The history of energy rating

In 1953 Roy Muncey of CSIRO’s Division of Building Research published a paper in the Australian Journal of Applied Science called ‘The Calculation of temperatures inside buildings having variable external conditions’. Thus began the CSIRO’s work on building energy modelling using a frequency response analysis of a single zone model.  Later Muncey, with his colleague John Spencer and others turned this method into a computer model ‘CARE’.

In the 60s CARE was replaced by STEP, a single zone time series analysis model that did away with the need for pre-analysis of climatic data required by CARE to do an hour by hour analysis using measured climatic data. STEP was operated with CSIRAC in the 60s.

By the end of the 70’s ZSTEP had been developed by Spencer, Pat Walsh and others using the same method as STEP with the added benefit of modelling up to 10 separate zones in the building. This was operated on the mainframe computer in Canberra.

By the mid 80s desktop computers were becoming more popular and Angelo Delsante produced CHEETAH a desktop version of the calculation engine with a simple front end to allow ready calculation of energy and/or temperatures in dwellings.

In the 1990s the Australian Government wanted a Nationwide House Energy Rating Scheme and Delsante and Steve Moller produced a new front end, based on some work done by Moller at the Gas and Fuel Corporation.  This was the start of the NatHERS software (the predecessor of AccuRate). The calculation engine from CHEETAH was used for the NatHERS version and was called Chenath.

Delsante and Yuguo Li added features including natural ventilation to the model in the late 1990s.

Delsante continued the development of AccuRate and Chenath and in the mid-2000s tested it against the other major international software models using the BESTest (building energy simulation test) method that was developed by the International Energy Agency Solar Heating and Cooling Programme.

BESTEST comparisons of low-mass annual heating energy
BESTEST comparisons of low-mass annual heating energy

The results confirmed that the Chenath model gave good reliable results under a variety of scenarios. So much so, that when the international BESTest team wanted to test slab on ground models they chose the model developed by Delsante for Chenath as the benchmark case.

Since the mid 2000s, Dong Chen and Zhengen Ren continue the work of improving the modelling and the range of building features that can be modelled using Chenath.