passive house

Building energy efficiency is a layered subject. It has to do with making buildings that work well. It has to do with aligning our lives and practices with the wellbeing of others and that of the world's vital systems. But it is also about warmth, coolness, light, shade, air and, through them, about the human experience of being in the world. Yet, because of access to technology and inexpensive energy, architects have developed the habit of dealing with these issues through systems and equipment rather than through architectural exploration and expression. Passive solar design, which takes direct advantage of the sun's heat as it enters a building through its windows, is one strategy for treating building comfort and energy efficiency as architectural concerns. The focus of passive solar is on optimizing passive heat gain in order to minimize the heat that would otherwise be generated by a building's mechanical system. It is an important tool, but a limited one for projects with little access to the sun because of climate, siting or orientation, or because other design influences conflict with passive solar design requirements. An emphasis on minimizing heat losses through improved building envelope performance is a more basic and universally applicable strategy for maintaining building comfort and minimizing heating energy use.

Passive House combines building enclosure efficiency and passive solar strategies in a system for designing and building cost effective, comfortable, energy efficient buildings. Its effectiveness has been demonstrated in projects ranging from single family homes to very large commercial and institutional structures. More than 20,000 examples have been completed worldwide. At its core, Passive House is a set of performance standards, efficiency strategies, and a software tool for modeling building thermal performance and energy use. It's primary focus is on minimizing heat loss (or gain in cooling climates) by optimizing the thermal performance of building components. This is accomplished by paying careful attention to insulation, airtightness, and window performance, and also by providing high efficiency heat recovery ventilation. The next priority is taking advantage of passive heat sources, primarily solar, but also waste heat generated by appliances, lighting, hot water, and building occupants. Building form, siting, orientation, and thermal mass are additional considerations. Cooling is minimized or eliminated through shading and passive ventilation. Passive House strategies combine to create buildings that can be heated using around 85% less energy than comparable conventional buildings. A typical 1,500 square foot Passive House home could be heated with the energy it takes to run a blow dryer. High performance mechanical equipment can be used to reduce energy use even further. Lower mechanical system costs combine with very low operating costs to help offset investments in added insulation, air sealing, better windows, and other improvements.