Heating your home

Choose the right heating for you and your family

A warm home is vital for your comfort and health. The World Health Organisation's recommended minimum indoor temperature is 18°C. Recommendations for children, older people and those with chronic illnesses are even higher.

In New Zealand heating is expensive. As energy prices rise and houses are getting bigger it is likely to cost even more.

Most people use electricity, gas or wood to heat their homes. Some newer heating systems are more energy efficient and can reduce your power bills, while simple actions can make your existing heating options more efficient.

Heat and cool efficiently on the Gen Less website has an overview of the pros and cons of different heating systems.

Remember, insulating your home reduces the amount of heating you need to keep your home at a comfortable temperature.

All forms of heating have effects on the environment, so it is important to consider these issues when you are looking at the different options available.

Space heaters that use sustainably sourced wood or electricity, produce the lowest net greenhouse gas emissions. Coal, gas and oil-fired heating systems generate the highest, and should be avoided.

Heating systems

Electric resistance heaters

Electric heaters are most useful if you want to provide warmth for a small room.

Radiant heaters have an element that shines warmth directly onto you. Convection heaters (which include fan heaters, panel heaters and oil-filled column heaters) provide general background warmth. Using a fan means the room heats up more quickly and the heat is more even.

Good for:

• Well-insulated homes that don't require a lot of heating, or to heat a small room such as a bedroom.

Pros:

• Quiet, portable and convenient.
• Generally have a thermostat and some have a timer setting.

Cons:

• Only good for smaller spaces.
• Not nearly as efficient as a heat pump.
• Some radiant heaters have exposed glowing elements which can be a fire risk and shouldn’t be used in bedrooms or around young children. They generally don’t have thermostats.
• Electric heaters are an expensive way to heat.
• About 20 per cent of New Zealand's electricity is made from burning fossil fuels, which produces greenhouse gases and contributes to climate change.

Heat pumps

Heat pumps are among the most energy-efficient forms of heating appliance available.

They work by taking heat from the air outside your home and using it to warm the air inside, using a process that's a bit like a refrigerator working in reverse. They can do this even when the temperature is cold outside, although in very cold or humid areas they may shut down for short periods to defrost. In these conditions their efficiency drops, although it will rarely be less than an electric resistance heater.

Heat pumps are controlled using a thermostat, so you can set them to keep your home within set temperature ranges at different times of the day.

Heat pumps come in various sizes, from single room heaters to ducted whole-house systems. It is important to get a heat pump that is the right size for the area to be heated, and to install it in the right place.

In theory, you can make significant savings on your heating costs by using a heat pump. However, in practice, many people who install heat pumps keep their homes significantly warmer than before – so they get increased comfort rather than lower power bills.

Additionally, there is the temptation to use your heat pump for summer cooling instead of natural ventilation and shading, which increases your summer power bills.

Heat pumps are not necessarily the most energy-efficient option for cooling.

Cooling and air conditioning and Passive cooling have information about other options.

Heat pumps must be installed by a qualified installer. Professional installers are typically registered electricians and/or refrigeration technicians.

Good for:

• Room-specific heating.
• A good money saving option for people who are currently heating a lot with electric heaters.

Pros:

• More convenient than a woodburner, and without the air pollution.
• A range of space sizes.
• Heat pumps are much more efficient than other electric heaters.
• Modern heat pumps have Coefficients of Performance (COP) and Energy Efficiency Ratios (EER) of 4.5 and more which means for every kWh of electricity they use they will produce 4.5kWh of heat (COP) or coolness (EER). All heat pumps sold in New Zealand must also meet Minimum Energy Performance Standards.
• Depending on where you live, your local or regional council may offer loans for clean heating appliances.
• If you are ill or have a disability or are on a low income you may qualify for assistance. Contact your local Citizens Advice Bureau to see what’s available in your area.
• Highly controllable with a thermostat setting and, in most models, a timer for switching on and off to suit needs.

Cons:

• Less efficient when outside temperatures drop below 7°C and can stop working completely in deep snow or in very cold, humid conditions.
• More expensive to install than electric resistance heaters.
• Can be noisy (particularly for neighbours).
• Heating costs can be higher than expected if used for cooling in summer or for those who have increased the amount that they heat.
• Completely reliant on electricity supply, like most other heaters (except woodburners).
• In some old heat pumps, the refrigerant used to extract heat is harmful to the ozone layer if it escapes. Check the manufacturer’s label on the unit to see what sort of refrigerant it uses, and contact your local council or landfill about safe disposal options.

