The construction and operation of buildings takes about 50% of all energy consumed in America. Making buildings more energy efficient will have a much larger impact on our carbon footprint than making cars more fuel efficient. In thinking about how to make buildings more energy efficient, there are three areas to focus on, and they should be addressed in this order:
- Site: Use the site to minimize climate loads on the building (low to zero cost)
- Envelope: Use a high-performance envelope to minimize the climate loads that get through to the conditioned space (medium cost)
- Mechanical Systems: Use high-performance mechanical systems to efficiently deal with the climate loads that do get through (high cost)
It makes no sense to site a building on top of a hill where it is buffeted by winter winds, and then put an expensive mechanical system in it to keep the spaces comfortable. Planting shade trees is more sustainable, and affordable, than installing more insulation.