Insulating, shading and weatherproofing your house can save you up to 45 per cent on your current energy bills while increasing the comfort and value of your home.
Minimising the need to heat and cool your home from the extremes of our summer and winter weather will also reduce your household’s contribution to global warming.
Strategically placed trees that provide shade to your house in summer will cut electricity use, saving you hundreds of dollars over the life of your home. Similarly, increasing the R-rating of the insulation in the walls, ceiling and floor of your house will permanently reduce your energy needs. And what’s more, many insulating, shading and weatherproofing actions are inexpensive and easy to do.How to do it now!
Insulation is the single most energy-efficient addition you can make to your home. Insulation provides a barrier to heat flowing in and out of your home and is essential to keeping your home warm in winter and cool in summer.
Insulation is measured on an R-rating scale: The higher the R-value, the more resistant the insulation is to heat flowing into and out of the home and the greater the energy savings.Remember, it is not the thickness of the insulation product that counts; it is the R-value. The higher the R-value, the better the thermal performance. All insulation that meets the Australian Standard has its R-value clearly marked on its package.
There are two main types of ceiling insulation – bulk insulation and reflective insulation. There are many different products available.
Bulk insulation resists the transfer of heat by trapping pockets of air within its structure. Bulk insulation includes materials such as glass wool, wool, cellulose fibre, polyester and polystyrene and comes with one R-value for a given thickness. Its thermal resistance is essentially the same regardless of the direction of heat flow through it.
Reflective insulation works by reflecting heat from its surface usually shiny aluminium foil laminated onto paper or plastic. The total R-values for reflective insulation are supplied as ‘up and down’ values. Total values depend on where and how the reflective insulation is installed. It’s important to check that the values provided by the manufacturer relate to your particular installation situation.
Selecting the appropriate level and type of insulation for your house will depend on the climatic conditions and must account for seasonal as well as daily variations in temperature. Establish whether the insulation will be predominantly needed to keep heat out or in (or both).
Below is a table showing the recommended insulation levels for your climate.
Climate Type and Example LocationsMinimum Insulation Levels (Material or Total R-values)
Roof/CeilingWallCool Temperate and Alpine – Reducing heat loss is the main priority
- Melbourne, VIC – r-values roof/ceiling: 3.7, Wall: 2.2
- Canberra, ACT – r-values roof/ceiling: 4.3, Wall: 2.4
- Hobart, TAS – r-values roof/ceiling: 4.3, Wall: 2.4
- Mt Gambier, SA – r-values roof/ceiling: 3.7, Wall: 2.2
- Ballarat, VIC – r-values roof/ceiling: 3.7, Wall: 2.2
- Thredbo, NSW – r-values roof/ceiling: 4.8, Wall: 2.3
High humid and Hot Dry – Reducing heat gain is the critical priority
- Darwin, NT – r-values roof/ceiling: 2.7, Wall: 1.9
- Cairns, QLD – r-values roof/ceiling: 2.7, Walls: 1.9
- Broome, WA – r-values roof/ceiling: 2.7, Walls: 1.9
- Marble Bar, WA – r-values roof/ceiling: 2.7, Walls: 1.9
- Mt Isa, QLD – r-values roof/ceiling: 2.7, Walls: 1.9
- Tennant Creek, NT – r-values roof/ceiling: 2.7, Walls: 1.9
- Townsville, QLD – r-values roof/ceiling: 2.7, Walls: 1.9
Warm/Mild Temperate and Warm Humid – Reducing heat loss and heat gain are equally important
- Brisbane, QLD – r-values roof/ceiling: 2.7-3.0, Walls: 2.2
- Perth, WA – r-values roof/ceiling: 3.2, Walls: 1.9
- Alice Springs, NT – r-values roof/ceiling: 2.7, Walls: 1.9
- Bourke, NSW – r-values roof/ceiling: 3.5, Walls: 3.2
- Sydney, NSW – r-values roof/ceiling: 3.2-3.7, Walls: 1.9-2.2
- Adelaide, SA – r-values roof/ceiling: 3.2, Walls: 1.9
- Katoomba, NSW – r-values roof/ceiling: 3.7, Walls: 2.2
Reference – www.yourhome.gov.au
When choosing your insulation product, compare the environmental benefits of each product. Currently, some brands of polyester insulation contain up to 80% recycled PET (the plastic commonly used in drink bottles). Some brands of cellulose fibre contain 100% recycled paper. Fibreglass insulation usually contains between 25 and 60% recycled glass.
After doing your comparison, seek advice from an energy-efficient builder, designer or insulation retailer to help you match the right insulation product to your situation.
Where to install insulation
The biggest loss of heat is through your ceiling and roofs (up to 45%), so good ceiling and roof insulation is the number one priority. Install insulation under the roofing material to reduce radiant heat gain. Install insulation in the ceiling to reduce heat gain and loss.
Walls can allow up to 20% of heat into/out of your home. While not likely to be as accessible as the ceiling or roof take the opportunity to insulate your walls, during major renovations or re-plastering.
Floors do not always require insulation, but can lose up to 10 per cent of heat through floors in the cooler Australian climates. Insulation can be stapled under suspended floors if accessible. Carpeting a bare floor is also worth considering. Concrete slabs use the insulating value of the ground below and need minimal insulation except in alpine areas or where groundwater is present.
Tips for good insulation performance:
- Do not compress bulk insulation
It must retain its normal thickness wherever possible. Make sure there is sufficient space between the roof and the ceiling lining for installing the insulation without compressing it, particularly in the case of cathedral ceilings.
