Money / Energy

How to save money on your power bill

14:30 pm on 11 April 2022

It's been a rough six months for rising prices across the board and as winter approaches the cost of lighting and heating a home can go through the roof. 

Someone who knows their water heaters from their insulation seals is New Zealand Energy Efficiency and Conservation Authority senior advisor Gareth Gretton.

Photo: 123RF

Listen to the full interview here

Efficiency of appliances

People often think that heating rooms consumes the most energy, Gretton says, but the average New Zealand household consumes about a third of energy on keeping warm, a third on heating water, and a third on everything else - lighting, cooking, appliances etc.

The surprise for some, he says, is when they find out that running their old fridge is costing them about $150 a year.

But the development of more efficient fridges is looking to set things right, with annual electricity consumption from fridges going down by half over the past 20 years, he says.

"I said the old one that might be in the garage, if that was a 20-year-old one, it's costing you $150 but the new one might be costing you something like $75."

The same goes for clothes dryers - Gretton says old ones will be using about a $1.30 of electricity for a single load.

"With clothes dryers ... there's some new ones that are coming out and becoming much more common these days that are based on heat pump-based technology.

"They are actually quite a bit more efficient so their power use would be something around half that, so that's definitely something [worth considering for] someone who does use a clothes dryer quite a lot, like a big family."

If you don't have the budget to splash out on newer appliances, you could look at making your existing appliances run more smoothly. For example, try cleaning your heat pump's indoor filters once a month during winter so the fan inside uses less power, Gretton says.

"Also make sure that with the outdoor unit of the heat pump, that the air circulation around it is nice and clear because any obstructions to that air circulation will make it hard for it to do its job.

"And you might give it a little bit of a gentle clean. Outdoor units have loads of fairly thin aluminum fins on them so you don't want to be going and attacking it with a hose pipe or anything but if you want to give it a gentle clean with a soft brush, that would help."

Gretton says the myth that it's better to keep your heat pump running in one go instead of switching it on and off as needed is not quite so true for saving costs.

One thing to consider about heat pumps though is that they are most efficient when running at lower temperatures.

"So that's down around 18C. But we do realise 18C might be a little bit on the cooler side for some people, so our guidance is to think about 18C to 20C for the sort of optimum balance between energy conservation and comfort."

Insulation

Draughts are pretty bad in New Zealand houses, Gretton says, and the best way to find out where they are is to feel them as you walk around your house on a windy day.

"It will be making quite a big impact on your ability to heat your house."

Draught-proofing and sealing of windows and doors can help keep the elements at bay.

"The simplest things [you could find at a hardware store] would be a foam rubber type thing that you'd use around your windows.

"So you'd open up your windows, you'd give them a good clean, the frames that is, then you'd get these draught-proofing products ... which are often self-adhesive so it makes them quite easy to apply and then you stick them to your existing frames."

Double glazed windows are big tick-off item if you are retrofitting a cold house, but they need to be good quality to make a difference, Gretton says.

"If you've got single-glazed timber frame windows and you've replaced those with fairly low-quality double glazing on aluminum windows then the percentage gain that you would get might not be that much.

"Whereas if you have good quality thermally broken aluminum or PVC or indeed timber and you go for low E double glazing, which means it's got a special coating on it which reduces the heat loss and also has argon between the panes of glass, then that's when you really start to see the gain, and then that's when you are able to reduce your heat loss by about half."

A more budget-friendly option would be to look at getting thicker curtains, which would act like insulation, he says.

"You really want long curtains that span down from the window ledge. If you've got window ledges that are already quite low in the wall, then taking the curtains all the way down to the floor is something that helps because that reduces the flow of air around the curtain."

Ventilation

Just as important as stopping the warm air from escaping is ventilation, Gretton says. But are the systems worth the money?

It is possible to ventilate a house or room yourself, he says, but it can be worthwhile to invest in a system if you have problems with dampness and aren't able to leave windows slightly ajar during the day.

"We advise that the best way to ventilate your house is to open your windows really wide for something like just 10 minutes a day in the morning, and that's especially good for things like bedrooms where you can get a bit of moisture build-up overnight ... and then you're able to let it heat up again during the day.

"It's really a balance of getting the right amount of ventilation, which as I say with ventilation systems they kind of do that without you having to think about it, whereas with open and closing windows it's a bit more of a balance because you're having to adjust it for all sorts of things like how windy it is outside."

Installing moisture barriers under the house is one way to protect your home from dampness, he says.

"If you don't have good ventilation under your house - and this is obviously thinking about traditional timber buildings with suspended floors - then there can be a lot of water that actually evaporates off from the ground underneath the house and ultimately ends up in your house, contributing to your house getting damp."

Extract ventilation in the bathrooms and kitchen will help take out moist air before it circulates in a house.

Ventilation also comes into hand when you're trying to get rid of hot air during summer, especially if you're not using a heat pump to cool down, Gretton says.

You can compare power companies’ plans and prices with Powerswitch’s website.