We’ve compiled a comprehensive list of passive house FAQs for you, with the most commonly asked passive house questions and also some of the other questions that are more difficult to find answers to. The questions and answers are loosely grouped by topic.
If you have a passive house question not listed here, please leave your question for us in the comments below.
What are the key advantages of owning a passive house?
The leading benefits when owning a passive house are:
- consume 75 – 90% less heating and cooling energy when compared to conventional buildings
- reduced reliance on outside energy
- fresh, pollen-free and dust-free air year-round
- consistent temperatures
- a quieter living environment
- higher construction quality and durability
Are there any disadvantages to owning a passive house?
There are a few possible negative aspects to consider:
- the up-front investment is higher
- the thicker walls and windows could necessitate modifications to the architectural design
- in older neighbourhoods, where a high-performance home stands out, passive houses may not retain their value as well
- in very harsh, prolonged winter conditions a backup heating system may be advisable
What does “Certified Passive House” mean, and is certification required or important?
Passive House Building Certification is a building certification system that is internationally recognized, involving third-party verification that the home meets the high performance and comfort levels set forth by the passive house standard. You work with a Certified Passive House Consultant to determine the best pathway for PHI (Canadian Passive House Institute) certification. It is possible to build a very good, high-performance home that meets or exceeds the BC Energy Step Code and also satisfies the passive house criteria, that has not been PHI certified.
The primary criteria passive houses must fulfill, as set forth by Passive House Canada, are:
- a space heat demand maximum of 15 kWh/m2a or peak demand maximum of 10 W/m2
- a pressurization test result @ 50 Pa max. 0.6 ACH (overpressure / under-pressure)
- a total primary energy demand maximum of 120 kWh/m2a (heating, cooling, hot water and domestic electricity) per square meter
Will a passive house reduce our energy costs?
Yes, passive house buildings typically use 75 – 90% less energy for heating and cooling than similar-sized buildings built with traditional design and materials. Passive houses make effective use of solar energy, internal heat sources, and heat recovery, and consequently, traditional heating systems are not required even during the coldest months of the year. They also make use of cooling techniques like strategic shading during summertime to keep the temperature within comfortable limits, reducing or eliminating the cost of air conditioning.
Isn’t there a big energy cost to keep the Heat Recovery Ventilation (HRV) fans running?
Passive House buildings use up to 90% less energy for heating and cooling than similar-sized buildings built with traditional design. There is a cost to running the HRV system, but because of their amazing efficiency, there’s an overall saving when compared with traditional heating and cooling systems.
Depending on the size, make and model, an HRV can recover up to 85% of the heat from the outgoing airstream. The Passive House Standard doesn’t require mechanical ventilation; it requires that strict comfort and energy efficiency criteria are met. Therefore, mechanical ventilation is needed for comfort and energy efficiency, not because the building is airtight.
Will I have to increase the energy efficiency of my passive house with solar panels, geothermal systems and wind generators?
The efficiency or thermal performance of your home, and the energy source or technology used to supply its heat or electricity are two different design considerations. In a passive house the main goal is to build a building envelope that is superbly insulated and airtight; then deliver fresh air through a high-efficiency heat recovery ventilation (HRV) system. Renewable energy sources are certainly an option with a passive house, but not a requirement.
Are passive houses more expensive to build?
For a single-family home, the cost increase for the building envelope upgrades (more insulation, triple pane glazing) ranges from 5 – 10%. But then there is typically a savings of 4 – 5% that comes from eliminating the central heating system and installing a point source heating system instead. Passive house ‘smart’ design can save significantly on construction costs. Factor in energy rebates and incentives, which can offset up to 2.5% of construction costs, and the up-front cost difference is typically around 10%; with a potential break-even point within ten years through energy savings.
Are passive houses worth it?
Passive houses are incredibly eco-friendly, which is reason enough for some homebuilders to choose to own one. These homes are very comfortable, year-round. Air quality is outstanding, with HRV systems removing damp, stale air and delivering dry, fresh air continuously to every room. An airtight building envelope, with state-of-the-art insulation and vapour barriers, also translates to a more durable home. Outside noise levels are greatly reduced. Energy savings of 75 – 90% are typical.
Many families are well on their way to recouping any additional up-front costs. The energy savings will cancel out much of the increased up-front investment cost of increased insulation, better-quality windows and ventilation systems.
Are airtight passive houses healthy?
