4 Results of the Literature Review

Nature of fuel/energy source

Wood

Availability of fuel/energy source

Wood is widely available from commercial suppliers but can also be collected free from a variety of sources (eg, untreated off-cuts from timber yards, manufacturers, building contractors, forestry, demolition timber).

Fuel/energy consumption

0.4-0.6 m³/100 kWh delivered; 125-200 kg/100 kWh delivered.

Efficiency of conversion of energy to heat

5-15%: accepted range though may even be negative at times.

The low efficiency of open fires is the result of heat lost by convection through the chimney. Most room heating occurs through heat radiation, but the effectiveness of this may be reduced by the effect of draughts caused by the movement of air towards the fireplace. The maximum efficiency of open fires is generally assumed to be 15%. Operating costs presented in this work are based on efficiencies of 10 and 15%.

Typical operating costs

These will vary according to the source of wood and the efficiency of the fire.

Ministry for the Environment: 26-36 cents/kWh

Christchurch City Council: 30-40 cents/kWh

Own calculations: 27-53 c/kWh delivered:

• Figures are based on retail prices in December 2004.
• The upper range of the calculated cost reflects the very low efficiencies at which open fires can operate.

Typical capital costs

It has not been possible to obtain a precise cost for installing an open fire within an existing building because this appears to be an unusual occurrence. It is likely that the installation of an open fire in a new property would add a cost in the order of $6,000. However, this is not an option in the increasing number of areas where local councils have prohibited the installation of open fires because of their high emissions and low efficiency.

Heating capacity

Typically around 2 kW of effective heat output into living areas.

Nature of the heat (radiant, convection, etc)

Heating is mainly radiant, with limited convection into the room (most convection heat is lost up the chimney). However, if the fireplace includes a wetback then some of the convection heat will be captured by this to provide water heating.

Fuel/energy handling issues

Operating a wood fire is labour intensive and involves cutting wood to size and stacking it in a dry location.

Fuel may be required to comply with local regulations (eg, Environment Canterbury regulation for water content of wood to be less than 25% by weight).

A large, dry fuel store is required and a steady supply of fuel must be kept handy during use. Fuel must be placed directly into the burning fire.

Convenience of use

An open fire requires regular refuelling and frequent attention during use.

Ease of heat control

Heat output is not constant and is difficult to control accurately.

Effectiveness of heat transfer

Heat transfer is poor, with only very local heating. Considerable heat (approximately 85%) is lost via the chimney and by the creation of draughts.

Heat-up rate

Slow

Ability to heat whole house vs single room

The form of heat output, mainly radiant rather than convection, combined with the limited heat output and the lack of means to circulate or distribute this heat make this form of heating unsuitable for heating a whole house.

Some older homes have multiple fireplaces, which allow heating of multiple rooms, but will still suffer from the very low efficiencies inherent in open fires.

Particulate emissions

PM₁₀: 9 g/kg; 490 mg/MJ

Greenhouse gas emissions

SO_x: 0.2 g/kg; 11 mg/MJ

NO_x: 1.4 g/kg; 77 mg/MJ

CO₂: 1700 g/kg (94,000 mg/MJ) but considered neutral. Wood fires may be considered to be CO₂ neutral because this gas has been in atmospheric form before being incorporated into the wood as part of the growing process of the tree. CO₂ resulting from the burning of fossil fuel may be considered to be a net addition because this gas has not been in atmospheric form before combustion.

Other emissions

CO: 68 g/kg; 3700 mg/MJ

PM_2.5: 8 g/kg: 440 mg/MJ

Emissions will depend on the wood being used – treated wood may contain hazardous chemicals.

Hazardous emissions can result from incomplete combustion.

Ash residue from burning must be disposed of.

Health and safety issues in the home (eg, indoor emissions and moisture)

Objects can come into contact with naked flames or sparks if the fire is not screened adequately.

Radiant heat can also damage or ignite fabrics or objects close to the fire.

Smoke released into the room increases local concentration of hazardous pollutants. No detailed information is available to quantify this risk.

Embodied energy

Firebricks; concrete; hearth grate.

Wood harvesting; transport of fuel.

Special features

Open fires are considered to be aesthetically pleasing by some.

They could be used for basic cooking in the event of a disruption to the electricity supply.

Risks associated with this option

See Health and safety issues (above).

Open fires can be used to burn materials other than firewood or coal, which will contribute to emissions.

Open fires can be highly polluting when allowed to smoulder.

