Academics and practitioners often build a career in their own work domain and remain somewhat separated from what the others are doing.

As a teaching scholar in academia, when an opportunity came along to cross over and design and build a new house, I was eager to see how well our teachings on sustainable design and construction applied to the real world.

Whilst still teaching at Deakin across several property units, choosing and buying a development site was the first step into this real-world project where we’d design and build a residential house, aiming for a 10-star energy rating, and then evaluate if we could truly call it a sustainable house also.

Two of the taught topics that relate to sustainable new builds are: (1) Principles and Components of Sustainable Design, and (2) the Business Case for Sustainability (BCfS). We also teach retrofitting, though it’s the two teaching topics that relate to new builds that we were keen to test out.

Sustainable Design: here we teach using the acronym of MOTIVE to discuss Materials, Orientation, Thermal Mass, Internal room placement, Ventilation/insulation, and energy efficiency. In these areas, we consider the sustainable options available at dozens of decision-making times all throughout a project’s full process, from inception to occupancy.

BCfS: here we look at different ways to justify a sustainable decision based on the financial gain received. This has become easier to do, at least on paper, with each passing year, largely due to:

  • cost reductions in areas such as double-glazed windows
  • new and improved technologies
  • increased buyer demand.

The taught theory asks students to look for sales-value gains, lower running costs, longer life cycles, marketing advantages and ‘other’ which covers topics that vary across different project types such as rebates or green loans and leases. We consider both for-sale projects, as well as projects that are built to be retained.

House design

As our project was to be retained as a Build-to-Rent (BTR) project, the focus was placed on the builder/occupier elements. Certain aspects soon came strongly into focus such as site selection (to seek optimum north winter light) and specific material choices, of which we were surprised at just how many individual materials and components needed specific decision making.

For example, it’s easy to say in class that timber is sustainable and decide on timber use, though the reality was then of detailed decisions on timber type, finish, source (plantation location and management), travel miles, alternatives, raw vs CLT, new or recycled, laminate only, off-cuts management and more.

What also became obvious quite early was that there were many different views, knowledge levels and common practices in the industry. There was often a ‘usual’ material or process available, or put into the specs by default, and so, many times, we had to pause and think if that was the correct option. A standard mix concrete slab was a given, for example, for costings and sourcing unless someone stopped to ask if maybe fly-ash could be added.

The development estate this house is built on was helpful in highlighting greener options as they had in place many useful design guidelines that guided a house towards their minimum 7.5-star rating. This ensured some of the key elements like glazing would not default to a minimum building standard.

Despite this guidance, there were still many surprises. While we were around the 100th buyer to purchase a lot on the estate, we were still able to choose a premium site for optimum orientation and wondered why others overlooked it.

Earlier buyers had chosen sites that were far more difficult to design a passive-house on, and it left us curious as to why they chose the sites that they did. It was another reminder that in the real world, many factors affect decision making, and that a sustainable design priority can be overridden by other factors such as land size, privacy, views, etc.

The project clarified also that sustainability and energy efficiency were two separate things in terms of application. Energy efficiency was easy to understand, easy to plan for and control, and, also very simple to measure and quantify. It was about clear technology and design choices.

An 8.4-star rating was easy to achieve and also had a good business case to justify itself. Building a Sustainable House under the UNESCO definition that asked us not to harm future generations was far more complex and remains difficult to quantify. It’s easy to casually self-assess one’s own project and loosely describe it as sustainable when it contains certain design elements and materials, but the term ‘more sustainable’ seems more fitting.

Towards the project’s end, we were happy to realise that we could indeed follow our own teachings and achieve a high energy efficiency rating. We also recognised that in reality, several practicalities indicated that around an 8-star rating was a more likely outcome than a 10-star rating. We were also happy to find that the taught MOTIVE principles guided the project’s design well and lead, for example, to the inclusion of a very effective air-lock door system in a windy coastal moderate climate.

The biggest hurdles were a project partner’s differing expectations on design and materials, and the cost with the 9th and 10th stars proving more difficult to afford. Pushing for a 10-star house would require it to be the absolute priority at every step of the project.

As for being a ‘sustainable’ house or not, the house gets ticks for its materials, passive design features, internal lay-out, air-lock front door, energy efficiency and more, but we’re still left wondering if something with a concrete base and steel roof could ever truly be called sustainable. Perhaps if it performs its function of ‘shelter’ for 200 years, and if the garden surrounding it has 200 years of ecological activity, it could be seen as sustainable.

The Indigenous population who lived in the area for thousands of years lived in a truly sustainable way, and so perhaps the answers lie at the mid-point of the early and current ways of sheltering. In the meantime, the teaching material was found to be sound. The best part of this project was that, as hoped, the teaching helped to make the real-world project better, what we learnt in the project helped to make future teaching better, and that’s the beauty of learning.