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How data was collected

As there was no comprehensive New Zealand list of non-residential buildings available at the start of the study, BRANZ developed one from property valuation records for all potentially BEES-eligible buildings in New Zealand.

The data collected enabled all the research questions in BEES to be answered. This included looking at where the highest energy and water savings could be achieved and informing modelling and forecasting work into the likely future changes as building stock and distribution around the country changes.

In developing a list of New Zealand non-residential buildings using property valuation records, it was vital to ensure it was accurate. This required extensive checking, including the use of web-based searching, and it provided new knowledge about the BEES-eligible non-residential building stock, including size distribution. This was used to prepare a random, stratified sample for surveying.

The buildings selected for the aggregate survey were a random sample stratified into five groups by floor area, selected from the property valuation list. Each floor size quintile represented a similar total floor area, although the number of buildings varied considerably.Within each group, an equal number of buildings were selected to participate in BEES, making sure each was represented in the study.

Each building was then verified by a street visit to check the property's existence and estimated actual floor size and the use of the building.

The premises or businesses within that building were also identified and matched with phone numbers. A sample of premises that agreed to participate in the aggregate survey was then selected for detailed monitoring.