Chimneys must be swept regularly to prevent the risk of fire.

General comments

Energy and labour intensive; messy to operate and maintain.

Not an option in new houses in some areas due to local council restrictions on allowable emissions.

Suitability for use with heat-transfer system

No

Nature of fuel/energy source

Coal

Availability of fuel/energy source

Kyoto Protocol obligations may influence coal's future cost and availability. Solid Energy, the main supplier of coal to the domestic market in New Zealand, has indicated that it will begin phasing out the supply of coal for domestic heating. This will be done approximately in accordance with various local government bans on the use of open fires. Note that other retailers of coal have not made any similar commitment to withdraw from this market, but will be obliged to act in accordance with any legislation on the burning of coal and/or use of open fires.

Coal miners and others in mining areas may receive a free or cheap coal allowance. However, the number of coal-fire users who receive these benefits is not considered to be significant nationally.

Fuel/energy consumption

104-157 kg/100 kWh delivered.

The wide range of values results from the factor of three between the worst- and best-case efficiencies (10-15%) estimated for open fires.

The low efficiency of open fires is the result of heat lost by convection up the chimney. Most room heating is from radiation, but the effect of this will be diminished by the effect of draughts produced by the movement of air towards the fireplace. The maximum efficiency of open fires is generally assumed to be 15%. Operating costs presented in this work are based on efficiencies of 10 and 15%.

Efficiency of conversion of energy to heat

5–15%: accepted range, though may even be negative at times.

The low efficiency of open fires is the result of heat lost by convection through the chimney. Most room heating is the result of radiation, but the effectiveness of this may be reduced by the effect of draughts produced by the movement of air towards the fireplace. The maximum efficiency of open fires is generally assumed to be 15%. Operating costs presented in this work are based on efficiencies of 10 and 15%.

Typical operating costs

Ministry for the Environment: 23–32 cents/kWh

Christchurch City Council: 30-35 cents/kWh

Own calculations: 37–55 cents/kWh

The upper range of the calculated costs reflects the very low efficiencies at which open fires may operate.

Typical capital costs

It has not been possible to obtain a precise cost for installing an open fire within an existing building because this appears to be an unusual occurrence. It is likely that the installation of an open fire in a new property would add a cost in the order of $6,000. However, this is not an option in the increasing number of areas where local councils have prohibited the installation of open fires because of their high emissions and low efficiency.

Heating capacity

Typically around 2.5 kW of effective heat output into living areas.

Nature of the heat (radiant, convection, etc)

Heating is mainly radiant, with limited convection into the room (most convection heat is lost up the chimney). However, if the fireplace includes a wetback then some of the convection heat will be captured by this to provide water heating.

Fuel/energy handling issues

Operating a coal fire is labour intensive and potentially messy. Coal produces dust during handling and storage.

A dry fuel store is required.

Operation of the fire requires a steady supply of fuel to be kept handy during use. Fuel must be placed directly into the burning fire.

Convenience of use

Coal fires require regular attention to burn efficiently. A small fire must be lit using another fuel source before coal can be burnt.

Ease of heat control

A coal fire produces an unsteady heat and is difficult to regulate accurately.

Effectiveness of heat transfer

Heat transfer is poor, with only very local heating. Considerable heat is lost via the chimney and by the creation of draughts.

Heat-up rate

Slow

Ability to heat whole house vs single room

The form of heat output, mainly radiant rather than convection, combined with the limited heat output and the lack of means to circulate or distribute this heat, make this form of heating unsuitable for heating a whole house.

Some older homes have multiple fireplaces, which allow heating of multiple rooms, but will still suffer from the very low efficiencies inherent in open fires.

Particulate emissions

PM₁₀: 21 g/kg; 910 mg/MJ

Greenhouse gas emissions

CO₂: 2721 g/kg; 118,000 mg/MJ

SO_x: 5.1 g/kg; 220 mg/MJ

NO_x: 4.1 g/kg; 180 mg/J

Other emissions

CO: 70 g/kg; 3000 mg/MJ

PM_2.5: 20 g/kg; 870 mg/MJ

Elements in coal, including mercury, are released to the atmosphere during burning.

Emissions produced by incomplete combustion may also be hazardous.

Ash residue from burning must be disposed of.

Health and safety issues in the home (eg, indoor emissions and moisture)

Objects can come into contact with naked flames or sparks if the fire is not screened adequately.

Radiant heat can also damage or ignite fabrics or objects close to the fire.

