How to Design a Passive House: The 5 Core Principles

By Neil Norris
Expanded by the Passive House Accelerator editorial team
Published January 1, 2019 • Last updated April 29, 2026

Designing a Passive House requires balancing five interlocking principles: a superinsulated envelope, airtight construction, high-performance glazing tuned for solar gain, thermal-bridge-free detailing at junctions, and heat-recovery ventilation. None works in isolation — an excellent envelope can be undone by window-to-wall thermal bridges, and a tight building without proper ventilation traps moisture. Passive House design is fundamentally holistic, balancing all five against each other to deliver up to 90% lower heating and cooling energy use than conventional construction.

Passive House is considered the most rigorous voluntary energy-based standard in the design and construction industry today. Consuming up to 90% less heating and cooling energy than conventional buildings, and applicable to almost any building type or design, the Passive House high-performance building standard is the only internationally recognized, proven, science-based energy standard in construction delivering this level of performance. Fundamental to the energy efficiency of these buildings, the following five principles are central to Passive House design and construction: 1) superinsulated envelopes, 2) airtight construction, 3) high-performance glazing, 4) thermal-bridge-free detailing, and 5) heat recovery ventilation.

All these key principles are linked to and impact each other in the design. No one principle can be neglected without having a negative impact on the rest. To effectively create a Passive House building, the design should be looked at holistically to incorporate all five design principles.

1. Superinsulated Envelopes

The building envelope is what separates the interior of the building from the exterior; it consists of outside walls, roofs, and floors. In cold climates like Canada, where inside air is heated to keep the building comfortable, some of that heat will be lost as it moves through the envelope (via the process of conduction). In order to reduce this heat loss, insulation made of low-conductivity materials is installed within the wall and roof assemblies.

Passive House makes the most of the envelope by superinsulating the building in order to minimize the heat loss. For a Passive House, the aim is to use assemblies with enough insulation to double or triple the heat resistance compared to what is required in current Canadian building codes. The result is a significant increase in the thermal performance expected from the building envelope. Insulating to Passive House levels has the added advantages of greater soundproofing, improved durability, and greater building resiliency—including the ability to maintain interior comfort for extended periods even if there is a power failure.

Achieving Passive House levels of heat resistance is not just about how much insulation you have, but whether that insulation is used effectively. Insulation is most effective when it wraps the building uninterrupted by other materials, but there will always be areas where this is not possible, such as around components used for structural reasons. When a material bypasses the insulation, it is known as a thermal bridge and can significantly reduce the effectiveness of insulation, especially if that material is very conductive, like metal.

Minimizing repeating thermal bridges and aiming for continuous insulation where possible, as in the assemblies shown in Figure 1, helps make the most of the insulation within the building envelope.

2. Airtight Construction 

Heat can also be lost through the envelope via air leakage. A building’s air barrier is a layer of material (membrane, tape, seals) around the envelope that restricts the movement of air in and out of the building. Gaps in the air barrier can allow air to move in and out of the building uncontrolled; they occur when there is insufficient detailing during construction, when there are numerous ducts or other penetrations in the air barrier, or when construction is of generally poor quality.

High volumes of uncontrolled air exchange with the exterior can lead to a whole host of problems, including increased energy use from having to repeatedly reheat the air, discomfort from cold air drafts near the walls, and localized moisture and condensation problems. While air exchange is necessary for ventilation and providing fresh air, it is far more effective to control air exchange by tightening the envelope and using mechanical ventilation.

There are strict design and construction requirements for a Passive House project to be certified airtight. Quantitatively, this means that when tested the building needs to have less than 0.6 air changes per hour (ACH50) to achieve Passive House certification. This stringent value can be compared to other high-performance building standards, such as the R2000 program, which allows up to 1.5 ACH50 from air leakage. As additional quality assurance for a Passive House project during construction, at least one on-site air leakage test must be completed to demonstrate that the building meets the airtightness requirements.

Achieving this degree of airtightness requires careful planning in the design stage, including making sure that the air barrier is continuous and evident on drawings, that effective air barrier materials are used, and that clear detailing for penetrations and terminations is provided. Construction quality with thorough quality control, from the contractor down to the trades, in the installation of the air barrier is critical. The entire construction team should be aware of the important role that airtightness plays in a Passive House project.

Airtight construction on a Passive House project will further reduce space-heating costs and localized condensation problems and will provide better comfort inside the building. In a Passive House building these advantages cannot be achieved by tightening the building envelope alone but must be coupled with a suitable ventilation strategy to deal with excess humidity in the building.

3. High-Performance Glazing 

While the walls typically make up the largest area of a building’s façade, the glazing systems (windows and glazed doors) can play an even bigger role when it comes to contributing to space-heating energy. Due to their function (providing light and visibility), glazing systems cannot be insulated to the same degree as a wall, resulting in the windows being the weakest areas of the envelope in terms of heat-flow resistance. Therefore, it is very important that high-performance glazing systems, such as Passive House-certified windows, are used to reduce that heat flow as much as possible.

