Over time buildings change use, but there is a cost in transforming a building from its originally designed use to a different one. While this has relevance to resource efficiency, particularly in relation to materials and land costs, it also raises issues about the extent to which changes in use may result in inefficient building performance - particularly in relation to energy consumption.
The BEES study sample includes only buildings that are primarily used for office or retail. In order to determine whether buildings were eligible for inclusion in the BEES study, the study team obtained QV use category codes and then carried out web-based searches and site visits to check what the building was currently used for. The study team investigated buildings that were classified as Liquor Outlets Including Taverns (CL), Motor Vehicle Sales or Service (CM), Office Type Use (CO), Retailing Use (CR), Service Stations (CS), Tourist Type Attractions (CT), Vacant Land (CV), Other Commercial Uses or where there are Multiple Uses (CX). The team also investigated buildings classified as Industrial Service (IS) and Industrial Warehouse (IW) in case they had subsequently changed use to office or retail.
This analysis took the valuation use category codes allocated by QV and compared them with the uses found by the BEES project. If it is assumed that QV use categories for building records are allocated at the initial valuation and that they are updated as a result of a building consent, subdivision, sale or other inspection, then this would suggest that differences between the QV category and the use identified by BEES has resulted from a change in use after the allocation of the QV code. It needs to also be assumed that rules for allocating QV use category codes are consistently applied, or if there are in errors in application that these occur randomly for the different floor area groupings and regions.
The analysis has shown that approximately 30% of buildings in the IS and IW QV use categories have changed to retail or office use (i.e. are eligible for inclusion in the BEES research). This is a significant proportion of buildings.
These proportions are about the same regardless of floor area size, and there does not seem to be any regional difference between Auckland the rest of New Zealand.
Figure A gives the percentage by count of eligible BEES buildings (office and retail buildings) by QV use categories and the floor area size (strata).
It appears from these findings that about 30% industrial and warehouse buildings are being used in a way that would require the NZBC Clause H1 to be applied differently if they had been built for the new use i.e. instead of Industrial they would be classified as Commercial uses.
The implications of this change-of-use for energy performance require further investigation. For example, what would be the energy consequences if a warehouse (IW) was changed to retail (CR) use without any of the energy efficiency activities that would be have been required should the building have been designed and constructed for this specific use? What would be the cost and consequences of retrofitting to meet these requirements?