Gas heaters

Burning gas releases greenhouse gas emissions that contribute to climate change. A gas heater is a long term investment, so you want to think twice before committing to a new gas heater. A heat pump, wood or pellet burners are more sustainable options.

You should only use fixed gas heaters which are flued to stop the accumulation of pollutants and water vapour inside a home, see Avoid unflued gas. They can be installed in most places in a home, as the flue on some models can be run down and out, horizontal or vertical.

The Central heating section below has more information on gas central heating systems.

Good for:

• A range of space sizes.
• When your house is already hooked up to the gas supply.

Pros:

• Fast and responsive.
• Convenient to control and operate.

Cons:

• Unknown future in terms of gas supply and prices – a fossil fuel that contributes to climate change.
• Gas prices are rising, and line/bottle hire charges mean it’s expensive if you are only using gas for heating.
• Generally, will only heat one room, except for central heating.
• Portable gas heaters which are unflued (such as LPG heaters) produce pollutants and a lot of water vapour – they are a health hazard, see Avoid unflued gas. 

Open fires

For a small proportion of New Zealand households, open fires are a major source of heating, typically along with other forms of heating.

While open fires are appealing, they're inefficient and there are environmental drawbacks. Most of the heat they generate goes up the chimney instead of into your home. Open fires are very inefficient compared to a modern woodburner. They can spark and be a fire hazard. When they’re not being used, heat goes up the chimney anyway. Older chimneys are often an earthquake hazard. Open fires have been banned in many towns and cities as they produce a lot of smoke which can be a health hazard.

If you have a disused open fire, consider permanently disabling it and blocking off or removing the chimney to avoid losing heat out of it. An added bonus is that when the chimney is removed the risk of it collapsing in an earthquake is removed.

Woodburners

Modern, enclosed woodburners are much more efficient than open fires, and with a wide range of models available (8kW–30kW), most houses can be heated by a woodburner.

Authorised woodburners on the Ministry for the Environment's website shows which ones are permitted to be installed and what their respective efficiencies and emissions are. There are ultra-low emission woodburners available.

Wood is a renewable fuel. If you have a free supply of dry, untreated timber, this form of heating will be your cheapest heating option.

Selecting the right size of woodburner is important because they are most efficient when run at full capacity. Air quality rules mean most urban woodburners cannot have the damper closed to control heat output and speed of burning as starving the fire of oxygen increases the emissions.

Where a woodburner has a larger capacity than required to heat a space, consider using a heat transfer kit to move excess heat into other areas of the house.

Good for:

• Heating large spaces.
• Where wood is cheap or freely available, or in areas with poor electricity security.

Pros:

• Can be combined with a wetback to provide hot water heating.
• Works even in a power cut and may be able to be used for cooking.
• They can heat more than one room with a heat transfer kit.

Cons:

• Generally are large heaters – at least 8kW, which can result in overheating if the heat is not moved around through open doors or through a heat transfer system.
• Does require a dry space for storing wood and wood needs to be dried before burning. Stacking, chopping and moving wood are required.
• Woodburners need flues to be cleaned at least once a year (more when they are heavily used).
• Woodburners can contribute to air pollution, particularly older models and those burning damp wood. Woodburners emit tiny particles of smoke which, if inhaled a lot, can cause respiratory disease. All woodburners sold since September 2005 for non-rural use have to comply with national environmental standards. Regional and local councils may further restrict the use of woodburners to reduce smog and improve air quality.

Council requirements

Woodburners must comply with air quality standards and local council requirements.

Authorised wood burners on the Ministry for the Environment website has more information.

You'll need a building consent to install a woodburner, and have the woodburner installed by a specialist installer. The council will have to inspect the burner before issuing a code compliance certificate.

Pellet burners

Pellet burners are typically cleaner and more efficient than woodburners. They burn compressed wood pellets which are made from sawmill waste – so burning wood pellets is a form of recycling. The pellets contain nothing but wood.

Pellet burners start with an electric lighter and many come with a thermostat and timer.

