Imagine a house where every room was toasty warm and there didn’t need to be a mad dash down the freezing hallway after a shower.
A house where the heat was pumped out of the foundations, leaving no trace of cold spots.
The idea of central heating is something that is common in many countries around the world, but it has only recently started to gain traction in New Zealand.
Underfloor heating means no need for heat pumps or radiators taking up wall space, no cold rooms or hallways, just a lovely warm floor and even heat distribution throughout each room.
It could be snowing outside and you could comfortably walk around your house with bare feet.
That you would pay more in your power bill to keep the whole house so toasty warm, as opposed to only heating the rooms that you are in seems ridiculously luxurious.
So what does it cost to install and run? And is it worth the money?
How does it work?
Underfloor heating is generally installed during a build, although there are expensive and disruptive options for retrospective installation.
There are two different types, electric underfloor heating and hydronic systems which use heat pumps to warm up water pipes laid across the floor.
It is recommended that an underfloor heating system be run continuously over the cooler months, as it takes much longer to heat up than other forms of heating.
Good insulation is recommended to increase efficiency. This includes insulating the concrete foundations.
Warmth.nz technical advisor John Kipping said it was important to consider the space that was being heated, not the floor size of the house, as most people wouldn’t heat their garage.
He said the installation costs varied depending on circumstances, but they had calculated it as about $115 per square metre.
A house smaller than 100sqm would see a higher installation cost per square metre, while a house bigger than 250sqm would have a lower installation cost.
Kipping said running costs were a harder thing to quantify, as it depended on how much sun came into the home, whether the concrete floor was insulated, how large the house was and how warm the house needed to be.
He said his company estimated running costs to be about $1.20 per square metre per month in an average house.
Christchurch builder Glen Davidson installed underfloor heating in his 300 sqm family home and now recommends it for all new houses.
Davidson said he kept his underfloor heating on for five months straight through the winter and it had added about $10 a week to the family’s power bills.
“We heat the whole house a nice warm temperature, rather than just two rooms. It’s just really made the house warm – underfloor heating is the ultimate,” he said.
The one mistake Davidson had made was not insulating his concrete foundations to keep more of the heat in and that was one thing he said he would do differently next time.
Do you need any other heating?
Kipping said underfloor heating should be enough to heat a house without other forms of heating, but some people used a heat pump to bring up the temperature slightly as well.
One thing underfloor heating couldn’t do so well yet was cool the house down in summer, so some people choose to have a heat pump installed as well for that purpose.
Is it efficient?
Energy Efficiency and Conservation Authority strategy manager Michael Henry said underfloor heating had the potential to be very energy efficient and sustainable but this depended to some extent on the specific circumstances.
“Underfloor heating will have either electrical resistance elements embedded in the floor or a number of pipes which water circulates through as hydronic systems. The heat for hydronic systems can be provided by many different fuel types from diesel and gas through to electrical heat pumps,” he said.
Underfloor heating uses relatively low temperatures which can increase the efficiency of the heat pump or gas boiler used to supply the heat.
Henry said a heat pump hydronic system would be much more efficient than an electrical underfloor system, and this was similar to the relative difference between an electrical convection heater and a heat pump.
What if something goes wrong?
Kipping said the pipes that his company used were guaranteed for hundreds of years and he had never heard of an issue arising with underfloor heating after the build was completed.
One thing that happened from time to time were plumbers or electricians drilling through the pipes during the build, but that could be a quick fix and something his Christchurch-based company did at no charge, Kipping said.