AccuRate: helping designers deliver energy efficient homes

CSIRO software is at the heart of the programs and design tools developed by industry and government for designing and building energy efficient homes

• 3 August 2011 | Updated 14 October 2011

• Background
• The Chenath Engine and AccuRate
• Using AccuRate
• Assessing heating and cooling energy efficiency 
• Meeting international testing standards

Background

The use of commercial simulation software to rate residential buildings in Australia began in the early 1990s with the introduction of the Nationwide House Energy Rating Scheme (NatHERS) - a joint Federal, State and Territory Government initiative.

These software packages are available from developers throughout Australia in a number of different forms, but at their core is CSIRO’s ‘Chenath Engine’ a software package that encapsulates the basic science used by each of these commercial rating tools.

The Chenath Engine and AccuRate

As building design becomes more inventive, CSIRO's 'Chenath Engine and Accurate' software are helping builders and architects deliver greater energy savings in residential buildings, and reduce greenhouse gas emissions.

The Chenath engine is used throughout Australia by the housing industry in their design tools, to understand and improve the heating and cooling energy efficiency of residential building designs.

It is the driver behind one of the building industries most comprehensive design tools – CSIRO’s ‘Accurate’.  Accredited assessors use AccuRate to understand and improve the heating and cooling energy efficiency of residential building designs.

AccuRate is the second generation of residential energy rating software for Australia from CSIRO, and overcomes many limitations of previous software.

Using AccuRate

AccuRate is available commercially from Hearne Scientific Software.

AccuRate can model up to 50 living spaces within a home and its improved natural ventilation model rewards good design practice in hot and humid climates.

The Association of Building Sustainability Assessors (ABSA) provides training in AccuRate, and examination of prospective assessors.

This qualification is a requirement for ABSA-accreditation as a House Energy Rating Accredited Assessor, using AccuRate software.

Assessing heating and cooling energy efficiency

AccuRate calculates hourly temperatures and heating and cooling energy requirements in a multi-zone dwelling.

It provides significant improvements over previous software, including better modelling of:

• natural ventilation and roofspaces 
• user-defined constructions 
• sub-floor spaces
• skylights and horizontal reflective air gaps 
• extra climatic zones.

The incorporation of 69 climatic zones, derived from Bureau of Meteorology weather data, means that AccuRate's calculations can be more specific to the actual climate in the location of the proposed building.

AccuRate can model up to 50 living spaces within a home and its improved natural ventilation model rewards good design practice in hot and humid climates. Its focus is to model the building thermal energy performance rather than the occupant’s energy use behaviour.

Meeting international testing standards

The International Energy Agency BESTEST protocol - a tool for revealing program bugs or deficiencies - found AccuRate compared well against their eight reference programs from Europe and the US.

Developed in partnership with the Australian Government Department of Climate Change (formerly the Australian Greenhouse Office), AccuRate gives building designers and builders a tool to accurately analyse, measure and compare energy efficient design options.

Read about CSIRO's work in Sustainable cities and coasts.