SOLAR EFFICIENT RENOVATION IN SURREY HILLS
Peter Campbell, 28 August 2003
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Our goals
Two years ago, my partner Lena and I were faced with the prospect of living in a dark and dingy 1930’s duplex “one of a pair” solid brick dwelling built in 1930, renovating it, or buying another house. The old house had a maze of small pokey rooms. We viewed the high cost of selling and buying property, where a lot of money goes to the “middlemen and the taxman”, as a waste of money. We were really keen to make maximum use of the sun for heating and natural lighting, and decided to go ahead with renovating. We prepared a detailed brief covering our requirements, with a strong focus on low environmental impact features.
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Designing the house we wanted
After discussing the project with Andreas and Judy Sederof from Sunpower Design, we felt confident that we could achieve what we wanted, although the site and the existing dwelling presented challenges. It soon became clear to us that the expertise and ideas that experienced “sustainable and solar efficient” architects provide is invaluable.
After the renovation every room was changed. The front living room became the master bedroom with an ensuite and walk-in-robe attached. The rear of the building was removed. The streetscape and the connection to the neighbouring duplex were maintained.
The design incorporates the use of courtyards and glazing on the north face to maximize solar gain. Extensive double glazed roof glazing over the dining/living area also brings light in from the north, which compensates for the lack of windows on the northern party wall.
In summer, all the north-facing glazing can be shaded my sails and blinds. This is essential to prevent the house getting too hot when the sun is strong.
The extension was built with a suspended concrete slab for thermal mass. The party wall was built from “aerated autoclaved concrete (AAC)” blockwork, which is light to handle, easily shaped, has good thermal mass and insulates well. There is a basement below the living room has to accommodate batteries, storage, a dog shower and a cellar.
Maximum cross flow ventilation has been achieved with carefully positioned windows. A window positioned above the stairs creates a thermal chimney/venturi effect when it is open; warm air from the entire house can be vented through this in the evening in a matter of minutes.
The open plan nature of the kitchen, dining and living spaces opening onto an external north-facing deck and internal courtyard are very conducive to a relaxed lifestyle. A shade sail also protects the deck in summer, and is removed in winter to allow maximum solar penetration into the building.
We have a large double study above the living areas with views across the leafy valley of Back Creek. The pitch of the North-facing roof was designed to accommodate twenty solar panels and a solar hot water service. The design conformed to building and planning regulations, so a planning permit was not required.
A summary of the features that add to the sustainable nature of the house include:
Materials
- Forest friendly
timbers; plantation pine, recycled
Mountain Ash and Jarrah (but Western Red Cedar for windows)
- Cabinet timbers are New Age Veneers from plantation Poplar
- External cladding is rendered fibre cement sheet and AAC blockwork
- Double glazing for all new windows and glass doors
- Recycled bricks were used for masonry walls and paving
- Recycled steel was used for slab reinforcement
- Concrete slab is GB slag blend (recycled content) and provides thermal mass
- Polyester insulation in walls and ceiling does not irritate the skin
- Astrofoil insulation was used as roof blanket upstairs
- Foil insulation is used under the floorboards
- Foam insulation is used under the slab
- Foil under roof tiles over the brick part of the house prevents heat entering the roof space
Fittings and design features
Recycle bins in kitchen are easily removed to the exterior via a hatch to a hall cupboard
Ceiling fans circulate air and provide cooling effect - no air conditioner is used
Draught proofing with window and door seals
Sail and blind systems can selectively shade north facing and roof windows
Cross-flow ventilation has been provided by careful window placement and design
Solar chimney created by window above stairwell
Comfort glass was used in existing window frames. It has better thermal properties than normal glass
Passive solar design is provided by regulation of sunlight from North facing windows (via selective shading) onto thermal mass
Finishes
- Tung oil based finish with a low toxicity is used on all timber flooring
- Paints are Berger BreathEasy (low toxicity)
- Light internal paint colours reduce need for electric lighting
Energy usage
- Motion detectors switch external lights
- Low energy light bulbs can be used in surface mounted and pendant lights
- Photo voltaic system is grid interactive and has 500ah battery backup. We operate off-grid 4 hours every night, or longer during power outages. We have twenty 75-watt solar panels and are producing more power than we consume, which is sold by the power company as “green power”. The inverter is 5kVA and connects to a PC serrial port so data can be downloaded. Details
- Solar hot water with gas boosting is used. Details
- Gas central heating is the most energy-efficient form of heating
- Gas oven and cooktop is the most energy-efficient. We found a Westinghouse gas wall oven after being told that nothing like this was available!
