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You are here: Home Our Projects Biosensitive Futures Part 5: Social Change Built environment Housing - retrofitting

Housing - retrofitting

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Retrofitting existing houses - cool temperate zones

Derek Wrigley

How can we modify the houses we now live in to reduce our growing consumption of polluting electricity and other resources?

A very high percentage of our houses have been built simply as shelters against the wind and the rain with little concern for effective internal comfort, even for the stable climate we once knew.

We now have the added problem of global warming and the promise of unstable climate changes which are emphasising the weaknesses in our shelters. In Canberra the temperature can be 35º one day and 19º the next.

Briefly, our houses leak like sieves, letting in cold air in winter and heat in summer, but provide very little control over these discomforting elements. Instead of trying to understand how we might design better structures to counter these climate extremes we have tended toward the easier alternatives of superimposing technologies which almost invariably involve the consumption of electricity, such as air conditioning and heating.

Environmental costs - Viewed holistically, these ‘extras’ often make matters worse as they are reliant on fossil fuelled energies such as coal, natural gas and oil which continue to pollute our atmosphere – exacerbating the problem of global warming In addition, we squander valuable resources such as rain, grey and black water as worthless, through reticulated systems conceived over 150 years ago. These services have served us well but we continue to take them for granted, ignoring some of the environmental costs which are now becoming evident. Centralised systems may make sense in compact countries like Europe, but become nonsense in a huge country like Australia when seen in the light of emerging environmental degradation.

Remedies - This cannot continue, and techniques of a more decentralised nature need to be considered at the source of consumption. We must adopt more self-reliance at the point of consumption by:

  • urgently reducing our consumption of fossil fuels in our houses, (and elsewhere)
  • modifying all our existing houses to use natural energies rather than by adding corrective, consumptive technologies
  • conserving our more tangible resources at source, such as rainwater, soil, domestic wastes, biodiversity
  • designing better new houses

Most of the remedial measures listed below can be applied to every existing house and some can return big improvements in comfort, conservation, convenience and cash – by considering water, electricity and gas, warmth, coolth and waste (resource conservation).

  • The size of this paper limits the possibilities that are available, but do seek advice on the action you intend to take as a single retrofit may not be effective - there is often a cumulative synergy in coupling various techniques


Winter warmth - ‘ maximise free solar gain – minimise expensive heat losses’.

  • Capture solar radiation through northern windows in winter by not covering the glass with curtains, internal or external blinds of any kind when sunny.
  • Reduce heat losses through windows when sunlight does not penetrate by closing curtains, blinds.
  • Install adjustable solar shades outside northern windows which admit maximum winter sun but exclude all summer sun.
  • Be aware that fixed eaves are not fully effective in both seasons.
  • Insulate above flat ceilings with bulk insulation to at least R4 rating. If a sloping ceiling, apply insulation below ceiling (more difficult)
  • Increase the northern window size if at all possible.
  • Apply double glazing if possible, or apply an internal clear plastic pane, (almost as good and much cheaper)
  • Use heavy weight, dense weave, woollen curtains with air-tight lining, sealed against wall at vertical edges, anti-draught sealing at the top and close to the floor to minimise convective heat losses.
  • Insulate all cavity walls, ceiling and under wooden floors against heat loss, particularly in the warmer rooms
  • Apply draught stripping to all opening windows, external doors to reduce intake of cold air
  • Seal up exhaust fans in winter.
  • Install natural gas heating in preference to electric heating.
  • If you have a conventional brick veneer house, install some internal brick, stone or concrete walls to work in harmony with solar gain from windows.
  • Remove evergreen trees which shade any solar gain windows, replace with deciduous
  • Install southern reflectors to gain free, cheerful heat through southern windows, (don’t underestimate the psychological value of solar cheerfulness).


Summer coolth – ‘don’t open up – close up’

  • Do not install air conditioners. They are often seen as the easiest, cheapest answer, but they only exacerbate climate change
  • Install effective adjustable sunshades to all east, north and west windows which keep out the hot sun in summer and let in all the warming winter sun)
  • Install closable ceiling and open ridge vents to cool house structure overnight in summer
  • Insulate ceilings and walls as for winter
  • Keep the house sealed up on hot days to conserve coolth gained from previous night – only open all doors, windows and ceiling vents around 6pm when the outside temperature falls below inside temperature and leave open until breakfast time next day
  • Close curtains to minimise albedo radiation through glass
  • Grow deciduous, vigorous, clinging vines (e.g. Boston ivy) on east and west blank masonry walls.


Water – ‘just enough is plenty’

  • Install water tanks to serve all domestic needs
  • Wherever possible use water twice before finally disposing of it
  • Water down the drain from showers, washbasins and laundry tubs is a waste, put it on the garden
  • Repair dripping taps
  • Install water saving shower heads
  • Shower in two minutes
  • Try washing your hands and face in the equivalent of an egg cup full of water
  • Modify the toilet cistern to a simple manual raise and lower operation
  • Wash up in half a sink of hot water, return the dishwasher to the manufacturer
  • Scrub vegetables under a 2mm diameter flow of water and collect it in a sink bucket to water plants in the garden
  • Collect cold water run-off in the bucket wherever appropriate
  • Use cold water washes in the washing machine
  • Restrict number of washes, using full basket loads, divert into the garden
  • Rinse your teeth in a 2mm dribble of water after brushing and turn on tap only when needed
  • The ultimate aim is to use water at least twice for lesser quality internal usage.


Electricity – ‘conserve’

  • Electricity (as currently generated) is really a dirty, inefficient, polluting fuel and a major contributor to global warming and climate change
  • Switch off all appliances at the power point
  • Switch off the little green/red LED lights on appliances – they are still consuming
  • Switch off the little black transformers at the power point – they also consume, even though the appliance itself is not in use
  • Choose low-consumption electrical fittings when buying
  • Don’t leave external lights on at night – use proximity switches
  • Empty rooms don’t need the lights on
  • Use compact fluorescent lights
  • Avoid halogen lights; prefer LEDs
  • Avoid downlights
  • Install a photovoltaic array if you have a suitable roof
  • In-slab electric heating is a big consumer of electricity – switch it off at the board and use natural gas instead
  • Install solar hot water heaters, preferably evacuated tube type or heat pump
  • Install as big a photovoltaic array on your roof as you can afford. It will not only reduce your CO2 emissions and supply free electricity but will also shade your roof, reducing the intake of solar heat in summer and reducing the heat losses to the night sky in winter.


Resource conservation – ‘waste not want not’

  • Repair broken items if possible, rather than throw away and buy new
  • Recycle all disposable material – glass, plastic, paper, cardboard, metals, aluminium foil
  • Take re-usable equipment to recycling centres
  • Compost all kitchen waste and build up the garden soil structure
  • Obey water restrictions
  • Put in rainwater tanks (as much as you have space for and can afford)
  • Eliminate all lawns and replace with low maintenance covers, (lawns are a highly consumptive garden feature, totally unsuited to our climate)
  • Use rechargeable batteries
  • Become a DIY person and encourage your children to do so. It is a highly valuable survival skill.