Retrofitting for net zero energy

A Victoria University of Wellington study shows that retrofitting New Zealand’s commercial buildings to use less fossil fuel-generated energy could save enough energy to power many homes on the South Island.

Shaan Cory, a building scientist with a PhD in Architecture, investigated whether New Zealand’s current commercial building stock could be converted to net zero energy. He explained, “A net zero energy building is one that is energy efficient and offsets any energy that was generated from greenhouse gas-emitting fuels with renewable energy generation such as hydro, solar and wind.”

Cory reached his findings by constructing energy models for a sample of existing buildings, matching their attributes and energy performance. The models were then retrofitted with a set of energy conservation measures.

He found the current commercial building stock could be converted to eliminate the use of greenhouse gas-emitting energy without New Zealand needing to generate more renewable energy. The energy saved by retrofitting all commercial buildings could power 330,000 homes, with the reduction in greenhouse gas emissions equivalent to the methane emissions produced by 200,000 dairy cows.

According to Cory, half of the net zero energy target could be achieved by retrofitting just 1200 of the largest of New Zealand’s 27,000 commercial buildings. The savings from these large buildings would be equal to the annual electricity generated by all wind turbines in New Zealand.

Cory said the most effective energy-saving techniques are more efficient plug-in equipment, lighting, heating, ventilation and air conditioning, and the installation of electric light dimming. The benefits of a net zero energy building stock, he said, would include lower carbon emissions, improved energy security for New Zealand and better thermal comfort for buildings’ occupants.