A random survey of nine commercially available insulated flexible duct products in Australia has found all samples failed to comply with mandatory energy efficiency performance standards. Paul Skelton reports.

With so much attention given to energy efficiency by regulators, Standards and home owners alike, there really is no scope for building contractors to be installing sub-par products. The problem is, when it comes to insulated ducting, you may be installing noncompliant products without even realising it.

A survey of the thermal performance of nine brands of flexible ductwork was recently performed through the commissioning of independent sampling, measurement and testing. Of the nine test specimens, none achieved their declared performance. The average measured thermal resistance of all specimens was 76% of that expected, with a best result being 95% and the worst being 62.5%.

All of the ductwork tested came from well-known suppliers and claimed an R-value of R1.0.

The survey was conducted as part of an industry report titled ‘A Survey of Thermal Performance of Flexible Duct’, commissioned by the peak body Insulation Australasia (IA) and conducted by Dr Cameron Chick from Acronem Consulting Australia.

The report involved a scientific analysis of nine ‘like’ samples of insulated flexible duct products with claimed thermal efficiency ratings (R-values) of R1.0, which is the legislated national minimum requirement.

Insulated flexible ducts are used to channel conditioned air throughout buildings for heating or cooling purposes. Most flexible ducts consist of an inner metallised plastic tube, typically supported and strengthened by coiled wire, covered by a bulk insulation material and outer protective sheath. These ducts are commonly found in residential and commercial buildings, and their efficient performance is vital – space heating in homes involving flexible ducts accounts for 38% of all household energy consumption.

Warrick Batt is a director of IA.

“Those of us in the industry are well aware of the extent of this problem and that it has been an ongoing issue for some time. In fact, it has probably gotten worse over the past few years,” he says.

“This is why we commissioned the report and it has shown that right across the board there was a dramatic underperformance of ducting.”

Tests, conducted at CSIRO Infrastructure Technologies, Thermal Test laboratory, involved careful assessment of the outer sheath, polyester thermal insulation material and the inner core (with metal wiring removed), using approved examination techniques.

Results demonstrated an average R-value of just R0.763 (m2K/W) with a standard deviation of 0.10 (m2K/W), significantly below the claimed targets of R1.0. The best performing sample achieved R0.957 (m2K/W), the worst R0.625 (m2K/W).

These uniformly poor results are disappointing and clearly contravene the regulatory requirements of the National Construction Code, Building Code of Australia (NCC, BCA), Energy Efficiency provisions, which necessitate that insulation provided on ductwork shall comply with the requirements of AS/NZS 4859.1 Materials for the Thermal Insulation of Buildings.

“The worst performing sample achieved an R-value of 0.625. That’s 62.5% of its stated and required performance value,” Warrick says.

“The NCC is very clear about what the performance levels of ducting should be; there’s no ambiguity surrounding the fact that you need to achieve a rating of R1.0 for this type of ducting.

“This particular ducting was labelled as R1.0, sold and represented as R1.0, but was in fact R0.625. It’s not that difficult to have a product tested to ensure that it is meeting the requirements. At this stage, though, there is no policing to ensure ducting is being manufactured to the Standard.

“This shouldn’t be the job of building certifiers, either. They’re not in a position to be, or capable of checking an R-value.

“Yes, they can check labelling, but they don’t have the ability to test it. Instead, there is a need for third party certification. Instead of manufacturers of ducting and insulation being able to make their own claims, it needs to be independently verified.”

The report calls for tighter monitoring and policing of product compliance, as well as reforms to the way products are assessed, with a shift to ‘as installed’ performance assessment rather than the current process of assessing raw materials.

“The type of third party certification that we believe is necessary is already widely available and it could very easily be applied to ducting. It simply needs to be changed from being a voluntary system to being mandatory. “Mandatory third party certification is really the only way to ensure that compliant product is being sold to market and that consumers are provided with the level of energy efficiency that they are looking for.”

Due to the massive societal impacts of energy-wasting, non-compliant ducts, numerous governmental and regulatory bodies – including the Department of Climate Change – have shown an interest in the issue of noncompliant flexible ducts. The report also indicates an expectation that the Australian Competition & Consumer Commission (ACCC) will scrutinise the sector on behalf of consumers.

“Selling non-compliant product and saying that it is R1.0 is quite simply fraud. There is plenty of ducting out there that is knowingly being produced and sold that is well underneath where it should be.

“Yes, it’s a competitive market, but the difference to the contractor between a compliant and non-compliant duct is only around $50 to $75 a house lot. That’s not a huge amount considering a 15 year system life is it?”

“Whenever poor-quality or non-compliant product is used, the entire sector is tarnished. Low standards adopted by rogue operators diminish the credibility of reputable manufacturers, undermine price points and threaten ongoing research and product development.”

As for liability, well, that’s a grey area. Building contractors who ask for R1.0 ducting and install product marked as R1.0 should be covered according to the NCC, but that has never been tested. Do you really want to be the first?

What makes more sense is for building specifiers and contractors everywhere to start applying pressure on ducting suppliers to provide third party certification with their products to ensure they and the consumer and not being dudded.