Heating options

Most people use electricity, gas or wood to heat their homes. These options can use a lot of energy and some create harmful emissions without necessarily keeping your home as warm as it should be.

There are a range of heating options that can keep your home cosy while using energy wisely. 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. For example, about a third of New Zealand's electricity comes from burning coal, gas and oil at power stations - a process which produces greenhouse gases leading to climate change. Gas and LPG are more energy efficient than electricity but they still produce greenhouse gas emissions (although less than electricity generated by burning fossil fuels). Wood and electricity generated through renewable sources such as hydro, wind and solar produce the lowest greenhouse gas emissions.

Electric heaters

Electric heaters are portable and convenient. They 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 means the room heats up more quickly and the heat is more even – but fans also use more energy.

For well-insulated homes that don't require a lot of heating, panel heaters and oil-filled column heaters are good options.

Radiant heaters can be useful in poorly insulated homes since they shine warmth directly onto you. They’re also useful in spaces you’ll only use for short periods such as the bathroom (take care to keep the heater well away from water). Because of the risk of fire and burns, radiant heaters shouldn’t be used in bedrooms or around young children.

Environmental effects: greenhouse gases are produced when fossil fuels, such as coal, gas and oil, are burned to generate electricity. About a third of New Zealand's electricity is burned in this way and so contributes to climate change.

Gas heaters provide easily adjustable, instant heat and there are a range of options available. This includes fixed and portable heaters, as well as gas central heating systems that 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 - increasing fresh air flow into your house reduces dampness, condensation, stale air and musty smells. In addition, new technology is being developed including 'condensing' appliances which reduce fuel bills by extracting more useful heat out of the gas.

Environmental effects: natural gas and LPG emit less greenhouse gas emissions than electricity generated using fossil fuels and can provide large amounts of heating to a home without contributing to winter peak electricity demand. However, pollutants from unflued, portable gas heaters such as nitrogen dioxide, carbon monoxide and carbon dioxide can be a significant health risk if they are not removed from a room. The portable models also produce a lot of water vapour which increases condensation and the spread of mould and dust mites. 'Consumer' recommends you only use fixed gas heaters which are flued to stop the accumulation of pollutants and water vapour inside a home. 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.

Modern, enclosed woodburners are much more efficient than open fires. 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, woodburners are among the cheapest heating option.

Pellet burners are a cleaner option 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. They are among the cheapest and most environmentally friendly heating options.

Emissions

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. They take into account local conditions.

Pellet burners have fans and burn with a large amount of air, so produce very little smoke. The pellets have a low moisture content so they burn more efficiently.

Legal requirements

You'll need a building consent to install a woodburner or pellet burner.

Heat pumps

Other than passive solar, heat pumps are among the most energy-efficient forms of heating 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.

Heat pumps are controlled using a thermostat, so you can set them to keep your home within a set temperature range.

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

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.

Other things to consider:

• Heat pumps can be expensive to install. A unit to heat your living room might cost $4000 (2006 costs) and a ducted system to heat a large house would cost much more.
• Some heat pumps also incorporate air filters that remove dust and pollen, which can be helpful for people with asthma and allergies.
• By operating in reverse, heat pumps can provide cooling in summer.
• Heat pumps work best if the temperature outside is not below freezing.
• Heat pumps can be noisy.
• Heat pump installations need electrical and plumbing work to be done by qualified tradespeople. Look in the Yellow Pages under 'Heating & Ventilation' or 'Air Conditioning' for suppliers.
• In some heat pumps, the refrigerant used to extract heat is harmful to the ozone layer if it escapes. Contact your local council or landfill about safe disposal options.

Solar central heating

The sun's energy can be harnessed to heat water which, in turn, can be used to provide warmth for your home.

This type of system is known as solar hydronic heating. Heat is absorbed by water-filled hoses fixed in your roof space. It can be used to heat radiators throughout your home or heat water in flexible pipes beneath your floor.

These systems are best where you get good winter sun. You will need an alternative form of heating for when the sun doesn't shine for a few days.

Solar hydronic systems use free solar heat, but are complex and expensive to install. They need to be installed as a house is being built.

They're not common in New Zealand, but some companies do offer them. Search the internet for 'hydronic solar underfloor'.

Underfloor heating

Underfloor heating can be embedded in a concrete slab when you build a new home or laid under the flooring of a new or existing home.

The floor needs to be well insulated underneath or you will lose most of your heat. You shouldn't carpet over a heated floor - the carpet will keep the heat in the floor.

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 best used if you are home most of the time. A lot of energy is used to heat the floor, especially a concrete slab. But once the floor is heated, it acts as a low temperature radiator.

If you have problems with underfloor heating, you may have to rip up the floor and repairs can be expensive. 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.

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. Other fuels include oil, coal, wood or wood pellets.

The heating unit is 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.

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.

Ventilation and heat recovery systems

Forced ventilation systems take filtered air from a roof space and blow it (using a fan) into the rooms of a home. This air is usually drier and easier to heat.

Though ventilation systems are sometimes marketed as alternative forms of heating, they are really for ventilation.  During sunny days, the systems draw air from warm roof spaces and distribute it throughout a house via ventilation ducts. However, at night there is no 'free heating' and all the outside ventilation air that is introduced inside must be heated.

Heat recovery systems can be used if your ventilation system has specific extract ducts. These systems use a heat exchanger to transfer heat from the inside air to the incoming fresh air from outside. In this way, most of the heat is recovered.

Heat recovery systems transfer heat when the temperature difference is higher which is exactly what you want in winter. They are only economic in cold climates.

More information

From Smarter Homes

• Energy-saving tips for home heating
• Passive heating
• Passive cooling
• Orientation
• Insulation
• Glazing

From ConsumerBuild

• Heating

From consumer.org.nz

• Heating options
• Choosing a heater
• Oil-filled heaters
• Unflued gas heaters
• Heat pumps
• Woodburners
• Woodburner emissions
• Heat pumps
• Forced ventilation systems

Note: you may need to be a subscriber to access some of this content.

From other sites

The Energywise website has a page about home heating, and the Energy Efficiency and Conservation Authority’s website has information about appliances for heating and cooling. Also see www.energystar.govt.nz for information about energy efficient appliances.

The Ministry for the Environment’s Warm Homes Project web page has information about efficient home heating and health effects from cold homes. 

The National Institute of Water and Atmospheric Research has a web page providing an overview of New Zealand's climate.

You can get local weather information from the Met Service website.

The Ministry for the Environment’s website lists woodburners that comply with emission requirements.