After 2.5 years of planning, building and rigorous testing, the team recently held a traditional ‘Topping Out’ ceremony bringing together the designers, trades and support staff to commemorate the completion of the roof and lock-up of the new building. The practise of ‘topping out’ is based on the ancient Scandinavian tradition of placing a tree on the top of a new building to appease spirits that had been displaced and to bring good luck. Adam and the team didn’t need to look far, with the new structure purposely built around an existing 50-year-old Pepper tree.

For award-winning carpenter and builder Adam Souter from Souter Built, creating functional and beautiful homes has always been on the agenda. After welcoming twins to the family, he realised the importance of not only an aesthetically beautiful home, but a healthy home – one that was good for the environment and its residents. Exploring the benefits of a passive home, a popular building standard in Europe, Adam set his sights on building the Illawarra’s first certified passive house in collaboration with architect Alexander Symes.

The principles of a passive house

Completely airtight
Excellent thermal insulation
High-performance windows
Thermal bridge-free construction
Comfort ventilation

Passive house design, incorporating standards that originated in Germany in the 1990s, has a unique advantage over traditional housing. Energy efficiency is a key feature, as is the desire to develop the most suitable building based on the location and geography of the site that incorporates sun direction, potential winds, existing greenery, and repurposed or sustainable materials. However, its benefits for the health and wellbeing of residents that stretch beyond the obvious environmental and cost-savings that is most compelling. For Adam, the health of his children prompted the new direction: ”When our twins were born, they had asthma. We had seen multiple doctors but couldn’t work out what was going on. We realised our gas heater was a part of the problem, but we were in an existing house that had already been built… not by us,” explains Adam. “It wasn’t a healthy environment. Our air conditioning recycled the same air. I thought something's not being done right here. How can I improve this?”

A conversation with Wollongong-born architect Alexander Symes pushed the idea of a passive house project into reality. A mutual interest in the future of housing – from an environmental, economic and health perspective – revealed they were both on the same track. Minimising building waste, clean and healthy living and cost efficiencies for smaller, low-cost housing where all topics of interest.

“Our environmental interests aligned really well, in terms of figuring how we can deliver sustainability in an economical way. When Adam proposed the idea of doing a certified passive house, working with him was a no brainer,” explains Alexander. Adam decided to utilise space on his own property to put their ideas in to practice, building the 60sqm Pepper Tree Passive House behind his own home in Unanderra, with plans for people to come and learn about passive house design. “This is a test case building – Adam wants people to come and stay in a passive house so people can understand and feel the difference of a passive building. It’s also been done deliberately as a secondary dwelling, so that it can be an example of infill development and a way of providing more affordable housing.”

Minimise waste, maximise usage

**Green roof** – additional insulation
**Pepper Tree** – provides shade and mulch to green roof
**Double membrane walls** – waterproof, allows moisture to go out but not come in
**Triple glazed windows and doors** – improved heating and cooling without appliances, reduce electricity and gas usage
**Sustainable timber** – locally sourced eucalyptus black bark and plantation pine, with beeswax coatings
**Charred timber exterior (Shou Sugi Ban)** – maintenance-free, termite proof, flame resistant
**Concrete stepping stones** – excess from concrete piers and foundations
**Recycled bricks on internal walls and floor** – retains heat from the sun
**Timber offcuts** – repurposed for internal joinery and doors

Passive house performance

For Adam and Alexander, embracing the true features of passive house design is a balance between form and function. Passive housing is renowned for increasing energy efficiency, requiring 90% less energy to run than a standard house, but it’s as much about great design and comfort. Adopting solar design elements, like installing solar panels, are regularly implemented into design but it is the passive house criteria and rigorous testing that pushes the envelope to ensure the building is as sustainable and self-sufficient.

To be certified, a passive house must be completely airtight, have excellent thermal insulation, high-performance windows, thermal bridge-free construction and comfort self-ventilation with high heat recovery. Self-ventilating systems keeps air cold or warm, depending on the weather conditions, without the need for additional technology. Home owners can avoid the need for heaters to keep a home warm, saving on cost in the use of electrical appliances, while the natural air let in by the ventilating systems does everything in a much healthier way.

“Once you start looking more and more into this technology, you realise how unhealthy we're living and how bad it is,” says Adam. “Instead of having a gas heater, which pollutes your house with the carbon monoxide or a gas cook top, these elements aren't allowed in a passive house because it's not healthy.”

Aesthetics, style and an exceptional view aren’t overlooked when it comes to the Pepper Tree House’s design: “It's most efficient to design it just as a standard north-facing passive house. However, in the example of Adam's site, the views to Mount Kembla are what's special about the space. If we were just to block out the views we wouldn't be maximising the enjoyment of the site,” explains Alexander.

“What's great about the passive house standard is that we've been able to reduce the window to wall ratio and have great windows that frame out the view towards the west, and then strategically position north-facing windows so that we maximum heating and cooling that [align with] passive house standards. Recycled brickwork is being used very strategically, so that exposed brickwork is just where the winter sun comes in and hits the building. Where timber [is used], whether it's recycled or it's responsibly forested new timber, the idea is to have a very warm, natural interior and creating a healthy internal environment.”

Keeping the 50-year-old pepper tree in the backyard was of utmost importance, says Adam. “A standard builder would just say ‘chop down the tree’ but as an environmental builder, I wanted to celebrate the tree. We've actually designed the house to be around it - a lot of planning has gone into the care of the tree!”

Cost-effective and better for the environment

“As energy costs go up and as people realise that the climate is changing in terms of it's becoming a lot hotter for a lot more days, we have to spend more time in the design and more money on the construction, so that we can be comfortable, safe and healthy on these really hot days, which unfortunately is going to be part of our future,” says Alexander.

Despite the overwhelming benefits, the trend for homeowners to adopt passive design elements has been gradual: “Because it was originally designed in Germany, there's a misconception where people think that passive houses only are designed for cold climates. You can design a passive house anywhere on the planet - even the Sahara Desert,” says Adam.

The Australian building industry and manufacturers have also taken time to embrace passive house standards: “There’s been a gap between design and implementation, in terms of the technical skills in Australia,” explains Alexander. “The suppliers of the actual products - heat recovery, ventilation systems, special membranes and high performance windows, and you need people who do the certification. Hopefully in five or 10 years’ time, it will become the norm. In the end, it's about creating a better quality space and more efficient homes.”