Explanation of terms used

Unit cost of installation

Approximate full installation costs for materials and labour (excluding VAT) for a typical 3 bed semi-detached. Unless otherwise stated the figures quoted assume measures are installed by a professional installer.

Carbon or carbon Dioxide

Carbon emissions and savings are expressed as the equivalent weight of Carbon, rather than Carbon Dioxide (CO₂) which is used in setting targets in Part L of the building regulations. One kilogramme of Carbon is equivalent to 3.67 kilogrammes of CO₂.

Fuel prices

The fuel price assumptions used in this report are the same as those built into SAP 2005, and as such are averaged over a period of 3 years. At the time of writing the cost of energy was rising rapidly, thus the fuel price assumptions may be lower than actual prices. The fuel costs used within this manual are reproduced below so that the reader can make more accurate estimates of running costs and savings.

Note that costs vary regionally and are very dependent on the precise specification for the work. The costs quoted are thus indicative only to allow comparison between different measures. Some measures may be eligible for grants which would reduce the costs given. Information on available grants can be found at http://www.est.org.uk/myhome/gid/

Fuel prices - extracted from SAP2005

Bulk cost of installation

Approximate installation costs for a cluster of dwellings. Unless otherwise stated the figures quoted assume measures are installed by a professional installer.

Indicative energy costs and carbon emissions

For heating systems - this represents the indicative annual energy costs, and carbon emissions, calculated using BREDEM; (it includes any standing charge additional to the standard electric tariff). Calculated for a typical semi-detached house using a standard heating regime (whole house heated morning and evening weekdays, all day at weekends and 21°C demand temperature in the living area). Note that actual costs will often be very different because of many factors including heating regime, house size, and location. Costs and carbon emissions are given for an un-insulated and an insulated house, so that the range of values can be appreciated. Note also that changing from room heating to central heating will often also result in a higher heating standard. Electric storage heating and heat pumps include a proportion of peak rate electricity for 'top-up'.

Indicative cost and carbon saving

For insulation measures - this gives an indication of savings. The range reflects the maximum and minimum savings possible, depending on the heating system. Maximum cost savings are for peak electric heating; minimum cost savings are for gas central heating (90% boiler efficiency).

In reality, after installation of a measure householders may heat more of their house to a better standard (i.e. one or more of: the house being heated for longer; more of the house being heated; or heated to a higher temperature). However, a higher heating standard, as well as any actual reduction in running costs, is a benefit. Therefore, the values given here can be used to indicate the overall benefit of installing insulation - some of which may be taken in actual reduced running costs and some in improved heating standard. A software tool ('Fuel Prophet') has been produced by the Association for the Conservation of Energy (ACE) to model the cost effectiveness of combinations of measures taking into account changes in fuel pricing. The tool can be downloaded from http://www.fuelprophet.org/

Maximum carbon savings are for electric storage heating; minimum carbon savings are for gas central heating.

Maintenance

Type, frequency and costs of maintenance.

Lifetime

Generally accepted average values.

Technical suitability

Appropriateness of measure - situations where alternatives might be better.

Non-technical constraints

Circumstantial or institutional issues such as need for planning permission.

Potential concerns with fuel poor

Issues that may have a disproportionate impact on the most vulnerable (i.e. fuel poor) households.

Ancillary benefits

Benefits beyond simple fuel bill reductions and carbon savings.

Trigger points for work

Opportunities for installing measures when other work is in progress.

Performance limitations

Boundary conditions required for acceptable performance beyond which performance may be impaired.

Technical guidance available

Best Practice programme or other guidance.