Keith Anderson explains why energy rating schemes can be a breeding pit for inaccurate results.
Energy ratings schemes play an important role in the Australian building industry. They are an important tool to assess and rate the sustainable qualities of homes and drive improvements in product sustainability and performance.
In addition, energy rating schemes afford building and design professionals creativity, flexibility and innovation in their designs that they couldn’t achieve if they followed a deemed-to-satisfy (DTS) approach to Building Codes of Australia compliance.
Finally, they allow for energy modelling to be performed before anything is built, enabling building professionals to optimise designs and avoid costly fixes later on.
Clearly, there are benefits to such schemes, however, all these beneficial aspects are in question if the system is inconsistent and inaccurate.
Discrepancies in popularly used energy rating software tools are misrepresenting product performance and misleading building professionals and consumers.
Lack of calibration between the software used by energy assessors is leading to inconsistent energy assessments for new homes, allowing builders to cherry pick the software program likely to give a better result, using in some cases product solutions that might not actually be delivering the expected energy savings.
A recent independent report was commissioned to ascertain the level of discrepancy across software packages for identical designs in identical locations. It also sought to assess the level of discrepancy within each software package for different types of insulation products in roof and wall applications, with the expectation being that different types of insulation products with the same theoretical R-values should yield the same star ratings.
The study was performed by CADDS Energy and compared Kingspan Air-Cell Glareshield with bulk insulation and 50 mm glassfibre insulation blanket in a range of scenarios. The software pack ages tested were AccuRate — the base program which all others must be calibrated against; FirstRate5 — commonly used in Victoria; and BERS Pro — generally employed in Queensland.
The results were alarming. In each of the scenarios the test results of all three software packages differed significantly.
In one scenario, Kingspan Air-Cell Glareshield under the roof +R3.0 ceiling insulation returned a discrepancy of almost a full star — varying from 4.7 stars to 5.6 stars.
Another scenario consisted of 50 mm glassfibre insulation blanket under the roof with no ceiling insulation. This returned a discrepancy greater than a full star — the variance swung between 2.9 stars and 4.2 stars.
In another scenario which compared Kingspan Air-Cell Glareshield against 50 mm glassfibre insulation blanket, a discrepancy of over 25 per cent in energy loading was the result using BERS Pro. This scenario should have delivered almost the same results for both products given the same theoretical R-value.
Using AccuRate as the baseline software, the percentage variance in total energy loading across software packages was as high as 33 per cent when using 50 mm glass fibre insulation blanket. According to government protocols, this should only be +/- 5 per cent.
The clear implication is that the industry and home owners are being misled and ultimately disadvantaged by higher costs for heating or cooling a home. And it is not only home owners losing out as a result of these issues. It is also the environment.
Stringent government moves to increase energy efficiency and reduce greenhouse gas emissions are diminished as inferior products take the place of those with real sustainable credibility.
State and federal government urgently need to effect changes that can guarantee consistency across all software packages and provide assur ances that the performance of thermal efficiency products like insulation are accurately represented in the software.
Both the industry and consumers deserve to once more have faith in the integrity of energy rating schemes.
Keith Anderson is Kingspan Insulation’s technical manager. He has a background in construction materials and engineering materials testing and 10 years of experience in the insulation industry. Anderson is also a qualified energy assessor accredited by the Association of Building Sustainability Assessors (ABSA) and is a Green Star accredited professional.
