Take Control of Light

08 December 2009

Lighting control plays an increasingly important role in helping organisations to reduce overheads and meet their sustainability objectives. Stephen Woodnutt explains why a more inclusive and sustainable approach is the best way forward

IN RECENT YEARS IT HAS BECOME increasingly accepted that controls for building services in general, and lighting in particular, are essential in achieving maximum energy performance. The reality is that it doesn’t matter how efficient an item of building services equipment is designed to be – it will only realise its full energy-saving potential if it is controlled effectively.
Lighting systems often waste a considerable amount of energy when they are not controlled effectively. A common ‘uncontrolled’ scenario in an office, for instance, is that people turn on the lighting in the morning and then forget about it through the day. Consequently, the lights remain at full light output irrespective of how much natural daylight enters the space, or whether the space is even occupied. The same can apply to common areas such as staircases and corridors and in warehouses where individual aisles are often unused for hours at a time.
Thankfully, such uncontrolled scenarios are increasingly rare. Regulations such as Part L of the Building Regulations, BREEAM and LEED have made it mandatory to include some lighting control in new build and major refurbishment projects while for larger users the CRC energy efficiency scheme and EPCs are of major significance.
Given all of these factors, it’s not surprising that the majority of new build and major refurbishment projects now include some level of lighting control while organisations seeking to reduce overheads and energy consumption are retrofitting controls to existing installations. However, there is still a long way to go, and the latest lighting management systems offer much more in terms of efficiency and sustainability. For example, where lighting management sensors are helping to control the lighting in relation to occupancy, it makes a lot of sense to relate heating/cooling temperature control to occupancy as well. In this way, temperatures can be allowed to fluctuate more widely in unoccupied areas, rather than trying to maintain precise comfort conditions in a space where there are no people. Once the space is reoccupied, of course, the design set-point temperature is restored – again through the lighting occupancy sensors. As a rule of thumb, this approach will save around 4 percent energy for every temperature degree saved.
In addition, there is now more scope to integrate lighting management systems with other networks and infrastructure in the building. Historically, a lighting control system has used dedicated wiring but high speed, open protocol technologies will allow integration with commonly used networks such as Lon or IP. As well as the savings on energy and installation costs, there are also significant materials savings by sharing the infrastructure in this way.
Daylight-linking is a very effective lighting control strategy. Dimming may also be used in situations where different lighting levels are required at different times – out of hours cleaning, for example.
One of the major breakthroughs in lighting control has been the DALI (Digital Addressable Lighting Interface) protocol which allows a high level of functionality and is proving to be very efficient. However, most DALI systems will still use residual power when on standby – so selecting the latest zeropower DALI systems will give even greater energy savings.
The ability to dim lighting is now spreading to areas where this hastraditionally not been possible. Warehouses, factories and retail ‘sheds’, for example, have tended to use high intensity discharge (HID) light sources such as metal halide and high pressure sodium. Historically, these could not be dimmed, so lighting was often left on all day with a significant waste of energy. Some newer HID lamps, though, can be dimmed so that these applications can take advantage of modern control strategies.
Incidentally, many of these buildings are switching from HID lighting to high output
fluorescent T5 lighting, a highly controllable light source that also opens the door to sophisticated control strategies.
One aspect of improved control is that the running hours of lamps are reduced, so they last longer and need less frequent replacement. However these benefits are not realised if lamps are changed in bulk on the basis of average lamp life. Consider the introduction of hours-run measurement, which identifies the optimum time for individual lamp replacement. This approach reduces maintenance costs, as well as the financial and environmental costs of lamp disposal.
Developers want to keep the initial capital outlay as low as possible, often opting for controls that meet the minimum requirements of the Building Regulations. Unfortunately, this arrangement may not meet the requirements of incoming tenants, who may discard the shell and core controls and replace them with a more functional system.
There are now systems on the market that not only deliver this level of functionality but also offer the potential to upgrade to a higher level of functionality simply by inserting a capsule into the standard controller. This could be an upgrade to DALI digital dimming, or to a fully addressable, integrated Lon system.
Modular capsule hardware also enables the benefits of future technology to be enjoyed without major environmental impact. Lighting control system hardware with modular intelligence can be upgraded to the latest technology through the insertion of a small intelligence capsule – all other hardware and cabling remains as before. In this way, systems some 20 years old have been transformed from proprietary, obsolete technology to open protocol, IP-enabled systems – all without change to the original installation.
Building in the maximum amount of flexibility from the beginning of the project will ensure that not only are the control systems designed for the near future but will also be able to continue to address the occupier’s needs through the life of the building.
● Stephen Woodnutt is Managing Director of Delmatic