Social housing supplement Lighting
Shining light on technology
Electrode-less fl uorescent lights: Offers effi ciencies
similar to conventional tubes; suitable for large spaces in non-domestic settings.
Metal halide lights: For high brightness applications; generates excessive heat; requires complex electronic ballasts; incompatible with occupancy sensors. In electrode-less plasma lighting, radio frequency excitation of the metal halide salt can produce light more effi ciently. Directional output can be used to realise useful energy savings; domestic versions are said to be in development and timing and likely pricing are not clear.
lumens per Watt, but they might not be very effective in task-lighting, such as for reading or preparing food. Issues with early LEDs include low brightness and
poor colour rendition, which made them unsuitable for illumination applications. But white LEDs are now comparable in effi ciency with fl uorescent tube lighting, and there is no hazardous waste issue with LEDS. But in lamp format, it is tough to conduct heat away from the LED chips, compromising both effi ciency and lifetime. In the last couple of years, commercial and high-
end residential projects have used LED chips built into dedicated light fi ttings. LED thermal management and performance (light output, lifetime) can be optimised by integrating LEDs within the luminiare. This offers higher system effi cacy and typical projected lifetimes of 50,000 or more operating hours (lifetime being defi ned as a drop to 70 per cent of the initial light output – a change barely detected by the eye). Until about six months ago, LED lighting was considered
too costly for homes. Today, in many cases, there is cost- parity with code-compliant CFL downlights. LED lighting was installed in an award-nominated Decent Homes refurbishment of 54 fl ats in Danesthorpe, Doncaster, by Chevin Housing Association last year. Maintenance had been identifi ed as a key concern for residents, coming top of tenants’ priorities in an informal consultation. Although the lighting products were initially more expensive, Chevin calculated that it would make worthwhile long-term savings because of reduced callouts to replace fixtures and fittings. Tenants would also benefit from operational savings. Chevin is monitoring maintenance savings, with an eye to rolling out dedicated LED fi ttings throughout its stock. Now white LEDs are poised to take over the majority of lighting tasks in the next fi ve to 10 years. They have a number of strong advantages and are already delivering a competitive solution in retrofi t and new-builds. Trials are being carried out in communal areas of social housing in England, with support from an Environmental Transformation Fund programme being administered by the Energy Saving Trust. The TSB’s Retrofi t for the Future programme embraces
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A stairwell at Cavendish Mill, an apartment block owned by New Charter, before and after LED luminaires were used as part of trials to test the technology.
Electron stimulated luminescence lamps: Replicate
incandescent refl ector lamps; accelerated electrons stimulate light emission from phosphor coated inside the lamp; still a prototype. Projected to produce around 600 lumens, require less than 15 watts of power to replace a 60 watt refl ector lamp. The colour rendition is expected to be very good and they offer instant-on capability, with dimming capability said to go all the way down to zero per cent.
Thin-fi lm, doped silicon oxide emitters of red,
green and blue light: To replace traditional tungsten fi lament; details of projected performance are scant; prototypes not expected until next year.
OLEDs (Organic Light Emitting Diodes): Still in
developmental stage; concerns over absolute levels of light output; questions over lifetime.
“This restriction to two types of low energy lamp shows a lack of ambition for further, cost- effective energy savings”
Micro-plasma panels: Similar to plasma TV screens; homogenous white light can be produced, depending on phosphor; claimed output of 30 lumens per watt currently is ultimately projected to rise to 100 lumens per watt.
Light panels: Developmental stage; may exceed 100 lumens per watt; not expected to be very effective in task-lighting, such as for reading or preparing food.
a number of projects that incorporate LED illumination solutions. It’s true that there are cost issues with LEDs. CFLs are generally available with a continuing subsidy in place, such as the Carbon Emissions Reduction Target (CERT) scheme, but there is no such subsidy available to support the introduction of LED lamps. Yet prices are falling. The April issue of Chemistry World, published by the Royal Society of Chemistry, reported that LED lamps intended to replace 60W incandescent bulbs were $100 (£66) last year. They are more like $50 (£33) today. Following a very similar price trajectory, one can purchase
a complete integrated LED fi tting with better performance. It is in this retrofi t and new-build context that LEDs have their place today. Fittings that cost £20 could be achieved with a possible CERT subsidy, increased performance and growth in scale. ●
Robin Morris is a sustainable technology adviser at solid-state lighting designer and manufacturer, PhotonStar LED Ltd.
June 2010 CIBSE Journal
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