Ingrid – In addition to the environmental agenda, we knew from the outset the client wanted this project to embrace prefabrication.

Diego –Yes, that’s right. Speaking to the client – as naturally inquisitive types – we asked whether we should start investigating typical module sizes? To that, the client said “No, I don’t want to limit your design with those considerations. We’ll overcome the technical challenges later” 

Ingrid – What were the drivers behind the prefabrication?

Diego – Well, their house in Italy was also prefabricated and it also ties into the environmental initiatives. Though you don’t have to prefabricate to meet those challenges, it does help in minimising waste.

The benefits dovetailed together because a Passivhaus home requires a lot of taped seals. This is far easier to achieve in a clean factory than a dusty site. The benefits for us in prefabrication were not the typical ones of modularisation. In fact, each panel we have here are different in shape and form. In this case, the benefits have been in quality control, waste management, time management due to wet and heat on site and working with tight site constraints. In addition to this, the basement structure could be progressed whilst the panels were being fabricated in the factory.

Ingrid – In the Living Building Challenge, the process of sourcing the materials and the materials themselves form part of the requirements. There is a list of banned substances and chemicals that aim to create a very healthy kind of indoor environment – particularly in the first year where many of these products are off-gassing.

Diego – Here again, you see these two environmental agendas working together because as part of the Passivhaus system fresh air is constantly being delivered into the house, creating an incredibly healthy indoor air quality.

Also, with the Living Building Challenge, the goal was to find sustainable local materials which actually throws a real kind of focus on what’s available in this country. It’s about supporting local products and local trades which our practice has always enjoyed doing. There’s also been a focus on finding recycled materials. The external timber is repurposed from a shed in NSW and the internal timber is reclaimed eucalyptus from Lake Pieman in Tasmania.

Ingrid – Yes, timber was an obvious choice as it’s relatively easy to source locally in a recycled form, but the stone that we’ve ended up using has come about due to a confluence of reasons.

Diego – Yes,  the site is at the end of a cul-de-sac and the bedrooms have ended up positioned to the front of the block, so privacy became a significant concern. We wanted a solid external material and Mt Gambier limestone emerged, as it’s quite an easy material to sculpt and comes from South Australia. As we started detailing the project we began to think about cutting away at this solid stone block. Suddenly it started drawing out this language of carving and how you express depth. The sustainability agenda led us to choose a material which then developed into an approach to the detailing of the building.

Ingrid – Going back to Diego’s thought about what is available in this country, we’re in a bit of a catch 22 situation at the moment because the Living Building Challenge is an American standard. The market for this in Australia is quite immature but there seems to be increasing interest in the industry about this and Passivhaus. In a short period of time, there has been a lot of sharing of information with other professionals, builders and developers.

Diego – Passivhaus, for example,  requires certain membrane types and thermal components that are readily available in Europe and America but not in Australia. Then the Living Building Challenge limits the amount of those components in the project that can be sourced overseas.

Though for every challenge in the ways the two frameworks clash there’s an example of how they work together beautifully. The Living Building Challenge requires the house to generate 110% of its energy requirements. Conforming to Passivhaus we have an incredibly well-performing house that requires very minimal energy for heating and cooling so achieving the Living Building Challenge energy target is easier than you would expect.

Working in the two sustainability standards has added real depth to the project which complements the design. There are so many of these principles which we plan to implement into future houses but also see great possibility for their implementation into the other project types within the office.