Passive House: An In-Depth Guide
Last Updated: Feb 19, 2025Passive House is a rigorous, performance-based, energy efficiency construction standard. It consistently and predictably provides a high level of comfort, even in the most extreme of weather conditions. Passive House is the highest energy efficiency standard for buildings in the world.
Table of Contents
- What Is a Passive House?
- What Is the History of Passive House?
- Five Core Principals of Passive Design
- Principle #3: Thermal bridge free
- What Is the Difference Between Passive House and Passive Solar Design?
- Comparison to Other Certifications
- Details Matter: More on Passive House
- Does a Passive House Need Heating?
- Can You Open Windows in a Passive House?
- Does a Passive House Need a Ventilation System?
- Does a Passive House Cost More?
What Is a Passive House?
Homes built to the Passive House standard use a building envelope's first approach consisting of insulation, air sealing, and no thermal bridging. Windows, doors, and any other penetrations in the building envelope are all extremely high-performing. A Passive House is oriented to best take advantage of the sun's energy for heating in the winter and shade in the summer.
There are certification levels within the Passive House Standard. A building that achieves Passive House Plus certification is net-zero. One built to Passive House Premium will be net-positive energy usage. All Passive House's will reach an 80-90% reduction for space heating and cooling demand than the current code minimum. There is also a Passive House certification program for retrofits called EnerPHit. These upgrades have reduced homeowners' energy usage by up to 93%!
Passive House offers the opportunity for homes to be resilient, healthy, economical, and environmentally friendly. They protect the homeowner from possible rising energy costs and extreme weather conditions. They also provide a very high comfort level throughout the year and superb indoor air quality due to the continuous provision of fresh, filtered air throughout the home. They can have a significant "feel good" factor by dramatically reducing your home's environmental impact. A Passive House avoided a whopping 128 tons of carbon dioxide emissions versus a conventional home over 20 years in one case study.
It is important to note that any building can be built to the Passive House Standard - from schools to apartment buildings, churches, community centers, grocery stores, factories, and offices. The "house" in Passive House is just a translation from its origination in Germany as Haus.
Passive House Institute - US Standard
PHIUS+ is the "made in America" version of PHI. Buildings built to PHIUS+ standards use 40% to 80% less energy than conventional buildings, proving environmental and economic value. PHIUS has been responsible for the certification of over 4.2 million square feet in North America. PHIUS standards were first developed in 2003, formalized in 2015, and updated in 2018 to become PHIUS+.
Principle #4: Windows, Orientation, and Shading
Windows and doors can be a significant source of heat gain or heat loss in a home. Energy Star windows are often double pane and filled with argon glass. In contrast, the Passive House standard almost always requires triple-pane windows, along with insulated frames and glass spacers and a quality installation.
Not only are the windows and doors very high-performance, but their placement is essential. Passive House buildings are optimally oriented and designed to make the most of the available natural light and heat. Solar gain through passive solar heating is strictly managed to maximize heat gain in the winter while limiting overheating during the summer. Specifically, windows with a high solar heat gain coefficient (SHGC) are placed in south-facing walls. This way, the low-angle winter sun can flood into the home, and overhangs can keep the high summer sun out. Windows with a low SHGC are often placed on east and west elevations where the heat of the rising and setting summer sun cannot be blocked by overhangs alone. Deciduous trees are beneficial for providing shade in the summer but letting the sun's warmth through in the winter when the leaves are off the trees. When we get hot in the summer, we stand in the shade, so too should our buildings.
Principle #5: Mechanical Ventilation
Some homeowners might fear that a super-insulated and very airtight home might be a recipe for unhealthy interior air quality. Yes, it is true that once we have built an airtight, thermal bridge free thermos, we can no longer breathe through the cracks in the walls. For this reason, Passive House requires the provision of continuous, filtered, fresh air and stale air removed. Most often via an efficient, silent, balanced, and commissioned Heat Recovery Ventilator or an Energy Recovery Ventilator (HRV/ERV). These devices transfer heat (and ERVs also transfer moisture) for maximum energy efficiency and healthy indoor air quality. Designers often opt for low or zero VOC building materials.
