Passive design is a crucial part of sustainability and ensuring better energy efficiency and thermal comfort in homes.
The concept of the Passive House (Passivhaus) originated in Germany in 1991. It is a set of design principles that have been highly influential globally.
The aim of passive design is to create sustainable houses which require very little energy to create comfortable dwellings, with excellent ventilation and air quality.
In passive design, the building envelope does most of the work to achieve thermal comfort, without active input from energy-consuming devices such as air conditioners and heaters.
Passive House standards are performance-based, rather than having set guidelines as to materials that should be used.
The Passivhaus Institut oversees a global certification scheme that assesses these performance standards. If you wish to build a certified Passive House, you should contact an accredited Australian Building Certifier during your planning process.
In practice, this means that there is a very limited amount of gaps and cracks, reducing drafts and giving you control over the internal environment. Removing drafts ensures optimised thermal comfort.
Excellent insulation provides a sufficient layer between the heated or cooled inside environment and the outdoors. This will reduce radiant heat gain in summer and conductive heat loss in winter.
This improves comfort and reduces condensation by minimising cold surfaces; mitigating the risk of dampness and mould.
At Thermotek, we glue the window sashes to the pane. This ensures that the window has excellent insulation and enhances its stability. Windows no longer need reinforcing with steel, which is more favourable for thermal comfort.
A Mechanical Heat Recovery Ventilation (MVHR) system effectively salvages heated and cooled air that would otherwise be wasted while also filtering the air that’s coming into the building. This means cleaner air plus a lower risk of condensation – without needing to open your windows.
It brings in fresh outdoor air without letting heat escape, continuously removing unwanted moisture and pollutants and providing improved filtered air — leading to a better overall indoor air quality.
‘Thermal Bridges’ are areas that cause increased heat consumption and increased condensation risk.
The insulation needs to be a good thickness and continuous. This means keeping interruptions to the insulation to a minimum. If penetrations or cut throughs must be made for construction, it should be done with materials that are less conductive, like timber. Or thermal breaks can be used, whereby a material that doesn’t conduct heat well separates two conductive materials (like metal).
Wall wrapping is one example of a commonly used insulation barrier. However, unless it is properly wrapped, sealed and incorporated around joints, joins and windows it can easily be ineffective in areas.
Windows should have good levels of insulation, prioritising low-emissivity double or triple glazing with thermally broken or non-metal frames. The size of the windows should also be consistent with the building envelope, to allow for the right amount of solar radiation in summer and winter.
Windows should have rubber seals for airtightness, plus frames should either have a thermal break or be made from a non-conductive material like uPVC.
The uPVC used has high thermal insulation properties, while the IGUs (insulated glass units) use standard Low-E glazing with argon gas.
Our frames consist of various fusion welded air chambers. These give a superior seal which increases insulation, and the dual TPE (thermoplastic elastomer) seals further enhance thermal performance.
The gap between the two panes in Thermotek windows is the main source of insulation, which slows down thermal transfer by conduction. The systems slow down air circulation to reduce the amount of heat lost in winter and gained in summer.
Passive House design principles are positive for both people and the planet, using the building envelope to increase thermal comfort without energy consumption. It:
Passive buildings include houses, high-rise office towers, apartments, schools, or any building type. Passive House design improves energy efficiency in new construction as well as retrofits. There are generally three building performance targets:
Passive design optimises both building performance and value for zero-carbon buildings by:
There are many benefits to Passive House design, including health benefits. The U.S. EPA estimates that 90% of our lives take place indoors. Better internal air quality can significantly improve health, with reduced pollutants and CO2 levels.
Passive design promotes clean, oxygen-rich air when inside thanks to the ventilation systems. The engineering of passive houses also reduces condensation, mitigating dangerous mould and mildew.
Reasons for superior comfort levels include:
The smart design of both solar gain and shading, etc.
Passive homes are insulated against noise thanks to their robust high-performance walls, windows, and doors. They also reduce sound transmission from outside.
You will notice the significant difference in ambient noise as soon as you walk inside a passive house.
The recent updates to the National Construction Code (NCC) put the focus squarely on energy efficiency. There were two key changes to residential works, including apartment buildings:
Passive house design principles help achieve optimal thermal performance, plus also reduce the need for appliances and heating/cooling systems.
Passive House and passive solar are both ways to design energy-efficient homes, but they work a little differently.
Passive House is a strict standard focused on making homes super-insulated and airtight.
Passive solar, on the other hand, focuses on harnessing the sun’s heat. It involves positioning the home and windows to face the north (in the Southern Hemisphere) to capture winter sunlight while blocking out summer heat, often using thermal mass to store and release warmth naturally.
Both approaches aim for comfort and energy efficiency, but with Passive Houses, solar power isn't considered as the only way to generate energy and heat. You can read more about their differences here.
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