Development of a Local Embodied Carbon Database for Construction Materials

According to WWF, the construction sector was the second largest contributor to Hong Kong carbon footprint and emitted nearly 4 million tons of carbon dioxide in 2007. In addition to the operational carbon generated during building operation and maintenance, the embodied carbon of construction materials also contributes a significant part of the life cycle carbon emission in the built environment. Studies have shown that the embodied carbon of buildings is close to the operational carbon over 20 years, and contributes more than 30% of the life cycle carbon emission of buildings. In Hong Kong’s construction sector, 85% of its carbon footprint was embodied in imported goods and services. Therefore, it is crucial to study the embodied carbon of construction materials and select the low carbon materials in order to achieve a low carbon built environment. This project aims to develop a local embodied carbon database, namely ECO-CM (Embodied Carbon Of Construction Material), for the commonly used construction materials in Hong Kong. A “Cradle-to-Site” life cycle boundary was used in the ECO-CM database, which includes raw materials extraction and transportation, material manufacturing, and product transportation to the use site. As the fuel mix and material manufacturing and delivery in different areas may vary substantially, embodied carbon values are region-specific. Therefore, first hand data were collected from the material vendors through questionnaires for calculation. The methodology framework used in the development of the ECO-CM database is presented and illustrated in this paper. The completed ECO-CM database will provide a basis for selection of green materials, development of carbon labels, and estimation of building facility carbon footprint, thereby helping to construct a low carbon Hong Kong.