Building efficiency is important for new homes and can significantly reduce energy consumption, but the time scale we now have left on climate change is too short to only focus on new homes. We must focus on retrofitting old homes and providing solutions that any home can use at any income level. We must solve this problem for all the houses that already exist in the world.
Building standards for extremely efficient homes that need no net energy input, such as ''passivhaus,'' are a good idea. Exactly what constitutes ``no net energy input'' is up for debate because of the complexities of tracing material and energy flows. Some will argue that with a sufficiently good passivhaus you do not need heat pump heating, and that may be true, but we have to solve this problem for the houses we already have as well as the houses we build tomorrow - in the U.S. only 1% of our housing stock is built new each year.
These houses, no matter how they are built, will be rare birds. Remember also, only about 2% of houses are built with an architect; the majority are built from common plans by a contractor. I think of passivhaus and other similar architectural plans as a wonderful library of very good ideas for building efficient houses, and even some retrofits, and we all, especially architects and builders, should embrace the ideas and create even more.
An idea with perhaps more potential for impact are the culture shifts required to live in smaller, simpler houses. Mobile homes have gotten a bad cultural rap, but have a smaller carbon footprint than conventional houses, and could offer one of the fastest pathways for adopting modern decarbonized domestic infrastructure.