Choosing the right glazing and window treatments for your home can help you save on energy bills and create a more comfortable home all year round. If you are building a new home, correct design and orientation of windows will help your home achieve maximum thermal efficiency.
Own the best dressed windows in your street
If you live in a home where fitting new windows would be expensive or impractical, here are a few suggestions for improving your thermal comfort:
- Install thick curtains that seal around the edges and drop down to the floor, with block out attached but not bonded, and pelmets; or
- Fit honeycomb blinds snugly within the window reveal; or
- Add tight polystyrene shutters over the windows on the outside; and
- Minimise the air leaks around the window to improve the insulation level.
Alternatives to window replacement - treat your windows to a makeover
If you are not able to replace inefficient windows with more modern types, consider the following suggestions. These will cost half as much as new timber double glazing, or less.
- For timber framed windows, replace the sashes with new double glazed sashes, and replace fixed panels with double glazed unit inserts.
- For aluminium windows, install a secondary window set in the sill with an air gap to the main windows.
- For windows with timber frame or aluminium window, a secondary window made of acrylic with a magnetic frame can be fitted to the sill and has good thermal performance.
- Some companies specialise in retrofitting single glazed windows with double or secondary windows, but after-market products are available that you can install yourself.
- The cheapest secondary window solution is to fit a transparent membrane to the window architrave or onto a separate timber frame. fitted to the sill.
Choosing new windows
If you are building a new home or are able to change the windows in your existing home, double glazing cannot be beaten for thermal efficiency.
- Standard double glazing can reduce the heat loss of single glazing by 50 per cent or more.
- The cost difference between single and double glazing is no longer significant compared to cost differences for window frame materials.
- Fibreglass and PVC window frames are becoming cost competitive as well as being good at reducing heat conducted into and out of the home. Fibreglass frames with double glazing are only slightly more expensive than aluminium frames with double glazing, but they perform far better.
- Double glazing is more efficient during the day and the night, unlike window coverings that increase heat flows when open during the day to let in the light.
- Double glazing will be needed in Canberra in all new houses to meet mandatory energy efficiency requirements.
- Double glazing has many other benefits, including increased strength (meaning widows will last longer and be more protected against breakage, increased fire resistance, and reduced noise from outside.
To help you make the right choice when purchasing windows, the Window Energy Rating Scheme (WERS) website lists window products in Australia, rating their performance and suitability for a particular climate and the best application.
Positioning windows in a new home
In Canberra’s climate most expenditure on interior temperature control is for heating rather than cooling. So the best orientation for the largest areas of glass is north, to let in the winter sun. If you want to have large areas of glass facing east west, then good internal window treatments and external shading will be needed to reduce summer heat gain.
Skylights and roof glazing
Think carefully about the heating and cooling impacts before you install skylights or roof glazing as they can cause extreme heat gains or losses in Canberra’s climate.
If you want more natural light without substantial heat gains or losses, install a “daylighting device”. This will collect and concentrate sunlight through a lens on the roof and transmit it through a reflective tube to dispersion lens inside the room where light is needed.