- Owners and Builders
Did you know the Chenath Engine has been around in different forms since the 1950s? Over the years a large number of very clever people have worked on improving it and it has evolved along the way. It has also had a number of different names and fed into different programs.
Behind the front end software (FirstRate5, BERS Pro, and AccuRate) and based on agreed rules, Chenath works hard to model the thermal comfort of a home. It uses the historical weather data for 69 different climate zones, along with the building orientation, construction types and materials, windows/doors, and eaves/shading/curtains. It also assumes windows are opened and closed at times when temperatures inside or outside are appropriate. Chenath uses all of these factors to calculate the amount of energy required to keep a home at a comfortable temperature.
There are a number of complicated calculations that Chenath uses to work out when a change in temperature is needed in different rooms of the house (otherwise known as a zone type), for different climate zones. The different zone types help to predict the behaviour of residents in that room type. For this reason it is important that the zoning of a room reflects how the room will be used. If you would like to know more about how to zone a house, please have a look at the zoning examples on the NatHERS website.
Chenath is an intelligent and complicated piece of software and getting to know the way it works can be very helpful for assessors when calculating ratings. To help people better understand Chenath, the CSIRO have recently released a repository of documents outlining much of the detail of how Chenath calculates ratings. While targeted at a technical audience, the repository provides a lot of information about the underlying assumptions that Chenath makes and explains concepts like the Area Adjustment Factor.
For more information on how the software works see: