The transaction records ratio between green buildings and non-green buildings in the two cases is 1:1. The sample of residential developments consists of small to large size units in both cases; with the price range of the buildings selected is HK$3,800 and HK$7,000 per sq. ft. The number of transactions records used in the study is 1,947 in case 1 and 2,259 in case 2. The transaction price of a housing unit refers to selling price of the flat record in the Economic Property Research Centre (EPRC) Limited. All agreement of sale and purchase (ASP) records of the selected buildings in this period are selected for the study.
The data came from secondary sources such as from EPRC limited and governmental publications, which is a usual practice. The information of unit orientation was also collected from Centaline and Midland Realty web sites. In the study, the transaction records of all selected green and non-green buildings in the period of 1 July 2003 and 1 September 2008 were obtained from the EPRC. This particular transaction period was specifically chosen in order to avoid the SARS outbreak in 2003 and global financial crisis in 2008. The data of transaction price, building age, floor level, floor area, orientation and view were obtained from the EPRC. The information of the HK-BEAM certification and HK-GBC awards was obtained from their web sites. As the properties were transacted in different times, the price index issued the Rating and Valuation Department was used to deflate the property price.