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The Challenge of Part L (1/2/2007)

By John Bullock, John Bullock Lighting Design

Let's face it - no one wants to pay for their lighting. Regardless of how good the design may be, as soon as the meter starts turning and the lamps start failing, there's only one item on the agenda; how to lower costs. So the drastic need to reduce our energy footprint sits very comfortably with the technological progress made over the past quarter century. This article looks at the place where the light comes from - the lamp - because that's where our future lies.

Lamp developments have always been towards more light, more life and less power, and formidable progress has been made since the mid-70s. Then, we had no low-voltage tungsten halogen lamps to speak of, no compact fluorescent lamps, no fibre optics, and no LEDs. Spotlight fittings were as big as woks and the fluorescent tubes we did have were rubbish. Good grief - how did we ever manage?

It is worth noting that the first calls for a proper energy policy coincided with the first compact fluorescent lamps coming to market. At the time, only committed eco-folk were interested in using fluorescent lamps in their homes, and I doubt that anyone really foresaw the time when the government would legislate for their use.

That doesn't mean to say that everyone is happy about it, of course. I recognise three kinds of client; those who seriously care about regulations; those who mutter in protest but get on with it, and those who say 'over my dead body'. The third group are by far the most interesting, because they are the ones with the most to learn about the amazing level of technology now available to us.

The Building Regulations

So what do the Building Regulations actually say about lighting and energy saving? Let's look at the basics. There is a straightforward relationship between the amount of light that is produced by a lamp, measured in lumens, and the amount of power required to drive the lamp (and make the meter go round), measured in watts. Getting more light for your watt saves you energy and reduces the need for more power stations.

Ordinary tungsten lamps perform at about 10 lumens per watt (10lm/W). So a 100W light bulb delivers 1000 lumens. It's as simple as that. Tungsten halogen lamps are around twice as efficient as that, delivering around 20lm/W. Back in the 1980s, the tungsten halogen lamp was often advertised as an 'energy saving alternative' to the standard light bulb. Well, yes, I suppose so. But the big leap comes when you look at fluorescent lighting, which can be over eight times as efficient as a light bulb.

The Library at the Royal College of Physicians of Ireland in Dublin is lit using custom-designed chandeliers that use fluorescent tubes as the main source. The bookshelves on the gantry are uplit using a fluorescent linear washlight
(Designer: John Bullock, photographer: Jim Ashley-Down)

For dwellings, Part L of the Building Regulations calls for one in four lamps to be energy efficient, and it defines energy efficient as being better than 40lm/W. So you can see where they're going; all filament lighting i.e. tungsten and tungsten halogen lamps, fall outside of the criteria set by the Building Regulations. So where does that leave us?

Fluorescent lighting

Unless your client is a real tree-hugger, no one really wants fluorescent lighting. It doesn't do what filament lamps do. It's not as friendly and nowhere near as sexy. When you dim a filament lamp, it doesn't just get darker, it changes colour and even pretends to be candlelight. Maybe it's a hang-over from our cave-dwelling ancestors that we feel so attracted to such a basic idea, or is it just propaganda from the lighting designer?

Don't think the boffins haven't noticed this problem - contrary to popular opinion, they live on the same planet as the rest of us and are well aware of fluorescent's shortcomings.

The popular prejudice against fluorescent lamps is that they make you look like a zombie, they hum and flicker and give you migraines. It's an old argument and should have gone to the recycling plant along with the old lamps. The latest generation of fluorescent lamp, both linear and compact, have excellent colour rendering qualities, many can be dimmed, and their physical size makes them more user-friendly to the fittings designer.

The Entrance Hall at the Royal College of Physicians of Ireland in Dublin maintains its traditional 19th century appearance through the creation of special candelabra using clusters of compact fluorescent lamps in frosted tubes, mounted on a glass 'salver'
(Designer: John Bullock, photographer: Jim Ashley-Down)

LED lighting

Can fluorescent lights perform like a tungsten halogen spotlight? No, they can't. But we're looking elsewhere for the answer to that. We've all seen the startling advances made in LED lighting, all the way from a dim glimmer on the dashboard to colour changing washes of light across building facades.

Arts and Crafts House Dining Room: the original Voysey frieze around the top of the walls is lit using a miniature LED linear uplight. The physical size of the source and the small amount of light available from each chip makes this a perfect solution for such a situation
(Designer: John Bullock, photographer: Jim Ashley-Down)

But be careful, while the LED has been promoted as an energy-efficient device, its strength has actually been more to do with its ability to get light from almost nothing - albeit not sufficient light to do everyday tasks by. Indeed there is more than a bit of smoke and mirrors in LED promotion, and once the fog has cleared, you'll find that a good deal of the technology isn't much more efficient than a tungsten halogen lamp.

Nonetheless, the big companies developing LED technology have Part L in their sights, and we are now seeing the first Part L-compatible LED sources. They have broken the 40lm/W barrier and it won't be long before the low-voltage tungsten halogen downlight - that bane of the lighting designer's life - gets elbowed aside by its energy-friendly LED pal.

Arts and Crafts House, Picture Light: there has never been a better source to light wall-mounted artwork than the LED. Here, a linear arrangement of LEDs is located within a hand-wrought iron/steel frame which has then been burnished with beeswax to re-create the appearance of mediaeval armour. (Designer: John Bullock, photographer: Jim Ashley-Down).

Conclusion

Is that it then? Can we show how grown-up we are and plan 100% part L-compatible installations without compromising design quality? I'd say yes to that, but don't think that the technology has stopped yet. We've gone through a tipping point and there will soon be a whole lot of new technology to get used to.

Energy-efficient lighting, be it fluorescent, LED or anything else, must be controllable by using ordinary wall-mounted dimmers and it must produce a warm colour that is appropriate to home lighting. Anything else would be a bonus. We're almost there - there are a few companies making threatening noises that they can already do it, and 2007 may be the year it all kicks off.

(For all images - LEDs supplied by NJO LEDS Ltd, special fittings manufactured by Lighting Force Ltd).

John Bullock is the Principal of John Bullock Lighting Design, providing independent architectural lighting design and consultancy, as well as running courses on lighting design for architects, interior designers and other design professionals.

www.jb-ld.co.uk