- Make sure corners of ceilings, walls and floors are properly insulated
These are areas where heat leaks are often found.
- Keep bulk insulation dry at all times
With the exception of polystyrene, which is water resistant, performance will be significantly reduced if insulation becomes wet.
- Make sure your wiring is appropriately rated
Have it inspected by a licensed electrician to ensure it can be safely covered by bulk insulation.
- Do not install insulation within 90mm of hot flues or exhaust fans.
- Do not put insulation over or around recessed light fittings
Leave at least a 200 mm gap around their perimeters.
- Avoid gaps in the insulation
Even if only 5 per cent of an area is left uninsulated, up to 50 per cent of the potential benefits may be lost.
- The R-value of loose-fill insulation depends on its density, not simply the depth to which it is installed
If density is not consistent throughout, the R-value will vary. It is difficult to ensure this consistency if installing loose-fill by hand. Loose-fill insulation may settle over time by as much as 20 per cent.
- Avoid loose-fill insulation if your roof space is excessively draughty, unless a sealant can be added to bond its top surface
Loose-fill insulation should not be installed on steeply sloping ceilings.
- Reflective foil should be installed with a still air gap of at least 25mm width next to the reflective surface
Tape up any holes, tears or joins in the foil according to the manufacturers specifications. Foils in ceilings and roofs perform best when the shiny surface is facing down.
- Have a fully licensed contractor install insulation, particularly if you have down lights.
For detailed information on choosing insulation visit the Australian Government Your Home website.
When thinking about installing insulation it’s worth considering ‘passive design’ strategies. For example, if insulation is installed but the house is not properly shaded, then insulation can have a negative effect creating an ‘oven’ effect.
Planting deciduous trees and plants, is often your best solution to shielding the summer heat, as well as solar gain in winter.
Weather proofing your house is also important, as draughts can account for up to 25 per cent of heat loss from a home in winter.
Shading your home and outdoor living areas is vital to cool your home in summer and in turn reduce your energy bills.
Shading of glass to reduce those hot summer rays is critical. Unprotected glass is a major source of unwanted heat gain in a home. Shading can block up to 90 per cent of heat gained from direct sunlight. But while shading windows in summer is crucial, a well placed window can also be fantastic source of heat gain in cooler seasons. Shading requirements vary according to climate and house orientation.
A general guide is:
Orientation – Suggested Shading Type
- NORTH – fixed or adjustable shading placed horizontally above window
- EAST and WEST – adjustable vertical screens outside window
- NE and NW – adjustable shading
- SE and SW – planting
During the cooler months you can halve the heat lost through your windows by insulating them with curtains. Close fitting heavy curtains work best. Floor length curtains reduce both heat loss and condensation. Pelmets above windows will also minimise heat loss. Use external light coloured shading devices over windows as they reflect more heat than darker colour shading. Internal shading will not prevent heat gain unless it is reflective. In colder climates, it’s also worth considering double-glazing and window insulation, especially for south and west facing windows exposed to extreme weather.
Use plants and trees for shading
Plants and trees are an effective way to shade your home, particularly outside windows to reduce unwanted glare and heat gain. Evergreen plants are recommended for high humid and some hot dry climates. For all other climates use deciduous creepers or trees.
Match plant characteristics (such as foliage density, canopy height and spread) to shading requirements. Choose local native species with low water requirements where possible.
Shading from trees and plants will enhance your outdoor living spaces creating pleasing ambient light. Creating appropriate shading also reduces the chance of exposure to harmful UV rays, is low cost and improves air quality by filtering pollutants.
Weatherproofing your house from draughts and air leaks provides fantastic potential for energy savings on your heating and air conditioning costs. In Australia, households produce around 20 per cent of our total annual greenhouse gas emissions, of which heating and air-conditioning account for around 27 per cent. Draughts can account for up to 25 per cent of heat loss from a home.
Weatherproofing and draught sealing can very effectively prevent heat loss in winter and trap cool air in summer, whilst maintaining healthy indoor air quality. And many draught sealing measures are inexpensive and easily done yourself. Remember however, that some fresh air is needed for ventilation and to prevent condensation and mould growth. Exhaust fans, windows and doors should be used to provide ventilation when needed and closed off when not required.
Where to start sealing the gaps
- In your roof area and underneath your home, check that all openings for pipes, ductwork, and chimneys are well sealed.
- Look for gaps where pipes and wires pass through floors and walls and check for air leaks along the edge of the flooring and around door frames.
- Seal gaps between floorboards. Caulking compounds, such as silicone or latex based fillers can be used to seal cracks and gaps.
- Outside, look for any cracks and holes in the mortar and foundations.
- Inspect windows and doors for air leaks. If you can see daylight around frames, or if they rattle when shaken, then they will leak air.
- Exhaust fans, ceiling mounted ducts, wall vents or vented skylights provide an easy escape for internal air, which is then replaced by air from outside the house.
- Remember to seal off unused fireplaces – a lot of heat can be lost up the chimney.
You can find a wide range of draught sealing products at your local hardware store. A current list of manufacturers and some suppliers are listed in the Yellow Pages under ‘Weather Seals and Strips’ and ‘Fireplaces’.
Consider seeking advice from an energy-efficient tradesperson and/or retailer to help you match the right process and product to your situation. There’s some great information on this government website Your Home Design Guide.
There are number of rebates and assistance programs helping you improve your households energy efficiency. For more information visit the Australian Government’s Living Greener website.