case studies / Environmental credentials of housing in Australia - AV Jennings Homes
This case study estimates the life cycle environmental impacts of the construction and operation of an AV Jennings Project Home in Sydney, Australia. The study was conducted over a sixty year period, with the home being demolished after this period. The house was assumed to be occupied by four people for the duration of the study. Appliances and fit out items were replaced every ten years.
To provide a fast and user friendly, interactive LCA case study, which allows the user to investigate the life cycle impacts of a range construction, transportation, recycling and utilisation, options.
Nominal house construction includes three bedrooms, a reinforced concrete raft slab with reinforced thickened concrete edge beams, timber frame, extruded clay brick cladding, internal plasterboard lined walls, timber roof framing, uniform 2.4 m high plasterboard lined ceiling, concrete roof tiles, and R1.5 fibreglass insulation. A garage is not included in the construction of the home but can be selected within the example.
Utilisation of appliances can also be selected, with the default being the average consumption of an average Sydney household.
Heating and cooling factors calculated from the CSIRO Cheetah model have been applied to consider the effects of construction materials, and general design on the heating and cooling loads. These factors can be changed by the user to customise the example to any climate.
The systemanalysed included the manufacture of all building materials from resources in the ground, building site activities, construction equipment, repairs/maintenance, periodic refurbishment and finally, decommissioning.
Heating and cooling factors calculated from the CSIRO Cheetah model have been applied to consider the effects of construction materials and general design on the heating and cooling loads. Heating and cooling loads were calculated from Sydney meteorological data and are not applicable to other locations.
The entire life cycle is considered, from resources in ground through to demolition and recycling/landfill of the structure. Landfill emissions are excluded.
Transportation mode and distance are included for each material.
Environmental impacts investigated were resource energy consumption, GGE (greenhouse gas emissions), NOx, SOx, NMVOC (non-methane volatile organic compounds), SPM (suspended particulate matter), and fresh water consumption.
Gross energy (GJ/t), or high heating value (HHV), is used. Feedstock energy is included for all materials except timber.
Feedstock energy is the specific energy, also termed calorific value, of a material. Traditionally, feedstock energy has not been included in the life cycle energy or embodied energy for timber. Timber is the only material treated in this way. This anomaly results in an artificially low value of embodied energy for timber of approximately 4 GJ/t. Including feedstock energy increases the embodied energy of timber by 10-20 GJ/t, depending on dryness.
This discrepancy, and the increased importance of timber products as a direct energy source (particularly in Europe), is leading to a trend to include feedstock energy for timber products. In this analysis, therefore, both values (ie timber with and without feedstock energy included) were calculated.
IPCC weighting factors (global warming potentials) are used in the calculation of greenhouse gas emissions, eg for CH4 and N2O.
Australian LCI data. The data are maintained in EMMA (Eco-model for Material and Manufacturing Assessment), BHP's LCA data system. Construction data were based on a report entitled "The Use of Steel in Housing Construction (Sydney - Melbourne)" by W Lawson and S Craig, SOLARCH, University of New South Wales, January 1995. These data have been updated for 1999. Data for utilisation were gathered from various sources, including manufacturer data and the Australian Bureau of Statistics.
This study did not require any allocation. Recycled materials have displacement credits allocated based on the displacement of virgin production.
The approach and allocation rules used in the LCI data conform to ISO guidelines for LCA, and attempt to simulate reality as closely as possible.