFICATION FOR LEVELS OF BEMS OPERATOR
To provide a better understanding of the different potential operating roles of
BEMS, the following four categories show typical aspects of various levels and
typical posts in which they would be suited. Important Note: Any adjustments,
control function or accessibility to BEMS plant should be approved in writing by
the Property Manager. This should detail the specific tasks and level of
controlability to be authorised including the name(s) of the individual(s) being
given the authority. These levels are generic and actual allocation of roles and
responsibilities would benefit from input by experienced personnel.
Level One- typically fits within the role of Energy Warden and may include/
require:
basic understanding of BEMS purpose and method of beneficial operation
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no or very limited permission to make alterations to set points
ability to call-up and view data from schematics and points list
ability and access to view and interpret trend logs for relevant areas
access to pertinent limited areas of the site only.
Level Two - typically fits within the role of the Property Manager or other
Managers and may include/require:
as Level One above but also requires access to information and data for
the whole site. Not normally permitted to make alterations to set points.
Level Three- typically fits within the role of the WSM, EWC or other similar
service provider organisations and may include/require:
a detailed understanding and knowledge of all aspects of the BEMS required
a detailed understanding and knowledge of all plant integrated with the
BEMS. Able to call up and view point data from schematics and pointslist for whole site
full access to all control functions, liaison with Site Energy Manager,
advised if environmental set points or time setting to be altered
ability and access to acknowledge system alarms
ability and access to add analogue and digital inputs and outputs to the
system
ability and access to change control strategies
ability and access to view trend logs.
Level Four- typically fits within the role of the Site Energy Manager and may
include/require:
a full understanding of the BEMS architecture, design philosophy and
capabilities
a full understanding of the functions of the engineering systems
controlled by the BEMS
access and ability to call up and view point data from schematics and
points lists for the whole site
access and ability to view all system data and set up trend logs or
exception alarms
visibility of all system alarms for relay on to relevant maintenance
personnel
access and ability to make changes to time and occupancy controls and
set points and alarms
ability and access to add or change graphics
ability to change control strategies and add analogue and digital inputs
and outputs to the system.
These four levels are only indicative and the particular site and its requirements
will dictate those appropriate. In some instances, levels may be combined, inothers, sub-levels within those shown may be created.
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4.3 TRAINING
To obtain the full benefit of a BEMS it is essential that people who are
authorised to use, operate and maintain it, are trained to allow them to have a
good understanding of its capabilities, purpose and potential. Such training
needs to be an ongoing process.
Operators need to understand the prime function of the BEMS, which may have
changed since the original design specification was produced. They also need to
be trained in the operating method of the system. Problems that may arise when
established procedures are not followed should be part of the training
programme. The procedure for making changes, alterations or additions to the
BEMS should already be defined, but will need to be explained, together with
how to record system malfunctions or concerns about incorrect performance to
enable them to be resolved by the maintainer.
BEMS operators will need to be trained to understand the displays, how to
monitor and change time schedules, set points and environmental control
settings, acknowledge and cancel alarms and take action following alarmmessages. They should also be able to carry out routine maintenance of the
system central station hardware (eg. replace printer cartridge).
Maintenance staff require training in any specialist procedures related to the
specific installation. They also need to understand the generic requirements set
out in the HVCA maintenance schedules for BEMS. (See Section 5.3).
4.4 COSTS OF OPERATING BEMS
These can be divided into two elements. The first is maintenance of the installed
equipment. An indicative annual cost for this is some 7% of the original installed
cost for the complete controls installation. However, the controls components(sensors, actuators, controllers etc.) will need to be maintained in any event. The
cost of maintenance of the BEMS components (ie. control operator station and
communications network) should be identified separately. In the absence of
other information, a value of 0.5% of the total installed cost could be considered.
This value is included within the 7% stated above (see 5.2 Maintenance Costs).
The second element is the operator cost for the system. This will depend on the
role of the person acting in this capacity, and whether energy M&T is included.
