Monday, January 22, 2007

I've seen the light!

A few weeks ago, I saw an article on Energy Saving lamps by Seth Godin, a Marketing Guru who is a prolific writer and presenter. In the blog, he questioned why so few American households had even one compact fluorescent lamp in their house.

(Notice that I call them Lamps rather than light bulbs. At a very early age, I had it drummed into me by older and wiser theatre electricians that bulbs were things you planted in the garden).

Read the article, then return if the whimsy takes you and read on... (shift + click keeps this window open whilst you are gone)

The humble light bulb (oops, lamp) works by the heating effect of a current. The filament reaches a high enough temperature to glow but not high enough to melt. Lamps have one main purpose in life- to emit visible light. Your average 100 Watt lamp is surprisingly Cak at this, converting the power used to roughly 97.5% heat, 2.5% light. The efficacy of a lamp is expressed in a rating known as lumens per watt and a typical figure for a domestic lamp is about 15. (A lumen is a standardised unit of measurement that replaces the more quaint candle-based measurements in the sam e way that car engine ratings are in DIN kW rather than horse-power). Without getting bogged down in maths, it can be seen that the better the lumens per watt rating, the more efficient the lamp.

Conventional lamps with tungsten filaments can get up to roughly 25 lumens per watt, particularly if they use Tungsten-Halogen technology. Some specialised lamps such as photo-floods can emit much more than this, but at the expense of lamp life.

Standard fluorescent tubes are much more efficient than regular lamps because they work in a different way. A mercury vapour arc is struck down the length of the tube in the same way as a neon tube, however the arc emits invisible ultra-violet light and the coatings on the inside of the tube fluoresce, i.e. convert the UV light to visible light. Florry tubes are typically 80 lumens/watt. So why don't we fill our houses with them?

Well, the simple answer is that we hate them outside of the kitchen or workshop, because their light is somewhat contradictory- whilst suitably soft regarding shadows, the colour rendering has traditionally been hideous and they make a cozy living room look bleak and institutional.

So, Seth Godin, this is one very big reason why the Merkins don't stampede towards compact fluorescents- for the same reason that they wouldn't put a twin 5' tube in their lounge, it ain't nice.

Compact fluorescents are the same principle as their big brother tubes but with electronics to regulate them rather than a simple choke/starter circuit that most florry fittings have included.

Another nuisance with florrys is that they can't be dimmed in the conventional sense. It isn't impossible- indeed the Newcastle City Hall had dimmable tubes in the ceiling laylights with a sophisticated push-button Thorn control. You had to use a special tube which was basically the same but it also had a metallic strip that linked the two end caps in order to earth it better. With ordinary tubes fitted, the arc would spiral around the electrodes inside the tube giving a visible swirly effect with the lamps on check. It also needed special control gear which kept the electrode heaters on at all brightness levels. The dimmer was somewhat of a "partial success" as when it reached about 40% it would chatter the relays and make the lights flicker to full somewhat alarmingly, an effect familiar to thousands of Geordie Concert-goers during the 70s.

The other downer with a compact florry is the length of time it takes to reach full brightness- particularly awkward on hall stairs where you can end up going upstairs in gloom and it isn't a decent level until after you actually need it any more.

The other downer with the lamps is that they are somewhat longer than a regular lamp, so their optical centres are generally not aligned properly in many light fittings, making them look a bit silly.

Sometimes you want a soft light source, sometimes a sharp one, compact florrys don't do sharp, sorry. Morley Town Hall suffers from this.with the large impressive electroliers which have lost their sparkle by having been relamped with inferior units. When Newcastle Odeon was open, the Chief would rather relamp the foyer fittings with long life clear regular lamps than succomb to energy efficiency because with florrys in, they lost their sparkle and looked extremely lacklustre.

Having condemned them, now let me praise them. All of our lamps at home are compact ones, with the exception of two bedroom pendant fittings and a large lounge uplighter (which are all on dimmers). Their colour rendering and warm-up times have improved dramatically in recent years and the range is much wider, although some brands are better than others. However, the comparable brightness figures need to be taken with a pinch of salt and I am yet to be convinced that a 23W compact is really equivalent to a 150W general lighting service filament lamp and domestically, 23W is as bit as it gets in B&Q.

However, I have found a source of 30W spiral lamps (in both daylight and warm white) which will be great for the kitchen table (jigsaws anyone?). There is even an 80W version available that will be great for the Garage. A couple of our home lamps are slow or have a very odd pinkish-tinge whilst warming up and one of them even turns itself off randomly so it is time to buy a few more.

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