The standard assessment procedure (SAP)

What is SAP?

SAP is the Governments 'Standard Assessment Procedure' for energy rating of dwellings. SAP, was designed to be included in the 1995 Building Regulations and it is now a compulsory component in Part L of the Regulations. Every new house has to have a SAP rating. 'SAP' can be defined as follows:

• SAP provides a simple means of reliably estimating the energy efficiency performance of dwellings. SAP ratings are expressed on a scale of 1 to 100 the higher the number the better the rating. Thus SAP is similar to the fuel consumption of a car under standard driving conditions.

• SAP is calculated by a procedure contained in the Building Regulations, which predicts heating, and hot water costs. These depend on the insulation and air tightness of the house and the efficiency and control of the heating system. The calculation uses the Building Research Establishment's Domestic Energy Model (BREDEM).

• The procedure for calculating SAP is defined by the published SAP worksheet - though in practice most people calculating SAP use one of the approved SAP calculation programs. These are computer programs, which are approved by the Building Research Establishment (BRE).

• SAP programs are used to enter data on the size of the house, its insulation levels, it ventilation system and its heating and hot water systems. SAP rating can then submitted for Building Regulations approval and is checked by the local Building Control department.

Any one can produce a SAP rating for the purposes of regulation 14A or regulation 10A; and for the purpose of part L ! However as with all building regulation matters, it remains the building control body's responsibility to check the accuracy of the calculations. As a Consequence small developers, who build between 1-15 units per year, are increasingly asking plumbers and Installers to provide SAP ratings.

Why should plumbers be aware of SAP?

SAP calculations are required for all new dwellings as well as those that have been created as the result of material changes of use involving building work, and extensions over a certain size, (check this requirement with your building control authority).

Allowances will be made for dwellings that have efficient gas or oil fired heating systems installed. Electric, solid fuel and inefficient gas or oil boilers will require higher levels of insulation. A further requirement will be the certification of heating and hot water systems to show that they have been correctly installed and commissioned, and the provision of operating and maintenance instructions for users.

The type of heating systems & controls, and the level of insulation and ventilation units installed, influences SAP calculations. Here are a few tips: -

• Condensing boilers produce higher ratings than traditional boilers and can increase the rating by up to 10 points. An electric heating system using an economy 7 boiler can reduce the SAP by 11 when compared with a conventional gas fired boiler.

• The Boiler Efficiency Data File is published as part of the DETR's Boiler Efficiency Database scheme. It holds data on domestic boilers, gas and oil fired only, current and obsolete, for the purposes of carrying out SAP energy ratings. Follow this link for further information.

• If an existing older boiler is being re-used in a conversion, the engineer must ensure that when the pump switches off, the boiler switches off also. The feed to the boiler is not the "permanent live" but is switched supply used for the pump. Normally referred to as a "boiler interlock".

• Most new and refurbishment designs will require a minimum of; programmer, room stat and TRV's to obtain a good rating. With additional points being added for delayed stats, energy managers etc.
• Cylinder stats are compulsory for a SAP pass.

• Primary pipework insulation is also compulsory and must be insulated within 1.5 meters of the cylinder to prevent losses, and to obtain a pass. The depth of cylinder insulation also has a significant effect on the rating.

• If the pump is fitted in the heated space it will have a positive effect on the rating, if it's fitted in the unheated space it will have a negative effect.