Passive House Design
The Passive House concept was developed back in Germany in 1991 by a professor Dr Wolfgang Fiest. Born out of a need to build homes that were not only sustainable, but were ultra-low energy, comfortable, affordable and have excellent indoor air quality. The name comes from the German “PassivHaus”, the literal translation is passive building. Passive House is passive only in the sense that the building envelope does most of the work to maintain the comfortable temperature inside the building (without the active input from the occupants).
How does Passive House Design work?
Designed and built in accordance with 5 building-science principles.
The house must be well sealed. The building envelope creates a solid air barrier, so no air leaks in or out giving full control over the internal environment and significantly improving thermal comfort, (windows are still openable though).
Sufficient insulation is required within the building’s envelope, providing enough thermal separation between the heated, or cooled, conditioned inside environment and the outdoors. This improves thermal comfort and reduces the risk of condensation.
An airtight building needs reliable source of fresh air for both human comfort and building longevity. Good ventilation is essential as it prevents accumulation of handful contaminants such CO2, volatile organic compounds (VOCs) and excess moisture which can lead to mould growth. In traditional buildings, fresh air enters the building through a series of vents and through infiltration or draft. This system is uncontrolled and cannot guarantee even ventilation throughout the building. In a Passivhaus mechanical ventilation is combined with heat recovery, known as Mechanical Ventilation Heat Recovery (MVHR). It uses the thermal energy within the building to pre-heat or pre-cool (depending on the season) incoming fresh air, ensuring clean, filtered air is provided regardless of outdoor conditions.
The insulation not only needs to be sufficient in thickness but also needs to be continuous. This means keeping penetration through the insulation to an absolute minimum, and if unavoidable then using materials that are less conductive to heat (eg. timber instead of metal) and/or incorporating thermal break to avoid thermal bridges.
Thermal bridges are the points at which a conventional house loses energy. They are often unaccounted weak points in the building fabric, resulting in high local discomfort, moisture and mould, while providing a highway for energy loss between the interior and the exterior of the house that.
Benefits of a Passive House
Comfort
The temperature is maintained at a comfortable range (between 20 and 25 degrees).
Healthy
The ventilation system must provide 30m3 of fresh, healthy filtered air every hour for every person in the building. The system is able to filter out pollutants, smoke and allergens to create a healthy indoor environment.
Economical
Efficient heating systems are used in combination with mechanical ventilation which uses a heat recovery system. In hot weather there is no need for reliance on air-conditioning. When compared to a standard building, there is a reduction of 90 percent energy use for heating and cooling.
Sustainable
Ultra-low energy use significantly reduces CO² emissions and provides a positive contribution to mitigating climate change. Each Passive House is built to incorporate characteristics that are optimised to the local climate, so the heating and cooling requirements are minimised. A Passive House building has structural longevity, due to the ultra-low risks of condensation within the building structure (and interiors).
Passive House in Australia
Although the concept started in Germany, the uptake in Australia is gaining momentum as an increasing number of astute homeowners see the immediate and long-term benefits.
The Passive House Standard has a general methodology that is used worldwide, whilst each project will have individual components that respond to the local climate.
To ensure that a home is built to this standard, a qualified Passive House Architect should be engaged at the very start of the project. Here at Archisoul, our senior architect and project leader, Carole Huard is a qualified Passive House Designer and Consultant.
Passive House FAQ
Passive House projects are high performance and high-quality buildings, where the initial investment costs are typically higher due to the additional design input and superior building components. However, over the building’s life span they are more cost effective than your standard build, due to the low running costs.
The benefits for the inhabitants and for the environment outweigh the initial outlay.
No! Each Passive House if designed with a qualified architect can accommodate most design styles. Passive House is a standard, not a building design, meaning that owners can choose to build as big or small, simply or extravagantly as they please!
A Passive House is always designed to individual requirements and is always unique. See the diversity of Passive Houses worldwide.
Yes, you can! To allow in breezes and air and sunshine. But when you want to shut out hot/cold/pollutants/smoke etc, then you can shut the windows and doors and make the home airtight and comfortable. With the constant flow of filtered fresh air, the atmosphere within the home should be fresh and temperate 24/7.
You can quite successfully retrofit older homes. It won’t be quite as successful as a new build Passive House, but most homes can be adapted with alterations and additions to increase the levels of comfort.
Request a consultation with our Passive House Designer
If you would like to learn more about Passive House Design and its sustainability, costs, processes, and what to expect, please contact us.