Thornleigh Passivhaus

This stunning new Thornleigh house is one of the first certified passive homes in Sydney.

The owners bought the property in Thornleigh so they could build their forever home.

The existing building was quickly demolished to make way for a family friendly, energy efficient Passivhaus. The brief was clear.

A three bedroom, two bathroom home, with an office/guest room for visiting parents.

It all started with a tree

There is a beautiful, expansive tallowwood tree in the middle of the site, which the owners wanted to keep – and magnify as a key feature.

“The living spaces are orientated to enjoy the view of the tallowwood tree that is at the geometric heart of the site.”

The house structure was elevated to preserve the tree’s root system, and the home was built around it. The deck wraps around the tallowwood so that the tree becomes part of the home. Directors Dick and Andy explain:

“The large ‘lift and slide’ doors provide an intimate connection to the rear yard and the deck wrapping the tallowwood. This presents a seamless flow when the weather permits and still ensures the visual connection when the weather is less accommodating.”

Location, location, location

The site for the home is tucked between a busy road and a train line. To create the tranquil oasis the owners wanted meant factoring the noise and air pollution into the design.

Triple glazed windows, thick walls and continuous insulation work together to substantially reduce noise. The airtight exterior of the home and the Mechanical Ventilation Heat Recovery (MVHR) prevent pollution entering the house and guarantee clean fresh air fills the home.

This has resulted in a quiet, peaceful home filled with light and fresh air, with views of the magnificent tallowwood from every living space.

Cool in summer, warm in winter

One of the owner’s chief concerns was to keep the home cool during the harsh Australian summer. The designers tracked the sun’s path over the house and oriented the home to capture the winter sun whilst protecting it from the summer heat.

The varying window sizes on different orientations reflect this goal, as do the windows themselves. The windows on the Thornleigh house are made of UPVC and are triple glazed. This reduces noise, allows for maximum light but does not conduct heat. This prevents the enormous amount of heat transfer that occurs from windows in standard houses.

We also used strategic shading around the home. The shading comes in many forms and is unobtrusively built into the home design. Examples include roof overhangs, operable window shutters and retractable shading blinds.

The MVHR also helps control heat. In summer, the heat carried by the incoming fresh air is transferred to the exhaust air and pre-cooled before entering the rooms of the house.

In winter, it works in reverse, with the warmth carried by the exhaust air transferred to the incoming fresh air – without the two air streams ever physically mixing.

There are also 10 large internal water tanks positioned to capture the sun and help regulate the home’s temperature.

The continuous insulation also protects the home against excessive temperatures.


Passive homes are renowned for their ultra-low energy bills. But the owners of the Thornleigh house wanted to go even beyond the Passive House Certification standards – touted as the highest in the world – and make their home entirely self-sustaining. So, we did!

“The building form responds to the sun path across the site, maximising solar gain for winter while providing high levels of shade to keep cool in the summer months. The large north facing roof allows for a significant photovoltaic system, sufficient to be energy positive over the year,” explains Dick.

The home has a 17,000-litre rainwater tank that collects and stores all roof water, providing most of the water the home needs.

Landscape Architect: Elke Haege Thorvaldson

Photography by Petri Kurkaa and Brandee Meier

Thinking of designing your own dream home?

Talk to us today and discover the possibilities.

Contact Passivhaus Design & Construct