passive timber house by alex symes wraps around 60-year-old tree in australia

pepper tree passive house by Alex Symes Architect

Within a lush pepper tree canopy in Illawara, Australia, Alex Symes Architect has designed a secondary timber dwelling built to the Passive House standard, the most sustainable structure standard in the world. The new residence wraps around a 60-year-old tree in the steeply sloping disused courtyard of the existing main house, and is formed to serve as an office during the day, and a short-term stay cabin at night.

all images by Barton Taylor

24-hour space with improved passive character

Although the existing home had a dated and thermally inefficient brick facade, its internal layout worked nicely for the young family. Therefore, the project brief evolved into one where the existing home’s exterior was upgraded, adding new insulation, a ventilated timber screen facade, new skylights, a wraparound deck, a solar panel pergola, as well as a striking secondary dwelling.

Alex Symes Architect (find more here) built the new dwelling around an old Pepper tree, envisioning it as a 24-hour environment, that provides office space for the family’s growing company during the day, and short-stay accommodation at night. The house was designed in accordance with the Passive House standard, giving guests a chance to experience the improved quality of the space while also constructing a future-proofed studio with western views of Mount Kembla and the treetops outside. Meanwhile, this secondary residence hosts an endemic-planted green roof on each of its wings, allowing the site’s biodiversity to recover despite the larger construction footprint.

natural materials and passive design strategies

The works to the existing home make it more thermally comfortable, whilst adding new leisure spaces throughout. The biophilic link of the entire site with its immediate environment is emphasized by the use of a natural and raw materials, which include timber, indigenous rooftop gardens, and a tree canopy deck.

Utilizing salvaged and ‘waste’ materials lessened the project’s environmental impact without compromising the quality of the materials. The project’s overall grid energy consumption is just 14% of that of a comparable-sized home, thanks to the installation of a 12kW photovoltaic panel system that complies with the Passive House standard. In this way, the design reduces the lifetime cost (both economical and environmental) to the clients. As opposed to thermally upgrading 160 sqm to the passive house standard, only 60 sqm will actually be comfortable in future peak climatic conditions. This method establishes a precedent for making modest, climate-adaptive extensions without incurring the prohibitive expense of renovating every existing structure.