PASSIVHAUS STANDARD The

Buildings are a significant culprit of carbon emissions – accountable for 35% of total global energy consumption. Passivhaus is an international standard for energy efficiency in a building, which reduces the building's ecological footprint.

A Passivhaus design creates a comfortable and consistent interior climate without an active heating or cooling system - hence the term Passivhaus (Passive House). It achieves this by combining key features such as high-quality insulation and ventilation.

In a standard building, heat is usually lost through small openings like cracks, inefficient windows, or overall poor insulation. Heat flows from hot to cold areas which are known as the “thermal bridge.” A thermal bridge acts as a heat highway that leads straight to the outside of the building causing inconsistent internal temperatures.

A Passivhaus building eliminates this by sealing these areas. High specification insulation and ventilation help prevent heat loss and regulate temperatures so that building occupants remain comfortable, whatever the external climate.

Since there is no active heating system, a passive building uses “free heat”, generated by electrical and gas appliances such as ovens and lightbulbs as well as body temperature. In warmer climates, where heating isn’t as necessary, a passive building uses shade to help cool the internal temperature — making for a highly efficient indoor environment, irrespective of location.

To achieve the rigorous standards set by the Passivhaus Institute, every aspect of building design must be carefully considered, including the selection and placement of windows, doors and rooflights. These elements play a critical role in ensuring optimal energy performance while maintaining functionality and aesthetic appeal.

High-Quality Insulation and Airtightness

Windows, doors and rooflights in Passivhaus buildings must adhere to stringent insulation and airtightness requirements. The frames and glazing are typically designed to have low U-values, indicating their ability to prevent heat transfer. Triple-glazed windows with thermally broken frames are commonly used to minimize thermal bridging and maximize insulation. High specification rooflights carrying Passivhaus certification are also available. By reducing heat loss, these products contribute significantly to the overall energy efficiency of the building envelope.

Strategic Placement for Solar Gain and Shading

Passivhaus design leverages the sun's energy to heat the building during colder months while minimizing excessive heat gain in warmer months. The strategic placement of windows, doors and rooflights plays a crucial role in achieving this balance. South-facing windows are designed to maximize solar heat gain during winter, while overhangs or shading devices help prevent overheating in summer.

Careful consideration is given to sizing and orientation to optimize daylighting and passive solar heating, reducing the need for artificial lighting and heating systems.

Ventilation and Heat Recovery

Windows and rooflights can also contribute to the ventilation strategy in Passivhaus buildings. While airtightness is essential for energy efficiency, controlled ventilation is crucial for maintaining indoor air quality. Energy recovery ventilation systems are commonly integrated with windows or doors to ensure a continuous supply of fresh air while recovering heat from the outgoing air. This approach not only enhances energy efficiency but also creates a healthier and more comfortable living or working environment.

Functionality, Design, and Comfort

While energy efficiency is a priority in Passivhaus design, functionality, design, and comfort are equally important. Occupants should have ease of use, adequate natural light and views to the outdoors. The design and operation of windows, doors and rooflights must consider factors such as ease of cleaning, security, and sound insulation. Proper selection of glazing, frames, and hardware contributes to noise reduction and enhances overall comfort within the building.

By carefully selecting and installing windows and doors, Passivhaus designers can create sustainable buildings that prioritize energy efficiency without compromising functionality or aesthetic appeal. The result is a harmonious integration of energy-conscious design principles with the needs and desires of occupants.

paul@daylightingmag.co.uk