For BEMS operation, an indicative figure of 10% - 20% full time attendance
would need to be available for this role. Should energy M&T also be included,
the time proportion increases to 30% - 40%.
4.5 UPGRADING AND REFURBISHMENT OF BEMS
The cost of upgrading or refurbishment of BEMS will need to be demonstrated to
be cost effective. Anticipated energy savings are likely to be the principle
jus tification, though other potential advantages, listed in para 1.5, may also be
appropriate. A life cycle cost analysis showing anticipated operating,
maintenance and repair costs of the existing equipment, compared with the cost
of upgrade or refurbishment, over say 15 years, can help to make the case.
At the design stage, adequate spare capacity should be provided in the system
for known or anticipated system expansion. This extra capacity needs to be
available at the central station, outstations and the communications network.
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Specific site requirements and known proposals should be used as the basis for
expansion planning. However, in the absence of detailed information an
allowance of 20% should be made in each of the component elements with
potential for expansion such as the central station, outstations and
communication network.
If the BEMS is a modular system, it may be reasonable to provide minimal
expansion capability during the initial installation and provide additional
modules when required.
When upgrading an existing system, the initial consideration is likely to be to
use the same equipment supplier. This should avoid problems with the
communication standards protocols and interfaces between different suppliers'
equipment. The age, reliability and performance of an existing system may
influence the decision to continue with the same supplier.
When an existing BEMS has insufficient capacity to upgrade to meet current
requirements, it may be practical to retain field devices and the communication
network to limit the project cost. It is possible that the existing equipment from
a particular supplier may not be compatible with their current product range.
BEMS equipment suppliers claim to be able to interface with the majority of
competitors equipment. Careful programming of the project will be required to
ensure all systems are operational during the upgrading.
CIBSE have published the following economic life factors for BEMS components,
which may be useful when considering upgrading or refurbishment. The specific
applications and quality of maintenance will dictate the remaining life of
existing components.
Equipment Item Typical Life
Factors (Years)
BEMS operating system 5-10
AutoDial modem 5-10
Communication network (hardwiring) 25-30
Network communications services 10-15
Damper actuators 10-15
Outstations 5-15
Sensors 3-10
Control valves 15-20
Control dampers 15-20
Utility sub-metering 10-20
Electronic controls 12-18
Hydraulic valve actuators 10-15
Pneumatic valve actuators 15-20
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5 BEMS Maintenance
5.1 PREAMBLE
With the increasing complexity of BEMS it is essential that their integrity
(including software and applications) is checked and the requirements reviewed
at regular intervals. Ignorance of a system's capabilities, coupled with poor
commissioning and lack of client commitment can result in a BEMS becoming an
expensive time clock.
If the equipment is not correctly and fully commissioned and maintained by
specialist, trained personnel and supported by the manufacturers, the benefits of
the investment will be lost, energy wasted and operational costs will rise.
Where a BEMS is installed, the client should be aware of the need for
continuous monitoring of performance. Switching off because of a malfunction or
lack of data update can negate the considerable investment and give rise to
unacceptable environmental conditions and energy wastage.
Building operators with a BEMS should ensure that the operators have had
appropriate training to understand the equipment and carry out routine daily
and weekly maintenance tasks, such as monitoring and changing time
schedules, set points, environmental control settings and simple computer
hardware maintenance (eg. changing printer cartridges). Such training needs to
be an ongoing process.
5.2 MAINTENANCE COSTS
It is essential to make provision for the ongoing maintenance of a BEMS once it
is installed. As a budget indicator, an annual cost of 7% of the installed cost (ie.
the hardware, software, outstations, sensors and actuators, and communication
interfaces) should be allowed for the complete controls installation. This figurehas been obtained from suppliers, BEMS specialist maintenance contractors and
MOD users. This would cover, depending on the size of the installation,
maintenance of the central operator station, data communications, controllers
and software functions, calibration of sensors, and operational checks of
actuators. Spare parts and replacements would be additional costs. As noted in
para 4.4, Costs of Operating BEMS, the maintenance of the BEMS components
is a small proportion of the 7% figure.
