case studies / Environmental credentials of a generic small building in Australia
This case study estimates the life cycle environmental impacts of the construction and operation of a generic small building in Australia.
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.
This case study enables the user to interactively estimate the environmental impacts of the construction and operation of a home or small building. The casestudy includes common building materials and construction systems, which can be selected by the user to create a specific example. Utilisation of appliances can also be selected.
User parameters are operational energy such as lighting and air conditioning, transportation type and distance, building materials and construction systems, number of occupants, maintenance such as painting, life span of building and appliances, recycling of decommissioned items, and transportation of materials to and from the house.
The system analysed included the manufacture of all building materials from resources in the ground, building site activities, construction equipment, repairs/maintenance, periodic refurbishment and finally, decommissioning.
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 2000. Data for utilisation was gathered from various sources, including manufacturers 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.