on lighting, technology and behaviour

Have you noticed that in the past decade or so as low energy light bulbs (compact fluorescent, CFLS) have become more prevalent the total number of lights you see have increased? Where once we were happy with a single bulb dangling in the centre of the room and one or two lamps dotted strategically about we now expect illumination in every corner as we up light, down light, mood light and spot light ourselves out of the darkness.

This phenomena is particularly prevalent in new homes. I have observed in one case a tiny kitchen that could not have been more than 2.5m2 with a grand total of 9 recessed ceiling lights. How can a low energy home have so many lights? Oh it’s alright the nice man told me, they are all low energy. So quick and dirty calculation: one 100w incandescent bulb of olden days (ok it was probably a fluorescent tube in the kitchen but I never said this was going to be exact) has been replaced by 9 low energy bulbs. If we assume that the new super dooper low energy lights were about 12 watts each then 9 x12 = 108 watts. And what happens if you factor in the manufacture and installation of the additional fixtures. Hmmm? Efficient?

So I was interested to read a paper on lighting, new efficient technology and the rebound effect (Tsao et al 2010).

For the past three hundred years, and many technological transitions and advances in efficiency, artificial lighting has consumed an estimated 6.5% of world primary energy and an estimated 0.72% of world gross domestic product (Tsao and Waide 2010). This equates to the consumption of roughly 16% of the world’s total electrical energy generation in 2005 (EIA 2009).

The authors conclude that the consumption of light increases as cost of light decreases. But consumption of light also mediates an increase in GDP, and this also causes consumption of light to increase. And increased consumption of light also has the potential to increase both human productivity and the consumption of energy associated with that productivity.

Furthermore, new performance attributes associated with new technologies have the potential to unleash new and unforeseen ways of consuming light further increasing the consumption of light.

So, if history is a guide, the potential for reduced consumption of light from new technologies such as solid state lighting (SSL) may, as has happened during previous technology transitions, ultimately be dwarfed by the potential for increased consumption of light.

The conclusions suggest a subtle but important shift in how one views the consequence of the increased energy efficiency associated with new lighting technologies such as solid state lighting (SSL) is going to be required if the efficiency is to be realised as an overall reduction in total energy demanded and bucking the trend of three hundred years of history.

To continue to view such technological decreases in energy consumption without consideration to the actual consumption of light is too simplistic and misguided. We need to factor in the effect such technologies may have on human productivity and quality of life. In short we need to not only engineer a change in the technology but also the expectations and behaviour associated with its consumption concomitantly.

Mood lighting anybody?

J Y Tsao, H D Saunders, J R Creighton, M E Coltrin and J A Simmons 2010: Solid-state lighting: an energy-economics perspective. J. Phys. D: Appl. Phys. 43 (2010) 354001 (17pp) doi:10.1088/0022-3727/43/35/354001

EIA 2009 Annual Energy Outlook 2010 Early Release Overview http://www.eia.doe.gov/oiaf/aeo/) Energy Information Administration

Tsao J Y and Waide P 2010 The world’s appetite for light: empirical data and trends spanning three centuries and six continents LEUKOS 6 259–81