A move towards highly energy efficient buildings would pay off more than a large-scale uptake of rooftop solar power in New Zealand, researchers from the University of Otago say.
University of Otago energy programme director Associate Prof Michael Jack, of the department of physics, looked into how an international drive towards "net-zero energy buildings" — highly efficient buildings that generated their own renewable electricity through solar panels — would work in a New Zealand setting.
Assoc Prof Jack found in this country improving the energy efficiency of buildings should be job one.
"The focus, from a system-wide perspective for New Zealand, should remain on improving the energy efficiency of our building stock as fast as possible rather than self-generation as we have other low-cost options for renewable electricity," Assoc Prof Jack said.
"Solar PV [photovoltaic] can be very beneficial in some regions, especially when it aligns with growing cooling demand.
"It can also provide increased energy resilience and electricity supply in remote regions, but it shouldn’t be prioritised above energy efficiency or become a requirement of future building codes nationally as is the growing trend in some countries."
In a just-published paper in Energy and Buildings, Assoc Prof Jack and co-author Hannah Konings compared the effect of creating highly-insulated, energy efficient buildings and buildings that generated their own electricity through solar power on New Zealand’s electricity grid.
Their study found if there was to be large-scale uptake of very high efficiency buildings, without solar power generation, electricity demand would drop by 30% a year.
The seasonal variation on electricity demand would drop by 50% a year by 2050, they said.
In contrast, if there were no changes to building standards but solar power generation for buildings was taken up on a large scale, there would be a drop in annual electricity demand by 30% — but the seasonal variation would actually increase by 40%.
The study also found that if there were highly efficient buildings powered by self-generated solar power there would be a 65% annual demand decrease, but a seasonal demand decrease of only 4%.
"For New Zealand, given the low cost of renewable electricity from a variety of alternative sources, scenarios of large-scale uptake of solar-powered net-zero energy buildings are not favourable from an electricity system perspective," the study said.
"In New Zealand, the winter peak in electricity — which is becoming harder and harder to meet with renewable supply — is largely caused by residential electrical heating.
"On the other hand, we chronically underheat our houses, leading to well-documented health problems."
He said the solution was to significantly improve New Zealand’s new and existing building stock to make highly efficient nearly-zero energy buildings which required very little energy for heating.
