The energy efficiency goal in the design of any home is ultimately passivity. Everyone would like to have a really comfortable home interior living environment with little or no cost for heating and cooling. But what defines a truly “passive house” can be hard to nail down and even harder for most homeowners to understand.
Passipedia technically defines passive houses as:
“A Passive House is a building, for which thermal comfort (ISO 7730) can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”
Wikipedia offers a less technical definition for a passive house: A house that is designed as an ultra-low energy building that requires little energy for space heating or cooling.
Basically, a passive house is one designed to take into account local climate factors, advantage of site-specific conditions and engineering to achieve the highest energy efficiency possible and lower environmental impacts. Such houses are so tightly sealed and insulated, while using natural energy sources and climate control, they require only minimal HVAC systems to maintain temperature comfort levels through all seasons.
The Boston Globe website has an excellent pictorial Engineering A Passive Home that provides visuals for an easier understanding of this concept. The seven slides provided in this article give a very good overview of the concepts behind a true passive house. Although there is much more engineering behind a passively designed house, this is a good primer to help clarify the basic elements.
The fact is most houses in the U.S., and around the world for that matter, do not achieve passive house levels. However, it is possible to implement many of the concepts outlined in the Globe article to effectively lower utility bills and reduce impacts on the environment. Architects and builders are driven by homeowner demand and preferences. As more homeowners become aware of the benefits and eventually get a better grasp of the practical aspects of passive house designs, they will demand this in new homes.
From a practical aspect, the first step is to improve the air sealing and insulation in homes. These are possible to engineer into any new home construction plan or remodeling project, simple for builders to explain and easy for homeowners to understand.