What is a passive house?
Passive Houses are the world’s leading standard for sustainable living. They are homes built with both comfort and efficiency in mind. The name comes from the German ‘Passivhaus’, which was developed in the 1990s by Professors Bo Adamson and Wolfgang Feist. It is called a passive house because, through rigorous design, the building does most of the work of temperature regulation and ventilation by itself, with minimal input from people or technology like heating and cooling systems.
5 Principles of Passive House Design
While the passive house movement started as a conversation between two professors, it has developed into a genuine movement for change with key principles of sustainable construction and energy efficiency. The five principles of Passive House Design are:
Thermal insulation
All opaque building components of the exterior envelope of the house must be very well-insulated. For most cool-temperature climates, this means a heat transfer coefficient (U-value) of 0.15 W/(m²K) at the most, i.e. a maximum of 0.15 watts per degree of temperature difference and per square metre of exterior surface are lost.
Passive house windows
The window frames must be well insulated and fitted with low-e glazings filled with argon or krypton to prevent heat transfer. For most cool-temperature climates, this means a U-value of 0.80 W/(m²K) or less, with g-values around 50% (g-value= total solar transmittance, proportion of the solar energy available for the room).
Ventilation heat recovery
Efficient heat recovery ventilation is key, allowing for a good indoor air quality and saving energy. In Passive House, at least 75% of the heat from the exhaust air is transferred to the fresh air again by means of a heat exchanger.
Airtightness of the building
Uncontrolled leakage through gaps must be smaller than 0.6 of the total house volume per hour during a pressure test at 50 Pascal (both pressurised and depressurised).
Absence of thermal bridges
All edges, corners, connections and penetrations must be planned and executed with great care, so that thermal bridges can be avoided. Thermal bridges which cannot be avoided must be minimised as far as possible.
The Passive House Standard
The Passive House Standard is an international standard of Passive House design set out by the Passive House Institute. To be certified as a Passive House, homes are tested, must meet specific criteria, and then be certified by a registered body. The Passive House certification criteria are:
Heating demand
The Space Heating Energy Demand is not to exceed 15 kWh per square meter of net living space (treated floor area) per year or 10 W per square meter peak demand.
Cooling demand
In climates where active cooling is needed, the Space Cooling Energy Demand requirement roughly matches the heat demand requirements above, with an additional allowance for dehumidification.
Energy demand
The total energy use for all domestic applications (heating, hot water and domestic electricity) must not exceed 60 kWh per square meter of treated floor area per year. For context, in 2022, the average annual modelled energy use for homes in England was 231 kWh/m2/year
Airtightness
A maximum of 0.6 air changes per hour at 50 Pascals pressure (ACH50), as verified with an on-site pressure test (in both pressurised and depressurised states).
Thermal comfort
Thermal comfort must be met for all living areas during winter and summer, with no more than 10 % of the hours in a given year over 25 °C.
1. Allowances made for more humid climates where dehumidification is necessary
2. Classic, Plus and Premium certificates awarded based on renewable energy use
3. Verified with onsite testing
1. Allowances made for more humid climates where dehumidification is necessary
2. Classic, Plus and Premium certificates awarded based on renewable energy use
3. Verified with onsite testing
What are the benefits of a Passive House?
Passive Houses are a positive force for people and the planet. Designed to live in harmony with their environment, reduce the demand for heat and energy and create a more comfortable living environment, the primary benefits of a Passive House are:
Comfort
One of the key drivers behind the passive house movement was to create more comfortable homes. By regulating temperatures and airflow, homeowners are comfortable year-round no matter what the weather’s like outside.
Better air quality
With regulated airflow and a focus on natural materials, there are fewer airborne contaminants, leading to better air quality and a healthier lifestyle.
Reduced energy bills
Passive homeowners can expect heating and cooling-related energy savings of up to 90%, according to the IPHA (International Passive House Association).
Independence
With less energy requirement, a passive house makes you less reliant on the grid and more independent in the long run. Many passive houses generate their electricity in surplus and can even sell it back to the National Grid.
Peace & quiet
Equipped with triple-glazed windows and thick walls of insulation, passive houses not only keep your home’s temperature regulated, but they also keep out the sound of traffic, pedestrians, and noisy neighbours.
Meet Our Passive House Architect
Our in-house Passive House Architect, Jenny Booth, recently became certified as a Passive House Designer. Passive House designers are certified by the Passivhaus Institute to design and advise on Passive House projects. Jenny’s certification also includes EnerPHit, a passive house standard used for retrofitting existing buildings. If you’re interested in working with Jenny on an upcoming project, get in touch with our team today.
“I love helping people bring their dream homes to reality in a way that feels fun, collaborative, and genuinely rewarding. I also genuinely enjoy diving into the nerdy details and the science behind it all! Passive House Design means creating year-round comfort, delicate use of natural resources, and designing homes that do the hard work for you. It’s amazing what’s possible when clever design meets sustainable thinking.”
Yes - Passive Houses are often slightly more expensive to build. According to the IPHA, a Passive House in Germany, for example, can cost up to 8% more—however, the long-term benefits and savings of owning one more than pay off the initial cost.
While there are many benefits, there are some things to consider as a Passive House owner. As construction is airtight, you must have an efficient ventilation system to maintain air quality. Also, due to the requirements for ultra-efficient windows and doors, designs for large windows may be limited or cost more to customise for your home.
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