By Pattrick Smellie
A swing away from heavy industry and more use of electricity for home heating contributed to an overall improvement in New Zealand's energy efficiency between 1990 and 2011, figures show.
However, the statistics from the Ministry of Business Innovation and Employment show the mining sector has become much more energy intensive over the same period.
The move to larger cars and less use of public transport has seen the overall energy efficiency performance of passenger vehicles worsen.
Total energy consumption grew in all categories owing to population and economic growth, and the figures, developed with the Energy Efficiency and Conservation Authority, seek to isolate the impact of improved energy efficiency.
They divide New Zealand's energy use into three broad categories: residential, transport, and a business category covering all industry, commercial activity and public sector consumption, other than oil refining and chemical manufacturing such as methanol and agri-chemical production.
Energy intensity in the business category, accounting for 64 per cent of total energy consumption, fell by 21 percent over the two decades, from an average of 2.9 Petajoules of energy per $1 billion of output in 1990 to 2.3 PJ's per billion dollars in 2011.
Among reasons for this were a slump in energy use after the global financial crisis, with gross consumption falling from a peak for the period of about 260PJ's in 2007 to just under 250PJ's in 2011.
But structural changes to the economy were also important contributors, as energy intensive activities grew more slowly than the commercial sector, reflecting a switch to wood waste from coal in wood product manufacturing, and a drop in highly energy-intensive wood processing from 2005 onwards.
NZN