Some key characteristics of a high-performance Passive House glazing system, as shown in Figure 2, include nonconductive framing or large thermal breaks; insulated framing; double- or more likely triple-glazed units; argon or krypton gas fill; multiple low-e coatings; and warm-edge or nonconductive spacers.

It is important not only to make sure to specify high-performance windows, but also to carefully consider how they are incorporated into the building design. Passive House designs take advantage of free passive heating from the sun. Solar heat gain through appropriately placed windows can help offset the amount of heat a building needs during colder months. During the summer months, this needs to be counteracted with shading to prevent too much heat from the sun from getting into the building, causing overheating. For each Passive House project, there will be an ideal number of windows that can balance the advantage of free heat from the sun with minimizing the heat loss from having too many windows.

The final consideration for glazing systems is surface temperatures. When outside temperatures are low in winter months, the inside surface temperatures on low-performing windows can also be quite cold. Low temperatures around the window can result in a higher risk of condensation (and potential mould growth) and feeling colder when you are close to the window because of radiant heat loss or from temperature-induced drafts. To reduce these risks, certified windows must be assessed according to hygiene and comfort criteria that set minimum allowable surface temperatures around the window.

4. Thermal-Bridge-Free Detailing 

The last envelope consideration is the minimization of thermal bridging. This was discussed earlier for repeating thermal bridges in the general wall and roof assemblies, but Passive House designs also aim to be thermal-bridge-free when it comes to architectural interface details. These are parts of the building where different architectural features meet that require additional attention in construction. Examples include how a window is attached to the walls, how a wall meets a balcony, and how walls meet at corners, as shown in Figure 3. The way these building features connect and are designed can also introduce thermal bridging that’s not always easy to recognize.

Thermal bridging from interface details can have numerous effects on building performance. For highly insulated envelopes like those in Passive House projects, thermal bridging can significantly reduce the benefits of superinsulating by allowing heat to flow around the insulation and out of the building, and can also create localized cold spots, increasing the risk of condensation and mould growth around these details.

The easiest way to avoid thermal bridging is by making architectural design changes (where possible), such as using self-supported decks and canopies for low-rise buildings or reducing the number of cantilevered balconies and articulating architecture (lots of corners) on larger buildings. This is not always realistic or achievable, and in these cases, special attention needs to be paid to these interfaces. Reducing direct conductive connections between the interior and exterior is important. Examples include installing intermittent connections for shelf angles, overinsulating in front of certain connections around the foundation, wrapping insulation around protruding details, or using special materials such as thermal breaks.

While it may not seem obvious, the thermal bridges caused by window-to-wall interfaces can have a very large impact. The total perimeter of all the window-to-wall connections can add up to several kilometers on some projects, so how a window is installed into an opening plays an important role in minimizing the heat flow. Reducing thermal bridging at this connection involves positioning the window to line up with the insulation layer, overinsulating in front of the frame, and minimizing how far closure flashings penetrate the rough opening while still maintaining adequate drainage paths. Eliminating or minimizing thermal bridging on Passive House projects helps ensure the effectiveness of the envelope performance in reducing space-heating energy use.

5. Heat Recovery Ventilation

Since Passive House projects are airtight, a ventilation system is needed to bring in fresh air and exhaust out built-up pollutants, odours, CO2, and moisture. During winter, this means dumping out warm air and bringing in cooler air that needs to be heated up again, which increases the heating energy. A Passive House ventilation system uses a heat recovery ventilator (HRV) to continuously remove stale or moist air and deliver fresh air. During this process, it extracts heat from the exhaust air and puts it into the incoming air without directly mixing the airstreams together. This way, all the heat in the exhaust air is not completely lost to the outside. For a Passive House HRV, at least 75% of that heat needs to be recovered.

For warmer summer months, most Passive House-certified ventilation systems also feature a summer bypass damper that diverts air around the heat recovery core. That way the system can still bring in fresh air but doesn’t recover heat when it’s not needed.

In dry locations, like the prairies, buildings without humidification in winter can leave the interior spaces at low interior humidity (under 30% RH), which leads to discomfort, potential health issues, and damage to interior materials. In these cases, an energy recovery ventilator (ERV) can be used. Unlike HRVs, which only transfer heat, ERVs can also transfer moisture from the outgoing exhaust to help maintain more-comfortable moisture levels in interior spaces. Occupants can also utilize natural ventilation (using cool summer breezes) from opening windows to exchange stale air by nonmechanical means and are encouraged to do so when it makes sense. Passive House designs utilize both methods to keep ventilation energy to a minimum. While Passive House projects can still be fitted with a heating system (such as air source heat pumps, electric baseboards, or boilers) having heat recovery in ventilation can greatly reduce the size, capacity, and maintenance needs of this equipment, shifting project costs from the mechanical systems to a superior building envelope.

