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Article Excerpt
Abstract: This pilot study seeks to identify the relationships between real energy consumption data and building design data. A number of houses were randomly selected as sample buildings for the study which introduces a method to use real energy consumption data to calculate the extra energy use related to winter indoor thermal conditions. Winter mean energy data and the extra energy usage related to winter indoor thermal conditions are used for investigating the relationships with design data related to the main architectural features, building elements and building materials. This study presents and identifies relationships between the increase in mean daily energy consumption data and trends of building design data of the sample houses, and establishes the starting point and feasibility for further study to identify, in more detail, the quantitative relationships between building design data and energy consumption data for further developing passive design guides for building energy efficiency.
Keywords: Energy efficiency, Design guides, Housing design, Passive energy design
Introduction
The first and best place to consider building energy efficiency is during the design of the building, not when the building has been completed and is in operation. "It is not hyperbole to suggest that the better design of new buildings would result in a 40-75% reduction in their energy consumption relative to 2000 levels, and that appropriate intervention in the existing stock would readily yield a 30% reduction" (Clarke, 2001). A number of recent studies have investigated the upgrading of insulation levels to improve housing thermal performance or energy efficiency (Lloyd, Callau, Bishop & Smith, 2008; Milne & Boardman, 2000; Verbeech & Hens, 2005) and to improve indoor health conditions (Bullen, Kearns, Clinton, Laing, Mahony & McDuff, 2008; Gilbertson, Stevens, Stiell & Thorogood, 2006; Howden-Chapman, Crane, Matheson, Viggers, Cunningham, Blakely, O'Dea, C. Cunningham, Woodward & Saville-Smith, 2005; Su, 2002, 2006). This study focuses on the impact of building design features on housing thermal performance and energy efficiency. On average of New Zealand houses, space heating is the largest single enduse (34%), followed by hot water (29%), appliances (13%), refrigeration (10%), lighting (8%) and cooking (6%). Heating to raise low temperatures is the main use of household energy (63%), comprising space heating (34%) and hot water heating (29%) which are closely related to the winter indoor thermal conditions of a house (Camilleri, French, Pollard, Saville-Smith, Fraser, Rossouw & Jowett, 2006). Auckland does not normally need air conditioning or a ceiling fan for cooling during summer and only needs temporary heating during winter. In Auckland, the design of a building should focus more on its indoor thermal conditions and thermal performance related to winter conditions for building energy efficiency (Su, 2004).
This study mainly focuses on winter energy consumption and the extra energy used in response to winter indoor thermal conditions. To minimize the influence of differences in housing facilities and climates the study randomly selected 100 sample houses in the Auckland region which had been using electricity as their only energy resource for space heating, hot water, cooking, lighting, refrigeration and other appliances. The electricity consumption data for each sample house are for the same period of twelve months. Sample houses for this study include 50 houses with insulation materials in their roofs and walls and 50 houses without such insulation. Design data for the study were obtained from copies of the sample house plans provided by Auckland City Council. The 50 sample houses with insulation include 18 one-storey houses, 30 two-storey houses, 1 three-storey house and 1 four-storey house. The range of floor areas is 63 - 430[m.sup.2] and the mean floor area is 208[m.sup.2]. The range of occupancy per dwelling is 1 - 6 persons and the mean number of occupants per dwelling is 3.6 persons. The range of floor areas per occupant is 20 - 172[m.sup.2]. There are 25 houses with metal roofs (18 houses with brick walls and 7 houses with weatherboard and other walls), 22 houses with concrete tile roofs (7 houses with brick walls and 15 houses with weatherboard and other walls) and 3 houses with cedar shingle roofs. There are 39 houses with internal garages and 11 houses without. The 50 sample houses without insulation include 29 one-storey houses, 19 two-storey houses and 2 three-storey houses. The range of floor areas is 54 - 4l4[m.sup.2] and the mean floor area is 148[m.sup.2]. The range of occupancy per dwelling is 1-6 persons and the mean number of occupants per dwelling is 3.3 persons. The range of floor areas per occupant is 19-184[m.sub.2] There are 27 houses with metal roofs (5 houses with brick walls and 22 houses with weatherboard and other walls), 22 houses with concrete tile roofs (8 houses with brick walls and 14 houses with weatherboard and other walls) and 1 house...
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