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Passive House

Our passion for sustainable home building at Sowden Building Solutions constantly drives us to innovate and find cutting edge ways to provide environmentally friendly services. This deeply held value saw us discover the wonders of Passive House building in 2019.  Since then we haven’t looked back.


We have successfully completed 2 certified EnerPHit projects so far with another EnerPHit project starting in 2024. 


Our Balmain EnerPHit project won the BDAA first ever Passive House division in 2023.


The Annandale EnerPHit is Australia's first and only certified EnerPHit 'PLUS' as of 2023. 

What is Passive House?


The term “Passive House” refers to a design standard that is entirely focused on producing energy efficient buildings that have as little environmental impact as possible. Developed by European academics in the 1970s, over decades of implementation Passive House design has become well-defined and renowned worldwide for its accomplishments. Despite being developed almost 50 years ago, this design philosophy still remains on the cutting edge for sustainable home building, thanks to its rigorous dedication to five key principles at the heart of every Passive House.

The Five Key Principles of Passive House Design


Any true Passive House must abide by a set of five key principles, created to guide builders in constructing the most efficient home possible. Heavily backed by a foundation of building physics, each Passive House that follows these principles provides high performance and comfort for the lifetime of the building. At Sowden Building Solutions, we make sure to strictly follow each of these key principals before designing any Passive House.


Key Principle 1: Airtightness

The first principal, and one of the most essential in the entire process, is ensuring your Passive House is airtight. What this means is we design the house to have as few gaps or cracks in the building envelope as physically possible. Doing this gives the homeowner complete control over the house’s internal environment, leading to an overall increase in comfort. Following this principal completely eliminates those annoying and uncomfortable draughts, allowing you to rely less on heating systems.


Key Principal 2: Thermal Insulation

The next principal of a Passive House is thermal insulation. By using sufficient amounts of insulation within the house a buffer is created between the internal house climate and the outside climate. Doing so drastically increases the comfort inside the building and lowers the risk of issues like condensation, which can stimulate the growth of mould — a potentially serious health threat. At Sowden Building Solutions, we go above and beyond the required insulation levels mandated by Australian building codes to ensure we meet this key principal.


Key Principal 3: Mechanical Ventilation Heat Recovery

Each Passive House employs a mechanical heat ventilation recovery system, which provides a number of really interesting and helpful benefits. This ventilation unit means you no longer need to rely on opening windows or doors to maintain ideal indoor air quality. Mechanical heat ventilation systems are able to recapture heat and cold that would normally be wasted, while at the same time filtering all of the air that is being sent into the house. Doing this results in less pollution in the air, giving you a healthier indoor environment, while again lowering the potential for condensation to form. To top it all off, the system uses very little energy.


Key Principal 4: Passive House High Performance Windows

Windows are a vital aspect of any well built Passive House. Double and triple glazing are used on each window and then combined with thermally broken or non-metal frames. The size of each window is adjusted based on where they are located too. What this combination of qualities does is optimise the amount of solar radiation brought into your house. In the winter months an ideal amount of sun will be able to penetrate through the windows, giving you a warmer house that doesn’t have to rely on traditional, environmentally impacting heating methods. Alternatively, in the summer months it restricts how much solar radiation is let in to keep things cool and comfortable. In summary, it dramatically reduces the carbon emissions required to keep your home in a pleasant climate.


Key Principal 5: Thermal Bridge Free Construction

The final principal of a Passive House build is all about reducing thermal bridges or eliminating them entirely. While having adequate levels of insulation is important for a Passive House, many of the benefits that specific key principal brings to your house are negated by the presence of thermal bridges. A thermal bridge is the weak point of a building that creates what is known as a “thermal highway”. These highways effectively remove many of the climate control benefits of the other four principals, which can reintroduce those nasty condensation and mould issues. Without reducing thermal bridges you’ll find yourself back at square one, having to rely on expensive traditional heating methods to keep your home climate comfortable.

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