Information for SuperHeat users:

Elemental Method Requirements - Domestic buildings

(not applicable to Northern Ireland)

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General

You can show compliance using the Elemental Method, Target U-Value Method or Carbon Index Method. You do not have to comply with all three, just one.

The Elemental method is the easiest to understand: firstly the various elements of the building (walls, floors and roofs) must be constructed so as to meet specified U-value limits; secondly, the total area of openings is limited to a stated proportion of the floor area; and lastly the heating system must be of a type specified in §1.2 and have the efficiency required by Table 2 (in Scotland, the Elemental Method can still be used with other heating systems, but lower U-values are required; in England and Wales you will need to show compliance using the Target U-value or Carbon Index methods).

U-value limits

The U-value limits (all U-values are given in W/m²K) are as follows.

*The second figure applies where the heating system is not in compliance with Table 2:

Note that larger ground floors may not require additional insulation, but the risks of cold areas around the edge of the floor should be considered.

Semi-exposed walls and floors (i.e. walls and floors adjoining unheated spaces) are now subject to the same U-value requirements as exposed walls and floors, but in calculating their U-values account is taken of the buffering effect of the space on the other side of the wall or floor (§0.8/J2.3.a).

Opening area limits

For dwellings the combined area of doors, windows and rooflights should not exceed 25% of the total floor area, assuming an average U-value of 2.2 (2.0 if metal framed windows are used) - these figures are maxima in Scotland. Where the average U-value of the glazing differs from this figure, SuperHeat will make the necessary adjustment (the figures are calculated on the basis that the combined heat loss through glazed and unglazed areas should not exceed a set figure). The total floor area is entered in the Dimensions page of the SAP data dialog (see page 33).

Where you have a mixture of metal and non-metal framed openings the AD is not clear on how the permissible area should be calculated. SuperHeat works out the permissible area of each type and the actual areas as a proportion of the permissible. The proportions are summed and the building is taken as complying if this sum is less or equal to 1.0.

Extensions

An extension to a dwelling not exceeding about 6m² in floor area may be accepted as satisfying Regulation L.1 if its construction is similar to the construction of the existing building (§1.3). Other extensions will usually be checked using the Elemental method, though in England and Wales (but not in Scotland) a higher U-value for one part of the structure may be acceptable if another part of the extension has a lower U-value than would be required by the Elemental method. The permissible areas of doors, windows and rooflights are detailed in §1.14.

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