Smoke released into the room increases the local concentration of hazardous pollutants. No detailed information is available to quantify this risk.

Embodied energy

Firebricks; concrete; hearth grate.

Mining; transport of fuel.

Special features

Open fires are considered to be aesthetically pleasing by some.

They could be used for basic cooking in the event of a disruption to electricity supply.

Risks associated with this option

See Health and safety issues (above).

Open fires can be used to burn materials other than firewood or coal, which will contribute to emissions.

Open fires can be highly polluting when allowed to smoulder.

Chimneys must be swept regularly to prevent the risk of fire.

General comments

Coal fires are energy and labour intensive, and are also messy.

These fires are not an option in new houses in some areas due to local council restrictions on allowable emissions.

Suitability for use with heat-transfer system

No

Nature of fuel/energy source

Coal or wood

Availability of fuel/energy source

Wood is widely available from commercial suppliers but can also be collected free from a variety of sources (eg, untreated off-cuts from timber yards, manufacturers, building contractors, forestry, demolition timber).

Kyoto obligations may influence the future cost and availability of coal. Solid Energy, the main supplier of coal to the domestic market in New Zealand, has indicated that it will begin phasing out the supply of coal for domestic heating. This will be done approximately in accordance with various local and national government bans on the use of open fires. Note that other retailers of coal have not made any similar commitment to withdraw from this market, but will also be obliged to act in accordance with any legislation on the use of coal for domestic heating.

Fuel/energy consumption

Coal: 20-28 kg/100 kWh of heat delivered.

Wood: 0.07–0.09 m³/100 kWh of heat delivered, 26-36 kg/100 kWh of heat delivered.

Efficiency of conversion of energy to heat

55-75%

This will vary with the type of fuel being burned and the design of the fire.

While these burners have the flexibility to burn a range of fuels, the optimum design of a coal burner is quite different to that for a wood burner. This results in the design of a multi-fuel burner being a compromise, with efficiency reduced as a consequence.

Typical operating costs

Ministry for the Environment: 4-12 cents/kWh

Own calculations: 7-10 cents/kWh

Typical capital costs

Approximately $3,000 installed.

Heating capacity

15–19 kW

Nature of the heat (radiant, convection, etc)

Convection; some radiant.

Fuel/energy handling issues

Wood:

Labour intensive, involving cutting wood to size and stacking to dry.

A large, dry fuel store is required.

Fuel may be required to comply with local regulations (eg, Environment Canterbury regulation for water content of wood to be less than 25% by weight).

Coal:

Coal dust; mess from handling coal.

A large, dry fuel store is required.

The operation of a coal/wood fire requires a steady supply of fuel to be kept handy during use.

Fuel must be placed directly into the burning fire.

Convenience of use

A multi-fuel fire requires regular refuelling and frequent attention during use.

Ease of heat control

There is only limited ability to regulate the operation of the heater accurately and the output will not be steady.

Effectiveness of heat transfer

This depends on whether the heater is inbuilt (in fireplace) or freestanding within the room. Since inbuilt models have less surface area from which to radiate heat, they transfer less heat to the room. As a result, an inbuilt heater will typically be less efficient than the equivalent freestanding device.

Heat-up rate

Slow

Ability to heat whole house vs single room

Can achieve moderate heating of whole house if heat can be distributed. Good air/heat circulation is required to prevent overheating in the vicinity of the heater.

Particulate emissions

PM₁₀:12-19 g/kg (660-830 mg/MJ) reported by Environment Canterbury.

However, the latest models from Harris Flame Technology are claimed to be in the range of 3.4-5.2 g/kg (187-230 mg/MJ).

Greenhouse gas emissions

Greenhouse emissions will vary with the fuel burnt, as follows.

Coal:

CO₂: 2170 g/kg; 94,350 mg/MJ

SO_x: 1.1 g/kg; 48 mg/MJ

NO_x: 1.6 g/kg; 70 mg/MJ

Wood:

CO₂: 1730 g/kg; 94,800 mg/MJ

SO_x: 0.2 g/kg; 11 mg/MJ

NO_x: 1 g/kg; 55 mg/MJ

Other emissions

Coal:

CO: 110 g/kg; 4800 mg/MJ

PM_2.5: 17 g/kg; 740 mg/MJ

Wood:

CO: 98 g/kg; 5400 mg/MJ

PM_2.5: 11 g/kg; 600 mg/MJ

This will depend on the wood being used - treated wood may contain hazardous chemicals. Ash residue from burning must be disposed of.