6. How the Five Principles Work Together

The incredible year-round fresh indoor air quality and stable temperature, the substantial reduction in energy use and operating costs, and the quiet atmosphere that the Passive House standard delivers are directly attributable to these five principles and the way they are integrated into a Passive House building. By following a holistic approach with these five principles through the design and construction on any project, owners, designers, and builders can be confident that they can achieve a truly high-performance building.

Frequently Asked Questions About Passive House Design

Q1. What are the five principles of Passive House design?

The five principles are superinsulation, airtight construction, high-performance windows and doors, thermal-bridge-free detailing, and mechanical ventilation with heat recovery. They work together as an integrated system — each one amplifies the others, and a building that gets all five right delivers the comfort, indoor air quality, and energy performance that define Passive House. Both certifying bodies in North America (the Passive House Institute and Phius) share these five principles, though each applies its own performance thresholds.

Q2. How much insulation does a Passive House need?

While many Passive House envelopes use two to three times the insulation of a code-minimum building (roughly R-38 to R-60+ in walls and roofs, depending on climate), on larger buildings with a favorable surface-area-to-volume ratio, the amount of insulation can be much less. Common strategies include exterior continuous insulation over standard framing, double-stud walls with dense-pack cellulose, or Larsen truss systems.

Q3. How airtight is a Passive House envelope?

A Passive House envelope is exceptionally airtight — typically about 5x tighter than the 2021 International Residential Code requires — and that airtightness does two important jobs. First, it shuts down the uncontrolled airflow that drains conventional buildings of heating and cooling energy through every crack and gap. Second, it stops air from carrying moisture into wall and roof assemblies, where that moisture can condense on cold surfaces inside the wall and feed rot or mold. Performance is verified by a mandatory blower door test. The specific target depends on the certifying body. PHI requires ≤0.6 air changes per hour at 50 Pascals (0.6 ACH50), a metric based on building volume. Phius CORE requires ≤0.060 CFM50 per square foot of building enclosure, a metric based on envelope surface area. Phius CORE Prescriptive is stricter still at ≤0.040 CFM50/sf. ACH50 and CFM50/sf are not directly convertible because they reference different geometries.

Q4. What makes a window "high-performance" for Passive House?

High-performance Passive House windows are usually triple-glazed, with insulated or thermally broken frames, warm-edge spacers, multiple low-e coatings, and argon or krypton gas fills. PHI typically targets whole-window U-values of ≤0.80 W/(m²·K) (≤0.14 Btu/hr·ft²·°F). Phius applies a comfort-based criterion in which the maximum allowable U-value scales with window height and the project location's ASHRAE 99% design temperature. Installation matters as much as specification: the window should sit within or overlap the insulation layer to minimize thermal bridging.

Q5. What is a thermal bridge, and why does it matter?

A thermal bridge is any path where heat bypasses the insulation layer — typically at structural connections, balconies, window perimeters, or material transitions. PHI defines "thermal-bridge-free" detailing as a linear thermal transmittance (Ψ) of ≤0.01 W/(m·K). In a highly insulated envelope, thermal bridges have an outsized effect: they sap envelope performance and create cold spots that risk condensation and mold. Analysis tools include THERM (free, from LBNL) and Flixo.

Q6. How does a Passive House deliver fresh air?

In a Passive House, every room gets continuous, fresh, filtered air — delivered by a balanced mechanical ventilation system rather than pulled in through whatever cracks and gaps happen to be in the walls. Outdoor air comes from a known, filtered source and stale air is removed at a steady, balanced rate, around the clock. The system uses a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV) that captures ≥75% of the heat from the outgoing air (best-in-class units reach ~90%), so the energy cost of constant fresh air is minimal. HRVs recover sensible heat only and suit cold, dry climates; ERVs also recover moisture and suit hot-humid or mixed climates. Both certifying bodies require commissioning to verify supply and exhaust flows are balanced; Phius additionally requires room-by-room pressure balancing.

Q7. How is Passive House different from net zero?

Passive House is a conservation-first standard that minimizes a building's energy demand. Net zero refers to a building that generates as much renewable energy as it consumes annually. The two are complementary: the easiest way to reach net zero is to start with a Passive House envelope, because there is far less energy to offset. PHI addresses net-zero performance through its Plus and Premium tiers (which require on-site renewables); Phius addresses it through the Phius ZERO tier (net source energy = zero, no on-site fossil fuel combustion).

Q8. Does Passive House apply to large buildings or only houses?

The "Haus" in "Passivhaus" is German for "building," not "house" — the standard applies to every building type. There are certified Passive House high-rises, schools, office towers, healthcare facilities, supermarkets, factories, and supportive housing developments. In dense urban contexts, the standard often performs even better than for single-family homes because the surface-area-to-volume ratio is more favorable.