Perhaps you’ve heard the term “passive house” bandied about and are excited, skeptical, or just intrigued. This article will help you get your feet wet (but keep your insulation dry!).
Passive House (or the German version “Passivhaus”) is an internationally recognized building standard that was started in Germany in the early 1990s. Over three decades later, it is still one of the most stringent building energy efficiency standards in the world. Yes, it has “house” in the name, but it can be used for any type of building. It’s not just about energy though: the Passive House standard sets a high bar when it comes to indoor air quality, occupant comfort, noise levels, and building durability as well. Projects can be certified to the Passive House standard, which is administered by the Passive House Institute, an independent research institute in Darmstadt, Germany.
Passive House is about more than just meeting a standard. At its core, it is a design and construction concept that is rooted in building science and prioritizes efficiency, comfort, health, affordability, and sustainability. The design strategy relies on creating an energy model of the building to optimize its energy efficiency through five key principles:
Airtightness – ensuring the shell of the building includes a continuous airtight layer, to prevent air from escaping from or entering the building via gaps and cracks.
Superinsulation – choosing the amount of insulation based on the climate and on energy modeling, not based on the width of the wall studs. In cold climates, this may be 300-600mm (12-24 inches) of insulation, rather than the typical 140mm (5.5 inches) of wall insulation.
Good solar orientation + high-performance windows – choosing highly-insulating window glazing and frames. Additionally, locating windows and shading, and choosing glazing to help gain solar heat in the winter, and avoid it in the summer.
Low/no thermal bridging – Keeping the insulation layer continuous around the building and avoiding gaps in the insulation or areas where non-insulating elements (such as a brick chimney or concrete balcony) stick through the insulation layer.
Balanced ventilation with heat recovery – Providing ventilation air via a heat/energy recovery ventilator, which can transfer heat and humidity from the stale exhaust air to the fresh incoming air, saving energy.
What unites these design principles is the priority placed on saving heating and cooling energy passively, before looking at more efficient heating and cooling systems, or adding renewable energy generation such as solar panels to a building.
This “passive” approach to sustainable buildings has multiple benefits. Firstly, passive components such as insulation will last much longer than more “active” components such as heating and cooling systems. Secondly, many passive efficiency strategies have additional benefits such as improved comfort, air quality, resilience, and building durability. Thirdly, when comparing increasing efficiency to adding renewable energy generation such as solar panels, we can see that sometimes the sun isn’t shining when our building needs heating, while insulation is always reducing our heating requirement right when we need it to. Finally, passive design strategies are often less expensive to purchase and to operate than adding more energy generation or more efficient mechanical systems. This is not at all to say that we shouldn’t include efficient mechanical systems and renewable energy generation into our buildings. It is just to explain the benefits of incorporating passive design strategies first.
We have just scratched the surface of the Passive House design principles and the accompanying building standard. If you’d like to learn more about Passive House, check out the Passive House Institute, Passipedia, Passive House Canada, or Passive Buildings Canada.
If you’d like help with the design of a Passive House project, please contact us!