What is Passive House?
Passive House is a set of stringent design principles aimed at dramatically increasing the energy efficiency, health and comfort of buildings. The Passive House standard is applicable to most building types for minimizing the energy used for heating and cooling. As concern about the climate impact of buildings has increased over the past decade, interest in Passive House has grown. The standard is now routinely met on many projects in the US every year.
What is the history of Passive House?
The principles and concepts that form the foundation of Passive House had been used in various forms for years prior to the development of the formal standard. Traditional homes in many parts of the world have made use of intelligent design to build structures that require no active heating or cooling. The “Conservation House” built in 1977 in Saskatchewan is often identified as the first home to fully employ what were to become the Passive House principles of superinsulation, airtightness and heat recovery ventilation.
The Passive House standard grew out of conversations in 1988 between Bo Adamson of Sweden’s Lund University and Dr. Wolfgang Feist of Germany’s Institute for Housing and the Environment. In the early 1990s, Dr. Feist developed these principles into an organized system of standards, and went on to found the Passive House Institute (PHI) in Germany.
A German architect, Katrin Klingenberg, was instrumental in bringing the Passive House standard to North America. Her work eventually led to the founding of an alternative Passive House certification agency, the Passive House Institute US (Phius). Phius has adapted the original standard – which was developed for the climate in central Europe – to the many climate zones found in the U.S.
What is the Passive House Standard?
There are five basic principles on which all Passive Houses are based:
- Thick, continuous insulation that minimizes thermal bridging
- Airtight construction to control the flow of air and moisture
- High performance windows and doors, sized and located optimally
- Balanced heat recovery ventilation for continuous fresh, filtered air
- A space conditioning system appropriately-sized for low heating and cooling loads
These principles help to ensure that the home will be healthy, comfortable, energy efficient, durable and resilient.
Are there disadvantages to Passive Houses?
While there are many advantages to Passive Houses, there are also some potential drawbacks to fully following the system.
Cost is one potential hurdle to pursuing Passive House construction and certification. Estimates for the increased cost of Passive Houses over conventional construction range from 10% to 30%. In addition to upcharges for the high performance components and assemblies required for a Passive House, there are typically also costs relating to consulting, reviews and certification. Another potential drawback to Passive House is the additional time required for the certification steps.
You can learn more about the required steps to certification and their associated costs on the phius.org website.
Passive House Alternatives
Here at Unity Homes we don’t build Passive House certified homes, but our approach is very similar, and the performance of our homes typically matches that of Passive Houses in certain key aspects. In fact, Unity Homes are based upon the same five basic principles of Passive House that were mentioned earlier.
There are two primary differences between a Unity Home and a Passive House: energy modeling, and insulation levels. All Passive House projects are modeled in unique software to guide the design and to ensure compliance. We typically model the energy performance of Unity Homes, but not to the level of detail required by Passive House. In terms of insulation, although the R-values of our walls and roofs are high by most standards, they’re not quite as high as would normally be required by Passive House, because we’ve optimized the insulation for value and performance
At Unity, we strive to apply two additional principles that help to minimize the carbon footprint of our homes, and set them up for Net Zero performance. These are making our homes all electric (no fossil fuels burned on site) and renewable ready (prepared for the installation of photovoltaic panels).
The Passive House standard will continue to be a guiding light as we strive to reduce the energy use and lower the carbon footprint of our homes.
Because a new home is the largest investment that most people will ever make, we suggest exploring all of the options early in the planning process. We hope we’ve been able to provide helpful context for understanding what Passive House is. If you’d like to learn more about Unity’s state-of-the-art prefabrication process for building homes that are healthy, comfortable, energy efficient and low-maintenance, please reach out to us and we’d be happy to continue the conversation.