High-performance, energy-efficient passive houses utilize an HRV system (heat recovery ventilation) that can deliver the following health benefits to your living space:
- a dry mould-free environment
- fresh air is delivered to each room at all times
- significantly reduced allergens and other air contaminants
- a significant reduction in noise
The air quality in a passive house is far superior to that of a traditional home in Canada, and the BC Energy Step Code guidelines are now requiring builders to seal up the building envelope of every new home to reduce the use of fossil fuels. This is the direction all construction is going.
If passive houses are airtight, isn’t there a danger of suffocating?
There’s a common misconception that an airtight home is a stuffy home. The passive house criteria require the envelope to be ventilated, and this is usually achieved with a dedicated mechanical system that incorporates heat recovery. Heat Recovery Ventilators (HRV) or Energy Recovery Ventilators (ERV) systems can separate the types of air, take out stale, humid air and continually replace it with fresh air.
In the event of power failure, your home can be equipped with a backup power supply, or the windows can of course be opened to let in fresh air, so there is no danger of asphyxiation.
I understand the Passivhaus approach comes from Europe, but Canada’s winters are colder. Are Canadian passive houses cold?
Passive house design is a pragmatic approach, using PHPP software, that factors in regional temperatures, building science and economics. Therefore, a certified passive house in Saguenay, Quebec would be built to withstand far colder winter temperatures than one in Naples, Italy. In severe climates, the energy savings become even more attractive, and therefore you’ll find passive houses in Russia, Finland, northern Minnesota, northern Sweden and Winnipeg, Canada.
Is there any regional climate data available for passive houses?
The PHPP v9 software Canadian Passive House Consultants use includes climate data for many locations. If your consultant can’t find climate data for your region in PHPP, the Passivhaus Institut (PHI) provides a service whereby they will verify and format data for you to enter into PHPP. The cost is around €400, with a discount for Passive House Canada members. This data will then be added to the PHPP if your project certifies.
Do passive houses overheat in the summertime, with all the additional insulation and south-facing windows?
One of the design requirements your Passive House Consultant will work out is summer comfort in your geographic region. Your passive house must be designed with the right amount of summer shading on south-facing glazing. It often becomes necessary to minimize east-and west-facing windows, as well as use spectrally selective glass to reduce summer overheating. The amount of south-facing glass, like every other building component in a passive house, is determined by the designer according to client requirements and the PHPP software.
Do passive houses require triple glazing?
High-performance triple-glazed windows are a critical component when trying to achieve 75 – 90% energy savings in a passive house. Windows can account for upwards of 50% of all energy loss through a building envelope. Passive house windows should last at least 20 years when properly installed, but they could last for up to 40 years if well maintained.
Can we open the windows in a passive house?
Yes, the windows of a passive house can be opened, just like those of a conventional home. A passive house must be built to a high level of air-tightness, but you can leave windows open if you wish. The HRV or ERV system will remove stale air and moisture and bring fresh filtered air into every room of the house continuously, so there will never be a need to open windows to let in fresh air.
Can my house be retrofitted to Passive House standards?
It is definitely possible to retrofit some existing buildings to the EnerPHit Standard. If you own an older home, you can retrofit it by refurbishing your home to fit the criteria of the PassivHaus standard. It may not be possible to meet Passive House Standards on every retrofit project, but EnerPHit ensures an energy-efficient and future-proof home while utilizing passive house components.
Homeowners can expect to pay around 30% of the home’s value for a complete EnerPhit Passive House retrofit. Even for older homes that can’t be brought fully up to Passive House Standards, the owner will still enjoy the comforts of a super-insulated, energy-efficient home with a substantially reduced energy requirement.
Can a passive house also be LEED certified and/or achieve Net Zero?
There are very few LEED-certified passive houses in Canada. The LEED rating system consists of eight categories that encompass a broader spectrum of the building process, where the passive house’s focus is on the building’s envelope and performance. The objectives of LEED and Passive House can be combined.
Passive House and Net Zero were made for each other. When designing a passive house, you’re focused on the building first. The renewables are not a big stretch, and reaching net zero for the balance of the energy requirements generally doesn’t require much more.
What are SIPs or SNIPS in passive houses?
Structural insulated panels (SIPs) are a modern high-performance building system. Structural Natural Insulated Panels (SNIPs) material selection is limited to natural and renewable materials. SIPs/SNIPs panels combine framing, insulating and vapour barrier steps into one, with prefabricated panels. The insulating foam, spun volcanic rock or recycled glass bottle core is sandwiched between two structural facings, typically oriented strand board (OSB).
SIPs are a simple way to build high-performance houses that meet or exceed building requirements and energy codes. Many passive house designer/builder contractors choose to integrate prefabricated panels into the design to get the building envelope closed in before the autumn rains, reduce on-site waste and keep skilled labour costs down.