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How homes are Energy Rated

Homes are energy rated into one of seven bands from A to G, where A is high efficiency and G is low efficiency. This is a similar system to the energy rating of domestic electrical goods and new motor vehicles. An energy rating is calculated by entering data from a survey (property dimensions, wall construction, boiler type, loft insulation etc.) into a computer program which generates an output rating on a scale from 1 to 100 (1 being a low rating and 100 being a high rating). This energy rating is linked to the cost of heating, lighting and hot water per square metre of the property. The current average rating for a property in England and Wales falls within bands D - E. New build homes built to current building standards are likely to achieve a high C or low B rating.

Two charts will be displayed in the Energy Performance Certificate. The first is an Energy Efficency Rating and the second is an Environmental Impact Rating (based on CO2 emissions). There are small variations in the layout of these charts in England and Wales, Scotland and Northern Ireland.

Extent of Survey

The survey is non-intrusive and evidence-based only. An Energy Assessor who conducts the survey will only record what can be visually inspected. Ares that are inaccessible (e.g. under the floor or within a flat roof) will be assumed to have levels of insulation commensurate with the age and type of build. If insulation has been added at a later date, then documentary evidence (e.g. builder's receipts or photographs) will be required. An Energy Assessor is not permitted to accept the word of a homeowner alone as evidence. The energy survey is not a structural survey and does not convey any information about the structural integrity or condition of the buildign. All heating, lighting and plumbing systems found within the building will be assumes to be working correctly.

Access to Loft Space

An Energy Assessor should have access to loft spaces in order to measure the insulation. If the loft hatch is locked, difficult to open or has unsafe access, the Energy Assessor will not inspect this area. In circumstances such asthese the software will default to the level of insulation which would have been installed at the time of build.

Heating Costs

As well as producing an energy rating for the property, the EPC will give predicted annual heating, lighting and hot water costs. These are based on a standardised occupancy (according to floor area) and a standardised heating pattern. This assumes the heating will come on from 7 am to 9 am in the morning and 5 pm to 11 pm in the evening (Monday to Friday). At the weekend it is assumed the property is heated for 16 hours per day. The default temperatures are 21°C for the main living room and 18°C for the rest of the dwelling. This enables heatings costs to be compared on a like-for-like basis and not on the actual use of the heating system by a homeowner. For example, there ay be two identical dwellings, one of which is occupied by a single person who heats only one room for a few hours of the day, and the other is home to a large family heating the whole house for most of the day. Both will obtain the same scores on the A to G scale.
The heating costs displayed are very sensitive to the type of fuel used by the heating system. Some fuels are much more expensive than others and are likely to result in a lower energy rating for the property.

Summary of the Home's Energy Performance Related Features

The EPC will contain a table giving a description of the energy efficiency and environmental performance of the walls, floor, roof, windows, main heating and main heating controls, hot water and lighting. These descriptors are based on the data input and are defaulted by the software (the Energy Assessor does not write these). For example, if the heating controls in a property comprise of a programmer only, the default descriptor would be 'Very Poor'. Most modern homes would have a programmer, room thermostat and thermostatic radiator valves, for which the descriptor would be 'Average'. A boiler energy manager of full zone control (where the temperature in different parts of the property can be controlled at different times) would be described as 'Good'.


Association of Residential Letting Agents ARLA National Association of Estate Agents NAEA Stroma Certified Energy Assessor Elmhurst Accredited Energy Assessor The Association of Professional Inventory Providers
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