Finding an energy-efficient air purifier technology that actually works can be a tricky proposition. Most purifiers use ionizers that generate ozone or have HEPA and carbon filters that require inefficient fans that run constantly. Oh sure, you could try to keep toxins out of the house in the first place, but if you should find yourself living with a cigar-smoking roommate with a humidor made from non-CARB-compliant urea-formaldehyde particleboard (and, honestly, who hasn't?) and happen to be searching for a purifier, what are ya gonna do? As we look to the future of air-purification technology, maybe we need to take a look back to the Middle Ages for a possible solution. Zhu Huai Yong, from Queensland University of Technology, studied medieval stained glass and found that windows colored with tiny gold particles work as a "photocatalytic air purifier with nanostructured gold catalyst" (see article in Science Daily). When sunlight hits the windows, an electromagnetic field is formed that destroys volatile organic compounds, with only small amounts of CO2 as a by-product. Sure, gold mining is an environmental disaster, the long-term environmental impact of nanotechnology is unknown, and the frames of the stained glass windows were probably lead, but still — this is as viable as some air purifiers we've seen submitted to GreenSpec! Now if someone can market a cost-competitive, triple-glazed, krypton gas, low-e version with a U-factor of 0.20...
