Sapling

Sapling by Anderson Architecture represents the pinnacle of sustainability in construction, operation and liveability. Designed to achieve the prestigious Passivhaus Premium certification, Sapling is an architecturally striking home for a growing family, which through the implementation of Passivhaus principles and the installation of solar panels produces more energy than it demands. 

It provides year-round thermal comfort for its inhabitants, while preserving the indoor-outdoor lifestyle they treasure.

Originally designed around two mature trees- a Jacaranda and a Cheese Tree- the unexpected felling of the Cheese Tree due to structural defects has made way for the planting of a new sapling in its place. Sapling itself echoes this transition, breathing new life into the site and serving as an example of an alternate, more efficient means of building, growing and thriving in the inner west suburbs of Sydney.

Oriented to the north, Sapling encircles the site's existing Jacaranda, capturing and controlling sunlight and daylight access through passive design means and high performance windows and glazing. Operable glazing throughout the ground and first floors of the home allow for passive ventilation and cooling when conditions allow, while a high level of airtightness and a heat recovery ventilation system (HRV) provides ample fresh air when conditions necessitate the closing of windows and doors.

Sapling by Anderson Architecture has been recognised at the Sustainability Awards 2024 with a highly commended mention in the Single Dwelling (New) category, sponsored by Billi.

Architecture & Design sits down with Alexandra Woods, Project Architect and Passivhaus Designer.

Architecture & Design: Can you describe the initial vision for this project and how it evolved over time?

Alexandra Woods: In terms of its brief, Sapling was to be a 5-bedroom home for a growing family of five, replacing a cramped and dark cottage existing on the site. The design was to capitalise on the city skyline views available from the property, and respect the existing mature trees present on the site. 

From the very first, it was also to integrate sustainability initiatives including solar passive design, the harvesting and reuse of rainwater and the generation and storage of energy on site. The home was to provide its occupants a light and airy haven with multifunctional spaces that could be used to entertain as well as to rest. 

The project evolved to become one of only four buildings in Australia to receive the prestigious Passivhaus Premium certification, providing a stable, healthy and predictable internal environment for our clients, in turn promoting resilience in the face of a changing climate.

What were the biggest challenges you faced during the design and construction phases, and how did you overcome them?

The biggest challenges faced were related to the site, planning restrictions and the pursuit of sustainable development, though it was through these challenges that the unique character and form of the home and its high level of sustainability were achieved. 

By responding sensitively to the site and its neighbours, the two wings of the home were arranged to respect and enhance the amenity of the development and that of its neighbours. Positioned to accommodate two large existing trees on the site, the two wings of the home open up to the site’s private open space and northern aspect, capturing and controlling sunlight and daylight access across the year. 

Unfortunately, one of the existing trees was lost to storm damage just prior to the commencement of works on site, and so a sapling has been planted in its place. Planning restrictions also spurred on one of the home’s unique features, the round Reading Room, designed to capture views of the Sydney city skyline. 

This required some negotiation with council but ultimately resulted in a mutually agreeable outcome. The pursuit of carbon negative construction and attaining the Passivhaus Premium certification presented some challenges, particularly during construction, however our clients and the builder were enthusiastic towards both and actively worked with us to achieve these outcomes.

How did you ensure that the project met the client’s needs and expectations?

Our clients’ brief was for a home that had not only outstanding indoor environmental conditions but had a minimal impact on the environment in terms of both embodied and operational carbon, and ongoing resource consumption. 

Through the combination of refined architectural design, careful material selection, traditional passive design principles and its Passivhaus certification, Sapling has achieved, and can be expected to continue to meet, our clients’ needs and expectations. Sapling provides much needed space for its growing family, while being carbon negative in terms of both embodied and operational carbon. 

A fully electric home with a 20.88kW solar panel array, the Passivhaus modelling indicates that the home produces almost four times the energy it needs to run, leaving plenty for charging our clients’ EV and the pool pump which sit outside the Passivhaus calculations. 

The home also promotes the health of its occupants, with low and zero VOC finishes used wherever possible, and natural materials such as cork and exposed Cross Laminated Timber prevalent throughout the interior.

Were there any unique or innovative techniques or materials used in this project?

A Cross Laminated Timber (CLT) skeleton was chosen for Sapling, due to its environmental attributes including carbon sequestration, its strength, the speed of its assembly and the ability to leave selected surfaces exposed as the internal finish. The CLT has been externally wrapped in wood fibre insulation and supplementary mineral wool insulation added to wall and ceiling panels that our modelling indicated required further insulation.

How does this project fit into your broader portfolio and design philosophy?

Sapling is demonstrative of our firm’s belief that design and sustainability should be inseparable- that the buildings we build today should be designed to support the health and well-being of both humans and the natural environment as we face the climate of tomorrow. 

Beyond sustainability, Sapling demonstrates our focus on adaptability and resilience, and how we can promote both through the built environment without it costing the earth.