How to make light work of reducing carbon emissions
Simply replacing older-generation lamps with newer Eco versions can achieve energy savings of up to 20%.
40% can be lopped off carbon emissions associated with lighting — using current technology. Mike Simpson runs through a range of approaches.It is impossible not to be aware of the issues currently relating to climate change. Whether you believe the science or not, there has been a steadily increasing concentration of CO2 in the atmosphere. This is due to many factors, some natural and some manmade — but the highest cause is the production of electricity. Lighting is estimated to use 19% of the total electricity generated globally (14% for Europe) and the estimate is that there are potential savings of 40% on the current lighting stock. That is equivalent to 555 Mt of CO2 per year. This is achievable with current technology and with little negative effect on the user. We are not talking about downgrading design practice or reducing levels. The latest technology will deliver these savings without a compromise. Alongside these CO2 savings are reductions in cost of ownership due to the reduction in electricity used throughout life. An estimate is that of the energy used by lighting from cradle to grave, 90 to 95% will be in operation. So if we can reduce the operational energy use then significant monetary savings can also be made. There is a double win — save CO2 and save money. Potential savings fall into two categories — things we can do now and things that will be possible in the future. With both of these, the aim is to retain the quality of the lit environment.
Lamp replacement Simply replacing older generation lamps with newer Eco versions can achieve large savings. If you are using 26 mm (T8) lamps then 15% savings are up for grabs; if there are still 38 mm (T12) lamps in use the savings are 20%. Using high-frequency ballasts in fluorescent luminaires should be standard practice, but still many new luminaires are installed using copper/iron technology. Possible savings here can be up to 25%. Making a complete switch to 16 mm (T5) lamps can yield savings of up to 60% For display applications the latest versions of dichroic reflector lamps can save 40% of the energy compared to older types and give extended lifetimes. In the home we can replace conventional tungsten lamps with compact fluorescent and achieve savings of 80%. With decorative applications like chandeliers, the new plug-in halogen lamps will save 50%.
Controls One simple strategy is to introduce lighting controls. This will ensure that lights are not left on when the office is unoccupied, controlled to take account of natural daylight and switched off if an area is unoccupied. If a correct lighting control system is used, there are potential savings of an incredible 69% over the installed load. Very often such control systems are installed but not fully understood by the user, resulting in the lighting being left on unnecessarily. A new initiative launched by BSRIA called ‘Soft landings’ aims to improve the operation of installed services by introducing a phased handover to the client.
Using solid-state lighting, the facade of Buckingham is illuminated with a load of just 2.7 kW.
Many existing technologies available today can help to achieve these targets; what is needed is faster adoption. Some of the headline figures of what is available today are listed below. • In the UK we use an estimated 147 million tungsten lamps every year. Replacing these with low-energy fluorescent lamps would reduce CO2 emissions by 5 Mt per year.
• In retail, we can replace old-fashioned reflector lamps with small compact metal halide versions and save 115 000 t of CO2 per year.
• Replacing every halogen dichroic lamp with an LED equivalent will save 15 kg of CO2 per year.
• In the office just replacing existing T8 lamps on copper control gear with T5 on high-frequency gear would save 385 t of CO2 per year.
• In road lighting, we can replace some five million lower-power sodium lamps by a more efficient white light. This would yield savings of 34 000 t of CO2 per year and deliver better quality lighting. A crude calculation from the above shows at least a 6 Mt of CO2 savings a year are possible now. For the future we can look to solid-state lighting making a significant impact on energy use in buildings. Many buildings are already using this technology for their exterior lighting, with the façade of Buckingham Palace having a load of just 2.7 kW. Reflector lamps based on LEDs can replace a 20 W conventional lamp with a power of 11 W. And downlights using an LED light engine can make savings of 30% compared to compact fluorescent lamps. At the low end of the scale we can also see conventional look-alike bulbs appearing for the domestic market. We are now seeing practical LED solutions for road lighting and demonstration projects in offices. It is clear that although conventional light sources will not disappear overnight, solid-state lighting will be significant in all applications in the coming years. One further thought relates not to product innovation but design. Typical practice is to design to the task illuminance over the whole floor space. In practice it is needed over 1 m2 of desk where the task is. In a typical office this could mean that 60% of the space is being over lit by 100%. Greater thought to the design process and installing localised task based lighting will generate further CO2 savings. Many of the savings described are available today. The sooner they are adopted the sooner we can slow down the increase in CO2 emissions that result from lighting.
Mike Simpson is design and technical director with Philips Lighting and a vice president of CIBSE.
Energy can be saved in the home by replacing tungsten lamps with compact fluorescent and using plug-in halogen lamps in decorative applications like chandeliers.
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