How Much Does Underfloor Heating Cost to Run in NZ?

If you're considering underfloor heating for your New Zealand home, one of the first questions you'll probably have is: how much is it actually going to cost to run?

It's a fair question. While the comfort of warm floors, even temperatures and silent heating is appealing, nobody wants to install a heating system only to discover it sends their power bill through the roof.

The good news is that there isn't one simple answer. Underfloor heating running costs depend on the type of system, the size of your home, how well insulated it is, your chosen heat source and how you use the system.

For SunFlow® hydronic underfloor heating, the heat source is particularly important. The same in-floor system can be powered by different technologies, including an air-to-water heat pump, gas, wood or solar hot water. This means the cost of running the system can vary considerably depending on what's generating the heat.

Here's what New Zealand homeowners need to know.

What Determines the Cost of Running Underfloor Heating?

There are several factors that influence your heating costs.

1. The size of your heated area

The larger the area you're heating, the more energy your system will require.

Heating a 20m² bathroom or living area is obviously very different from heating a 150m² home. However, underfloor heating has an advantage here because it distributes heat across a large surface area rather than relying on a single heat source to blow warm air around the room.

A well-designed system can provide comfortable, consistent warmth throughout the home without needing to dramatically increase the temperature of the air.

2. Your home's insulation

Insulation has a major impact on heating costs.

A well-insulated home holds onto heat for longer, meaning your heating system doesn't need to work as hard to maintain your desired temperature.

This is particularly important in New Zealand, where older homes can have draughts, insufficient insulation and single-glazed windows.

Before looking purely at the cost of the heating system, it's worth considering the overall thermal performance of your home.

3. Your heat source

This is one of the biggest considerations with hydronic underfloor heating.

SunFlow® circulates warm water through pipes installed beneath the floor. The system itself doesn't dictate what creates that heat.

Depending on the home and installation, the water can be heated using:

• An air-to-water heat pump
• Gas
• A wood boiler
• Solar hot water
• Other compatible heat sources

An air-to-water heat pump is particularly attractive for homeowners looking for an efficient electric heating solution. Heat pumps move heat rather than creating it directly, which is why they can produce significantly more heat energy than the electricity they consume.

4. How you use your heating

Your heating habits also make a difference.

Keeping your home at a comfortable, consistent temperature can be more efficient than repeatedly allowing it to become cold and then turning the heating up significantly.

Modern heating controls and thermostats can also help you manage different areas of the home and heat your house according to your routine.

How Much Does Electric Underfloor Heating Cost to Run?

It's important to distinguish between electric underfloor heating elements and hydronic underfloor heating.

Electric underfloor systems use electrical heating elements installed beneath the floor. Their running cost can be estimated from the power consumption of the heating elements, the area being heated and your electricity rate.

For example, a typical electric underfloor system may use around 130–160 watts per square metre.

That means the cost can increase considerably as the heated area gets larger.

For a small bathroom, electric underfloor heating can be relatively inexpensive to operate, particularly when controlled by a thermostat and timer. For large areas or whole-home heating, however, the amount of electricity required becomes much more significant.

This is one of the reasons it's important not to compare the running cost of a small electric bathroom heating system directly with a whole-home hydronic system.

How Much Does Hydronic Underfloor Heating Cost to Run?

Hydronic underfloor heating works differently.

Instead of electrical heating elements heating the floor directly, warm water circulates through pipes beneath the floor. The floor then acts as a large, low-temperature radiator, gently releasing heat into the room.

The running cost therefore depends largely on what you're using to heat the water.

For example, an air-to-water heat pump can provide an efficient source of heat for a hydronic system. Solar hot water can also contribute, depending on the system design and available solar energy.

This flexibility is one of the major advantages of hydronic underfloor heating. You're not locked into a single energy source for the lifetime of the floor system.

Does Underfloor Heating Use a Lot of Electricity?

Not necessarily.

The answer depends on the type of underfloor heating and, for hydronic systems, the heat source being used.

It's also worth remembering that electricity consumption isn't the same thing as heating output.

