Designing homes to conserve energy and use it efficiently, from sources that cause least environmental harm.


A typical New Zealand home consumes 10,500 kWh of energy per year. Approximately 5,800–8,500 kWh of that is electricity (depending on location), with an average house using 7,000 kWh.

All energy consumption has environmental impacts, ranging from the production of greenhouse gases in burning fossil fuels to direct effects on landscapes from dams and other sources of generation.

Most of the total energy consumed in New Zealand still comes from non-renewable sources (fossil fuels), but the story is different for electricity – 85 percent of our electricity is produced from renewable sources.

Energy efficiency measures have also led to energy use in the average New Zealand household falling by 10% since 2000.

This figure comes from a study commissioned by the Equipment Energy Efficiency (E3) programme. There is evidence that people buying more energy efficient appliances explains a large part of the drop. There was a 26% improvement in the overall efficiency of heat pumps sold in New Zealand between 2004 and 2014, for example. The researchers go on to forecast that household average energy use will continue to fall in the near future, as will greenhouse gas emissions from households.

There are still many opportunities for making our energy use even more sustainable, however.

Sustainable energy use means designing homes to conserve energy, obtaining energy from sources that do the least possible long-term environmental harm and, where energy is used, to use it efficiently. (Find out more about embodied energy.) Energy efficiency will also reduce long-term energy bills for home occupiers.

Energy-efficient design may incorporate small-scale on-site energy production to meet demand.

In its 2018 Statement of Intent, EECA estimated that more than $470 million could be saved each year by improving the quality and energy efficiency of New Zealand’s housing stock. “While the residential sector only accounts for 6% of New Zealand’s total energy-related emissions…households have a significant impact on our peak electricity use when electricity tends to be at its least renewable and most expensive to produce (for example, winter evenings).”

Engineering New Zealand, in its report Engineering a Better New Zealand: Cleaner Energy, suggests that sometime in the future a smart grid could help provide a solution. A smart grid would automatically turn on smart appliances when supply is plentiful, “…rather than all the dishwashers in New Zealand running every evening.”

“Virtual power plants could help by aggregating small-scale generation … including domestic electric vehicles or solar panels and feeding it back into the grid. For example, to cover a sudden generation need, a virtual power plant could tell your fridge freezer to take a brief break and your electric vehicle battery to join with thousands of others in feeding energy back into the grid.

Virtual power plants overcome the fact that our distribution network was designed to supply power from the transmission network to homes, not the other way around.”

This section of the Level website incorporates material from the BRANZ publications Energy and Electrical design.


Updated: 18 December 2018