5.3 CONTRACT ARRANGEMENTS
The HVCA have produced a series of standard maintenance specifications for
mechanical services in buildings. Volume III covers Control, Energy and
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Building Energy Management Systems. The HVCA Standard can be used as a
means of checking that work has been carried out and conforms to the
requirements. It is essential that the specialist engineer appointed for BEMS
maintenance is familiar with the equipment and the manufacturer's
maintenance manual.
Maintenance schedule or contract needs to be in place from the date the BEMS
is handed over to the client. One option for the initial twelve month period is to
include the cost in the supply contract. If this is done, the cost details need to be
separately identified in the tender document.
Contract options are:
direct contract to specialist or equipment supplier
arrange call-out facility only with specialist or supplier
place BEMS maintenance through main M&E maintenance contractor.
Details of the arrangement also need to be addressed, such as minimum call-out
response time, whether a fully comprehensive contract is required (ie. costs
include all spares, consumables, and replacement following breakdown).
Maintenance contractors undertaking BEMS maintenance should have
specialists with:
necessary training
knowledge of the installed system
up-to-date awareness of manufacturers equipment
access to up-to-date diagnostic equipment
good technical support
access to good stocks of spares.
5.3.1 Operat ing and Maintenance Documentat ion
It is essential that a detailed manual be kept on site. This site manual records
the responsibilities of all parties involved with the BEMS, together with the
installed equipment, normal settings, control diagrams and location of theOperating and Maintenance manual relating to the specific plant and control
equipment. This site manual can also serve as a service log to record faults and
observed by the BEMS operator, changes to control parameters, set
points, program algorithms plus reasons why the change was necessary. It can
also be used to check when each entry is resolved.
5.4 SPARES AND CONSUMABLES
Investigation of typical BEMS installations at various MOD locations indicated
that spares and consumables may not need to be stored on site, as they are often
readily available from manufacturers and could be charged for on an 'as
required' basis.
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Therefore, it is not recommended that BEMS spares be held on site unless
particular requirements such as equipment serving a strategically essential
system justify this.
Items which are known to be regularly replaced such as sensors, valves and
actuators, which are common throughout the site, would justify being held at
minimum levels to allow replacement to be carried out.
5.5 RECOMMISSIONING
Over time, BEMS settings, performance and operating parameters will change
as items become worn, electrical items drift and other circumstances change.
Regular recommissioning of the BEMS can help ensure it is operating at its full
potential, maximum energy savings are being achieved and plant performance
and expected life is maximised. The frequency and areas of the BEMS for
recommissioning should be based on regular monitoring of the BEMS
performance and any major changes in the use or layout of the areas being
managed by it.
An indicative cost for recommissioning should be based on around 30 minutes
per point to be covered.
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Figure 4
Energy monitoring andtargeting
6 Energy monitoring and targeting
6.1 REVIEW AND RELATIONSHIP WITH BEMS
A target can be defined as a measurable objective to be achieved in a given time.
In terms of energy management, it may be a forecast over a twelve month period
of the expected utility consumption eg. electricity, gas, oil, water. For heating,cooling and lighting loads, there will be fluctuations over the twelve month
period due to variations in external weather conditions and the available hours
of daylight. This is in addition to the specific building requirements such as
changes in the hours of occupancy.
Figure 4 shows an exampletargetconsumption for an officetype building, with a
tolerance margin around the target line of 10% to show acceptable performance
criteria.
7000
6000
5000
4000
3000
2000
1000
0
By plotting the actual consumption on the target graph on say, a monthly basis,
a good indication of performance against target can be obtained, as shown by the
white line. As weather conditions are never the same year to year, or even month
to month, the results may need to be normalised by the use of degree-day
information. This provides detailed meteorological information of the days when
heating (or cooling) would have been required, which allows target information
to be modified to actual local weather conditions.
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Target ConsumptionTarget 10%
Actual Consumption
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