As one of the most time-honoured forms of energy efficient temperature control, insulation will always play a vital role in the development of sustainable, environmentally friendly buildings.
By acting as a barrier to heat transmission, insulation can be used to both retain warmth in colder environments as well as prevent its entry in balmier climes.
Much controversy has arisen of late within Australia’s building insulation industry, however, as a result of worker deaths in relation to the Rudd Government’s Home Insulation Program (HIP), and a Royal Commission into the program conducted last year that brought to light an internecine rivalry between the suppliers of different materials types.
A report, produced by sole Royal Commissioner Ian Hanger QC, observed that “the industry was very competitive and fragmented, containing players who spoke up for their own products and against all others.”
Insulation products are divided into two main types, bulk and reflective, which resist heat transmission by highly disparate means.
Bulk insulation impedes the passage of heat by means of pockets of air that permeate its layers, and generally consists of materials such as glass wool, wool, cellulose fibre, polyester and polystyrene.
Reflective insulation prevents radiant heat transmission by means of high reflectivity and low emissivity – which refers to the ability of a material to re-radiate heat energy.
Reflective insulation types usually assume the form of reflective foil laminate (RFL), which consist of shiny aluminum foil attached to sheets of paper or plastic arranged in a variety of forms, such as concertina-type batts or multi-cell batts.
The performance of reflective insulation depends upon a number of factors, including the presence of a layer of air at least 25 millimetres in thickness directly adjacent to the surface of the RFL, as well as the cleanliness and clarity of the reflective surface itself.
The Hanger report came as a major blow for the RFL sector, recommending that the installation of the material be restricted to walls and under flooring due to dangers in relation to electrical wiring, and calling for a nationwide ban on the horizontal installation of the product in roof cavities across ceiling joists during retrofits.
RFL has also been banned from the government's Insulation Rebate Program, with the government recommending that homeowners enlist an electrical contractor to check for any electrical faults as a result of the installation of foil insulation.
Some members of industry believe that RFL has been unfairly targeted, and that efforts to diminish its usage bode poorly for the energy efficiency of buildings in Australia, given that it's a more suitable type of insulation for the warm climates that encompass much of the country.
Building experts point out that RLF insulation is far better suited to hotter environments where the goal is to keep heat out and reduce indoor temperatures. RLF is capable of warding off as much as 97 per cent of radiant heat, making it ideal for many torrid parts of Australia. Bulk insulation, by contrast, is more appropriate for colder climates where the the objective is the retention of heat within a building.
Experts also note that the perils associated with RLF are related more to inadequate training for installers as well as antiquated or defective wiring in Australian homes.
In a submission to the Royal Commission Timothy Renouf, director of concertina foil batts supplier Wren Industries, stated that foil insulation had become the “whipping boy” for the HIP fatalities, and that “the electrical industry had tried to shift the blame for the death involving foil insulation onto the foil insulation industry and was taking no responsibility for the fact that it had failed to ensure that electrical wiring had been installed into houses in a way that would have avoided the deaths.”
The report itself acknowledges that “in a (perhaps large) number of houses to be insulated under the HIP, the existing wiring did not comply with AS/NZS 3000:2007 or its predecessor regulations.
“For that, the electrical contracting industry must take responsibility. If electrical wiring had been in accordance with the relevant standards it is possible that three of the young men would not have died.”