What is Passive House?
The Passive House building standard was created in Germany over 20 years ago. It is based on five principles to ensure a building performs at a high level with minimal energy inputs. The average Passive House building is so energy efficient that heating needs could be met with the energy needed to run two blow dryers.
The Passive House standard is based on Five Principles:
- Continuous Insulation
- Airtight Barrier Layers
- High Performance Windows and Doors
- Controlled Ventilation
- Solar Gain and Loss through Design.
- Continuous insulation: Passive House buildings have a continuous layer of insulation from underneath the foundation to the peak of the roof. Just like a Thermos prevents heat from escaping a hot cup of coffee, this unbroken layer helps maintain warmth during the colder months. When the temperature rises outside, the continuous insulation acts like a cooler and keeps the drinks (occupants) cool. So, continuous insulation works all year-round to maintain a consistent comfortable living temperature for the occupants of the Passive House building.
- Airtight Barrier Layers: Whether it is an icy breeze in winter, a sweltering blast in summer, or a damp fall draft that leaves windows fogged up, unwanted air movement through a home decreases comfort for residents and can cause serious structural and health problems (rot and mold!). To prevent this, Passive House buildings have an airtight layer. This layer functions a lot like a windbreaker jacket: it keeps the wind from carrying heat away from the wearer’s body and keeping them at an agreeable temperature.
- High Performance Windows and Doors: Windows are both the hottest and coldest places in homes: a single pane of glass can’t compete with the insulation in a wall. However, high performance Passive House windows are designed to rival the walls performance. They have multiple panes of glass and are filled with special low-heat-transfer gases. This means there are no cold spots by windows and therefore, no heating ducts necessary below windows.
- Controlled Ventilation System: Since Passive House buildings are so airtight, they require Lungs. A controlled ventilation system that can move fresh air into the building and old, stale air out. These systems are run by either a Heat Recovery Ventilator (HRV) or an Energy Recovery Ventilator (ERV). HRVs and ERVs perform the same basic function: during months when heating is required, they take the heat from warm, stale indoor air and transfer it to the cool, fresh outdoor air. This provides a supply of warm, fresh air for the occupants. In months where cooling is required, the opposite occurs.
- Solar Gain and Loss through Design: The angle at which rays from the sun hit the earth has a significant impact on the amount of heat transferred to the earth. Imagine being asked to hit a flat and level target with a Frisbee. A Frisbee that is dropped from directly above the target will stay on the target, but a Frisbee that is thrown from a distance will likely ricochet and slide off. Heat from the sun is a lot like this. High-angle summer sunlight transfers heat because it strikes the atmosphere and earth directly. Low-angle winter sunlight tends to glance off the earth before it has a chance to transfer as much heat. Passive House buildings are designed to take advantage of the changing angle of the sun. By incorporating features like overhangs and window shades sunlight can get in during the cold months when heating is needed, and keep hot summer sunlight out.
It is these five principles that allow a Passive House building to achieve the Passive House performance standard and create the most comfortable living environment with minimal energy inputted.