The most sustainable heating approach is to firstly maximise use of passive heating, and then specify efficient, environmentally-friendly active heating to meet the house’s remaining heating needs.

See the space heating and cooling introduction for key principles to consider when you’re designing a heating system, and the section on space heating energy sources for information about the efficiency and sustainability of different energy types ranging from solar to fossil fuels. Always start with the simplest and cheapest option for the circumstances.

The space heating options, in approximate order of efficiency (there are some overlaps), are:

Best Efficiency (Coefficient of Performance >1)	Good Efficiency (Coefficient of Performance about 1)	Average Efficiency (Coefficient of Performance <1)
solar energy (ie good passive design, appropriate glazing etc) for entire space heating needs air to air heat pumps (convective heat) domestic electric heat recovery ventilation system (convective)	electric radiant panel heaters electric fan convective heaters electric convective heaters electric radiant ceiling panels hot water radiators connected to an electric boiler underfloor (electric cable) low temperature radiant heating	flued natural gas convective heaters (with fan boost) flued natural gas radiant heaters flued LPG convective heaters (with fan boost) flued LPG radiant heaters underfloor (hot water) low temperature radiant heating gas fired underfloor (hot water) low temperature radiant heating electric boiler underfloor (hot water) low temperature radiant heating heat exchanger hot water radiators connected to a central gas condensing boiler hot water radiators connected to a central gas boiler ducted hot air from an electric source solid fuel burner oil fired ducted hot air hot water radiators connected to a oil fired boiler ducted heat from a gas fired central source ducted heat from an LPG fired central source

Living room or dining room heating

For living and dining rooms, the space heating system generally needs to provide for:

• heating of larger spaces
• longer periods of use
• variable occupancy levels.

Occupants should be able to control the heating, and it should have a relatively quick response time so both the occupants and the space can be quickly warmed when temperatures fall.

As activity within this space is often sedentary, it is important that natural air movements should not make the occupant feel cold.

Bedroom heating

The space heating system for a bedroom or bedrooms needs to allow for:

• long periods of occupancy with low activity levels
• gentle heating of the air in the room
• low noise levels.

This is best achieved using convection heating. In a well-insulated, passively warmed house, an oil-column heater or nightstore may be sufficient.

Bathroom heating

The space heating system for a bathroom needs to:

• provide for short periods of use
• have a very quick response (to warm occupants when the bathroom is in use)
• be effective and safe for use in a moist environment.

To minimise the risk of condensation forming, ventilation should be addressed first. After that, a low level of background heat is recommended, such as a hot water radiator or underfloor heating system.

Other options are

• ceiling-mounted heat lamps (with exhaust air duct)
• electric radiant heaters
• electric wall-mounted fan heaters.

Kitchen heating

The space heating system for a kitchen needs to allow for short or medium periods of use, depending on when the room is occupied and whether other sources of heat such as the oven are being used. The system also needs to allow for raised levels of moist air which will sometimes require ventilation.

In general, heating is not required nor installed in kitchens. If it is needed, the best heating option is an electric radiant heater.

Open plan spaces

Open plan areas generally include kitchen-dining, living-dining or a combination of both. The space heating system for an open plan space needs to allow for movement of air between areas, and for loss of heat from the immediate area around the heater.

Even heating without draughts will be achieved with underfloor heating. Even heating can also be achieved with ducted heat pumps, ducted central heating, or hot water radiators throughout the area.

Boost heating for specific areas such as the area where lounge seating is located can be provided by gas or electric radiant heaters.

Two-level spaces

The heating system for a two-level space needs to allow for convection currents causing warm air to rise from the heated lower level to the upper level.

In a well insulated home, there may be sufficient heat flow from the lower-level heating system that the upper level needs only a small radiant or convective heater for boost heating.

Indoor-outdoor flow spaces

The space heating system for a room that has doors regularly opened to the outside needs to allow for high air movement in and out and rapid fluctuations in internal temperatures.

For your clients

To help your clients make decisions about space heating options, refer them to www.smarterhomes.org.nz/energy/heating.