In 2019, Melbourne building designers Altereco Design were contracted to undertake a renovation on a house in Spotswood, in Melbourne’s inner west. The design brief was to undertake a major renovation on the rear of the dwelling, plus upgrades to the existing remaining cottage to ensure the house was thermally efficient, and, importantly, could provide some protection for the resident — specifically relating to air quality.

Altereco pride themselves on designing climate resilient homes, and were trialling the installation of air quality monitoring sensors at the time the design brief came in. Such sensors can track all the key pollution markers like particulate matter (PM1, PM2. 5, PM10), NO2, O3, SO2, H2S, NO, and CO gases. They also provide reliable data about key weather parameters such as temperature, humidity, air pressure, and wind from the location they are fitted in and can be turned into data reports to help both clients and designers understand potential pollutants in the home.

Altereco asked the client if they’d be interested in installing such a monitor during the initial consultation period to collect data on the types of pollutants and the relative accumulation of various particulates and humidity in the period home. James Goodlet, who undertook the design process says that back in 2019 there were few design firms undertaking air quality assessments as part of the design process.

“I’d highly encourage people to do the testing before they start the design – especially in bedrooms. It’s valuable to know what air quality is like, especially the relative C02 build up overnight, if you have gas appliances, you’d need something that has a carbon monoxide reading. In bathrooms, it’s important to monitor humidity levels.”

James says that for $150 you can buy a pollution monitor off the internet and install it in your home. In the case of the Spotswood residents, they had the monitor installed over the Christmas period in late 2019, just preceding the catastrophic black summer bushfires that engulfed Melbourne shortly after. James recalls that the readings for particulates went through the roof, basically all the smoke that had rolled through Melbourne in the week following, immediately penetrated in to the old leaky home.

They quickly learnt that thermal performance upgrades alone would not address the air quality issues that the clients required due to respiratory sensitivity. As most people that have renovated can appreciate, while the outcome will be far better than previous years, there is still some level of compromise. Compounded by the rising cost of construction and the actual cost to undertake the renovation, the clients asked what the cost difference would be for a new build, but one with air quality firmly centred in the design.

They decided to look to designing a Passive House, meaning a home that is built to strict air circulation criteria as a function of the design and temperature control. A key element of Passive House is a healthy indoor environment, and this relies on an air-tight envelope and building in mechanical ventilation through a heat (energy) recovery unit (MVHR) that provides 100% fresh air all year round, with high levels (up to 90%) of heat and energy recovery. By their design, and with the installation of a heat recovery unit they aim to have completely balanced (equal amount fresh air in to exhaust air out) ventilation to the entire building.

The clients decided to move forward with a rebuild and managed to find a new home for their existing home and it was reallocated to Ballarat where it is currently enjoying regional life. During this period, they also decided to abolish the gas meter, to ensure their new dwelling would be gas-free. Working with a certified Passive House builder, Carland Constructions, the team built a resilient all-electric home with an eye for good design, and air quality. Though Passive Houses are not for everyone, they demonstrate best practice when it comes to high-performance homes that mix architecture and sustainable building practices. Designing for the building to be air-tight, for health reasons in this case, is also best practice when it comes to maximising thermal efficiency, and making sure that energy bills will remain low for the life of the home.