Information for SuperHeat users:

Calculation Method Requirements

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Applicable to buildings other than dwellings

At a first glance the Calculation method has disappeared from the 2002 L2 AD though it continues as the Heat Loss Method in Part J. However it is effectively there in §1.15: the building will comply if its calculated heat loss does not exceed that of the corresponding notional building. The heat loss in each case is calculated by multiplying the area of each part of the building by its U-value to give the total loss in W/K. If one part of the building is insulated to a higher standard than would be required by the Elemental method the resulting reduction in heat loss can be used to justify lower standards of insulation elsewhere and/or increased areas of glazing.

The notional building

The notional building is a building with the same dimensions as the actual building, but constructed with elements having the maximum U-values set out in the Elemental Approach provisions. The notional building has the areas of wall or roof glazing permitted by the Elemental method or those in the actual building if lower. SuperHeat selects the appropriate figure when checking. As with the Elemental method you cannot trade off window areas against rooflights or vice versa.

Limits on the relaxation of U-values

As with other alternatives to the Elemental method, the extent to which the insulation standards can be lowered is limited by Table 3 which sets maximum U-values of 0.7 for the exposed walls and floors and 0.35 for roofs. No maxima are laid down for the U-values of ground floors, exposed floors and semi-exposed elements but if the ground floor of the actual building is of such a size as to have a U-value of less than 0.25 without adding insulation, this lower value is the one that must be used when calculating the heat loss of the notional building. SuperHeat does this automatically if you enter the floor as a 'Ground floor'. If you enter the floor with a user-defined U-value this value is used for the notional building floor if less than 0.45.

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