Mercury and other elements in coal are released to the atmosphere during burning.

There may be products of incomplete combustion.

Note that there is not a linear relationship between g/kg and mg/MJ for emissions. This is because MJ/kg values differ for wood and coal.

Health and safety issues in the home (eg, indoor emissions and moisture)

Smoke released into the room increases the local concentration of hazardous pollutants. No research into this appears to be available.

The appliance will be hot and thus may pose a risk of burning for children.

There is a risk that objects placed close to the fire may overheat and burn, or that sparks might escape if the door is opened for re-fuelling.

Fuel must be placed on burning fire.

Embodied energy

Steel; glass; ceramics; transport; flue; installation.

Special features

May be considered aesthetically pleasing if flames are visible.

Some models can heat water in a wetback but the energy used to heat the water reduces the reported efficiency of space heating.

Some freestanding models could be used for basic cooking in the event of a disruption to the electricity supply.

Risks associated with this option

Poor operation and inappropriate quality or type of wood or coal can result in emissions and/or the release of hazardous substances.

These heaters can be used to burn materials other than firewood or coal, which will contribute to emissions.

General comments

Versatility may result in compromised efficiency.

Suitability for use with heat-transfer system

Yes

Nature of fuel/energy source

Wood

Availability of fuel/energy source

Wood is widely available from commercial suppliers but can also be collected free from a variety of sources (eg, untreated off-cuts from timber yards, manufacturers, building contractors, forestry, demolition timber).

Fuel/energy consumption

0.07- 0.1 m³/100 kWh; 25-36 kg/100kWh.

Efficiency of conversion of energy to heat

55-75%. This depends on whether the heater is freestanding, inbuilt, or with a wetback. The results of wood burner efficiency tests carried out for Environment Canterbury indicate that inbuilt appliances are typically 3-5% less efficient than the equivalent freestanding model.

The efficiency of operation of wood burners may be affected if they are not operated in accordance with manufacturers' intentions. Removal of the firebricks by users, or operating the burner with the door open to enable large pieces of wood to be burnt, will reduce efficiency. This effect has been observed in a number of installations checked by Environment Canterbury as part of their Clean Heat Project.

Typical operating costs

These will vary according to the source of wood and the efficiency of the fire.

Ministry for the Environment: 4-8 cents/kWh

Christchurch City Council: 6-8 cents/kWh

Own calculations: 5-10 cents/kWh delivered.

Figures are based on retail prices of wood in December 2004.

Typical capital costs

Range: $1,500–$6,000. Most mainstream models can be supplied and installed for around $2,300–$2,600.

Heating capacity

5 kW-24 kW

Most mainstream models put out between 11 kW and 20 kW.

Appliances can be run at reduced output (eg, 11 kW can be run at 4 kW).

Nature of the heat (radiant, convection, etc)

Mainly convection, but also some radiant component.

Fuel/energy handling issues

Wood must be gathered in volume, stored correctly, dried, cut to size, kept handy and replenished during use.

Fuel may be required to comply with local regulations (eg, Environment Canterbury regulation for water content of wood to be less than 25% by weight).

Convenience of use

Requires regular, frequent attention. Can be filled up to burn for several hours.

Burner and chimney must be maintained to ensure efficient and safe operation.

Ease of heat control

The heat output of these heaters can be regulated by use of a damper, but this is not a very accurate means of control.

In some areas the introduction of low emissions standards has resulted in burner designs with a reduced ability to control the amount of air intake, which reduces the ability to control the amount of heat output.

Effectiveness of heat transfer

This depends on whether the heater is inbuilt (in fireplace) or freestanding within the room. Because inbuilt models have less surface area from which to radiate heat, they transfer less heat to the room. As a result, an inbuilt heater will typically be less efficient than the equivalent freestanding device.

Heat-up rate

Slow

Ability to heat whole house vs single room

Can achieve moderate heating of whole house if heat can be distributed. Good air/heat circulation is required to prevent overheating in the vicinity of the heater.

Particulate emissions

PM₁₀: 0.5-12 g/kg; 27-660 mg/MJ

Depends on the age of the heater and its operation. Appliances must be operated correctly to achieve low levels of emissions. Older wood burners can be operated with a restricted air supply. This may cause partial combustion and result in the appliance operating at lower efficiency and with higher levels of emissions than open fires. Newer burners are designed to prevent this effect.

