Information for SuperHeat users:

The Part L Approved Document Requirements for controlling the heat loss through the fabric of a building

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Dwellings

Scottish readers: This section deals mainly with the AD requirements in England and Wales. The Part J provisions in Scotland are similar but not identical: key differences are that the Elemental U-value for external walls is 0.3 (instead of 0.35) with a corresponding adjustment to the Target U-value formula, alternative (lower) Elemental Method U-values are given for dwellings whose heating systems do not attain the required efficiency, a high efficiency boiler cannot be used to achieve compliance using the Target U-value method and glazing U-values are more strictly controlled.

Northern Ireland users: The Part F requirements that apply in Northern Ireland are described in detail in the SuperHeat 5 manual Northern Ireland edition.

For an overview of the changes in the 2002 Part L Approved Documents see DTLR Circular 03/2001.

Building Regulation L1 (Conservation of fuel and power) states that :

Reasonable provision shall be made for the conservation of fuel and power in dwellings by:

• a. limiting the heat loss (i) through the fabric of the building; (ii) from hot water pipes and hot air ducts used for space heating; (iii) from hot water vessels;
• b. providing space heating and hot water systems which are energy-efficient;
• c. providing lighting systems with appropriate lamps and sufficient controls so that energy can be used efficiently;
• d. providing sufficient information with the heat and hot water services so that building occupiers can operate and maintain services in such a manner as to use no more energy than is reasonable in the circumstances.

L2 applies similar provisions to buildings other than dwellings with additional provisions to reduce solar gain and the consequent need for air conditioning.

As with other regulations expressed in functional terms, building designers have the option of showing compliance with the requirements in any way they choose, provided that the Building Control Officer or Approved Inspector accepts that the approach being adopted is a reasonable one.

In practice virtually all designers will use compliance with the Approved Document (AD) provisions (and their counterparts in Scotland and Northern Ireland) to demonstrate that their buildings comply. SuperHeat gives you a reliable way of checking buildings for compliance with L1(a)(i). When producing SAP Ratings you should also observe the guidance in the SAP-2001 document.

General requirements

The L1 and L2 Approved Documents contain the respective requirements for dwellings and for other building types. The latter are subdivided into other residential buildings (including hotels, hostels and institutions); places of assembly, offices and shops; and industrial and storage buildings. Mixed use buildings may need to be split into different parts, with each part of the building being checked against the requirements relating to that use (§0.7). These are all available as free downloads:

• ODPM Building Regulations home page
• L1 Approved Document and supporting information
• L2 Approved Document and supporting information
• Scotland Part J read online or download PDF

In considering ways of achieving compliance, designers should consider the risks of condensation and moisture penetration (§0.5). See BRE Report 262 Thermal Insulation: avoiding risks 2002 edition, and also note other Regulation requirements relating to combustion appliances and sound insulation.

Controlling heat loss through the structure of dwellings

The L1 Approved Document gives designers several alternative ways of showing that their design satisfies the requirement to limit heat loss through the structure of a building. These are:

• Elemental Method
• Target U-value Method
• Carbon Index Method

Buildings other than dwelling

The Approved Document gives designers several alternative ways of showing that their design satisfies the requirement to limit heat loss through the structure of a building. SuperHeat can check non-domestic buildings for compliance using the first of these:

Elemental method:

This sets maximum U-values for walls, floors and roofs, and limits for roof and wall opening areas (§1.7-1.68; 2.2-2.11). The former Calculation method (Heat Loss Method in Part J) has been retained as an extension of the Elemental method.

Whole Building method:

As the name suggests this considers the performance of the whole building and is applicable to offices, schools and hospitals. This method is outlined in §1.69-1.73 and considers the performance of the whole building including heating, ventilation, air conditioning and lighting in offices, schools and hospitals. The carbon emissions per m2 of floor area should be within the stated limits. Checking for compliance using this method is not included in SuperHeat 5.

Carbon Emissions Calculation method:

This is an extension of the Calculation Method and can be used for all building types - see §1.74-1.76. The annual carbon emissions from the building should be no worse than those from a corresponding notional building. Checking for compliance using this method is not included in SuperHeat 5.

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