The Passive House and Why it Could Be the Next Gen of Homes
I often find myself pondering real estate innovation and the concept of built cities. All around us, the world is in “fast forward”, with expectations of radical new technologies every month. Yet our expectations with the physical environment and our methods for designing communities are resistant to change.
The reality is that our built environment has the potential to create vast impact in our quality of living, our engagement with the environment, and our participation in a social purpose.
Which brings me to Passive House (Passivhaus), a german concept that uses design principals to enable a completely passive method to heat and cool a home/space, meaning no mechanical systems required. The concept is actually very intuitive - utilize natural air ventilation and cooling/warming sources to achieve a premium level of indoor thermal comfort. This small change in design approach results in a 75-90% reduced carbon footprint, and alters our engagement with our environment - turning our perspective toward building from “shield against external sources” to “work with and utilize external elements”.
Passive House is one example of a slow, but steady shift in thinking toward our built communities. As technology has brought the world closer together, and altered the way we engage with our communities, it’s time we translate that momentum toward urban development. The Sidewalk Labs’ tech-focused neighbourhood coming to Toronto, is a prime example of how this shift in thinking is manifesting in our built communities, and passive house will undoubtedly be a huge part of that.
What is Passive House
Passive House is a building standard that develops premium thermal comfort indoors while using 75-90% less energy than conventional Canadian homes. A passive house employs design and construction principles to create a structure and environment that can utilize natural sources of heat (solar and body), as well as fresh air mass ventilation, and systematic shading to create ideal air quality conditions.
The thoughtful design creates incredibly energy efficient homes with minimal intervention from external technologies. The key point comes from the distinction between thermal performance versus building efficiency. Passive homes do not require solar panels, wind turbines or geothermal heat pumps to make the structure energy efficient. The focus of passive house is to have well-insulated and airtight structures that use design principles to create a comfortable and efficient home.
Why This Is Important
There has been increasing focus and attention on climate change and environmental degradation. Communities are progressively coming to understand the impact that we have on our surrounding, and that those actions do have repercussions on us.
In response to climate change, much of the public opinion and media focus on the transportation, industrial, and agri-business industries. The reality is that in Canada, buildings account for a whopping 17% of our greenhouse gas emissions. Moreover, those numbers do not include building electricity usage. That 17% of emissions is from fossil fuel combustion — primarily natural gas — for space heating, water heating and other direct sources.
This outcome, is the natural result of the economic and cultural context in which our buildings have been developed. In Canada, we have been accustomed to low cost and plentiful supply of energy. This has placed the concept of energy efficiency on the back-burner.
However, our attitudes are changing as technology is accelerating innovation, and global connectivity is increasingly magnifying the potential impact of our actions.
our attitudes are changing as technology transforms our outlook on innovation, our ability to turn ideas into reality, and our global connectivity has us considering the generations to come.
As we face another wave of innovation, including Artificial intelligence and the Internet of Things, there is an opportunity for positive change within our built communities. There are huge possibilities for transformation within our real estate and development industries, including massive reductions in our carbon footprint, as well as changing the way we engage with our environment. Passive house takes us one step closer to a more sustainable world, and provides a simple platform for continued advances within the industry.
What Makes a Passive House - Design Fundamentals
Sourced from passivehouse.ca
Efficient Building Shape
Since the amount of heat loss from any building envelope is proportional to its surface area, the building’s surface area must be minimized to achieve exceptional energy efficiency. Passive House designers use a ratio known as the ‘Shape Factor’ to assess buildings, this being the ratio of the building’s surface area divided by its volume. So buildings with sprawling designs, exposed floors, heated garages etc. have higher shape factors, and will therefore experience higher heat losses, even if their floor areas are identical.
Passive solar gains normally form an important component of the heating requirements in a Passive House. In most regions of Canada high solar gains though south-facing glazing are potentially available and need to be utilized through appropriate design. At the same time, glazing on northern facades should be minimized. Both winter and summer shading performance, as well as year-round comfort design requirements are determined in detail using the Passive House design software (PHPP).
The insulation levels required for any building to achieve Passive House performance must be determined by modeling the building using the PHPP software and relevant climate data.
Depending on the climate zone, houses built in Canada will likely need between three and seven times better insulation performance than that provided by current national and provincial Building Codes, in order to achieve Passive House performance. The designer must ensure complete insulation coverage for all parts of the building shell (i.e. thermal bridge-free design).
As the thermally weakest part of a building envelope, windows are a critical component, often representing 50% of all heat loss in a building. The quality of the windows is also critical to interior comfort, and in a Passive House the interior glazing and frame surfaces need to remain warm enough on cold nights to minimize interior cold spots and downdrafts. In all parts of Canada triple glazing is essential to achieve this, using two low-e coatings and argon (or krypton) gas fill, as well as insulated spacers. It’s also critical that window frames are insulated. Most windows currently sold in Canada meet few, if any, of these requirements.
Passive House buildings must achieve very high levels of airtightness compared to conventional construction, in order to minimize heat loss from air infiltration, and also to protect the building structure against possible moisture damage.
Ventilation with Heat Recovery
All Passive House buildings include a ventilation system which provides excellent indoor air quality and which has exceptional heat recovery performance.
Ventilation Air Pre-heating
A simple and inexpensive geothermal heat exchanger is often incorporated into the Passive House heat recovery ventilation system, which allows for pre-heating of the cold incoming airstream and ensures that the HRV unit can be kept frost-free without the need for energy-intensive defrosting. Such systems can also provide some active cooling and dehumidification during summer.
Thermal Bridge-Free Construction
In order to certify a Passive House, the designer must demonstrate that all parts of the building fulfill a strict thermal bridge criterion. In practice, Passive House designers have developed a large number of appropriate thermal bridge-free construction solutions, and many of these are presented in CanPHI’s training course. Significant thermal bridging is found throughout all building envelopes in contemporary Canadian construction.