Well, for example, a substantial fraction of our marketed energy use is devoted to heating and cooling (more than 50%); better building designs (like those from the Passivhaus program) essentially eliminate that, at a minimal additional construction cost. A lot of what's left is transportation; a switch from trucks to trains, plus bicycles and local electric public transit for short-distance people-moving, plus better streamlining and saner traffic control, would eliminate the majority of that. Your laptop uses maybe 15 watts; your car is maybe 300 000 watts at full power. It's not a matter of eliminating "modern technology" but rather developing and deploying truly modern technology that focuses on energy efficiency.
The idea is to keep the heat inside, not the air. Passive houses typically come with special ventilation systems that completely exchange the air once every 2-3 hours, while keeping >80% of the energy inside. This kind of design is becoming increasingly popular here in Germany.
Cool. I asked because there have been some problems with energy efficient houses in the Netherlands. People actually got health problems because the ventilation doesn't work well enough. Have there been independent studies of air quality for the houses in Germany?
I don't really know, and I don't speak from first-hand experience. But from what I've heard, the main concern is not air quality, but humidity. When you heat up air, its relative humidity goes down. So especially in winter, the ventilation system can blow very dry air into the building. There are simple technical solutions that artificially "humidify" the air, but it's definitely something to look out for. Low humidity can cause all sorts of health problems.
