A 1-megajoule lamp
You really can't make that much of any material for 1 megajoule, which made this lamp somewhat challenging. Anything that used a subtractive process was ruled out straight away as this would throw away some of the tiny quota. We looked for a formable material that would give the largest volume per megajoule. This led, rather confusingly, to concrete. We were under the impression that concrete was an environmentally reprehensible material because it counted for around 7% of global emissions. In fact, it has one of the lowest embodied energy and carbon figures. The issue is not with the material itself, but that we use an awful lot of it (approximately three tonnes for every person on the planet each year). By casting the concrete, we could squeeze as much functionality out of 1 megajoule as possible, making a form that could sit in a few positions or be hung on its hook - not quite the functionality of the anglepoise, but not bad for a tiny fraction of the energy.