The Homeowners Insulation Program has been canceled and the rebate is no longer available. This is the result of dangerous electrical wiring in roofs and not the quality or performance of the insulation products and the work they do to reduce heat entering into your home in the tropics. Insulation plays an essential part in reducing the need for costly air-conditioning as well as reducing carbon emissions. Buyers beware of the products you choose to use and how they are installed. You have a choice. There are quite a few and some of them have proven health risks. Before you install thermal reflective insulation above a ceiling, ensure that a licensed electrical contractor has inspected the roof and installed safety switches on all circuits.
An important bit of knowledge
There are three types of heat affecting buildings, Radiant heat, Convective Heat and Conductive Heat. Radiated heat is the most dominant. Traditionally reflective insulation is used to combat radiated heat. Bulk insulation is used to combat convected and conducted heat. There are newer types of insulation that combines the two traditional types into one product.
Tell me about the newer products
The newer products combine reflective and conductive (thermal) resistance and come in thin light weight tough but flexible blankets. It has an inner layer generally made of bubbled air sacks or extruded polyethylene with outer layers of reflective foil.
The most commonly known products emerging with this new technology is Air-Cell®, E-Therm from Thermotec and Protherm. These products generally have reflective foil to the outer layers and extruded polyethylene or closed cell foam structure to the internal layer. The products are recommended for use in a healthy house as they do not have toxic chemical use such as formaldehyde or other VOC's (see chemical database on the "Healthy Living" page on this website.) used in their manufacture. These products are also fibre-free so they do not irritate are non-asthmatic and non-allergenic. They are suitable to be used in high humidity situations reducing condensation. The products are also generally rodent, insect, bacteria, fungus and mould resistant.
Product ranges include variations for particular uses. Installation instructions for Retro-fitting houses include placing the sheeting on top of the ceiling joists. Air-cell® has a product called Retroshield that also specifies a combined use of batts between the joists to the perimeter of the roof space. Thermotec uses E-Therm for retrofitting. The performance of the products is affected by dust on the foil.
Air-cell® Retroshield fitted into a roof cavity
E-Therm® by Thermotec being retrofitted into a roof cavity.
Insulation for tropical houses
In tropical climates, houses need to reduce heat gain without restricting heat loss. Concrete that has any exposure to the sun does all the wrong things to keep your house cool. It holds the heat and makes the house hot well into the night. A healthy house needs to incorporate a ventilation system so any heat gain that is in the building may escape. Air conditioners become necessary in hot climates in badly designed homes. If air-conditioning has to be used, energy consumption efficiencies are improved if bulk insulation is used.
The effectiveness of insulation is measured in 'R' values. There are DOWN or SUMMER R values and UP or WINTER R values. The higher the 'R' value, the better it is at stopping heat flow. Healthy houses in hot tropical climates need a very high DOWN or SUMMER 'R' values to stop heating coming through the roof and walls. When the insulation is used in combination with light coloured roofs and good ventilation, the total system 'R' value needs to be greater than R 2.7 or better to meet building laws and preferably R 3 or greater.
Insulation in new construction is most effective if products such as Aircell, E-Therm or Protherm are laid directly under the roof, thus creating a vapour barrier and insulation in one application.
Some Facts
BE WARY!! The introduction of the Rebate has seen many products entering the market which can’t substantiate their claims. So make sure the seller can prove their claims with authentic Certificates and/or certified calculations and are Registered with the Government as an Installer.
It is essential that the insulation can prove it meets the following Australian Standards with certificates issued by the CSIRO, BRANZ or AWTA.
| AS/NZS 1530.2 | Flammability |
| AS/NZS 1530.3 | Ignitability, Flame spread, Heat Release, Smoke Release |
| AS/NZS 4200.1 | 1999 Vapour Barrier Performance |
| AS/NZS 4859.1 | Thermal Performance |
| AS/NZS 4859.1 | App 1 Corrosion Resistance |
| ASTM C518 | Thermal Resistance |
| ASTM E408 | Emittance Performance |
| ASTM E96 | Vapour Transmission |
Insist on proof of claims and take a moment to look at, feel, breathe and smell the insulation before you choose; AND, call a few of the Registered installers to find one who is willing to install the insulation YOU choose.
Air-cell® Retroshield
Tell me about
Bulk insulation
ALL bulk insulations have the ability to absorb moisture and only achieve their R values when they are then not compressed.
Bulk insulation normally comes in batts or blankets and can be made from natural or synthetic fibres. Bulk insulation is generally used between ceiling joists and wall studs to absorb heat, stopping it from moving into a home. It looses its effect if it is compressed. It is better to use a bulk insulation which is cellulose, wool or recycled polyester (the best of the synthetic batts) with a safe fire and fungus protector. Bulk insulation such as glass and rock wool mineral fibres can contain toxic chemicals such phenol formaldehyde, isocyanates and styrol that are known carcinogens. Rock and glass batt dust can cause skin rashes and eye, nose, throat and lung irritation. Foam insulation also has toxic chemicals. In the manufacturing process, certain ingredients may not fully polymerise. Over time, the free molecules, softeners and fireproofing chemicals are released into indoor air. More information on bulk insulations and chemicals and toxins can be found on the ‘healthy living’ page in this website.
Reflective foils
May also be called sarking, sisalation or reflective foil laminates (RFL). It is made of aluminium foil laminates. The foil is a vapour barrier reducing condensation and has some ability to reflect heat. Its use alone, does not meet insulation building standards in Australia. It generally comes in large sheets and is laid under roof sheeting or behind external wall cladding.
Anticon blankets
You may decide to avoid the use of this product. The blanket or bulk insulation is made from fibreglass. It is an irritant and absorbs moisture from condensation. If it is installed directly under roof sheeting with the blanket facing up it may cause a roof to rust. The problem is so bad in the Northern Territory, the blanket has been installed “upside down” with the foil side up against the roof sheets. However, this then reduces the R value and if the blanket is compressed in any way it will not meet building standards in Australia.
Diagram showing E-Therm retrofit.
Recommendations for retrofitting roof insulation in a tropical house
Product ranges include variations for particular uses. Installation instructions for Retro-fitting houses include placing the sheeting on top of the ceiling joists. Air-cell® has a product called Retroshield that also specifies a combined use of batts between the joists to the perimeter of the roof space. Thermotec uses E-Therm for retrofitting. The performance of the products is affected by dust on the foil.
Before you install thermal reflective insulation above a ceiling, ensure that a licensed electrical contractor has inspected the roof and installed safety switches on all circuits.
