Eco Renovation

When Adelaide architects John Maitland and Maggie Slattery of Energy Architecture went looking for a place to live in close to the city, the last thing on their wish list was a heritage cottage.

“Been there, done that,” John says. “The last thing we wanted was to have to deal with heritage considerations. In fact we were for looking something we could responsibly demolish. But that’s not quite how it turned out.”

Instead, the nature of the block convinced them to buy an 1877 bluestone cottage. At 10 metres wide, it was large for its inner-city location. The cottage itself was structurally sound and previous owners had installed damp coursing. Some dodgy additions including a lean-to dunny at the back had to go but the east-west length meant they could extend on the southern five metres and face the extension north.

“Basically, we paid land value for four established rooms and had the space to extend sustainably and energy efficiently,” John recalls. “In the cottage we were able to deal with passive comfort conditions without doing anything external, so it was too good an opportunity to pass up.”

As one of the directors and architects of an environmentally sustainable community-based housing project, Aldina Arts Eco Community, John had access to a repertoire of recycled materials for the renovation.

Cobblestones that came from the UK as tall ship ballast and were reused as paving for the holding yards at the meatworks, which once stood on the eco village site, found new life in the house as a feature wall between the bedroom and the living area. The wall provides both acoustic separation and thermal mass.

Bluestone for repair work also came from the eco village, as did the loads of old oregon the architects used for benchtops, structural beams and timber frames for windows and doors.

John and Maggie began work by installing a below-ground 16,300-litre rainwater tank which they estimate will take care of more than 90 per cent of the household’s needs. (Their adult daughter, violinist Simone, who is doing the honours year of her music degree, also lives in the cottage). The tank is a sturdy, affordable and relatively easy-to-install “crate and bag” system, strong enough to support a courtyard on top and a tiny carport just large enough to hold their Smart car.

They also introduced a 600-litre grey-water collection tank. Once it receives Health Commission approval, the water will be stored in another 2000-litre tank to take care of their needs for toilet flushing, the washing machine and irrigation of their vertical herb and vegetable garden. Electricity needs are met by renewable energy rather than on-site generation.

Apart from minimal solar gain from the thermal mass of the bluestone, John says the original cottage was bitterly cold in winter. The installation of 90 Apricus evacuated solar tubes takes care of the household’s hot-water needs and is delivered to a 500-litre tank which also feeds gas-boosted hydronic underfloor heating in the extension and radiator panels in the original section.

High-level insulation to both the external and internal walls and the roof further takes care of climate control. The extension roof is white corrugated steel in Fielder’s Sea Mist for maximum reflection in summer. The roof angle is calculated for maximum winter solar gain. Thermal mass from the internal and external walls and reconstituted sandstone pavers in the extension and courtyard also takes care of solar gain during the colder months.

All new windows are double glazed in laminated clear Comfort Plus glass from CSR Viridian. Blockout fabric and blinds shade the courtyards and high-level and verandah windows, so unwanted radiation is excluded from the house. Cross-ventilation provided by carefully positioned vents and windows further contributes to climate control and a skylight over the kitchen adds light to the work bench and captures cool summer breezes. There’s a retractable blind for deflecting intense summer heat.

Cool pipes work in conjunction with cross-ventilation bringing cool air into the rooms through low-level vents and evacuating the hot air through vents in the ceiling, roof space or high-level windows in the extension. There’s also substantial external moveable shading for preventing direct sunlight on the windows, pavers and walls.

John reports that even before the cool pipes were operational the house performed remarkably well during a heatwave last summer. “Even on the worst days the interior temperature didn’t get above 24°C,” he says. “One night the temperature stayed around 32°C but inside it only reached 28°C. It was a bit uncomfortable, but nothing like it would have been in a brick veneer.”

Cabinets are made from E1 board, which is low-formaldehyde MDF (medium-density fibreboard), and the walls painted with low- or no-VOC (volatile organic compounds) paints. Carpet on the timber floors of the original cottage is HiFidelity by Tuffmaster, selected for its durability, pure wool content, natural backing with non-toxic adhesive and environmentally sensitive production practice. Hansa eco taps and showerheads, four-star appliances, no plasma TV screens and minimal standby usage all add to the cottage’s light footprint.

When asked if he is particularly pleased with any aspect of the design, John responds “its entirety”.

“It’s like the human body — it’s not just the skin that matters,” he says. “It’s all the organs and operating systems within. It’s the thermal mass, the orientation, the cool pipes, the cross-ventilation, the hot-water system and the insulation.

“It’s little things like using LEDs and CFLs [compact fluoro lights] and the little glass slot between the box gutter and the wall which adds a light airy texture to the living area, but has a shade blade to reduce summer radiation entering and reflect winter light into the space below.

“As an unexpected bonus, we’ve moved into a street that has a great sense of community. So in all it’s a lovely space in which to live.”

Article Tags:  Eco renovation, eco, green, construction, ventilation, cool pipes, insulation