Some newer models designed for markets where Clean Air regulations have been implemented produce PM₁₀ at the rate of 1 g or less per kg of fuel burnt.

Note that there can be a significant difference between particulate emissions from laboratory testing compared with those from real-life operation. A factor of 3:1 has been used in the past by Environment Canterbury in their modelling, and they are currently carrying out research into reviewing that ratio.

Greenhouse gas emissions

SO_x: 0.2 g/kg; 11 mg/MJ

NO_x: 0.5-1 g/kg; 27-55 mg/MJ

CO₂: 1730-1860 g/kg (94,800-102,000 mg/MJ) but considered to be neutral.

Other emissions

CO: 34-98 g/kg; 1870-5390 mg/MJ

PM_2.5 3–11 g/kg; 165-605 mg/MJ

Depends on source of wood (eg, treated wood may contain hazardous chemicals). Ash residue must be disposed of.

Health and safety issues in the home (eg, indoor emissions and moisture)

Smoke released into the room increases local concentration of hazardous pollutants.

The appliance will be hot and thus may pose a risk of burning for children.

There is a risk that objects placed close to the fire may overheat and burn, or that sparks might escape if the door is opened for re-fuelling.

Fuel must be placed on burning fire.

Embodied energy

Steel; ceramics and firebricks; transport - domestic freight.

Special features

Log burners can be used to heat wetbacks, but this reduces their efficiency and may also overheat the water.

Some freestanding models could be used for basic cooking in the event of a disruption to the electricity supply.

Risks associated with this option

Improper operation can lead to pollution problems.

General comments

There has been an improvement in open wood-burning fires, but they need care to operate at low emission levels.

Inbuilt models radiate less heat into a room, which places them at a disadvantage when calculating efficiency. This means that inbuilt models can often struggle to meet new target figures of 65% efficiency, even when the freestanding version of the same heater model can achieve the efficiency standard.

Some models are available with a wetback option to use heat to boost hot-water heating. This option reduces the measurement of the efficiency of the heater, as well as resulting in a cooler combustion temperature, which can mean slightly higher levels of emissions.

The National Environmental Standards design standard for wood burners is 1.5 g/kg of emissions and a thermal efficiency of 65% .

Suitability for use with heat-transfer system

Yes

Nature of fuel/energy source

Pelletised wood

Availability of fuel/energy source

The fuel for pellet fires is designed specifically for these appliances, using pellets of a particular composition and shape. Pellet fires cannot burn normal firewood so their operation is dependent on the availability of manufactured fuel. This fuel is currently only available from a limited number of sources. However, as pellet fires become more common, there appears to be an increase in the number of pellet manufacturing facilities in New Zealand.

Users of pellet fires could potentially also source pellets from other overseas outlets.

Fuel/energy consumption

21-26 kg/100 kWh delivered.

Efficiency of conversion of energy to heat

75-92%

Typical operating costs

Ministry for the Environment: 4-8 cents/kWh

Christchurch City Council: 8-10 cents/kWh

Nature's Flame: 7 cents/kWh

Own calculations: 7-9 cents/kWh delivered.

Typical capital costs

$2,700–$5,000

Pellet fires were until recently priced around the $4,500 level. However, Nature's Flame can now supply a lower-cost model for around $2,700 installed. This has the same firebox as the more expensive models but has fewer features (eg, no automatic lighter).

Heating capacity

10 kW-11 kW

Nature of the heat (radiant, convection, etc)

Mainly radiant; some convection.

Fuel/energy handling issues

Pellets must be loaded into a hopper. Large hoppers are available to reduce the frequency of loading.

Convenience of use

Easy to operate.

Ease of heat control

Good - output can be reduced to approximately 2 kW.

Effectiveness of heat transfer

This depends on whether the heater is inbuilt (in fireplace) or freestanding within the room. Because inbuilt models have less surface area from which to radiate heat, they transfer less heat to the room. As a result, an inbuilt heater will typically be less efficient than the equivalent freestanding device.

Heat-up rate

Slow

Ability to heat whole house vs single room

Can achieve moderate heating of whole house if heat can be distributed. Good air/heat circulation is required to prevent overheating in the vicinity of the heater.

