1970s office block gets an energy-smart transformation

The 46-year-old Aorangi House in central Wellington, New Zealand, has achieved a ‘market leading’ NABERSNZ base building rating, demonstrating an energy performance over 50% better than an average New Zealand office.

Situated at 85 Molesworth Street, the 12-storey office block was built in 1970 but over time its systems had become problematic. The property was later transformed with a full-scale refurbishment comprising a raft of energy-smart features which set the stage for energy saving.

Engineering consultancy Beca, which provided an environmentally sustainable design for the project, moved in to Aorangi House soon after its renovation. The building is currently owned by Anaro Group, which manages 44 commercial properties across New Zealand on behalf of private investor groups.

Aorangi House attained a 5-star NABERSNZ base building rating in October 2016, which is considered a thumbs up for the revival of older commercial building stock. Its refurbishment meanwhile earned a 5 Green Star Design rating, while tenant Beca has attained a 4.5 star NABERSNZ ‘excellent’ tenancy rating for its 40% reduction in tenancy energy use compared with an average New Zealand office tenancy.

Beca spokesman and NABERSNZ assessor Ben Masters said the project proves that age does not impede making a building commercially and environmentally sustainable.

“What makes the 5-star rating so significant is that Aorangi House is a recycled building,” Masters said. “It shows sustainable refurbishment is a viable option to the carbon-hungry alternative of demolition and replacement.”

The overhaul at Aorangi House included the addition of double-glazed windows (both manual and automatic opening), sunshade louvres and an insulation system that activates the building’s 1970s concrete structure to dampen peak temperatures and enhance natural ventilation. According to Masters, “It’s a fairly unique approach for a multistoreyed office where full-height glazing, air conditioning and mechanical ventilation are the norm.”

Masters added that constant energy monitoring and building tuning has been crucial to achieving low energy usage at Aorangi House. He noted, “Regardless of an office block’s energy efficiency features, we continually find that unless service controls are fine-tuned a building will never achieve its design energy performance targets.”

Anaro Group General Manager Toby Scott said his company is delighted with the 5 star rating for an iconic and mature building, noting that a NABERSNZ rating is increasingly relevant for both tenants and owners in the commercial property marketplace.

“For the tenant, it brings transparency while benchmarking and propelling constant reviewing and improvement in energy use,” he said.

“From the owner’s perspective, there’s growing evidence to support the view that efficient energy use ultimately improves a building’s value.”