And designers can build them into the structure of everything from buildings to furniture to fashion.
As lighting grows more varied and ubiquitous, the sum total of energy consumption could wipe out all the energy saved by switching to more efficient sources in the first place.
"However good your energy efficiency gain, there is a danger people will then take that gain and use it on additional services that they didn't have available to them before," Porritt said in a keynote presentation at the LuxLive 2012 lighting exhibition in London.
"If you look at the whole history of lighting, it's clear that efficiencies are increasing all the time," said Porritt, who is co-founder of sustainability group Forum for the Future.
In response to a question from the audience, he added, "We are beginning to move into a whole suite of lighting technologies where lighting will be used as much for mood enhancement - or as you say, 'vanity projects' ... You can see the rebound effect gather in the wings here.
"What if all that (efficiency gain) gets gobbled up as we decide there are other uses of lighting that we can really take advantage of. That's a really big dilemma. I don't think the industry is hugely aware of that as of yet."
Actually, the industry is aware of it. One executive from a leading international lighting vendor who asked not to be named told me that Porritt's "rebound" effect, "Does raise the question of how much energy do you really save. Where is the energy saving - that is a question."
This is not an unsolvable puzzle. Your answers welcomed below.
Photos: Tower Bridge by Jason Hawkes via GE/Reformer Films. Jonathon Porritt by Slowlife Symposium via Flickr Creative Commons.
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