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Smart guide

Heating your home

Traditional forms of heating use a lot of energy but don't necessarily keep our homes warm enough.

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 in living areas and 16°C in bedrooms. Recommendations for babies and elderly people are even higher.

In New Zealand heating is expensive (typically accounting for about 30 per cent of a household's annual energy consumption). 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. Newer heating systems are more energy efficient and can reduce your power bills, while simple actions can make your existing heating options more efficient.

Types of heater on the EECA Energywise website has an overview of the pros and cons of different heating systems. 

Choosing a heater on the Consumer NZ website is a comparison of the cost of different heaters and fuels (Note: You must subscribe to Consumer NZ to read it).

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. Coal, gas and oil-fired (collectively 'thermal') generation of electricity typically make up about 20-25 per cent of New Zealand's total annual electricity supply – a process that produces greenhouse gases which contribute to climate change.

Due to network losses, the use of natural gas and LPG in the home is typically more energy efficient than electricity generated by burning fossil fuels. However, their combustion still produces greenhouse gas emissions and any gas appliance should be flued or well ventilated when used. Sustainably sourced wood and electricity generated through renewable sources such as hydro, wind and solar produce the lowest net greenhouse gas emissions.

Heating systems

Electric resistance heaters

Electric heaters are most useful if you want to provide warmth for a single person or a single 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 uses a little bit of energy, but it means the room heats up more quickly and the heat is more even.

Good for:

  • Use panel heaters and oil filled column heaters in well-insulated homes that don't require a lot of heating, or to heat a single room such as a bedroom.
  • Use radiant heaters in poorly insulated homes since they shine warmth directly onto you, or in spaces you’ll only use for short periods such as the bathroom (take care to keep the heater well away from water, and keep anything flammable at least a metre from the heater).

Pros:

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

Cons:

  • Only good for smaller spaces.
  • 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.
  • At about 26 cents/kWh, electrical 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.

In recent years Auckland has experienced its peak demand periods during the height of summer rather than in winter, most likely due to heat pumps being used as air conditioners. 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.
  • Areas (such as Christchurch) where there are severe air pollution problems.
  • A good money saving option for people who are currently heating a lot with electric heaters.

Pros:

  • 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.
  • At 5–10 cents/kWh, heat pumps are more efficient than other electric heaters and very efficient models are now available.
  • 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.
  • Some heat pumps also incorporate air filters that remove dust and pollen, which can be helpful for people with asthma and allergies.

Cons:

  • Less efficient when outside temperatures drop below 7°C and can stop working completely in deep snow or in very cold, humid conditions.
  • Given they are essentially a one-room heater, they are expensive to install. A unit to heat your living room might cost between $1500 and $2500 (2016 costs) and a ducted central system to heat a large house would cost more.
  • 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.
  • 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.

Ground source heat pumps

Ground source heat pumps use the constant temperature of the ground to heat air or water. The water can be used for a hot water cylinder and/or for hydronic floor heating or radiators.

Underfloor heating and Central heating have more information.

Ground source heat pumps are expensive but a very efficient way to heat a large house or building. They may be viable in very cold climates such as Central Otago.

Gas heaters

Gas heaters provide easily adjustable, instant heat and there are a range of options available. While these include fixed and portable heaters, 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 heaters). 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.

Gas central heating systems can bring your whole home up to a comfortable temperature in minutes or can be zone controlled for greater flexibility and energy efficiency. These systems can also provide air circulation reducing dampness, condensation, stale air and musty smells.

Central heating has more information.

Good for:

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

Pros:

  • Fast and responsive.
  • A good use of gas (emitting less greenhouse gas emissions than burning it to make electricity in power stations).
  • At 15–16 cents/kWh, natural gas heaters can be very efficient. LPG would be somewhat more expensive at 19–26 cents/kWh.

Cons:

  • Unknown future in terms of supply – not a renewable resource.
  • Gas prices are now high, and line/bottle hire charges mean it’s expensive if you are only using gas for heating.
  • Generally, will only heat one room.
  • 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 heaters).

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 and, so long as wood that's burned is replaced with growing trees, it's carbon neutral. 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 areas.
  • Where wood is cheap or freely available, or in areas with poor electricity security.
  • Houses with poor insulation – we recommend that you insulate, but if you can't, this is the cheapest way to heat your home.

Pros:

  • At between 14–20 cents/kWh where wood is purchased, these are cheap heaters to run and can be combined with a wetback to provide hot water heating.
  • Near-carbon neutral and renewable 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 though 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).
  • Older models and those burning damp wood can contribute to air pollution. 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 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 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.
  • Carbon neutral and a renewable heating type.
  • Bags of pellets are easy to handle and control, and can help to manage heating costs on a weekly budget.
  • At 14–20 cent/kWh, these are a fairly cheap way to heat and 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.
  • Smaller output than woodburners (mostly 8kW–15kW) means large or older poorly insulated houses may need more than one pellet burner.

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 under-floor insulation.
  • The system can be combined with solar power or solar hot water heating.

Pros:

  • A range of fuel types possible (for example, electric, photovoltaic or thermal solar water, gas and diesel).
  • 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 may have to leave the heating on even when no-one is home to avoid freezing and pipes bursting.
  • Solar hydronic systems are complex and expensive to install. 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.

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.
  • If the homeowner is often at home during the day.

Pros:

  • Can heat the entire home to an even temperature.
  • 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.
  • Ducted systems experience heat losses from ducting under the floor or in the ceiling.
  • Radiators can take up floor space in the house.
  • May need to be installed into concrete floor slabs when poured.
  • Solar thermal hydronic systems can be are complex and expensive to install. 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.

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Other resources

  • Free winter heating guide

    Keep your home warm, dry and healthy in winter with this free guide, available on the Consumer NZ website.

  • Insulating for an energy efficient building

    Keep your home warm and save energy and money using this guide on the Building Performance website.

  • EECA Home Heating website

    The Energywise website has information about efficient home heating, cooling and ventilation.

  • Energy Star

    The Energystar website has information about energy-efficient heat pumps.

  • Authorised woodburners

    This Ministry for the Environment webpage has information on which woodburners can be installed and their respective efficiencies and emissions.

  • Eco Design Advisor: Heat pumps

    A factsheet on how to get the most out of your heat pump is available from the Eco Design Advisor website (see ‘How to Operate heat Pumps’).

Note that this document is published by the Ministry of Business, Innovation and Employment Chief Executive as Guidance under Section 175 of the Building Act 2004. This is a guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case.