Potential of zero carbon buildings in Hong Kong

Abstract

It is doubtless that global warming is enhanced by human activities, and being accelerated in recent years. The building sector is one of the main contributors in carbon emissions over the world, which contributed to over 20%. Hong Kong is a typical metropolis located in the sub-tropical region, whereas financing and servicing are the major industries supporting the development of the city. With these industries, it implies the major carbon emission is from buildings of commercial and residential sectors. A wide range of policies and researches on high efficient / green building design were conducted in the Western countries since the 90s, and there are more in the Asia Pacific since 2000. Among different countries there are many methods in calculating carbon emissions, which are similar in principle and different in the details. It is important to agree a consistenct framework on the calculation of carbon emission and study the performance of different carbon reduction strategies, hence to serve a reference for designers.

This study conducted a critical review on the calculation of carbon emission, hence definition of carbon emissions. The review classified different calculation methods by 7 factors, which are the major governors on the results. All methods reviewed in the section were either current standards or methods suggested by scholars. With the critical review, a potential calculation methodology is suggested and will used for the calculation in the later part.

A case study was carried out for the identification of the strategies used on two zero carbon buildings and one zero energy building. The study shows these buildings used similar strategies on the emission reduction, including photovoltaics, well insulated fabric, natural lighting, natural ventilation, high efficient lighting system and solar hot water system.

A computer simulation was used to analyze the performance of different strategies that could be used on buildings in Hong Kong climate. Commercial buildings and residential buildings are selected as sample buildings for the analysis. A baseline building is setup with typical design. The computer simulation studied the strategies used by other buildings from case study and compares their effect with baseline building.

The simulation shows that a zero carbon residential building is possible with sufficient offsetting on the building surface. However, office building cannot be zero carbon by applying the analyzed strategies. The study shows solar hot water is the most effective strategy for residential buildings and day lighting is the most effective strategy for office buildings.