Developed by the German physicist Dr. Wolfgang Feist, the Passive House construction methodology has become a foundation for my architectural approach to sustainability. Radically energy efficient, economically advantageous, results-driven and comfortable, it represents a proven bridge between our current climate crisis and a potentially sustainable future.
The essence of the method is this: an unusually high level of investment is made in the thermal performance of the building exterior. If the envelope is improved to a sufficient level – akin to the difference between a paper coffee cup and a thermos – it allows the size and complexity of the heating and cooling equipment to be dramatically reduced, offsetting much of the added first cost of the envelope. The result is a factor-10 reduction in the energy used to heat and cool the building.
The benefits are tangible. Operating costs are slashed for the lifetime of the structure. Energy needs are brought down to levels that can be met by reasonably-sized and currently-available renewable power technologies. Interior comfort is increased. The indoor environment is quiet and acoustically separated from outside. Fresh air is supplied throughout the building even when closed up during the heating season. Instead of being environmental excesses to avoid, interior electronics like that great big TV heat the building. And aesthetically, the small size of the mechanical system is no longer an imposition on the building, leaving an architecture that is once again an expression of structure and space rather than mechanical ducts and soffits.
The key is the envelope. A Passive House envelope typically has four defining characteristics. First, increased insulation, installed without interruption. Second, extremely high-performing windows and doors. Third, attention to building orientation and shape: for any given volume, a compact shape has less surface area through which to conduct energy. Fourth, reduced air infiltration and the accompanying introduction of a small heat-exchanging ventilation system. The choice of mechanical system becomes secondary, and can take whatever form is most suitable. Together, these simple elements create the most significant update to building envelope technology in – without exaggeration – hundreds of years.
And it’s not a theory. In a time of ever-increasing environmental salesmanship, there are now tens of thousands of built, proven Passive Houses around the world with a demonstrated track record of benefit and success. I believe it is the most sensible platform from which to update traditional climate-aware building techniques, and the most compelling underpinning for a new, contemporary, sustainable architecture.
I discussed Passivehouse construction with Curtis Wayne over the course of two episodes of his radio show Burning Down the House:
Burning Down the House: Episode 59 – Passivhaus Continued.
Burning Down the House: Episode 58 – Passivhaus.