System Control Of Building Engineering Services Systems Computer Science Essay

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The BMS Standard specification provides a full set of specification clauses with a wide range of functionality. The Building Regulations 2000 Approved document L2A (2002) establishes a Statutory requirement to address the issue of energy efficiency in buildings. This report in conjunction with statutory requirements and guidance (Annex A) and the BSRIA Library of Control Strategies examines part of the specification for a Building Management System within a modern office building.

Introduction

This specification relates to both performance and fundamental aspects of a Building Management System (BMS) required to control the environmental conditions within a modern office building in accordance with the client brief. A feasibility assessment was undertaken for the existing building the purpose of which was to identify the shortcomings with regard to the existing set up, method of control, customer satisfaction and occupant control. This was conducted based upon customer feedback and information supplied in the client brief.

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Staff training issues, levels of access and the system operator interface functions were examined within the remit of the specification to ensure that the proposed system's potential is fully realised. The process was to ensure that personnel are made fully conversant with the proposed control strategies and suitable training provided for the nominated users.

The function and importance of monitoring and targeting software is highlighted within the specification. Deviance, norm and CUSUM charts can be utilised with integral functions within the overall BMS package to;

Analyse and Actual energy consumption

Highlight potential problems. (Annex B)

The communication protocol is also discussed within the specification to provide full transfer of monitored, logged, alarm, backup and configuration data between the operator workstation and addressable field controllers.

In addition this report deals with the integration of additional systems with the BMS such as the fire alarms based upon the feasibility, current legislation and client instructions.

This specification has been issued not only to effectively manage the main office buildings engineering systems but provide an all encompassing regime of maximising energy usage based upon modern technology coupled with better education and training in accordance with the client's wishes and statutory regulations.

Feasibility

A feasibility assessment was undertaken based upon the information supplied by the client and guidance within CIBSE guide A for offices (Annex C). An appraisal was undertaken regarding the existing control strategy/ methodology for maintaining the working environment within the office building. The BMS system proposed is required to;

Reduce energy consumption and CO2 emissions

Improve occupant comfort

Operate building services plant more effectively.

Transfer data to other functions, such as monitoring and targeting software and maintenance management software.

Plant Considerations

Feasibility based upon;

Building is owner occupied and not multi-tenanted and hence no physical barriers in implementation of BMS scheme. Upgrade in controls preferable option to other energy efficient improvement measures due to potential payback period and long term cost benefit and greater financial return on investment.

Building functions remains the same as initial design, hours of occupancy reviewed due to changing business strategy but infra-structure, heating/cooling loads, sensor positions and heater emitter sizes essentially unchanged from initial design.

Potential for enhanced zoning identified and potential reduction of fuel/electricity costs identified by reducing hours of operation of boilers/chillers. Zoning may be accomplished to make use of different areas therefore the addition of the necessary sensors and control functions will schedule plant operation more closely with occupancy times to modulate the amount of heating/cooling delivered according to the actual load in the zone.

Existing BMS in poor state of maintenance with no maintenance contract in place. Direct Digital Control (DDC) controllers unsupported by the Original manufacturer and unlikely to be cost effective due to limited functionality. No regular maintenance records available and current system incompatible with up to date products, hence existing controls can not be interfaced with new proposed controls.

Occupant Considerations

Feedback from the client indicated the following;

Poor current system control, staff conservatism with little education on user control. Complaints were dealt with "in-house" but not to the user's satisfaction. No occupant control of their environment hence dissatisfaction within the workforce and this should be implemented.

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No energy reports/benchmarking or surveys available, spot checks on environmental parameters non existent. In summary no energy audit or energy performance has taken place.

Existing controls do meet current Building Regulations however they are not operated correctly or maintained.

It is cost effective to invest in training and a new BMS to control the environmental conditions within the building.

In fitting an improved method of environmental control adequately trained staff would be required to operate the BMS, capable of interpreting the data relating to the operation of the HVAC plant and services, simple controls strategies and reporting routines should be implemented with BMS data tailored to the function required. Investment in maintenance staff is integral with key individuals trained and able to utilise the data available.

The existing control philosophy and hard ware were deemed unsatisfactory and did not satisfy client's current requirements.

Staff Training

Staff training will be in accordance with the differing technical roles within the Client's organisation depending upon existing experience, capacities and understanding of the BMS;

The functions available to suitably authorised operators shall be as specified but to include as a minimum the following;

Acknowledge alarms, including muting of audible or flashing annunciators.

Add or delete points from the system.

