Rising to the energy-efficiency challenge
A 40% reduction in lighting bills is the expected benefit of high-efficiency luminaires and an Ex-Or integrated managed lighting system installed as part of a £1 million refurbishment of the Cliftonville House headquarters of Northampton Borough Council. The new lighting also provides much more comfortable lighting for the 600 people working in this 1970s 2-storey office block. The lighting scheme has been future-proofed to accommodate changes in layout and working patterns in the o pen-plan areas.
NEIL JONES examines the philosophy behind the use of controls to realise better lit buildings and lower energy consumption.There is still confusion and continuing debate over the Energy Performance of Buildings Directive, the European edict designed to increase investment in energy-efficiency measures in buildings. The timescale of implementation, methods of calculating energy use, type of certification required, how the rules will be enforced — none of these factors seem to be set in stone yet, at least in the UK. However, the construction of new buildings, and the refurbishment of existing ones, will not wait for the planners and legislators to dot the i’s and cross the t’s of the new directive. Architects, designers and specifiers need to ensure they are already incorporating sustainable and energy-efficient equipment and systems into current projects that will help meet the obligations imposed by the new directive. Responsibilities
The correct use and control of lighting will play a very significant role indeed in helping building owners and users meet their energy-saving responsibilities under the directive. Before taking a detailed look at the contribution lighting can make, let us set the scene for the Energy Performance of Buildings Directive. Published in 2003, its intention is to greatly increase awareness of the amount of energy that is expended during the day-to-day use of commercial buildings such as offices. There are 160 million buildings in the European Union. They account for 40% of Europe’s total energy consumption and 40%t of Europe’s carbon-dioxide emissions. Under the new directive, a calculation of overall energy use will have to be made for every commercial building. The calculation will cover space heating and cooling, ventilation, hot water and lighting. Far too often, lighting is the last thing to be considered when identifying both energy waste and opportunities for saving energy. However, lighting actually accounts for up to 25% of all emissions from commercial buildings. In the UK, the implementation of the new directive will be via Part L of the Building Regulations, which covers the conservation of fuel and power. Revisions to Part L were published in April 2006. Part L states that lighting controls for general lighting in all types of spaces ‘should be provided so as to avoid unnecessary lighting during the times when daylight levels are adequate, or when spaces are unoccupied’. Obligations
If unnecessary use of lighting can be eliminated, and the maximum use can made of natural light to offset electric lighting, any commercial building can be on target to meeting a quarter of its energy-saving obligations, before ‘big-ticket’ energy items like heating and air conditioning need even be considered. The Energy Performance of Buildings Directive says a methodology needs to be in place which calculates the energy performance of buildings. This must include information about every built-in lighting installation. It also says the positive influence of natural lighting must be taken into account in this calculation. What considerations should architects, designers and specifiers take into account in current new-build and refurbishment schemes to ensure that lighting has a real impact on these Energy Performance of Buildings Directive calculations?
| The Carbon Trust, an independent company set up by the Government to help meet its climate-change obligations, has installed an energy-saving automatic lighting-control system. The Ex-Or system switches lights on and off in response to the presence of people and the availability of natural daylight. |
Obviously the specification of the latest low-energy luminaires such as LG3-compliant T5 luminaires is vital. These feature thinner tubes and efficient reflectors to concentrate the light output to the working plane. They are more efficient than older types and deliver a higher light output, significantly cutting the amount of electricity needed to provide a given illuminance. But the most energy-efficient luminaire of them all is the one that is switched off when it is not needed. Automatic lighting-management and control systems are specifically designed to switch off or dim individual lights or designated lit zones whenever levels of natural light are sufficiently high or if occupants have vacated the monitored area. Taking control
Lighting-control systems range from basic timer-based systems to complicated methods involving lighting control integrated with building-management systems. Light fittings themselves are controlled automatically. Light fittings represent a large number of small loads, distributed through the whole building, so lighting controls need to be both cost effective and discreet. A variety of detection technologies is used to continuously monitor the working areas and detect the slightest movements that signify occupants are present passive; they include infrared, microwave and ultrasonic. Photocells are built in to measure the natural light available and tell the luminaires whether or not to switch on and at what brightness. Combined presence detection/photocell devices are delivering proven performance in office and commercial buildings throughout the country, often controlling areas such as corridors, stock rooms and meeting rooms. Energy savings of 40 to 60% are usually achieved in typical office applications. For integrated and intelligent building-wide lighting control, a managed lighting system offers the most efficient, cost-effective and installer-friendly solution. A managed lighting system allows groups of luminaires to be individually controlled in pre-determined work zones, in an open-plan office for example. Detectors associated with luminaires can swap occupancy information — useful for delivering the correct level of lighting to occupants in work zones and holding lights on automatically in key circulation areas and corridor routes. Think of it as creating the ability for an entire building’s lighting system to think for itself and make intelligent decisions about the optimum delivery of light. A managed lighting system can be further enhanced with, for example, a scene-selection capability to enable occupants can choose, at the touch of a button, previously set lighting scenes to best suit the current use of the room. An office could be brightly lit for cleaning, then lit at a low level for an audio-visual presentation — for example. Simplicity, ease of use and reliability should be the watchwords of lighting management and control. In an ideal situation, building users should be unaware that a lighting-control system is in operation because lighting levels are automatically set at the optimum level. It is clear, therefore, that automatic lighting control can deliver real energy savings and a significant push along the road to meeting Energy Performance of Buildings Directive obligations. However, let us not lose sight of the fact that automatic lighting control already guarantees compliance to legislation that is on the statute books now — including Building Regulations, health-and-safety legislation and display-screen equipment regulations. People
Remember, too, that commercial buildings which rely too heavily on the use of artificial light and do not exploit existing levels of ambient light can impact in a negative way on the productivity and performance of people working in them. Automatic lighting control delivers the most productive lit environment for occupants. Most organisations recognise that, ultimately, their employees represent the largest proportion of total building running costs, so that even small increases in employee productivity can significantly enhance their bottom line. Neil Jones is managing director of Ex-Or Ltd, Haydock Lane, Haydock, Merseyside, WA11 9UJ.