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Benefits of Insulation


Insulation is the most effective way to improve the energy efficiency of a home. Insulation of the building envelope helps keep heat in during the winter, but keep heat out during summer to improve comfort and save energy. Insulating a home can save 45–55% of heating and cooling energy.

Insulation acts as a barrier to heat flow. It can make your home more comfortable by reducing the amount of heat escaping in winter and reducing the amount of heat entering in summer. By insulating you can significantly reduce your heating and cooling bills and help to reduce greenhouse gas emissions. The higher the R-value of insulation the more it slows heat flow and the better it works.

R-value determines the effectiveness of the insulation.

Benefits of insulation:

  1. It reduces the cost of heating and cooling by over 40%;
  2. it pays for itself in around five to six years;
  3. Due to less use of energy to heat or cool it saves non-renewable resources and reduces greenhouse gas emissions;
  4. In most cases eliminates condensation on walls and ceilings
  5. Most thermal insulation materials have acoustic insulation properties

 Although ceilings and walls may be insulated, heat loss will still occur in winter if there are large areas of unprotected glass or through fixed wall vents and gaps and cracks around external doors.

Therefore to effectively insulate a house you need to carry out the following :- 

  • Ceiling insulation
  • Wall Insulation
  • Underfloor insulation
  • Draught sealing (sealing all the gaps around doors and windows)
  • Double Glazing

How much insulation do I need?

Generally 40% of the heat transfer in your home through the roof, up to 25% through walls and up to 15% through the floor.

Building Code of Australia recommends R 5 in the ceiling and R2.7 walls, R1.5 under floor in Canberra region.

Types of insulation

There are two types of insulation

Bulk insulation

Works by trapping tiny pockets of still air within its structure. This air provides a barrier or resistance to heat flow. Resistance to heat flow (R value) is not seasonally dependent for bulk insulation.

Reflective insulation

Works by a combination of reflecting heat away from its polished metallic surface and/or by reducing the radiant heat being emitted from the surface. To be fully effective there needs to be an air gap of 25mm beside the reflective side of the insulation. Because reflective insulation works by reflecting radiant energy, it is more effective at higher temperatures and generally has a higher rating for summer R-values than for winter values. A layer of foil under roof tiles provides R0.0.23 in winter and R0.9 for summer.

Since Canberra has a climate that requires far more heating than cooling it is generally easier to get adequate levels of insulation using bulk insulation rather than foil insulation.

Note to Installers

  • Fit: Avoid gaps in the insulation where it is practical.
  • Avoid loose-fill insulation if your roof space is excessively draughty, unless a sealant can be added to bond its top surface.
  • 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.
  • Caution! Allow clearance around appliances and fittings. Do not install insulation within 90mm of hot flues, or recessed light fittings. (Retain a clearance of 90mm for low voltage downlights). Restrain loose-fill insulation with non-combustible barriers.

Types of bulk insulation.

Glasswool (fibreglass) batts

Composition: Melted glass spun into a mat of fibres. Batts with different R-values are available. Glasswool batts are flexible and easily cut and installed by a householder or a contractor. A dust mask, gloves and a long sleeved shirt should be worn during the installation process. Fibreglass blankets with foil backing are also available and are typically used under the roof as insulation and a moisture (condensation) barrier. Gaps around and between the edges of batts can impact on the overall effectiveness of insulation. If you choose batts make sure they are installed without gaps. Once installed, it does not release dust or fibres and is not known to have any ill effects on health.

Rockwool Batts

Composition: Melted volcanic rock (basalt) spun into fibres. Available in loose fill form for vertical wall cavities and as batts and blankets for ceilings and frame walls. Rockwool is denser than fibreglass and possesses superior thermal and acoustic insulation properties, but is usually more expensive. The same precautions should be taken when installing rockwool as when installing fibreglass.

Cellulose fibre 

Composition: Finely shredded waste paper. Borax and boracic acid are added as fire retardants and to deter insects and rodents. Cellulose fibre is pumped or blown into ceilings by contractors to the required depth for the R-value purchased. Depending on the installation method, this material may settle over time with an associated reduction in performance. There are instances where houses with cellulose fibre has caught fire.

Please see sections under cavity wall insulation, double glazing and draught sealing for complete insulation of a home.