Inhibit alarms for reasons of time and/or priority as selected by the operator

Alter the limits at which the measured values cause alarms to be signalled

Alter plan "run" status on command from the keyboard.

Re-schedule plant operation times from the keyboard. It shall be possible to apply such re-scheduling globally to a number of items of plant at one or more sites as selected by the operator

Adjust and synchronise all real time clocks on BMS

Prepare a calendar for plant operation

Alter plant control parameters on command from the keyboard (e.g. increase temperature set point)

Obtain and display data from the BMS, including controllers, on command or at time intervals selected by the operator.

Set up central facility and controller logging procedures.

Archive and/or delegate logged data.

Reset counters from pulsed input signals.

Reset limits or zero the count of run-time totalisation.

Training to be provided by the BMS provider in relation to respective ability and training schedule as specified in Tender documentation;

Plant Operators - Require 1 day's BMS training

Technicians - Require 3 days training

Facilities Management Level/Maintenance Engineers - Require 7 days training

All training is to be carried out onsite in a dedicated location, training for up to 3 people at any one time. With regard to the more advanced staff, the training to involve 3 days at BMS providers training facility prior to completing training on site.

System Operator Interface

In accordance with the Specification there will be a wide range of users, consideration is given to tailoring the interface to the needs of the different user groups;

Facilities Manager

Energy Manager

Security

Operations Manager

Building Services Maintenance Staff

BMS Servicing/maintenance staff

Operator interfaces to be easy and intuitive to use with a flexible system allowing operators to extract information without excessive manual input or time. Over-complex control strategies are to be avoided.

Specification is to be in accordance with interests of end users as identified within the Client brief to cater for the future requirements of operators. Information reported back to operators should be limited based upon operator knowledge levels and interfaces should be Building plant based rather than BMS network based.

Clear procedures identified for staff with "basic" skill levels and fine tuning of alarms required.

Plant schematics are to be included in the specification for ease of use with operator interfaces allowing direct export of monitored logged data to a spreadsheet and data base software.

Operator Workstations

Within the specification Operator workstations are to ensure;

Independent control of the operator workstation

No control data is transferred unless there is system integration as defined within the Particular Specification.

Integrity and communication between the field controllers in event of workstation failure.

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Appropriate control strategy configuration data can be downloaded.

Display and modification of each addressable field controller's control strategy.

Control parameters/strategies can be altered.

Plant operation times can be altered and data storage available for archiving data at pre-determined intervals with complete back-up possible allowing transfer of data from the system memory to other storage devices.

Data Management system allows for data storage/archiving at pre-defined intervals.

Complete back-up of control strategies, set points and logged data.

Allow the transfer of data from the system memory/other storage devices to the archive mediums, and vice versa for the preparation of reports.

Back-up data and selected files can be fully re-loaded

Description

BMS designed to control building engineering services in accordance with analysis of client requirements. (Annex C).

Control functions and routines to include;

Automatic cycling of actuators/facility to drive open and closed

DDC of Plant

Two position control

User control of plant

Control of individual plant items/cascading of control loops

Logic modules covering logical combination of digital variables-

Logic timer module

Logic feedback module

Logic counter module

Logic delay module

Logic hours run module

BMS to incorporate;

Frost/Building Protection

Optimum Start /Stop facility for with an automatic self-learning process the heating system

Plant Rotation (Rotational Point) Control-

This programme shall initiate the altering of the control point designation (such as duty/standby and lead/lag) on the basis of run hours, elapsed time and calendar basis under any one of the following circumstances:

On a calendar basis (e.g. weekly, monthly);

Once a predefined hours run total has been reached;

Once a predefined time is reached.

Sequence Control

Start/Stop Control -

Standby plant shall operate automatically on failure of duty plant. Controllers shall report plant failure alarms to the central operator station.

Controllers shall be capable of alternating the lead plant where duty and standby equipment is installed. This shall be achieved both by an operator command and on a time-scheduled basis.

Time Schedules/Time Control

Weather Compensation Control

Load Cycling Control

Monitoring of system and plant failure and alarm conditions

Occupancy Control of lighting combined with daylight sensing to improve energy efficiency.

The BMS shall include the number of operator stations specified.

Operator's station basic purpose is to display and format data and enable manual control function. Operator's stations shall take no part in any plant or global control functions.

Operator's stations shall not be used to transfer data between controllers on the communications network.

The software for carrying out specific tasks shall be backed up at the operator's station irrespective of whether the routines are normally held and operated from a controller or unitary controller. The operator's station shall have the ability to upload and download controller configuration data via the communications network.