Depending on the building's climate and layout, the airtight, super-insulated building envelope home with strategically placed high-performance windows built to the Passive House standard might not need any supplemental heating. The internal gains that people, cooking, plug loads, and the sun provide may be enough.
During the summer, a heat recovery ventilator or energy recovery ventilator provides for fresh air. Simultaneously, shade, insulation, and low SHGC windows keep heat out of the home. Natural breezes and air movement can also reduce the need for mechanical air conditioning in the summer.
Most passive homes do incorporate backup mechanical heating and cooling systems for extreme temperatures. These units, however, are much smaller and simpler than in conventional buildings. The mechanical system costs less in Passive House construction.
What Is the Difference Between Passive House and Passive Solar Design?
When deep-diving into the Passive House certification, you may come across terms that are used interchangeably like "passive design," "solar design," and "passive solar design." While buildings built to Passive House standards use passive solar design principles, there is one primary difference. Passive House uses software based on physics, building science, and thermodynamics to predict the building's actual performance accurately. It uses strict performance metrics to ensure comfort and energy savings.
A home built using passive solar design can be high-performing, but results will vary. These homes can often require more active involvement from their occupants. This engagement would include the need to close windows on cold and hot days and open windows in the evening for the built-up heat to escape.
Comparison to Other Certifications
Comparing a Passive House to another certified building is like comparing apples to oranges as they are not competing but complementary. Passive House is only a performance-based energy efficiency design standard. LEED, Net Zero Energy, Living Building Challenge, Well, Zero Carbon, Pearl, and others are green or sustainable building certification programs.
LEED is a checklist-based certification program that includes eight categories of sustainability. One of these categories focuses on energy efficiency; however, it is not the primary driver of LEED-certified buildings. At the same time, LEED-certified buildings require an average energy consumption reduction of 20% or more than a reference code building. Passive House requires meeting set performance targets resulting in an 80% - 90% reduction in space heating and cooling demand. Passive House (PHI or PHIUS) certification can provide up to 48 points toward LEED certification, so it is the perfect starting point.
By its name, a Net-Zero Energy home is a home that produces as much energy as it uses within an average climate year. So, a Passive House is a perfect first step on the path to achieving net-zero and net-positive buildings as a Passive House provides a healthy indoor environment, resilience, and durability.
Of course, there are both benefits and drawbacks to each certification program. Some certifications are more appropriate than others depending on the building's location, features, and the occupants' behavior, values, and goals.
Details Matter: More on Passive House
Does a Passive House Need Heating?
A significant benefit to a Passive House is the minimal energy required to heat a home due to the insulation and tight thermal envelope. A Passive House offers resilience, even when the power goes out. Traditional homes typically require boiler or furnace systems. In contrast, Passive Houses only need a smaller and simpler system such as a ductless mini-split heat pump or electric resistance heater, depending on the climate.
Does a Passive House Need a Ventilation System?
Yes. A driving principle behind Passive House is a healthy indoor environment. Through minimal controlled ventilation, high-quality indoor air quality can be achieved. A ventilation unit with heat recovery features is recommended to meet the requirements of a Passive House. If you live in a location with harsh weather conditions, you will undoubtedly need a ventilation system with heat recovery.
Does a Passive House Cost More?
The upfront capital cost to build a Passive House is slightly higher at 5% - 10% more than a conventional home. You will spend somewhat more on the building envelope but will save on the heating system. This upfront capital cost will often be financed in your mortgage, resulting in slightly higher monthly premiums. However, these will be offset by lowered utility costs for the 50-100+ year life of the home. This combination can mean lower monthly costs overall. In other words, a Passive House is marginally more expensive to build but less costly overall than a conventional home.
Maria Saxton
Located in Roanoke, Virginia, Maria Saxton holds a Ph.D. in Environmental Design and Planning from Virginia Tech. She works as an Environmental Planner and Housing Researcher for a local firm specializing in Community Planning, Architecture, Landscape Architecture, and Historic Preservation. Her dissertation explored the environmental impacts of small-scale homes. She serves as a volunteer board member for the Tiny Home Industry Association.
