Your Guide to Windows for Passivhaus Homes

Drew Barker
Posted January 15, 2024

Passivhaus, a German concept that translates to ‘Passive House’ in English, is a holistic approach to sustainable building design. The main objective of the Passivhaus standard is to achieve superior levels of energy efficiency, comfort and quality.

In this blog post, we’ll explore what sets Passivhaus windows apart from their traditional counterparts, and the benefits they convey in terms of energy efficient and comfort.

Passivhaus is often referred to as a ‘fabric first’ approach to building design because it places the emphasis on the building’s envelope – or ‘fabric’ – as the primary means of achieving energy efficiency and thermal comfort. In accordance with the 5 principles of Passivhaus, the focus is on building a highly insulated, airtight and thermal bridge-free structure. Mechanical Ventilation with Heat Recovery (MVHR) is then added to provide a constant supply of fresh, filtered air.

High quality glazing rounds outs the five fundamental principles of Passivhaus

The Importance of Passivhaus Windows

In traditional UK houses, windows can account for a whopping 10% of heat loss. Clearly, a superior solution is required to achieve the stringent requirements of the Passivhaus standard.

For most cool temperate climates, Passive windows must achieve a U-value of 0.80W/m2k or less, with g-values around 50% (g-value = total solar transmittance, proportion of the solar energy available for the room). This low U-value keeps the internal temperature of the window at an appropriate level.

What is a U-Value?

“The U-value of a material or construction element is the rate of heat loss through that material, taking account of both thermal conductivity and thickness. The lower the U-value of a material, the less heat can pass through it and the better it is at insulating. U-values are measured in watts per metre squared kelvin (W/m2K). Homes built to the passive house standard in Ireland or the UK typically include a wall U-value of 0.15 W/m2K or better (more moderate U-values may be possible in buildings with more compact forms, which are inherently more efficient).”

Source: Passive House Glossary
A Passivhaus-Standard Self Build

Anatomy of a Passivhaus Window

The windows in a Passivhaus are a lot different to ordinary windows – they’re precision engineered to meet the strict energy efficiency requirements of the Passivhaus standard. Let’s take a look at some of the main differences.

  1. Triple Glazing – Unlike traditional double glazing, Passivhaus windows actually have three layers of glass, each separated by insulating gas (typically argon or krypton), to significantly reduce heat transfer.
  2. Airtightness – Advanced sealing technologies eliminate air leakage, creating a barrier against draughts.
  3. Insulated Seals – The frame of a Passivhaus window is typically constructed from insulating materials, such as uPVC, timber or composite materials. These frames contribute to the overall thermal performance of the window, minimising heat transfer through the frame.
  4. Solar Gain Optimisation – Passivhaus windows are strategically designed to maximise solar gain during colder months. They allow sunlight to enter the home, capturing and retaining heat and reducing the need for active heating and cooling systems.

Energy Efficiency and Carbon Saving Benefits of Passivhaus Windows

Triple glazed windows are an integral part of Passive design. The exceptional insulation they provide can lead to a significant reduction in the need for heating and cooling. This, in turn, also reduces the overall carbon footprint of the property.

As a result, occupants will enjoy lower bills, while maintaining a comfortable indoor environment throughout the year.

One of the often-overlooked additional benefits of Passivhaus windows is noise reduction. This is particularly beneficial for homes in urban areas because it provides a quiet and peaceful living space.

Closing Thoughts

It’s important to note that the specification of superior windows is only one of the five fundamental principles of Passivhaus. Realising the full benefits of Passivhaus design requires a holistic approach from the outset.

At Beattie Passive, every house we build is designed in the PHPP (Passivhaus Planning Package) and our Build System is certified by the Passivhaus Institut in Germany. We inspect and independently performance test every Beattie Passive home to ensure the highest standards of construction are maintained.

We always carry out stringent airtightness, thermal imaging and sound migration tests upon structural completion, and we will only issue a quality assurance certificate if our stringent design standards have been met.

We inspect and test each building for the following:

  • Airtightness
  • Sound Migration & Acoustics
  • Thermal Imagery (for continuity of insulation)
  • Structural Testing

These tests are performed at crucial stages of the build process. Through these ongoing and stringent testing procedures, each Beattie Passive build achieves the highest standard of construction to meet the requirements for final certification.