Hard to treat matrix

Click here for an explanation of the terms used.

Off peak Electric storage Bulk LPG Air source heat pump Solid fuel central heating Wood pellet central heating Ground source heat pump Oil central heating Gas central heating Micro CHP (Gas) CHP External insulation Internal insulation Insulating render Loft insulation Flat roof insulation Cavity wall insulation Flexible insulated linings Double glazing Secondary glazing Solar water heating Hot water tank insulation Floor insulation Draught-stripping Local extract fans Heat recovery room ventilators Passive stack ventilation Whole house mechanical ventilation Mechanical supply (+ve pressure) ventilation

Explanation of terms used in measures pages

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

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 21oC 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 includes 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, 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.
Maximum carbon savings are for electric storage heating; minimum carbon savings are for gas central heating.

Maintenance
Type, frequency and costs of maintenance.

Lifetimes
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 in progress.

Testing and accreditation
Relating to the performance of the measure (both energy and wider standards).

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

Technical guidance available
Best Practice programme or other guidance.