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From the Design Quarterly: What is the passive house?

February 06, 2018

By Andrea Frisque

Ask an expert: An approach to sustainable buildings that has emerged from Europe is expanding beyond the home

In each edition of the Design Quarterly, we query a Stantec designer on an emerging trend in their field. Today, we speak with Andrea Frisque about an approach to sustainable buildings that has emerged from Europe and we find out that a Passive House sometimes isn’t a house at all.

What does the passive house term mean? How does it work?

Andrea Frisque: Passive house is an energy standard. It focuses on creating of the most energy efficient buildings possible, while still making economic sense. Thousands of passive house certified buildings all over the world save owners up to 90-95% of energy for heating and cooling compared to a typical building of their type.

Originally, the most common passive house type was a residential building in a colder climate, but that’s recently changed. A “passive house” can be a school, an office building, a shop, a factory. If you design a highly-insulated building, make that building airtight to reduce infiltration of cold air and add controlled heat recovery ventilation, you’ve got a passive house—one that uses very little active energy for heating or cooling. That’s the main concept for residential and office buildings in cold climates. Passive house design strategies change to be appropriate to location. 

Wood Innovation Research Laboratory, University of Northern British Columbia.

Why passive?

Andrea: Here, the expression “passive” means design focuses on strategies that are part of the building, outside of the building systems, to make it as energy efficient as possible. A highly-insulated envelope, triple glazing, and orienting the building so it can harvest solar energy are all passive design measures ripe for implementation.

[Adapted from the Stantec Design Quarterly, Issue 01 – The Sustainable City. Read and subscribe to the Design Quarterly now.]

It also means arranging spaces so they fit with the orientation of the building; bedrooms oriented to north so they can be cooler throughout the day, living spaces to the south with large windows harvesting solar energy. Bathrooms and kitchens are organized with short exhaust lines that can easily combine for heat recovery. Short ducts and compact design are passive measures.

Where did it come from?

Andrea: Dr. Wolfgang Feist founded the Passive House Institute and built the first passive house in 1996. The Passive House Institute (PHI) is an independent research institute based in Darmstadt, Germany.

Why is the passive house becoming more attractive?

Andrea: Proven performance is driving passive house design to the top of the sustainable design list. The Passive House Institute and other groups put a lot of effort into confirming the performance of these buildings. A European Union study showed that on average passive house developments use less energy than predicted, especially for heating. The Cepheus study showed that total energy consumption (not just heating and cooling) of passive house apartment buildings was less than 50% than that of conventional new buildings and meets design targets.

If you design a highly-insulated building, make that building airtight to reduce infiltration of cold air and add controlled heat recovery ventilation, you’ve got a passive house.

That makes passive house really interesting to clients like the City of Vancouver. There is a bit of fatigue in the North American market with respect to promises for sustainable building performance that don’t measure up to results. Rightly, our clients are looking for buildings that perform as promised.

Passive house residences have proven that they do. And there’s tight quality control. The prediction calculation, the process, the quality control, all together lead to buildings that function and that people are happy in.

What else do people like about a passive house?

Andrea: Superior thermal comfort. It just feels nicer, you are surrounded by warm surfaces. It’s comfortable sitting on the floor. The traditional way of heating buildings just makes the air warm, but you still feel the temperature of the surfaces around you. With passive house, the floor is warm, the walls are warm, the inside of the windows are warm.

Where is the passive house taking hold?

Andrea: The largest number of passive house buildings are residential buildings in Europe. But it has recently exploded into the scale and type of buildings that are relevant to Stantec including very large residential developments, student dorms, even university lab buildings. There’s a glass tower bank headquarters that has been certified, a natatorium, and a bunch of supermarkets. There are many passive house daycares and kindergartens in Europe.

But the desire for passive house design is spreading. The City of Vancouver offers an Alternative Compliance Path for rezoning passive house-certified buildings. The City of Toronto is interested in it. BC Housing is exploring it.

Is Stantec applying this now?

Andrea: Our British Columbia-based Sustainability + Building Performance studio is working on two daycare centers for the City of Vancouver that will be passive house-certified as well as an almost all-Stantec project, the Wood Innovation Research Lab at the University of Northern British Columbia. It’s contractually required to be certified.

With a dedicated team of sustainability and building performance experts and best practice sharing across our network what we learn from our ongoing passive house projects is rapidly shared and applied to the other projects we are involved with around the world.

Wood Innovation Research Laboratory, University of Northern British Columbia.

What are the obstacles to adoption of the passive house?

Andrea: The hardest part right now is accessing building components that are passive house-certified. Every component has to demonstrate that it actually performs as the manufacturer claims, unless you buy a certified component. The Passive House Institute certifies buildings, it certifies people, and it certifies components. You can get passive house-certified windows, and passive house-certified heat recovery ventilators, and so on. But we just can’t access enough of that in the market, and it’s more expensive.

In our building in Prince George, that means the overhead door is being shipped by air freight from Germany. There was nothing comparable.

Passive house-certified buildings have been shown to perform. Because the passive house standard focuses on optimizing passive building components with the Passive House Planning Package (PHPP), a validated energy model, performance is predictable.

What’s the payback like?

Andrea: The idea is that if your building needs almost no heating, then you can cut out high-end, high-efficiency heating systems and go with a small limited heating system instead.

Roughly, you ought to be able to make a passive house-certified office or residential building for an additional 5-7% in capital cost. Construction costs for the high-performance elements are partially offset by shrinking the heating and cooling systems required. As energy costs continue to rise, the payback period for investment is shrinking and the business case for passive house design will grow.

Unlike sophisticated, high-maintenance systems, passive house strategies like insulation, airtightness, and external shading start saving energy right away and into the future, potentially for decades to come.

For more stories that showcase thoughtful, forward-looking approaches to design that build community, visit the Design Quarterly online.

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