Data Collection

In this study, we calculate the carbon footprint of construction materials using two methods. In the first method, embodied carbon databases in other countries are referenced and adjusted based on local fuel mix and electricity emission factors. For each construction material, the countries which supply that material to the Hong Kong market are considered. In this localization method, we assume manufacturing processes of the same material are identical everywhere.

In the second method, the concept of life cycle assessment (LCA) is adopted. First-hand data from material vendors are collected and used to calculate the embodied carbon in the “Cradle-to-Site” life cycle boundary. The collected data are from the companies by sending the questionnaire. As the life cycle inventory data are region-specific and construction activities in different areas may vary largely with different technologies and standards, this LCA method can provide a more accurate and local specific estimate of GHG emission from construction materials. Inventory of Carbon and Energy (ICE) developed by University of Bath in UK, which is a widely used embodied carbon database for construction materials, collected data from secondary resources in the public domain instead of obtaining first-hand data from manufacturers.

The calculation framework used in our LCA method references several international standards, including ISO 14064-1:2006 and PAS 2050:2011. Emission factors for fuels refer to the IPCC documents while emission factors for electricity and transport refer to the WRI document. This study also refers to some databases and regional statistics such as Chinese Life Cycle Database (CLCD). The transport distance, transport means, and energy consumption are first-hand data collected from different company.