I’ve just finished renovating my own place, an 1880’s workers cottage in inner-city Sydney. The plan was to add another bedroom and make the interior space more functional, whilst minimising both the physical and environmental footprint of the renovation. Specifically, I wanted to: retain and reuse as much of the home as practical and recycle what ever couldn’t be retained or reused; plan the interior efficiently to reduce the size of the extension; save energy and water (and utilise solar energy to be ‘carbon positive’); and choose building materials with a low environmental impact.

There were some challenges, mostly due to the age of the house, the tiny 4m x 30m site and the need to remain sym pathetic to the character of the existing area, which is part of a heritage conser vation zone. I wanted to retain as much of the house as I could, but had to com pletely demolish the old lean-to living area due to its dilapidated state.

The orientation was also a challenge, with the front of the house facing due north and the backyard and adjacent liv ing area due south. The front room was turned into a partially open home office to create ‘borrowed’ light for the rest of the house. The living area was designed to capture light and natural breezes and to maximise space. We built to the boundary in part, creating a north-facing lightwell to improve solar access.

Double glazing was used throughout, and for the extension we used a light weight walling system with panels made of recycled polystyrene. It was easy to construct and it was extremely thermally efficient — R2.5 even before we added the R1.5 insulation. Both new and exist ing ceilings were highly insulated using R3.5 batts for new ceilings and R2.5 for the existing attic roof (R2.5 was all we could fit without compressing the batts). Reflective foil sarking was added under new and existing roofs.

All lighting is compact fluorescent. Where possible, pendant lights have been used as they are a less energy- intensive way to light a room than down lights. Where downlights are used, they can be dimmed to 4W. In the bathroom, a 3 star showerhead, 4 star toilet and 5 star taps were installed. We also installed a gas-boosted solar hot water system and a 1,260W grid-connected photo voltaic system.

There were other challenges. Council regulations wouldn’t allow panels on the street facing roof, which was a problem as the house faces due solar north. After some negotiation we were allowed to install four photovoltaic panels on the street facing roof, and the remaining two on frames on the attic roof, hidden from street view. This allowed us to retain the perfect orientation and pitch for the photovoltaic panels, but we had to com promise and locate the solar hot water panels on the east-facing roof. This leads to about a 12 per cent reduction in annual solar contribution.

Finding room for a rainwater tank on the tiny site without excavating was a challenge. Because I had used a highly water efficient toilet and washing machine and native planting, I was able to get away with a 2,000 litre slimline tank. I also installed a pressure vessel to minimise the energy use of the pump.

I looked for more sustainable alterna tives to typically used construction mate rials, including:

• salvaging the front door, light fittings and garden pavers and reusing steel from the demolished roof

• high density polyethylene (HDPE) plumbing to avoid the use of PVC

• bamboo floating flooring (strand woven for hardness and durability)

• pine stair and skirting (no old growth/rainforest timber was used)

• low VOC paints with Environmental Choice label and low VOC joinery (kitchen cabinets, cupboards)

• decking made of sawdust and recycled PET plastic

The home is spacious, functional and uses about 3 kWh of electricity a day (the average home uses about 20 kWh a day), and so far the photovoltaic system has generated an average of 5.4 kWh a day. With the introduction of a feed in tariff, the ‘carbon positive’ home could potentially make money on bills. The rainwater tank has also provided 100 per cent of the water used.

I’m yet to do a final cost tally, but my sense so far is that (apart from the pho tovoltaic system), the sustainability fea tures added less than 3 per cent to the total construction cost. Many of the sus tainability features were cost neutral and some even saved money. This helped to subsidise some of the more expensive items, such as the HDPE plumbing and the solar hot water system.

The lesson for me was that it really pays to put in the effort during the design phase and when choosing prod ucts. It did take more time and effort to do the research, but I found websites like Your Home and ecospecifier really helpful. As far as I’m concerned, sustain able building has huge benefits and, as my builder said at the end of the proj ect, “It’s not just the way of the future, it’s here NOW!”

Caitlin McGee is research principal at the Institute for Sustainable Futures, UTS. McGee's research focuses on the sustainable built environment, learning and culture change. Before joining the Institute for Sustainable Futures in 2000, McGee worked as an architect.