Thermal performance of light-weight timber test buildings Mr Mark Dewsbury Centre for Sustainable Architecture with Wood, University of Tasmania Launceston, Australia Associate Professor Gregory Nolan Director, Centre for Sustainable Architecture with Wood, University of Tasmania Launceston, Australia Professor Roger Fay School of Architecture, University of Tasmania Launceston, Australia 1. Summary This paper will detail the construction and thermal performance of three thermal performance test cells in Launceston, Australia. In 2003, the Building Code of Australia (BCA) introduced its first thermal performance requirement of 4 Stars for residential buildings. The move to 5 Stars in 2006, has forced considerable change in building practise, especially in the use of timber platform floors. As a result, the Centre for Sustainable Architecture with Wood was asked to validate the Australian House Energy Rating (HER) software package, AccuRate, against a series of test buildings. In early 2006, three light-weight timber framed thermal performance test cells were built at the University of Tasmania’s Launceston campus. The construction types consist of an unenclosed platform floor, an enclosed platform floor and a concrete slab on ground floor. Detailed monitoring began in August, 2006. This paper details the varying thermal performance of the test cells during two four day periods, one warm and one cool. The documented variation in thermal performance between the three test cells is caused by a mix of fabric and environmental air flows. 2. Introduction In 2003, the BCA mandated a minimum performance rating of 4 Stars for residential buildings when assessed by approved rating methods. In 2006, this requirement was increased to 5 Stars. While the introduction of a 4 Star requirement had only minor impact on construction practices, the move to 5 Stars forced considerable change, especially in the use of timber Platform floors. The Centre for Sustainable Architecture with Wood (CSAW) with funding provided by the Forest & Wood Products Research & Development Corporation (FWPRDC), the Australian Greenhouse Office (AGO), and industry sponsors commenced a building thermal performance research program. The projects aim to better understand and quantify the thermal performance of lightweight timber construction, especially forms regularly used in the Australian residential sector, and validate the performance of the CSIRO-developed AccuRate HER software for these types of construction. The project has three components: the No Bills and Best Five Star Houses; the Thermal Performance Test Cells; and the Five Star Thermal Performance Houses. The No Bills and Best Five Star Houses component was the planned construction and monitoring of three test buildings at Mornington in Hobart. The houses were to be: the No Bills House - a high environmentally performing house with an 8.5 Star rating and no net external services requirements; a Five Star Timber House with an enclosed timber subfloor; and a Five Star Concrete Slab on Ground House. To be built by local developer, cb&m design pty ltd, and sold after an initial monitoring period, economic constraints prohibited their construction. The Thermal Performance Test Cell component evolved as a result of the faltering of the No Bills and Best 5 star Houses. With the assistance of funding agencies and building material manufacturers, the construction and monitoring of three thermal performance test cells began at the University’s Newnham Campus at Launceston between March and July 2006. This research is described in detail below. The Five Star Thermal Performance Houses component is the construction and monitoring of three two-bedroom houses to an identical plan and orientation on a sloping site at Kingston in southern Tasmania. The houses are: a Five Star Timber Floored House with an enclosed timber subfloor and an external fabric adjusted to rate with the AccuRate HER software as close as possible to Five