Electricity is measured in kilowatt-hours (kWh), with a 1,000-watt appliance operating for one hour using 1 kWh. Your actual cost is then determined by the electricity rate charged by your retailer.

With hydronic heating powered by an efficient heat pump, you're using electricity to move heat into your home rather than simply converting electricity directly into heat.

This is one reason the choice of heat source is so important when calculating the long-term running cost of a hydronic underfloor system.

Is Underfloor Heating Cheaper to Run Than a Heat Pump?

This is one of the most common questions, but it's not quite the right comparison.

A standard air-to-air heat pump and hydronic underfloor heating perform different jobs.

A wall-mounted heat pump is designed to heat the air in a room quickly and efficiently. Underfloor heating provides radiant heat across the floor, creating a more even temperature throughout the home.

With a SunFlow® system, an air-to-water heat pump can actually be the heat source for the underfloor heating.

So rather than:

Underfloor heating vs heat pump

the comparison can actually be:

Underfloor heating powered by a heat pump.

This combines an efficient heat source with a large radiant heating surface throughout the home.

As we covered in our previous guide, Underfloor Heating vs Heat Pumps: Which Is Right for Your Home?, the two systems don't necessarily have to compete with one another.

How Can You Keep Underfloor Heating Running Costs Down?

If you're looking to get the most from your underfloor heating system, there are several things you can do.

Improve insulation

Good insulation helps keep the heat you've paid for inside your home.

Wall, ceiling and underfloor insulation, along with well-sealed windows and doors, can all contribute to a more thermally efficient home.

Use thermostats and zoning

Modern controls allow you to manage your heating rather than simply switching the entire system on and off.

Zoning can be particularly useful in larger homes, allowing different areas to be heated according to how they're being used.

Don't overheat your home

Underfloor heating is designed to provide comfortable, consistent warmth.

You don't necessarily need to set the thermostat as high as you might with a conventional heating system. Radiant heating can feel comfortable at a lower air temperature because you're receiving warmth directly from the heated surfaces around you.

Choose an efficient heat source

For a hydronic system, the heat source can have a significant impact on ongoing costs.

An appropriately sized air-to-water heat pump can be an efficient option, while solar hot water can also play a role depending on your home's design and energy requirements.

Is Underfloor Heating Worth the Running Cost?

For many New Zealand homes, the answer comes down to more than the power bill.

Underfloor heating provides a different type of comfort from conventional forced-air heating. Instead of heating from a single wall-mounted unit, the entire floor becomes a low-temperature heat emitter.

That means:

• Even, consistent warmth
• No cold spots
• No noisy fans
• No visible heating units throughout the home
• Warm floors underfoot
• The ability to heat the entire home from one integrated system

And because SunFlow® hydronic underfloor heating can work with different heat sources, homeowners have flexibility when it comes to managing ongoing energy costs.

The best time to install a hydronic underfloor system is generally during a new build or major renovation, when the floor structure is already accessible. Retrofitting is possible in some homes, but the practicality and cost will depend on the existing floor construction.

The Bottom Line: How Much Will Your Underfloor Heating Cost?

There isn't a single running-cost figure that applies to every New Zealand home.

A small electric underfloor system used occasionally in a bathroom will have a very different running cost from a whole-home hydronic system.

With SunFlow®, the cost depends on factors including:

• The size of your home
• The amount of floor being heated
• Your home's insulation and thermal performance
• Your preferred indoor temperature
• How often you use the system
• The heat source powering the system
• Your energy prices

That's why online running-cost calculators can only ever provide a rough indication.

If you're building or renovating and considering underfloor heating, the best approach is to look at the whole system, rather than just the cost of the heating itself. A properly designed hydronic system, combined with an efficient heat source and good insulation, can provide comfortable whole-home heating while keeping energy use under control.

Frequently Asked Questions

The running cost is only one part of the decision.

The right system should be designed around your home's size, insulation, floor construction, heating requirements and preferred energy source.

If you're building, renovating or simply exploring your options, talk to SunFlow® about designing an underfloor heating system for your home.

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