CSIRO Energy rating news - Third Edition

Caution advised: NatHERS tools unsuitable for the NCC reference building Verification Method V2.6.2.2

The National Construction Code includes an option (V2.6.2.2 Verification Using a Reference Building) to calculate the energy consumed by a reference building that includes all the deemed to satisfy requirements in the NCC and compare that to the calculation of the energy consumed by the proposed building. Both calculations are done under conditions set out in the NCC.

It has come to CSIRO’s attention that some reference building assessments are being undertaken using NatHERS accredited tools for the calculation of the energy consumed by the reference and planned buildings. Users of NatHERS accredited tools need to be aware that these tools use a different set of conditions to those set out in the NCC, so that NatHERS tools may not be suitable to provide a Reference Building Verification to show compliance with the NCC.

V2.6.2.2 states that:

c) The calculation method used must be capable of assessing the heating load and cooling load by modelling—

(v) space temperature settings in the range 20ºC to 21ºC for heating and 25ºC to 28ºC for cooling;”

All NatHERS tools use set thermostat settings of between 22.5 º Celsius and 27.0 º C for cooling (depending on Climate Zone). For heating living spaces (including kitchens and other spaces typically used during the waking hours) a heating thermostat setting of 20° C is used and bedroom spaces (including bathrooms and dressing rooms, or other spaces closely associated with bedrooms) a heating thermostat setting of 18°C from 7-9 am and from 4 pm to midnight and a heating thermostat setting of 15°C from midnight to 7 am is used.

Users are unable to change the relevant conditions in the NatHERS accredited tools.

Therefore in most instances NatHERS tools are not appropriate for use in demonstrating compliance National Construction Code under V2.6.2.2. These tools are only designed and maintained to be used under the NatHERS pathway in the NCC and CSIRO is not responsible for any consequence due to such misuse of NatHERS accredited tools. Construction of buildings rated less than 6 stars using NatHERS tools may lead to poor comfort and energy performance in the finished dwelling.


NB. As at 14 August - BERS Pro v4.3, when used in a non-regulatory mode is able to be used to carry out assessments in accordance with Part V2.6.2.2.

Released: 19/07/2017

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