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Standard Assessment Procedure (SAP)
The Standard Assessment procedure was adopted by the Government
as the UK methodology for calculating the energy performance of dwellings.
The calculation is based on the energy balance taking into
account a range of factors that contribute to energy efficiency:
• Materials used for the construction
of the dwelling;
•
Thermal insulation of the building fabric;
•
Ventilation characteristics of the dwelling and ventilation equipment;
•
Efficiency and control of the heating system(s);
•
Solar gains through openings in the dwelling;
•
The fuel used to provide space and water heating, ventilation and
lighting;
•
Renewable energy technologies.
There are
several different indicators of the energy performance. These
are:
• An energy consumption per unit floor
area;
•
An energy cost rating (SAP rating);
•
An Environmental Impact rating (based on CO2 emissions);
•
A dwelling CO2 Emission Rate (DER).
The SAP
rating is based on the energy cost of the above parameters and is adjusted
for floor area so that it is essentially independent of dwelling size
for a given built form. The SAP rating is expressed on a scale
of 1 to 100, the higher the number the lower the running costs.
The Environment Impact rating is based in the annual CO
2 emissions associated with the above parameters and is
again adjusted for floor area. The Environmental Impact rating
is expressed on a scale of 1 to 100, the higher the number the better
the standard.
The Dwelling CO2 Emission Rate is similar to the
Environmental Impact rating, and is used for the purpose of compliance
with building regulations.
Visit the
BRE
website for further information, lists of approved software
and downloads.
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