"Use what you have, and get the best out of it," Neville Auton, energy manager at Otago Polytechnic advises.
After 25-plus years talking about energy efficiency, Auton still exudes enthusiasm.
And perhaps our hot water system should excite us more. In an all-electric home, hot water heating accounts for about 38% of our electricity needs.
Auton and his wife live in Dunedin with a standard hot water cylinder that runs on 11.7c/unit during the night with ripple control. The system required little new infrastructure, just a new energy plan, a tempering valve and a Grade A insulated 180-litre cylinder.
"I’ve got a blanket over that as well to stop the heat loss."
Despite having their cylinder turn on only at night, there’s always enough water, Auton says.
"We’ve never had problems when we’ve had visitors or anything like that."
When they use electricity is the key factor, Auton says.
"Sustainability-wise [night use] is good. Going forward with infrastructure investment in the system, it’s much better to have a night load at this stage; and that’s why it’s cheaper."
Almost 85% of New Zealand’s electricity in 2016 came from renewable sources, primarily hydroelectricity. High-use peaks (called peak load), along with dry winters when hydro-electric power stations struggle, are New Zealand’s main challenges. The system falls down when we overshoot maximum capacity and non-renewable coal and gas kicks in, contributing to climate change.
Beyond insulating and using night rates, there are other options for those looking to tame the power bill. These include big-ticket purchases such as solar hot water (SHW), heatpump water heaters (HPWH) and photovoltaics (PV).
Unlike other domestic assets, such as carpets and cars, people expect to see a reasonable financial return on their energy-saving expenditures.
This can, on paper, be achieved by using a lot of power, says retired Assoc Prof Bob Lloyd, a long-time energy researcher with the University of Otago physics department and now a climate change consultant.
When Lloyd first came to Dunedin from Australia, he considered getting SHW. But relative to his home country, he found prices here "gi-normous".
In addition, the ecological footprint of mining, manufacturing and disposing of solar systems cannot be overlooked in a country that already has high levels of existing renewable generation.
"That’s one of the reasons I’ve never put up a PV system on my house. There’s no point. I’ve got some panels stored just for an emergency in case the grid goes down."
Instead he installed a HPWH after calculating that in southerly Dunedin they are marginally more efficient across the year than their SHW counterpart.
"This is where the heat pumps work well because they work summer and winter."
Whatever your current budget, it pays to plan ahead, Auton advises.
"If you are going to stay in the house for retirement you can start to provision it up for low energy use going forward."
The Autons have also purchased a 2.25kW PV array to reduce daytime electricity bills, and a Nissan Leaf electric car that costs them less than $200 a year to run. Charging their car overnight is another perk of ripple control.Auton knows he is fortunate.
"The trouble is that for most people they won’t have the money to invest in the energy savings that we have done.
"I’ve got an electric bike as well, and a Vespa-type scooter. So we’re getting there. We’re making progress."