Operator's station shall be configured to automatically attain full functional status following switch-on or restoration of power supply.

When a controller suffers a loss of memory, the operator's station shall automatically download all relevant stored configuration data to the controller.

This feature shall be selectable on a controller by controller basis.

Controller's software is modified locally, so that the controller software differs to that stored in the operator's station, the operators station shall indicate the discrepancy. Uploading the new configuration data from the controller shall be a manual, not an automatic operation.

Each operator's station shall have a real time clock which shall not be affected by power failure and which shall be synchronised with all other real time clocks on other operator's stations, controllers and unitary controllers, whenever a controller is brought back on line.

All real time clocks to be;

Synchronised on a daily basis with a nominated operator station.

Real time clocks shall contain the necessary firmware to operate unaided until date specified.

The operator's station shall be provided with a removable media back-up facility of suitable size, with a minimum of seven storage media units to allow daily back-up to be repeated on a weekly basis.

Failure during back-up will therefore not lose all data. The back-up facility shall be fully automatic, on a specified time basis, with the ability to manually backup system. It shall be possible to load selected files from this storage facility on to the operator's station.

Programming such as alarm inhibition, sequence interlocking, addition and deletion of points, shall be through the operator's station.

Monitoring and Targeting

The BMS system will incorporate monitoring and targeting functions in order to monitor the plant and equipment and to provide monitoring and targeting for the energy use and consumption.

Plant monitoring:

The BMS will incorporate functions to monitor the plant and equipment and will allow direct transfer to maintenance management software of;

plant run hours

number and frequency of plant starts

critical alarms requiring immediate attention

maintenance (non-critical) alarms

Energy monitoring and targeting:

The energy monitoring and targeting software will provide the following:

An Energy account centre within the Client's organisation.

Energy performance bench marks.

Monitoring of energy consumption.

Establishment of energy targets.

Reporting protocols for energy usage.

Monitoring and logging functions are to provide the facility to;

Monitor point data at operator workstations, ensuring analogue, digital and soft points can be displayed simultaneously.

Record changes by staff/operators.

Ensure real time data displayed upon plant schematics with a re-fresh rate of 20 seconds.

Display four real time data points simultaneously.

Allow monitoring/trending and display of common criteria/plant functions on the same page.

Ensure hard or soft point logs can be displayed on operator workstations.

Ensure logs can be set up from operator work stations and that logging times/intervals are adjustable between 1 second and 24 hours and each log can be defined in terms of point identification, units, date/time.

Back up data and ensure sufficient data storage capacity at the workstation, the equivalent of seven days data at 15 minute intervals for 50% of the total number of physical points on the field controller.

Allow the simultaneous display of different logged data which is operator adjustable.

Allow for export of logged data to other software packages in accordance with the requirements established from the initial client brief/particular specification.

Communication Protocol

The system communication will allow full transfer of monitored, logged, alarm, backup and configuration data between the operator workstations and the field controllers. In the event of a failure of the operator workstation the field controllers will fully function independently.

The communication protocol will endeavour to provide error free data transfer and will:

Include an error detection check

Include an error correction and/or re-try technique

Limits on re-transmission

Raise an alarm condition on communication failure.

Selection of communication protocol

There are a number of communication protocols which will be considered in order to achieve the above. It is proposed that an open protocol is utilised which will enable the interfacing of a wide range of systems, such as fire, security, bms. The use of an open protocol will future proof the installation by enabling extra functionality to the building as the business function develops.

A Local Area Network (LAN) will be installed throughout the building in order to connect the various components of the building management system and other systems such as fire, security and access control, telephone, lifts, lighting etc. To ensure that voice and data transmission is achieved the cabling used will be CAT 5e.

IT network

- security and access control

- CCTV and PA systems

- telephone network, paging and fax

- fire alarm and emergency systems (subject to Fire Authority approval)

- lifts

- HVAC

- lighting

- energy management

6 SYSTEM COMMUNICATIONS

6.1 GENERAL 1 Ensure that the system communications allows the full transfer of monitored, logged, alarm, backup and configuration data between the operator workstation and addressable field controllers.

2 Ensure that the communication protocol selected seeks to achieve error-free data transfer. Ensure that the protocol:

includes an error detection check

includes an error correction and/or re-try technique

limits re-transmission

raises an alarm condition on failure.

3 Ensure that the available bandwidth is sufficient to avoid excessive delays in transmitting data. Ensure that the maximum permissible time delay does not exceed that defined in the Particular Specification.

