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An empirical validation of the house energy rating software AccuRate for residential buildings in cool temperate climates of Australia


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Geard, D 2011 , 'An empirical validation of the house energy rating software AccuRate for residential buildings in cool temperate climates of Australia', PhD thesis, University of Tasmania.

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In 2003, the Building Code of Australia (BCA) introduced its first thermal performance
requirements for residential buildings as a means to reduce Australia’s energy consumption
and greenhouse gas emissions in the construction sector. This mandated a minimum energy
performance rating of 4 stars for all new residential buildings. This requirement was
increased to 5 stars in 2006 and to 6 stars in 2010. The introduction of the 4-star requirement
had only a minor impact on construction practices and construction costs. However, the
adjustment to 5 and 6-star ratings resulted in changes within the building industry,
particularly on timber floor construction. The BCA's requirements for increased star ratings
and energy efficiency resulted in concerns within the building industry, one of which was in
relation to the accuracy of the House Energy Rating scheme's (HER) software "AccuRate"
and its capability to model the building envelope and provide the star rating. AccuRate was
developed gradually over a number of years by the CSIRO and was primarily used by
building designers as a design tool. When the energy efficiency section was incorporated into
the BCA as part of the building approval requirements, AccuRate was developed into a
regulatory tool. Consequently, industry and government have recognized the need to validate
this software empirically.
The University of Tasmania, in collaboration with Forest and Wood Products Australia, the
Australian Government, and housing developer Wilson Homes, constructed three test houses
in Kingston, Hobart for the purpose of validating AccuRate empirically for the cool
temperate climate zones of Australia. The test houses were built to standard building
practices, comprising: brick veneer walls, aluminum-framed windows and Colorbond steel
roofing. Two houses have suspended timber floors and the third house has a concrete slab
An extensive array of instruments and data loggers was installed to measure and document
the thermal performance of the three houses. Comprehensive AccuRate simulations of the
test houses were carried out, and hourly measured and simulated data were compared. The
research presents the findings of the graphical and statistical analysis of the variation between
the simulated and measured data from the three test houses.
The findings demonstrate that while simulated and measured temperatures had comparable
profiles for most zones of the three houses, individual hourly simulated temperatures did not
in most cases, match the measured temperatures, and were at times quite dissimilar.Simulated temperature ranges were larger in all zones of the houses than measured values.
Simulated temperatures were closer to measured values in the slab floor house than in the two
timber floor houses. In addition, simulated temperatures were closest to measured values in
the living room and bedrooms of the concrete slab floor house and were furthest away from
measured values in the hall way and roof space of all three houses and in the subfloor space
of the timber floor houses. The large discrepancies between simulated and measured
temperatures in these spaces of the houses require further investigation and resolution for the
continuing improvement and calibration of the AccuRate software. The considerable
disagreement of temperatures between simulated and measured values will significantly
compromise the accuracy of the heating and cooling loads and consequently, the star rating of
the software.

Item Type: Thesis - PhD
Authors/Creators:Geard, D
Keywords: empirical validations, energy rating software, residential buildings, cool temperate climates, Australia
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