For many homeowners, underfloor heating feels like a bit of a luxury, something you might see in high-end showhomes or glossy renovation magazines. But here in New Zealand, more people are realising it is not just about comfort. A well-installed system can make a home more efficient, healthier, and better to live in year-round.
At its core, underfloor heating works on a simple principle. Instead of blasting warm air from a vent or heating a room with a radiator, you gently heat the entire floor surface. The heat rises evenly, creating a stable, cosy temperature that eliminates cold spots. It is a heating method that works quietly in the background, with no clunky hardware taking up wall space.
There are two main types of underfloor heating available: electric and hydronic. Both can deliver that even, radiant warmth, but they differ in how they work, how they are installed, and what they cost to run. In this guide, I will walk you through each system, compare their strengths and weaknesses, and share the kind of real-world advice you only get from years on the tools.
Key Takeaways
- Electric underfloor heating is best for smaller areas, renovations, and rooms that need quick warm-up times.
- Hydronic systems are ideal for large areas, whole-home heating, and long-term energy savings.
- Installation complexity varies. Electric is simpler to retrofit, while hydronic is better suited to new builds or major renovations.
- Running costs depend heavily on the size of the heated area, insulation levels, and how often the system runs.
- Your final choice should balance upfront budget, energy goals, comfort expectations, and your home’s design.
Understanding Underfloor Heating Basics
The idea of heating a floor is not new. The Romans used a system called a hypocaust, where hot air from a furnace was channelled under raised floors. Modern systems are more advanced, but the principle is the same. Warm the floor, let heat rise naturally, and enjoy a consistent temperature from the ground up.
Underfloor heating is a type of radiant heating. Unlike convection heating, which relies on moving warm air around, radiant heat warms people and objects directly. This means less heat loss through draughts and more stable indoor temperatures.
In New Zealand homes, underfloor heating is most often installed under tile, polished concrete, or engineered wood floors. Carpet can be used, but only with a low thermal resistance so the heat can pass through effectively.
If you are looking at broader home heating options, check out our guide to central heating for New Zealand homes.
Electric Underfloor Heating: How It Works and Where It Fits
Electric underfloor heating uses thin cables or heating mats installed just below the floor surface. These are connected to the home’s electrical system and controlled by a thermostat.
It is a straightforward system to install, especially in small rooms or during a renovation where the flooring is already being replaced. You can have it fitted in a single bathroom in a matter of hours without disrupting the rest of the house.
Electric systems shine in spaces like bathrooms, ensuites, and kitchens. They heat up quickly, often within 20 to 30 minutes, making them ideal for rooms you only use at certain times of day. They are also well suited for retrofits because the cable mats can be laid over the existing subfloor before new flooring is installed.
The main drawback is running cost. Electricity prices in New Zealand mean that heating a large area with electric underfloor heating can get expensive. If you are only covering 5 to 10 square metres, it is affordable. If you are looking at 80 to 100 square metres, hydronic is usually the smarter option.
Hydronic Underfloor Heating: How It Works and Where It Fits
Hydronic underfloor heating uses warm water circulated through a network of pipes laid within the floor. The water is heated by a central source such as a gas boiler, air-to-water heat pump, or solar thermal system.
This type of system is far more efficient for heating large areas. Once the thermal mass of the floor is warm, it holds heat for hours, even after the heat source switches off. This makes it ideal for open-plan living spaces, whole-home heating, or situations where you want a constant background temperature.
The trade-off is installation complexity. Hydronic systems are best installed during new construction or a major renovation because the pipework is embedded in the slab or screed. Retrofitting into an existing home usually involves lifting floors or adding height to the floor structure, which can be costly and disruptive.
Hydronic systems have higher upfront costs, but they can last 40 years or more with regular maintenance. Pumps, controls, and heat sources need servicing every few years, but the pipe network itself is extremely durable when installed correctly.
Comparing Electric and Hydronic Underfloor Heating
Installation
Electric: Simple to fit in individual rooms with minimal disruption.
Hydronic: Requires more planning and is best suited to full builds or large-scale renovations.
Running Costs
Electric: Higher per square metre when heating large areas for long periods.
Hydronic: Lower cost to operate over time, especially in energy-efficient homes.
Response Time
Electric: Heats quickly, great for short-term use.
Hydronic: Slower to heat but excellent at maintaining steady warmth.
Maintenance
Electric: Minimal maintenance due to the lack of moving parts.
Hydronic: Occasional servicing for pumps and controls, but pipes last decades.
Factors to Consider Before Making a Choice
Home Size and Layout
If you are only heating one or two small rooms, electric is likely the better fit. For a whole-house solution, hydronic is generally more efficient.
Flooring and Insulation
Underfloor heating works best with floors that conduct heat well. Tile and concrete are top choices, followed by engineered wood. Insulation under the slab or between joists is essential to prevent heat loss.
Climate and Usage
In areas with short, mild winters, electric can be cost-effective. In colder climates where the heating runs daily for months, hydronic delivers better value over time.
If you’re upgrading heating in a rental property, make sure it meets Healthy Homes Standards, which specify minimum performance requirements for fixed heating systems.
Budget and Future Energy Costs
Consider not just the initial outlay, but what you will spend over the next 10 to 20 years. Rising energy prices can make the efficiency of hydronic systems even more appealing in the long run.
Common Mistakes Homeowners Make
One of the biggest errors is skipping insulation beneath the heating system. Without it, much of the heat can be lost into the ground instead of rising into the room. Another common issue is choosing a system that is too small or too large for the space. An undersized system will struggle to keep up, while an oversized one will waste energy.
Failing to plan zones properly is another pitfall. Being able to control different areas independently is key to managing costs and comfort.
Professional Advice from a Local Installer
Before making a decision, have a qualified installer assess your home. They can calculate heat loss for each room, check your existing power supply or heating source, and recommend a system that will perform well in your specific conditions.
A good installer will also walk you through the pros and cons of each option, explain running costs in real numbers, and design a layout that balances performance with efficiency.
Picking the Right Heat for Your Feet
Electric underfloor heating is an excellent choice for small spaces, retrofits, and quick warm-ups. Hydronic systems excel in large areas and long-term efficiency, particularly in new builds or major renovations.
Both systems provide a level of comfort that traditional heating methods cannot match. Whichever option you choose, underfloor heating will make your home warmer, more comfortable, and more inviting for years to come.