Water saving
- Water is provided by rainwater tanks (2 x 4500 and 13,500 litre) with collection from roof and first flush diverters. An electric pump supplies rainwater for all uses in the house. Go for a more powerful pump rather than one that just meets your requirements.
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Low flush volume toilets
- Water saving shower roses with a low volume water flow
- Grey water collected from showers and the bath can be diverted onto the rear garden. Don’t collect washing machine water if you are washing nappies!
- All appliances have 4.5 star energy rating or better
Some other features that may be of interest
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All rooms and desks have:
- Cat 5e LAN cable (for computers)
- Telephone cable (could use Cat 5e for this, which is more versatile)
- RG6 video coax (for video signal transmission into the room, e.g. from a DVD or VCR unit)
- RG59 antenna coax (could use RG6 for this as well)
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All wiring comes to a patch panel so it can be
connected as desired. A firewall/router shares the cable Internet connection to
all PCs
After one year in the house
After a year living in the house, we are amazed by how effective the passive solar design is. On a sunny winter day, the rear of the house is so warm that we don’t need the heater on. In summer with all sails and blinds in place, the house stays cool.
The double-glazing has been a great success in both regulating the temperature and keeping noise out. We use no soft furnishings over the double glazed windows as they restrict solar access if left closed during the day. Curtains are used on rooms where privacy is required.
If you are planning to build or renovate, and you want to avoid native forest timbers (as we did) you need to carefully research suitable timber and find tradespeople who are prepared to use it. Western Red cedar comes from old growth forests in North America, and some people are allergic to it.
Our resident brush-tailed possum has approved the polyester insulation. He fled the original garage roof when I demolished it, but he has since found his way back in with great persistence. I know how he gets in, but he does no harm, so we coexist in peace. They are clean with their nests.
The rainwater system has been a great success. We have only needed to fill the tanks with Melbourne water during the drought. I think the tanks will provide over 90% of our water usage.
We have been on a steep learning curve with grey water. The initial system using a tank and pump was not successful as the greywater quickly became smelly. We have converted the tank over to rainwater for the garden and can now divert grey water onto the garden directly. While you can now buy specially designed grey water systems, they are very expensive and will require maintenance. Rainwater is suitable for all uses, so I think it is better to set up the best rainwater system with the biggest tanks you can fit and/or afford.
We are now in the process of designing and planting a garden with natives and low-water requirements. We will also plant food-producing species in a permaculture system, including fruit trees, a herb garden and a vegetable garden.
We decided to commit to this project to take some personal and significant action to lower our environmental and lifestyle footprint and are both very happy with the outcome.
Forces for change
There is growing interest in the community about sustainable housing and there has been a lot of recent media attention. There are significant opportunities for government to further promote the design and building of energy-efficient and sustainable buildings, both through incentive programs and legislation. The Bracks government announcement of more brown coal power stations in Victoria is step in the wrong direction.
We need to keep political pressure on for development and promotion of the use of renewable energy and set some stretch goals for sustainable housing. It may be cheaper to put solar panels on everyone’s house rather than build another greenhouse gas belching power station. Every new dwelling should have solar hot water and large rainwater tanks. Solar efficient dwellings are good for the environment and very pleasant to live in.
Photos
Construction photos: http://www.lexicon.net/Webphotos/200108_DurhamRoad/album1.html
Latest photos: More photos
Credits
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Designer |
Andreas Sederof & Ryan Strating, Sunpower Design (03)
9386-3700 |
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Builder |
David Smith, Solarcon Constructions (03) 9437-1411, |
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Photovoltaics |
Rob McCauley, RJM Electronics (03) 9435-6376 |
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Water tanks and pumps |
Tanks A Lot (03) 9776-6016 |
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Recycled timber |
Shiver Me Timbers (03) 9397 5993 |
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Water heater |
Edwards Solar and Bosch |
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Insulation |
Astrofoil and Thermowool |