Mention the term “Passive House” and most people will immediately think of “energy efficiency”. But as our understanding of the interconnectedness between our living environments and health deepens, the passive house concept has rapidly gained global attention and recognition for its potential to improve the indoor air quality of our homes, and also enhance overall well-being.
Following the 2020 Covid lockdowns, more people have been working, exercising, eating, learning and enjoying their entertainment at home. The cost of energy has certainly become more a significant consideration, but so has the importance of indoor air quality and comfort.
The air quality and comfort benefits of a passive house can be obtained by building a new custom home with Passive House Building Certification, or by retrofitting your existing one under the EnerPHit Certification program. Passive houses can be designed and built to be ‘Net Zero Ready’, or fully ‘Net Zero’ certified with the addition of a CO2-free renewable energy source like a solar power system.
The existing inventory of homes in Canada is typically in need of major repairs, and these houses present potentially unhealthy conditions; whether that’s from dirt in the furnace ducts and filters, heat leakages through the building envelope, dampness and mould, and stale or poor air quality.
There’s a strong correlation between housing and health. According to the WHO Housing and Health Guidelines (HHGL), “Indoor air pollution harms respiratory health and may trigger allergic and irritant reactions, such as asthma.” Housing-related health risks can include respiratory and cardiovascular disease, resulting from chills, dampness and indoor air pollution.
Air quality, natural light, reliably comfortable temperatures and humidity control are widely accepted as key ‘quality of housing’ indicators that contribute to health; and they happen to align with core principles of the Passive House standard. By design, passive house buildings go beyond the local building codes to certify that homes are built to the highest standards, and that they support the wellbeing of their occupants.
What are the advantages of building to the passive house standard?
Before diving into the health benefits of living in a passive house, we should touch on the core principles of passive house construction. The Passive House standard was developed in 1988 by Dr. Wolfgang Feist and Prof. Bo Adamson, with a primary focus on reducing energy consumption and providing exceptional comfort. Current objectives are to reduce construction costs for passive houses and adapt the concept worldwide.
A passive house must meet 5 main principles:
- Superinsulated building envelope: The building envelope of your home separates the interior from the exterior, and it consists of the roof, the walls and the floors. To minimize heat loss, the goal is continuous insulation made of low-conductivity materials that are installed within the roof, wall and roof assemblies. The aim for a passive house is to use building assemblies with enough insulation to double or triple the heat resistance requirement of the current Canadian building codes. The U-values (thermal transmittance) of external walls, floor slabs and roof areas of passive houses range from 0.10 to 0.15 W/(m²K) to slightly higher or lower depending on the climate.
- Airtight construction: Heated air can also escape from the building envelope through air leaks. Your home’s air barrier is made up of a layer of membrane(s), tape and seals. Any gaps in the air barrier will allow air to move in and out of your home uncontrolled. Air gaps occur when there has been insufficient detailing during construction, or when there are penetrations or ducts in the air barrier materials. Uncontrolled air exchange can lead to increased energy consumption, cold spots and drafts near the walls, and condensation and moisture issues. When tested, your house needs to have less than 0.6 air changes per hour (ACH50) to achieve Passive House certification, and at least one on-site air leakage test must be completed to demonstrate that your home meets those airtightness requirements.
- High-efficiency windows and doors: The walls will usually make up the largest surface area of your house’s façade, but the glazing systems in its windows and doors will play a greater role when it comes to managing its space-heating energy. Glass provides visibility and light, and that makes it impossible to insulate glass units to the same degree as a wall. When it comes to heat-flow resistance, windows and doors are the weakest areas of the envelope. High-performance Passive House windows use insulated frames, triple-glazed units, with argon or krypton gas fill, multiple low-e coatings, and warm-edge or nonconductive spacers. Passive House designs also take advantage of the free passive heating provided by the sun.
- Minimization of thermal bridging: When materials bypass the insulation, a thermal bridge is created. Any direct conductive connection between the interior and exterior represents a potential issue. Passive house design aims to remove all thermal bridging when it comes to architectural interface details – ie: window and door frame mounting, mortar joints and wall ties in masonry, timber or steel studs, and any parts of the building where architectural features meet. With highly insulated passive house envelopes, thermal bridges can significantly diminish the benefits of superinsulating, allowing heat to flow around the insulation to the outside. This can result in condensation forming, mould growth and cold spots.
- Heat recovery ventilation: Passive house buildings are airtight, so they require a ventilation system to exhaust out built-up odours, pollutants, CO2 and excess moisture. During the winter months that would mean pushing out warm air and pulling in cold air that would need to be heated to return the home to the desired temperature. To eliminate heat loss, and the need for re-heating air, passive house ventilation systems use a heat recovery ventilator (HRV). The HRV extracts heat from the exhaust air stream and adds it into the incoming airstream, without directly mixing the two. At least 75% of the heat must be recovered, allowing the system to remove stale or moist air while delivering fresh air to every room, without noticeable temperature fluctuations. During the summer months, there’s no need to recover heat, so there’s a bypass damper that diverts the air around the heat recovery core.
Potential health benefits of living in a passive house
Improved respiratory health: One of the primary advantages of living in a passive house is the reduction of airborne pollutants that can trigger respiratory issues. Having a continuous supply of fresh, filtered air, free of particle and volatile organic compound (VOC) pollution, mould, and allergens, significantly reduces the risk of respiratory illness, asthma and allergies. Family members with pre-existing respiratory conditions often experience relief in a passive house environment.
Enhanced cognitive function and enhanced mental health: High quality indoor air and comfortable temperatures play a vital role in cognitive function and mental well-being. In the medical article, Air Pollution and Cognitive Impairment across the Life Course in Humans, Emerging studies suggest that exposure to air pollution may be associated with cognitive impairment. In a passive house, students and home business owners often experience improved concentration, decision-making, and productivity due to the absence of pollutants and a stable indoor climate. The lack of temperature extremes and superior indoor air quality can contribute to lower stress levels, reduced anxiety, and an overall sense of well-being.
Improved sleep quality: Consistent indoor temperatures and reduced noise levels in passive houses can lead to better sleep quality. Quality sleep is essential for overall health, affecting our mood, cognitive function, and physical well-being. The superinsulated walls, windows and doors that are key to passive house energy performance also reduce sound transmission from the outside, significantly blocking out urban noise, passing trains, sirens and traffic.
Allergy reduction: The advanced filtration built into the ventilation system significantly reduces allergens like pollen, dust mites, and pet dander, providing relief from allergy symptoms and improving your comfort. And the continuous air barrier stops dust from infiltrating building assemblies. Dust filtering through the walls and accumulating on any horizontal surface, and in your lungs, are a thing of the past.
Reduced stress: Passive houses provide increased resilience to extreme weather. Passive houses are designed to withstand extreme weather conditions, providing a secure and comfortable living environment during heatwaves, cold spells, or power outages. Passive house buildings can help us adapt to wild weather, extreme conditions, and energy grid failures, providing “passive survivability”. This resilience can reduce the physical and mental stress associated with such events. Living in a passive house typically means lower energy bills, which can reduce financial stress. The knowledge that you are minimizing your environmental impact by consuming less energy can contribute to a sense of well-being, knowing you are making an eco-conscious choice.
Passive house construction represents a transformative approach to building design that not only reduces energy consumption and greenhouse gas emissions but can also significantly enhance the health and well-being of your family. By prioritizing indoor air quality, comfort, and sustainability, passive houses provide a practical, holistic solution to the challenges of our changing world. With their robust building envelopes and lack of condensation-causing thermal bridges, passive houses are more durable and require less maintenance than conventional homes.