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The growing concerns over the environment have led to increasing demand for environmentally-friendly buildings. So far, only a few studies on environmental impacts of buildings have been conducted in the context of Sri Lanka. Reliable data sources that match the specific conditions of the country are limited. Using the life cycle assessment (LCA) methodology, this paper presents a cradle-to-gate energy and carbon emission study of a multi-storey residential building in a Sri Lankan university. The total embodied energy and carbon of the building are 3.84 GJm-2 and 229.34 kgCO 2 m-2 , respectively, which are comparable with results of similar studies found in literature. Reinforced concrete, the main structural material, contributed to 61 % of total embodied energy and 71 % of total embodied carbon of the building. Despite the relatively low material quantity used, aluminium, ceramic tiles and paint shared 18.67 % of total embodied energy. In order to achieve low-energy and low-carbon buildings in Sri Lanka, several strategies were identified; suitable construction practices and building designs to reduce quantities of mass materials, use of alternative materials with low energy and carbon intensities, material recycling and reuse, use of clean and renewable energy for production processes and popularising the concept of eco-labels for building materials. The reduction of embodied energy and carbon is expected to lighten the environmental footprint of buildings.

Buildings are known to significantly affect the global carbon emissions throughout their life cycle. To mitigate carbon emissions, investigation of the current performance of buildings with regard to energy consumption and carbon emissions is necessary. This paper presents a process-based life cycle assessment methodology for assessing carbon emissions of buildings, using a multistorey reinforced concrete building in a Sri Lankan university as a case study. The entire cradle-to-grave building life cycle was assessed and the life span of the building was assumed as 50 years. The results provide evidence of the significance of operation and material production stages, which contributed to the total carbon emissions by 63.22% and 31.59% respectively. Between them, the main structural materials, concrete and reinforcement steel made up 61.91% of the total carbon emitted at the material production stage. The life cycle carbon emissions of the building were found to be 31.81 kg$m-2 CO 2 per year, which is comparable with the values obtained in similar studies found in the literature. In minimizing the life cycle carbon emissions, the importance of identifying control measures for both building operation and material production at the early design stage were emphasized. Although the other life cycle stages only contributed to about 5.19% of the life cycle carbon emissions, they should also receive attention when formulating control strategies. Some of the recommended strategies are introducing energy efficiency measures in building design and operation, using renewable energy for building operation and manufacturing of materials, identifying designs that can save mass material quantities, using alternative materials that are locally available in Sri Lanka and implementing material reuse and recycling. This study is one of the first to undertake a life cycle carbon emissions assessment for a building in the Sri Lankan context, with the hope of facilitating environmentallyfriendly buildings and promoting sustainable construction practices in the country.

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