28 February 2017

Large potential for Victorian homes

Sustainability Victoria has released a series of technical reports detailing the potential energy savings for existing homes. Six years of research concludes Victorians can save on their energy bills and reduce greenhouse gas emissions by improving their energy efficiency.

The initial study, On-Ground Assessment, collected detailed data from a reasonably representative sample of Victorian houses and modelled a range of efficiency upgrades that could be practically applied to them.

The study found the houses were very inefficient, with an average House Energy Rating – the thermal efficiency of the building shell - of only 1.8 stars with:  

  • walls and floors often uninsulated
  • relatively low levels of ceiling insulation
  • high levels of air leakage
  • widespread use of single glazing with little winter protection such as drapes
  • lighting and appliances were generally much less efficient than those now available.

The study estimated that electricity and gas use could be cut by 45 per cent if all upgrade measures used in the study were applied, delivering annual energy bill savings of $990 a year and greenhouse gas emissions reduced by around 3.4 tonnes CO2-e.

Upgrading appliances was more cost effective overall than building shell upgrades, as they were responsible for 59% of the reduction in energy bills and only 39% of the upgrade cost.

This initial study is published with a series of targeted Retrofit Trials where key energy efficiency upgrades were undertaken in houses and monitored to assess the actual cost, energy savings, and the householder’s experience.

The nine reports cover:

  • Draught sealing retrofit trial (16 houses)
  • Cavity wall insulation retrofit trial (15 houses)
  • Window film secondary glazing retrofit trial (8 houses)
  • Gas heating ductwork retrofit trial (8 houses)
  • Halogen downlight retrofit trial (16 houses)
  • Refrigerator retrofit trial (21 houses)
  • Clothes dryer retrofit trial (4 houses)
  • Swimming pool pump retrofit trial (8 houses)
  • Gas water heater retrofit trial (6 houses)

The appliance upgrade studies found that large energy savings could be achieved by replacing old inefficient appliances with new high efficiency ones. The average energy savings achieved were:

  • 616 kWh/year (67%) when old refrigerators were replaced with new high efficiency ones
  • 623 kWh/year (69%) when conventional electric clothes dryers were replaced with high efficiency heat pump dryers in households that were heavy dryer users
  •  1,040 kWh/year (50%) when old single-speed pool pumps were replaced with high efficiency three-speed pumps.
  • Energy savings of 80% were achieved when 12 volt halogen downlights were replaced with 12 volt LED downlight lamps.

Further information on this research is available from Sustainability Victoria.