Beating the heat in newbuild homes without breaking the bank

With summer around the corner, residents in new-build town houses are set to feel the heat harder than others.

Sandamali spent around $6500 trying to cool her home in summer, $2000 for thermal curtains and then $4500 on air conditioning.

"Upstairs, especially in my son's bedroom... it's actually made his room liveable."

Suresh is considering a ventilation system for his home, to move cooler air from the bottom floor up to the top.

"In the summer, the whole top floor goes to I think 27, 28 or more. It's really, really, really hot."

Suresh and Sandamali live in separate Auckland suburbs in new-build townhouses, a style of building well known for being warm during winter months, but also too hot in summer.

Adding air conditioning is always an option, but the cost to install and run means it's not always the most economical choice.

Auckland Council Climate Action Solutions team lead Adrian Feasey said there's been a lot of talk about insulation making new build homes hotter, but windows letting in super-heated sunlight are the problem.

"Insulation is a part of the solution. If you think about like a chilly bin, a chilly bin keeps things inside cool, and so if you've got good insulation in the ceiling, or in the wall then it will keep things inside cooler. But at the same time like with the chilly bin if you've got some big cutouts in it and you're letting all this sunlight come in then it's not going to be as effective."

Feasey said external shutters can keep sunlight out, and changing the stove top from gas to induction will stop extra heat being released into the home.

Ventilation also helps.

"If the indoor temperature is particularly high, then if they live in a single [storey] dwelling home, opening a window at either end of the home can be very, very effective, particularly if there's some breeze that will help draw out the air. If they live in two storied dwelling, opening a window on the ground floor, and then the first floor can be very effective, it creates something called stacked ventilation and that helps pull through the heat."

Feasey cautioned against constantly running the air conditioning on a brisk 17 or 18 degrees to fight the heat though.

"If we had every home doing that during the day, that creates a lot of energy demand during the day. So we'd have to consider what's of impact that might have on the grid.

"And there's the cost directly to the householder. Running your heat pump to cool on 18 degrees, if you're not doing some of these other measures, is going to be quite an expensive process."

Gareth Gretton from the Energy Efficiency and Conservation Authority said if people put in air conditioning or a heat pump, they don't have to run it on cool all the time.

"Some air conditioning units have modes which where they just act as fans. Th t's worth a try to start with.

"Second thing is that some have a mode that just does dehumidification. One of the things that we find really uncomfortable is when it gets really kind of stuffy.

"If you can actually reduce the humidity without necessarily trying to cool the space that can use a bit less energy and actually kind of make you a lot more comfortable."

He said the one of the easiest things to do is install blinds that reflect the heat away.

Green Building Council chief executive Andrew Eagles said homes need to be designed to accommodate summers getting hotter and a small amount of extra planning in the early stages could have big benefits.

"If we just spend 30 to 50 minutes per home modelling, and that's about what it would come down to, think of that as an investment over a property which lasts 60 to 100 years. I mean, oh, my word it's going to pay off, isn't it?"

Sandamali, who has windows in her home where the light comes through but she can't open to ventilate, thinks some forethought when planning her home would have been a good idea.

"I feel really let down that these plans get approved without any idea about how people are going to live."

Sandamali said having air con in her home has added to her power bill, and during summer months she won't run it any lower than 22 to keep it affordable.