Particulate emissions

PM₁₀: 0.5–0.6 g/kg; 27-33 mg/MJ

Greenhouse gas emissions

SO_x: 0.2 g/kg; 11 mg/MJ

NO_x: 5.2 g/kg; 280 mg/MJ. Note that this is a relatively high level, but it is based on the only available data (Scott, 2004). Scott uses data derived from work carried out in 1998, which may well overstate the level of NO_x emissions from a current model pellet fire. It would be useful to test a current model for NO_x emissions.

2006 update: D Gong (2005) has found NO_x emissions from pellet burners to be in the order of 1g/kg of fuel. This is less than the originally stated figure of 5.2g/kg.

CO₂: 1480 g/kg (80,200 mg/MJ) but considered neutral.

Other emissions

CO: 15 g/kg; 815 mg/MJ

PM_2.5: 1.5 g/kg; 82 mg/MJ

Health and safety issues in the home (eg, indoor emissions and moisture)

The appliance will be hot and thus may pose a risk of burning for children.

Embodied energy

Fire: steel; ceramics / fire bricks.

Energy required to make fuel pellets.

Special features

Self-feeding from hopper.

Risks associated with this option

Requires electricity to power fuel feed auger, although some heaters have a battery backup in case of power failure.

General comments

Note that most models have two or three electric motors to drive fans, fuel feeders, etc, which means a dependence on electricity for them to work as well as some continual background noise. A battery backup option is available for some models.

Pellets are produced from waste material from a renewable resource. This is more sustainable than using fossil fuels directly, or indirectly in gas or peak-hour electric heating.

Only pellets can be burnt in a pellet fire. Because pellets are manufactured to a specification, there is a much greater degree of control over the fuel used in these fires, with a corresponding degree of control over the emissions.

Possible risk of high fuel prices as fuel is supplied from a limited number of firms.

Suitability for use with heat-transfer system

Yes

Nature of fuel/energy source

Gas - bottled or reticulated.

Availability of fuel/energy source

Reportedly plentiful despite concerns over commercial gas supplies from New Zealand fields.

Recent price increases have been attributed to constraints on availability.

There is a limited number of gas suppliers in any location.

Reticulated natural gas is only available in the North Island; reticulated LPG is currently only available to a very limited extent in some parts of the South Island, mainly in new subdivisions.

Delivery of gas cylinders to some locations may be difficult/expensive.

Fuel/energy consumption

8-10 kg/100 kWh delivered.

Efficiency of conversion of energy to heat

75-85%

Typical operating costs

Ministry for the Environment: 7.0 cents/kWh

Christchurch City Council: 18-21 cents/kWh

Own calculations:

• Bottled gas 14-21 cents/kWh delivered and 25 cents/day for cylinder hire.
• Reticulated natural gas: ranges from 7 cents/kWh with 92 cents/day connection charge, to 17 cents/kWh with 56 cents/day connection charge, depending on tariff.

Typical capital costs

$1,000–$3,000

Heating capacity

1.4 kW-6 kW

Nature of the heat (radiant, convection, etc.)

Convection

Fuel/energy handling issues

Gas bottle storage and supply; none apparent for reticulated gas.

Convenience of use

Very easy to use - timer options are available with some heater models. No operator intervention in fuel supply.

Ease of heat control

Good - many have thermostat options.

Effectiveness of heat transfer

Good if fan assistance available.

Heat-up rate

Fast

Ability to heat whole house vs single room

Larger heaters may have the capacity to heat the whole house but this will depend on the ability to circulate warm air through the house.

Potential for overheating room where heater is located.

Particulate emissions

PM₁₀: 0.05 g/kg; 1.4 mg/MJ

Greenhouse gas emissions

NO_x: 1.5 g/kg; 42 mg/MJ

CO₂: 2500 g/kg; 55,300 mg/MJ

Other emissions

CO: 0.2 g/kg; 5.6 mg/MJ

PM_2.5: 0.3 g/kg; 8.4 mg/MJ

Health and safety issues in the home (eg, indoor emissions and moisture)

Risk of gas leaks, but no figures are available for the incidence of this. However, there is only a low incidence of any notifiable gas accidents (see Risks, below), so the risk of gas leaks will also be low.

Embodied energy

Steel; ceramics.

Transport of bottled gas.

Special features

Programmable operation.

Risks associated with this option

Long term availability of gas supply.

Although there is a risk of explosion in the case of fuel leaks, there are no reports of any instances of this. Data from the Energy Safety Service shows a relatively low incidence (15–18 per year) of notifiable accidents for all natural gas and LPG applications. This includes home heating as well as other gas applications.

General comments

–

Suitability for use with heat-transfer system

No