Future Bulb less futuristic
Future Bulb less futuristic
The technology procurement competition for a replacement incandescent
lamp launched by the International Energy Agency's (IEA) procurement program
in 1997 never generated any entries that met the specification (see
IAEEL 3-4/97). The specification asked for a lamp that would work
and behave like a standard 60W incandescent (GLS) lamp but last at least
three times as long and consume approximately 30% less energy. Moreover,
it had to be competitively priced.
Although the specifications were technology neutral because they specified the function of the lamp, not the technical solution, it is generally thought that a manufacturer had to use incandescent halogen technology with an infrared (IR) reflective coating on the halogen capsule. This coating redirects heat back to filament, and heat is thus recycled and less power is needed to heat the filament to generate an equivalent amount of light.
The competition, asking for a "Future Bulb" was closed in the spring of 1998 without any qualifying entry. A little less than two years later, in late 1999, the specification had nevertheless challenged someone to come up with a working prototype. James Hooker, lamps editor of the UK-based magazine Lighting Equipment News (LEN) reported on how he and a small team built a prototype that met the specifications: the lamp could be operated on mains voltage (240 V in the case of UK) and it actually looked and behaved like a standard GLS lamp while using less energy and lasting up to four times as long.
The IEA project team had a functioning 120V prototype built before the competition was launched. It was based on a cannibalized American GE PAR reflector lamp that uses IR-reflective coating on the halogen bulb. This is, however, difficult enough to achieve at 120V mains voltage. At 230V it becomes even more difficult.
A tight fit
The LEN team realized that the specification could be met by taking advantage of the fact that the efficiency of a filament lamp increases as the voltage is decreased, reaching a maximum value at around 12V and then diminishing again. The LEN team now decided to explore the possibility of building a 12V, 50W IR-reflective coated capsule into a conventionally shaped GLS bulb.
Shortly after the IEA specifications were first presented in 1997, both Osram and Philips had unveiled low-voltage halogen reflector lamps (MR16) based on IR-reflective coating technology. It was this sort of capsule that the LEN team decided to use. Obviously, a 12V lamp needs a transformer of some sort to operate on mains voltage, and this had to be tiny to fit inside a GLS envelope. The LEN team could find no such product on the market, and after consulting a number of transformer companies they settled on an electronic micro-transformer.
The nice thing about the arrangement was that the whole package, capsule and transformer, was so small that it would fit into a lamp that was actually smaller than a standard GLS envelope. Again, an Osram lamp was cannibalized: the transformer and halogen capsule were crammed into the envelope of OsramÕs newest and smallest 5W GLS-shaped compact fluorescent lamp.
100 W equivalent
The result was a lamp that draws 50W, lasts 4 000 hours and performs just like any consumer would want it to. It has a color-rendering index of 100, white color temperature of 3000K, doesn't flicker, comes on to full power instantly, and is fully dimmable.
The lamp wouldn't save quite as much power as a CFL, but it gets pretty close, slashing electricity consumption from 100W to 50W. According to LEN, the lamp had a power consumption of 52W and a measured flux of approximately 1200 lm, which gives it an efficacy of 23 lm/W - not bad for a mains voltage incandescent lamp. It should be noted that a 60W equivalent would be less efficient, since efficacy tends to fall with decreased lamp power.
And the drawbacks: So far, only one single prototype has been built -
by the LEN team (a magazine with no ambition to produce lamps to IAEEL's
knowledge). And no manufacturer has been interested in picking up the
technology. "The IRC technology is still far too expensive for a
moderately priced consumer product," says James Hooker of LEN. "Philips
Master PAR lamp, which is very efficient and is based on the same idea
with an integrated transformer, doesn't sell very well, and they are going
for a high-value professional market."