Study Challenges Efficiency Rating Assumptions

Infrared thermovision image showing lack of thermal insulation on House



In Australia, the energy efficiency of new homes is required by the National Construction Code to be estimated through the Nationwide House Energy Rating Scheme (NatHERS) and meet certain minimum standards. However, research from the University of South Australia indicates that even housing that performs well on paper isn’t necessarily resistant to the stresses of heatwaves. 

The authors argue that NatHERS needs to account for the capacity of homes to resist heatwaves by reducing peak cooling demand, not just average annual consumption for heating and cooling. According to their research, a new, efficient 6-star rated home will consume more energy for cooling than a traditional double brick house under the same heat wave conditions. 

Among a list of measures suggested for the improvement of energy efficient home performance are the installation of reflective foil under roofing material, and greater use of the adaptive comfort model for assessing the home’s capacity to deliver a comfortable indoor environment. 

Ametalin manufactures a range of suitable reflective sarking membranes for installation under tile and metal roofs. Ametalin SilverSark xR double-sided foil-faced sarking provides an upwards reflective surface as a thermal barrier to solar heat gain. Ametalin ThermalBreak 7 double-sided-foil-faced 7 mm foam membrane meets the requirement for minimum R0.2 thermal break in steel frame construction. Both products deliver the additional benefit of effective moisture control in roofs when installed with the recommended drape and overlap. Ametalin recommends that the contribution of reflective insulation installed facing an air cavity should be assessed by a qualified engineer. 

For further information, the study can be found at Science Direct