Surrey Hills house

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Revision as of 10:46, 31 March 2007

Rear view
Rear view
Living room, looking outside to back yard
Living room, looking outside to back yard
Dining room
Dining room
Main bathroom
Main bathroom
Owners Peter Campbell and Lena Sanci
Location Surrey Hills, Melbourne
Country Australia
Type Sustainable renovation
House size Medium, 21 squares
Owner contact E-mail owner


Summary of house features

  • Passive solar design
  • Solar panels, grid interactive and batteries
  • Generate 75% of total electricity requirements
  • Solar hot water
  • Rainwater tanks, self sufficient
  • Low power appliances, no airconditioner
  • Double glazing
  • Forest friendly timber


Contents

Our goals

In 2001, 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. 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.

Passive solar design

Passive solar design is provided by regulation of sunlight from North facing windows (via selective shading using blinds or sails) onto thermal mass such as masonry walls and the concrete slab. This damps down temperature variations inside the house. In the Winter, sun is allowed onto the walls and floor slab to warm it up during the day. It then releases some of this stored warmth during the night. In the Summer, sail and blinds are used to shade the north facing windows. However, make sure you use a sail fabric that excludes maximum heat.

A solar chimney is created by a venturi peak with a window above the roofline overhead the upstairs stairwell. Hot air rises and leaves the house when this window is open. Cross-flow ventilation is achieved by the placement of wide-opening windows all around the house. When opened in the evening, these also allow cool air to be quickly drawn into the house when warm air is venting up and exhausted through the solar chimney.

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

  • 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 - we don't have an air conditioner
  • Draught proofing with window and door seals
  • Comfort glass was used in existing window frames. It has better thermal properties than normal glass

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

Solar hot water with gas boosting

Gas hot water booster
Gas hot water booster
  • Unit -- Edwards Stainless Steel LX305. 305 litre tank. Dimensions including tank 2500H x 2000W (2 x 14R copper collector panels)
  • Gas booster -- Bosch 18E Highflow booster (natural gas)

Heating and cooking

  • We use natural gas ducted central heating as the most energy-efficient forms 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! It has an electric grill though

Grid interactive solar array

Solar hot water panels, solar chimney and solar array
Solar hot water panels, solar chimney and solar array

The photo voltaic system (solar array) is grid interactive and has 500AH battery backup which can power the entire house for several hours during power failures or brown outs - the inverter automatically switches to the batteries to power the house. The surplus power we produce during the day goes back into the grid and is sold by the power company as “green power”. We get paid retail rates (known as 'net metering') for electricity we put into the grid as "green power". We were running off the grid from 8pm to midnight every night (4 hours), but now have the batteries there for backup. This can be set using a timer switch in the switchboard

Panels
Twenty 75-watt solar panels (BP Solar Modules, BP275).
Panel size is 530 x 1188
Maximum power output is 1.5kw
We generate about 70% of our total annual electricity usage. We are net power generators during Summer.
Solar panel
Solar panel

Batteries -- 500ah. 8 batteries X 6V each, in series = 48V

Inverter
Power Solutions Australia, SGB-5-48. Continuous output rating to 5kW. 48V
Connected to PC serial port for data download
Roof size
Roof area for solar panels is 3.25m x 5.5m + 1.8m x 2m
Roof area for solar hot water system panels is 3.25m x 2.75m
The roof are is North facing and has an angle of 15 degrees (approx)

Graphs of data downloaded from the inverter



Water saving

Main water tank
Main water tank
  • Water is provided by rainwater tanks (2 x 4500 and 13,500 litre) with collection from the roof. First flush diverters remove impurities in the water that first comes off the roof when it starts raining. A Davey electric pump supplies rainwater for all uses in the house. Go for a more powerful pump rather than one that just meets your requirements.
  • 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. All are manufactured in Europe.

Some other features that may be of interest

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)
  • 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 six years in the house

Passive solar design is a great success

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.

Using sustainable timber takes planning and effort

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 approved of the polyester insulation. He fled the original garage roof when I demolished it, but he found his way back in with great persistence. I eventually blocked out his entrance point (from next door's eaves) and put a possum box up in the large tree on the nature strip.

Rainwater collection has been a great success

The tanks have provided 99% of our water usage since we have been living in the house over six years. We added some Melbourne water to the tanks with Melbourne water during the drought in 2001, then twice again in January and March 2007.

Greywater systems can be difficult and expensive

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 foul. We have converted the tank over to rainwater for the garden are setting up a divert grey water diversion onto the garden. 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 install the best rainwater system with the biggest tanks (and electric pump if you need one) you can fit and/or afford.

Gardens with low water requirements are good

We have designed and planted the front garden with natives and other plants with low water requirements. In the back yard, we are planting food-producing species in a permaculture system, including fruit trees, a herb garden and a vegetable garden. In summary, we decided to commit to this project to take personal and significant action to lower our environmental and lifestyle footprint and we are both very happy with the outcome.

Keeping upstairs cool

We found that the study upstairs got too hot for comfort during very hot Melbourne days. This is partly due to our sails only screening out about 50% of the sunlight entering the windows. When purchasing sails, make sure you get fabric which excludes over 95% of incident sunlight. We fitted Renshade perforated aluminium foil screens inside the upstairs windows. The foil screen is simply cut to size using scissors then fixed with Velcro buttons. The manufacturer claims that the screens stop approximately 85% of all inward high temperature radiation. We agree; they have dramatically reduced the temperature upstairs.

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.

Credits

  • Photovoltaics Rob McCauley, RJM Electronics (03) 9435-6376
  • Water tanks and pumps Tanks A Lot (03) 9776-6016
  • Recycled timber Shiver Me Timbers (03) 9397 5993
  • Water heater Edwards Solar and Bosch
  • Insulation: Astrofoil and Thermowool

External links

Personal tools