6.2 COMMUNICATION

DEVICES

1 Ensure that modems comply with BS 6320:1992. Ensure that the speed of modems complies with the Particular Specification.

2 Ensure that connections to telecommunication systems complies with BS 6701:1994.

3 Provide an ISDN link if defined in the Particular Specification.

6.3 COMMUNICATION

PROTOCOLS

6.3.1 Field-level protocols

1 Ensure that the selected protocol can:

run on the required communications media

provide a communications throughput sufficient for the intended application

provide appropriate network topology options

allow sufficient maximum physical segment length

allow sufficient maximum number of nodes for each physical segment and the logical network

provide sufficient maximum distance between nodes

make use of off-the-shelf network devices such as repeaters, bridges and routers

allow control devices to be powered from the network where defined in the Particular Specification.

2 Ensure that the protocol is compatible with fully developed network configuration and management tools.

PART A SYSTEM COMMUNICATIONS

6.4 DIRECT

INTEROPERABILITY

Systems exhibiting direct interoperability allow the direct transfer of data between systems without recourse to gateways.

1 Where direct interoperability is defined in the Particular Specification ensure that each of the protocol's objects and attributes are consistent with the achievement of the specified level of direct interoperability. Ensure that each of the protocol's arrangements for physical connection, data packaging, network management and error detection/correction are the same.

6.5 GATEWAYS A gateway is a device that converts between two or more system communication protocols.

1 Ensure that the gateway can:

transfer the specified maximum number of points

limit loss of functionality to the level specified

add functionality where specified

limit any time delay across the gateway to the maximum specified in the Particular Specification.

2 Ensure that the specified contingency and alarm measures in response to a failure of the gateway are met.

3 Ensure that the gateway can be modified in response to any future changes relating to the type and amount of data transferred over it.

4 Clearly define who has contractual responsibility for the implementation of the gateway.

Integration

An integrated control system is one in which building control systems are combined to allow the display of information at a common operator interface. Systems that can be combined within the BMS include:

- IT network

- security and access control

- CCTV and PA systems

- telephone network, paging and fax

- fire alarm and emergency systems (subject to Fire Authority approval)

- lifts

- HVAC

- lighting

- energy management

CIBSE Knowledge Series: KS4

Annex A

STATUTORY REGULATIONS AND GOOD PRACTICE

Ensure that the specification complies with all appropriate regulations in force at the date of the project including:

• Health and Safety at Work etc Act 1974

• Management of Health and Safety at Work Regulations 1992

• Construction (Design and Management) Regulations 1994

• Workplace (Health, Safety and Welfare) Regulations 1992

• The Working Time Regulations 1999

• Electricity at Work Regulations 1989

• Gas Safety (Installation and Use) Regulations 1994

• Personal Protective Equipment at Work Regulations 1992

• Health and Safety (Display Screen Equipment) Regulations 1992

• Other project specific regulations.

GOOD PRACTICE

Ensure that the following safety procedures are followed:

• Perform risk assessments and produce the resulting method statements.

• Personnel must receive adequate training in safety matters before working on site.

• Site personnel must be issued with, and use, appropriate safety equipment. For example: hard hat, safety boots, eye protection, ear defenders and overalls etc where appropriate.

• Isolate electrical equipment before working if live work is not necessary. Use locked-off and local isolators.

• Cordon off live electrical panels and display warning notices.

• Personnel should stand on rubber mats when working on live panels.

• Use an adequate safety barrier when working on live equipment.

• Use a 'permit to work' system.

• An authority to proceed is granted before work involving rotating plant.

• Where possible use two-man working. In certain conditions two-man working is mandatory, egg working on live equipment.

• A responsible person on site is aware of the location of the commissioning personnel and the nature of their work.

Annex B

Typical Norm Chart for Gas Consumption

Typical Deviance Chart for gas Consumption

Typical CUSUM chart for Gas Consumption

Annex C

Environmental Criteria/Client Requirements

(CIBSE Guide A Table 1.5, Page 1-9)

Analysis of Client Requirements from Brief (Part 1)

Project -Ref 001/10 Building Reference - Main Office

Prepared by Price/Bradley Consultants Date - 06/03/2010

PROJECT REFERENCE 001/10

LOCATIONS COVERED

Yes No

Is there an operational requirement for central monitoring or control?

X

Is there an existing BMS?

X

Is an existing communication network available

X

Can existing controls be operated and maintained

X

Have good housekeeping measures been applied?

X

Are building occupants satisfied with their environment?

X

Is there an opportunity to integrate controls of different engineering services?

