Selection and correct installation of suitable insulation in homes and apartments will be important if residential builds are to achieve new 7-star requirements, leaders in the insulation industry say.

(above image provided by Bradford Insulation)

As Australia’s construction industry prepares to meet tighter residential energy efficiency standards, three industry leaders spoke to Sourceable about the role of insulation in meeting 7-star thermal performance requirements.

The three leaders are Kathy Hocker, General Manager of Marketing Bradford Insulation; Warren Stewart, Head of Product Development – Bradford Insulation; and Janine Strachan, CEO at the Insulation Council of Australia and New (ICANZ).

Hocker says the significance of the new 7-star requirements should not be underestimated.

“We are at a pivotal point in the industry,” Hocker says.

“The advent of this new rating is set to bring about a significant change in insulation installation and usage across Australian residences.”

The comments come as Australia prepares for new energy efficiency and condensation management requirements that will apply to residential construction as a result of the 2022 update of the National Construction Code (NCC 2022).

As part of the changes, new residential premises will need to achieve a minimum 7-star thermal performance rating under the Nationwide House Energy Rating Scheme (NatHERS).

This compares with the 6-star minimum rating that was required under the previous version of the Code (NCC 2019).

Adoption dates for the new requirements vary (refer link). In NSW, the 7-star requirement came into effect on October 1. In Queensland, Victoria, the ACT, South Australia and WA, adoption dates are spread across 2024 and 2025. Tasmania is not adopting the new requirements whilst the Northern Territory requires only 5-star thermal performance.

Speaking about 7-stars and insulation, Hocker, Stewart and Strachan say there are several misconceptions which can occur.

Regarding the 7-star rating in general, Stewart says there is a misconception that this can be achieved with only one or two changes in isolation.

Achieving 7-stars will require a holistic approach to home design. In addition to higher performing insulation and glazing, Stewart says that this could involve consideration of orientation within the block, modifications to design and layout, interior zoning within homes, use of fans and/or use of colour.

He stresses that movement along the energy rating performance spectrum is not a straight line but rather a curve that becomes steeper and increasingly more difficult to achieve with each star improvement.

Strachan agrees that a holistic approach will be needed.

Toward this end, she says builders will need to be familiar with the nuances of the NatHERS energy rating system as well as newly updated climate files upon which calculations for NatHERS are based. They will also have to work closely with the energy rater.

In addition, architects and designers will also need to consult energy raters during early stages of the design process. This will help to enable identification of any limitations of proposed design solutions along with identifying cost-effective ways in which the higher energy rating can be achieved. It is particularly important as not all designs will be suitable for every block and orientation.

Strachan says the need to redesign some homes may be challenging for volume builders, whose operations involve highly replicable designs which are delivered in new housing estates across multiple orientations.

A further misconception involves ideas that overly expensive glazing will be needed. This is important as the area of glazing within the wall space can now account for up to 30 percent of the floor area of a home. Across all climate zones, Strachan says solutions are available which involve either combinations of higher and lower performance glazing or reduced areas of glazing that could be filled up with wall insulation. This, she says, provides an example of how working early on with the energy rater will help generate optimal solutions.

Turning specifically to insulation, aforementioned commentators say there are several misconceptions which surround the material itself.

According to Stewart, there is a common presumption that insulation will always be there and will perform its role in a satisfactory manner. This is often the case as insulation is not readily visible to homeowners and is thus not subject to similar selection processes which are applied to kitchens, bathrooms or granite benchtops.

In fact, he says it is critical to ensure that attention is paid to selecting the highest performing insulation materials available for the home and that these are installed in the correct manner. This is especially the case as insulation lasts over the life of the home and changes which are needed after construction can be difficult and expensive.

On a related note, Strachan says the importance of insulation is not always fully appreciated within the building industry. This can be problematic as insulation may sometimes be moved whilst various trades are attempting to access plumbing, electrical, plaster or ductwork. In cases where the material is not correctly replaced, this can lead to gaps and reduced insulation performance.

In addition, Stewart stresses that there are different insulation products on the market. In the case of the Bradford range, CSR is promoting glasswool insulation which is primarily made out of recycled glass. Stewart says this offers advantages when compared to petroleum-based products in terms of a lower environmental footprint as well as greater permeability and thus improved condensation performance.

(image supplied by Bradford Insulation)

When moving to seven stars, aforementioned commentators say that several actions are important.

According to Hocker, these include:

  • Choosing the correct ‘R-value’ (a measure of thermal resistance). Higher R-values are often the most cost-effective option for achieving energy efficiency.
  • Selecting quality insulation materials which are durable and effective.
  • Considering the benefits of acoustic insulation to help to reduce noise transmission into the home and between rooms.
  • Ensuring that insulation is installed properly in accordance with design specifications as well as NCC requirements and Australian Standards. To ensure that it retains its correct design thickness, insulation should fit snugly between studs, joists, and beams without gaps or compression.
  • Ensuring that homes are well sealed and that gaps around windows, doors and other areas are adequately sealed. This is necessary in addition to insulation in order to prevent air leaks and to minimise draughts which blow through the home.
  • Ensuring sufficient moisture control and ventilation to reduce the risk of condensation, mould growth and poor air quality as homes are effectively sealed up.
  • Understanding the full cost. This involves not only the price of insulation products but also the installation costs along with ongoing savings in energy costs that the insulation will provide over its lifetime.

Whilst all points are important, Hocker stresses the need for effective condensation management and correct installation.

Particularly if buildings are well sealed, managing the formation of condensation is particularly necessary in order to ensure that homes are healthy and durable.

In addition, correct installation is critical.

Whilst many people will never see insulation, it remains an important feature in delivery of comfortable homes. Even small gaps in its installation could lead to compromises in performance along with a greater likelihood of condensation formation.

Strachan says action is needed in several areas.

As mentioned above, architects and designers should engage early with energy assessors.

Next, builders, architects and designers will need to understand the different climate zones in which they are working. Builders will also need to understand that it may not always be possible to simply apply their standard designs to each and every block and to still achieve the mandatory 7-star rating.

Third, it is important to think about the volume and quantity of glazing and to consider whether or not costs in this area can be reduced through either combinations of higher and lower performance glazing or reducing the volume of glazing and filling this with wall insulation as referred to above.

Turning to sarking, Strachan encourages designers and architects to specify how this should be installed in their designs, which call up the NCC and Australian Standards for insulation installation.

Fifth, given the aforementioned potential for insulation to be moved during the course of the build, it is important for builders to communicate with tradespeople and to ensure that insulation is not only correctly installed but remains in place throughout construction.

Finally, builders should ensure that they are confident with regard to client communication on insulation related matters so that they are able to respond to questions and advocate for any improvements.

Overall, Hocker says the benefits of insulation in achieving 7-stars should not be underestimated.

“Insulation delivers the lowest cost per star improvement (in energy efficiency) and the greatest flexibility,” Hocker said.

“Modelling shows that adding higher performing insulation first provides a significant star gain. This provides flexibility when making design choices about more complex or expensive building elements.”


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