Good for:

• Heating larger, well-insulated spaces.

Pros:

• Are controlled by a thermostat – some models have timers and remote controls to tailor operation.
• Pellet burners produce very little smoke and burn more efficiently than woodburners. It is also easier to control the heat output.
• A renewable heating type.
• Bags of pellets are easy to handle and control, and can help to manage heating costs on a weekly budget.
• Can sometimes be combined with a wetback to provide hot water heating.

Cons:

• Requires electricity to run.
• A limited range of wood pellet suppliers.
• Convective heat rather than the radiant heat of a woodburner – you can’t sit in front of it for that toasty warm feeling.
• To warm the whole house, heat needs to be moved around through open doors or a heat transfer system.

Legal requirements

You'll need a building consent to install a pellet burner and must comply with air quality standards and local council requirements.

Authorised wood burners on the Ministry for the Environment website has more information.

Like other woodburners they must be installed by a specialist installer. Council will have to inspect the burner before issuing a code compliance certificate.

Underfloor heating

Underfloor heating can be embedded in a concrete slab when you build a new home or installed under the flooring of a new or existing home. The floor needs to be well insulated underneath and around the perimeter or you will lose a lot of your heat to the outside and into the ground beneath.

Underfloor heating can use electric cables or water-filled pipes. The pipes may use any form of water heating including electricity, gas, heat pump or solar. These are called hydronic systems.

Underfloor heating cannot heat a room quickly and is most effective when left on all the time over the cooler months. A lot of energy is used to initially bring the floor up to temperature, especially a concrete slab. But once the floor is heated, it acts as a low temperature radiator.

Good for:

• If someone is home most of the time.
• Houses with very good insulation, particularly underfloor insulation.

Pros:

• The low-temperature heat of hydronic underfloor heating systems is particularly suited for highly efficient heat pump systems.
• Controllable with thermostat and timer settings (some with room-by-room control).

Cons:

• Often difficult to retrofit to existing homes without substantial renovation.
• Although fairly maintenance free, repairs can be expensive if something does go wrong – you may have to rip up the floor.
• With hydronic systems, in cold climates you will need to leave the heating in frost-protection mode, when no-one is home to avoid freezing and pipes bursting.
• Solar hydronic systems are complex and expensive to install, and generally require a heat sink (like a swimming pool) to dump heat in summer. They need to be installed as a house is being built and you will need back up heating when the sun doesn’t shine.
• Not very responsive – takes time for the heat to build up.
• Carpeting over a heated floor will trap heat underfloor so it doesn’t warm the house.
• Can be expensive to run depending on the source of the heat, and how well the home is insulated.

Central heating

With central heating, heat is generated at a central point and piped or ducted to several rooms. Central heating often uses gas or a heat pump, but can also use oil, coal, wood, wood pellets or solar energy.

The heating unit is typically located outside the living area of your home. Heat can be transferred using warm air ducted to vents in each room. Or hot water can be piped to radiators throughout your home. Some systems use combination boilers which heat the hot water for the taps as well as for space heating.

If you install central heating, make sure you can control the heat to each room independently. You don't want to heat rooms that people are not using, or have to heat all rooms to the same level.

Hydronic underfloor heating coils are typically incorporated into concrete floor slabs when they are poured, so talk to your designer about it at concept design stage.

Good for:

• Highly controlled heating.

Pros:

• Can heat the entire home to a healthy and comfortable temperatures.
• Can be timed to come on and temperature set using a thermostat.
• Running costs vary depending on the fuel used and are similar to the cost of using the same heat source in a single room.

Cons:

• Some types are difficult to retrofit into existing homes, depending on the home's layout and access to roof or subfloor space.
• Heating the whole home can be expensive if it is poorly insulated. It's essential that you are upgrading insulation and glazing as much as you can before installing central heating.
• Ducted systems experience heat losses from ducting under the floor or in the ceiling.
• Radiators can take up some floor space in the house.
• May need to be installed into concrete floor slabs when poured.
• Solar thermal hydronic systems are complex and expensive to install, and need a large heat sink (eg swimming pool) to dump heat during summer. They need to be installed as a house is being built and you will need a backup heat source (eg woodburner wetback) for when the sun doesn’t shine.