X

Has the building function changed since BMS installed?

X

Is a central station required?

X

If Yes, state location

Energy Managers Office

State Site Energy Management Procedures

No records available

Are these to integrate with BMS

New controls philosophy will integrate Energy management procedures

Does Energy use compare with published guidelines?

Energy use comparable to BSRIA rules of thumb for a generic office

Is it required to re-charge building occupants for energy

Not applicable for this survey

Are consumption records needed for tariff analysis?

Consumption records will be required for future energy benchmarking

Are any locations subject to development

No major works planned, change of use unlikely

Is a portable keyboard acceptable to access BMS

X

Will security/reception staff operate BMS

X

Will dynamic display of plant and system layouts be required?

X

Analysis of Client Requirements from Brief (Part 2)

Project -Ref 001/10 Building Reference - Main Office

Prepared by Price/Bradley Consultants Date - 06/03/2010

Operational plant to be connected to BMS

Monitor

Control

Operate

Energy M & T

Importance

High = 3

Med = 2

Low = 1

BMS not required

Heating plant

X

X

X

X

3

Heating distribution

X

X

X

3

Cooling Plant

X

X

X

X

3

Cooling Distribution

X

X

X

X

3

Vent Supply

X

X

X

X

2

Ventilation Extract

X

X

X

X

2

Toilet Extract

X

Kitchen Extract

X

Car Park Extract

X

Smoke Extract Control

X

X

X

2

Fume cupboard extract

X

Fume Extract

X

Air Conditioning

X

X

X

X

3

Air Curtain

X

Hot and cold water services

X

X

X

X

2

Electrical supply

X

X

2

Electrical Distribution

X

X

2

Standby Generation

X

Operational plant to be connected to BMS

Monitor

Control

Operate

Energy M & T

Importance

High = 3

Med = 2

Low = 1

BMS not required

UPS

X

1

General Lighting

X

X

X

X

3

External lighting

X

X

X

X

3

Security access

X

Fire Detection

Alarm

X

3

Lifts and escalators

X

1

Catering

X

Annex C

Operator Station Equipment

General

The Operator Station shall comprise a personal computer, complete with monitor, keyboard and mouse. The Operator station shall include a printer. The operating system shall support integral memory management and self test diagnostic routines.

Monitor

Each Operator Station shall be supplied with a high resolution colour graphic monitor with a minimum resolution of 1024 x 768 pixels. The monitor shall comply with the latest international standards for electromagnetic emissions. The monitor and graphic card combination shall be capable of a screen refresh rate greater than 72Hz (non-interlaced) for all screen resolutions used by the system.

A text only display shall consist of 80 characters per line with 25 lines.

Keyboard

Provide a QWERTY keyboard with full upper/lower case ASCII

key-set, numeric keys and mouse.

Printers

Dot matrix

Each operator's station on the BMS shall be capable of supporting a dot matrix printer.

The printer shall not hinder the operation of the BMS. Where this occurs, sufficient buffer memory shall be provided to overcome this.

The printer shall have push-button selection of printing quality. The printer shall be able to produce draft quality and letter or near letter quality text.

The printer shall have a 132 column format capability. The printer shall be capable of using both continuous and single sheet stationery.

The printer shall be capable of supporting all such functions as enlarged, double width, double height and reduced size test available on all software installed on the BMS operator's station.

Any printer specified for fire and security alarms only, shall be of the two colour type - fire alarms red, security alarms black.

Laser

Each operator's station on the BEMS shall be capable of supporting a laser printer.

The printer shall have a resolution of 600 dots per inch (dpi). The printer shall have a paper tray capable of holding at least 100 pages.

The printer shall have a manual paper feed capability and be capable of accepting smaller than A4 items of stationery e.g. envelopes.

The printer shall have a minimum printing speed of 12 full pages of text per minute.

The printer shall have a cartridge toner system which shall be simple to remove and replace.

The printer shall be compatible with printer drivers supplied with the BMS operator's station.

Ink Jet

Each operator's station on the BMS shall be capable of supporting a colour ink jet printer. Where specified, ink jet printers shall be used to copy any required graphic screens together with all dynamic data, graphical trend log displays and support "Print Only" functions as required.

The printer shall have a minimum of 16 colours.

The printer shall have a minimum printing speed of 4 full black and white graphic pages per minute.

The printer shall have a minimum printing speed of 1 full colour graphic page per minute.

The printer shall have a cassette ink system, so that ink renewal is a simple operation.

The printer shall produce a true copy of the graphic display i.e. have a true to life aspect ratio.