Life Cycle Assessment of Sustainable Construction Materials

Background to the research

The SUMACON network aims to work in conjunction with BRE Environment to develop a life cycle analysis (LCA) of traditionally used lime mortar composites and other construction materials. This will be supported by whole life performance and costing, carried out by the Centre for Whole Life Construction and Conservation at BRE.

Life Cycle Assessment is a method to measure and evaluate the environmental burdens associated with a product, system or activity, by describing and assessing the energy and materials used and released to the environment over the life cycle. It is a cradle (extraction) to grave (disposal) assessment tool for environmental impacts of products and processes.

LCA has developed into a technique that enables comparison of the environmental performance of specific products used for the same purposes but made of different raw materials or by different processes. In this way, it parallels whole life cost assessment for products and processes.

The International Organisation for Standardisation (ISO 14040) states: LCA is a systematic identification and quantification of inputs and outputs for the whole life cycle for products used for the same purpose but made of different raw material or by different method. Once data is collected for the LCA, the impact assessment phase is aimed at evaluating the data calculated in the analysis in terms of their environmental impact. Within the BRE methodology there are 13 impact categories. The inputs and outputs from the inventory analysis are then assigned to the appropriate impact category. A list of the 13 impact categories considered in the BRE LCA methodology are shown below:

• Climate change
• Acid deposition
• Ozone depletion
• Pollution to air: Human Toxicity
• Pollution to air: Low level ozone depletion
• Fossil fuel depletion and extraction
• Pollution to water: Human toxicity
• Pollution to water: Ecotoxicity
• Pollution to water: Eutrophication
• Minerals Extraction
• Water Extraction
• Waste disposal
• Transport pollution and congestion: Freight

Project Aims

The project aims to initially conduct a LCA for hydrated and hydraulic lime, to produce two generic Environmental Profiles on a per tonne basis. These profiles will then be used to compare different lime mortar mix designs using different composite materials. This will produce separate environmental profiles for each mortar mix on a per tonne basis. This data will be compared on an internal and external building specification context on a per metre squared basis. This can then be used as a direct comparison to existing profiles of OPC building specification. The energy gains from the reuse of materials built with lime will be taken into in the waste disposal category.

If time permits, a LCA will be conducted for cob block and unfired clay bricks. This will produce Environmental Profiles on a per tonne basis. These can then be placed into a building specification context for internal and external walls on a per metre squared basis. They can then be used as a direct comparison to existing profiles of more generic building materials.

Project timescales

The research will be carried out at BRE, Watford within the Centre for Sustainable Development and the Centre for Whole Life Construction and Conservation. A report of the findings of the research project will be produced at the end of the project. The project is envisaged to last approximately 5 months, staring in July 2005. The findings of this project will be presented at the workshop 'Towards Sustainable Building'.