Delivering the sustainable promise
While the industry is still coming to terms with the full impact of Part L of the Building Regulations, introduced in 2006, it is now facing new rules on long-term energy use in buildings.
Part L requires that buildings are designed and constructed to high standards of energy efficiency and air tightness. This has to be proved with air tightness testing and calculations to show projected and as-built energy consumption when the building is handed over.
The Energy Performance of Buildings Directive (EPBD) goes further, and introduces the notion of energy labelling for commercial and domestic buildings. In 2008, the UK will introduce building labels for commercial buildings, both private and public sector.
Both Part L and the EPBD put responsibility for energy use firmly in the hands of building occupiers and owners. They recognise that is little point having a well-designed building if it is not operated properly because the promise of the design objectives won’t be delivered. And with the extension of the EPBD to non-domestic buildings next year, building owners will really want to know how much energy their building consumes, and how it can be run more efficiently.
This is where building management systems prove themselves invaluable. In fact, Part L does state that all systems should be provided with appropriate controls to ‘allow reasonable levels of energy efficiency to be achieved in use’. It highlights the following features:
- Use of separate control zones for each area of the building that has a different solar exposure, pattern or type of use.
- Each zone must be capable of independent timing and temperature control – and, where appropriate, ventilation and air recirculation rate.
- Services should respond to the requirements of the space – for example, controls should ensure that heating and cooling do not operate simultaneously in the same space.
- Central plant should only operate when needed by each zone. The default condition should be ‘off’.
All buildings greater than 1000m² will have to include automatic meter reading and data collection. Energy meters will have to be set up so that they can identify at least 90% of annual energy consumption by end-use categories, such as lighting, cooling or heating.
John Fallon, Product Marketing Manager for Cylon Controls, says: “The building management system will provide the information backbone for remote meter reading. Monitoring and targeting can be integrated with a BMS to help deliver a full energy management system.”
A number of recent developments in building energy management technology are helping to deliver information on building operation where it’s needed. For example, web-enabled building controls reduce the need for training on complex software and give maximum flexibility. Remote access also means there is no longer a single dedicated BMS workstation. Everyone who needs the information – facilities managers, the maintenance team and increasingly the finance department – can get it quickly and easily.
The cost of BMS installation for energy management is also falling with greater use of wireless systems. They reduce time-consuming installation works such as wiring or cabling, and most modern wireless models do not require batteries so maintenance is reduced.
Building management systems are also very important in buildings where some element of sustainable or renewable energy is being used in the services, or as part of the design. For example use of some form of natural ventilation is being considered more often, either on its own or in combination with some form of mechanical cooling. For any type of cooling strategy which involves natural ventilation, the control system is a vital element.
John Fallon comments: “Where natural ventilation is used, the viability of this solution will depend on how closely a variety of parameters can be controlled. This is a challenge for building services engineers, because to achieve optimum performance they must juggle a range of elements. These include motorised blinds and windows, lighting and mechanical plant.”
Cylon recently installed a controls system at the Galway/Mayo Institute of Technology (GMIT) which utilises natural ventilation. The library at GMIT is a two storey building with three atria located centrally, creating a stack effect. Outside fresh air is induced through low-level dampers passing over temperature controlled finned tube heaters. These pre-heat the air when necessary. Exhaust air leaves the library through dampers at roof level which contribute to the stack effect.
The building management controls the dampers, as well as radiators for winter heating. Temperature is given priority in the control system but once the 21ºC set point has been reached this switches to CO2 levels. These are set at 500ppm maximum. In addition to tracking internal factors, the BMS also controls inlet damper settings in relation to wind speed, measured by a weather station on the roof. The building is in the line of strong westerly winds which have the potential to create strong draughts and noise so dampers are closed as wind speed rises.
This building highlights the importance of building controls where a number of different external and internal environmental factors must be balanced to achieve optimum performance.
Every building services engineer knows that any building, whether naturally ventilated or highly mechanised, is a dynamic environment. Occupancy patterns change, settings drift, new equipment is installed or manual intervention turns off plant. The BMS is the brains of a building, and can help to monitor what is happening. The traditional functions for a BMS are scheduling, monitoring and managing building services. In future the BMS will also become the information system for energy management.
Fallon believes that energy management in a building is a dynamic process; that BMS can help to bring about changes in behaviour as well as controlling it: “The introduction of building management systems enable real change in the operation of building systems. BMS can be used to monitor the effectiveness of change so that a well-managed BMS not only provides key information, but also allows it to be actioned.”
If you would like to find out more about building management systems and their importance in energy efficient buildings, come along to the free seminars at this year’s M&E Event taking place at London Olympia on 10 – 11 October.
Go to www.buildingservicesevent.co.uk to sign up for the free seminars.