A passive home relies on natural heating and cooling processes that don't require active assistance from your HVAC.
The process primarily depends on the placement, insulation, and ventilation of the home.
Passive design uses as much as 90% less energy than standard home construction.
The concept of passive home plans originated in Germany but inspired worldwide building organizations.
Both existing homes and new construction can adopt passive home design.
Just over 30 years ago, the Germany-based organization Passive House Institute (PHI), set the standard for a new green home movement. Passive house design combines five key principles for controlling home heating, cooling, and humidity without the energy-dependent devices we flip on with a switch.
Now with hundreds of partner organizations around the world—including many in the U.S.—passive home design offers an eco-conscious upgrade for both new and existing homes.
What Is Passive Home Design?
On a basic level, the secret to passive home design lies in the structure of the home itself. The home's placement, insulation, building materials, and structure all reduce the need for active cooling and heating—aka, your HVAC system. In other words, if your home naturally remains at the right temperature, you'll spend less time futzing with the thermostat (and less money on your utility bill!).
Historically, architects used eco-friendly home design ideas long before HVACs and furnaces even existed. Window placement, the shape of the roof, and ventilation all played a role in how the home would handle the local season.
Nowadays, home builders seek out certification in modern passive home design to catch the eye of more eco-conscious clients. After all, according to the PHI, passive homes have up to 90% energy savings compared to older homes.
5 Passive House Principles
So, what exactly is a passive house and how does it combat energy loss? Take a look at the PHI five principles of design—all of which act as guideposts for partner organizations:
Thermal insulation: Insulation should surpass government standards and stand up against the climate of the area to protect the full envelope (walls, floors, roof, etc.) of the house from outside temperatures.
High-performing home windows: Multi-paned and coated windows can help control the solar gain—energy and heat from the sun—during the winter and summer.
Ventilation strategy: Passive homes feature heat-recovery ventilation to properly circulate air and remove exhaust without electricity.
Airtightness: Properly sealing windows, doors, and joints protects a home against unwanted movement of hot or cool air between the envelope.
Thermal bridge reduction: A thermal bridge refers to materials in your home's envelope that are more conductive than the insulation—and therefore cause a home to lose energy. For example, the studs in between wall insulation will conduct enough heat to allow significant energy loss.
Features of Passive Design in Your Home
Whether you're building from the ground up, adding a new addition, or simply looking to add more green interior design elements to your home, there are plenty of opportunities for passive design. Keep in mind that the vast majority of passive home plans will require the help of a professional familiar with eco-conscious design.
1. North and South Facades
Homebuilders typically choose north or south-facing facades for passive design. When your windows and walls face north and south, you get a full day of indirect sunlight—which is more consistent and easier to manage. Designers may even opt for a longer, narrower building footprint to catch as much sun as possible.
Keep in mind that the direction of the house will heavily depend on the local system and the microsystem on your property. Trees, other homes, and slopes can all play a role in how much sun reaches your home.
2. Passive Ventilation
Your attic plays a significant role in controlling the heating and cooling of the rest of the house. When you combine proper ventilation and insulation, your attic keeps all the hot air from escaping in the winter and prevents heat against the roof from offsetting your AC in the summer.
The best types of roof vents for your home will come down to the shape and slope of your roof, the age of your home, and where you live. Both intake vents and exhaust vents work with the natural convection process to keep the temperature and humidity balanced in this crucial space.
Passive ventilation also relates to the placement and type of windows included in your home. Designers will consider the local climate and common airflow patterns to keep your AC from kicking on.
3. Efficient Window Design
You have a handful of options for fortifying your windows. Making your window more energy-efficient is a great option on this list for existing homes looking for green upgrades.
For example, Low-E window coating—aka low emissivity coatings—reflects a large portion of the infrared long-wave energy from the sun that creates heat. Similarly, those who live in an area with changing seasons can add solar window film for temporary heat control.
If you live in a cold climate year-round, designers may recommend additional window glazing—the addition of extra panes to each window.
Your window team may also recommend an Energy-Star approved window—windows that combine the tactics above as well as provide a strong seal against air leaks. And if replacing them is not currently an option, winterizing your windows and doors is a great alternative.
4. Insulation and Sealing
Speaking of sealing in air, insulation, window sealing, and thermal bridge reduction are all major pieces of the puzzle as well. Passive home designers may choose insulation with a higher-than-necessary R-value to ensure long-term savings of both money and energy.
As mentioned earlier, passive home design requires that thermal bridges receive special attention. Areas around your studs, for example, require additional insulation. Some homes even do best with continuous insulation placed under the home's exterior siding.
Who to Hire for Passive Home Design
Contractors can receive training and certifications from a range of organizations across the country, including the Passive House Institute US (PHIUS) or the Passive House Network (PHN). According to the PHIUS, These experts learn how to balance a home's comfort levels, indoor air quality, resiliency, and a method to reach a net-zero or net-positive building.
We recommend starting the process by contacting a local home energy auditor. These experts will be able to advise the best opportunities for passive home upgrades in your home. From here, your energy auditor will either be able to recommend certified contractors or you check a pro's background on one of the organization's sites.
Remember that passive design can be applied to both new construction and older homes—outside of changing the whole orientation of your house, of course. Window, insulation, and ventilation upgrades are all available to current homeowners.