Based on feedback Transpower received from the 2008 BRANZ Report, we commissioned a new study in 2009 with slightly adjusted assumptions and methodology. The report covers all regions in New Zealand.
This 2009 report supported the conclusions from the 2008 study, though the impact on both summer and winter demand tended to be lower as the 2009 study assumed the efficiency of heat pumps would improve over time.
Although more work needs to be completed, increases in summer and winter electricity demand above that which is currently forecasted may affect the timing and need for transmission investment in some areas. As result, Transpower is monitoring closely whether the current forecasting methodology captures the impacts of the rapid uptake of heat pumps.