Based on Britain’s Kenna system, the fifth generation ground-source heat pump network covers 68 homes being built for Queenstown Lakes Community Housing Trust’s (QLCHT) Tewa Banks project.
So, in addition to affordable housing, residents are likely to enjoy the Whakatipu’s cheapest heating, hot water and cooling.
Steve Jarvis, from Queenstown’s Therma, Kenna’s Australasian distribution agent, says the homes are connected to a shared ground-source collector field through 58 bores drilled about 120 metres deep.
"The system takes the ambient earth temperature of around 12°C, then increases it using a heat pump in the house to 50°C for use in the radiators and 65°C for use in the hot water cylinder."
Using a traditional heat pump, he explains, if you want to heat a room to 21° and it’s minus 10° outside, that’s a 31° gap to make up, whereas as it’s 12° in the ground, you’ve only got a 9° gap so it’s way more energy-efficient.
The system, Jarvis says, also provides passive cooling all summer for about $70 a year, while hot water should cost about half of what it normally does.
"Ground-source systems are currently the cheapest and quietest way to heat or cool a house in the world, unless you chop your own firewood."
He says QLCHT and his firm are tracking multiple houses over a year for a case study on their energy efficiency.
Due to the British design, the British High Commission’s deputy high commissioner John Pearson recently visited Tewa Banks.
"We are working with the British High Commission to increase awareness of these systems in government agencies, with the hope of providing further projects," Jarvis says.
