National Calculation Methodology (NCM) - Scottish Government

Versions Policy
9. All software tools, both the government’s Simplified Building Energy Model
(SBEM) and commercial Dynamic Simulation Models (DSMs), evolve with time as
improvements are made to the functionality and the quality of the underlying
algorithms. This means that it is necessary to have a procedure whereby new
versions can be accepted as appropriate for use within the compliance/certification
process. The rules in the following paragraphs define the approved procedures.
10. For certifying compliance with Section 6, when submitting a building warrant:
a. The latest version of a software tool should generally be used.
b. The previous version of a software tool (i.e. software and NCM databases) may
be used for a period not exceeding six months following introduction of a new
version, provided a change in regulations does not require use of the current
version (as would be the case, for example, from 1 October 2010).
c. Whilst the same version of a software tool may be used for any amendment to
warrant as for the original warrant, at any stage, applicants can elect to adopt a
more recently approved version of the tool, but having elected to use a later
version, building developers cannot subsequently revert to using a previous
one.
11. For the production of Energy Performance Certificates, the most recently approved
version of the adopted software tool must be used, unless the latest version has
been released less than one calendar month prior to the assessment date. In such
cases, the previous version of the tool may be used, provided a change in
regulations does not require use of the current version.
12. To allow the transfer and reuse of project data from an older to a newer version of
the tool, part of the procedure for approving a software tool is that a new version
must be backwardly compatible with all previous versions of the tool, i.e. it can
either read the data files of previous versions directly, or a file conversion utility
must be provided.
Choosing a Software Tool
13. While all calculation methods involve a degree of simplification, two classes of
software tools are available for use for Section 6 compliance checking and EPC
generation:
a. SBEM, which is the Simplified Building Energy Model developed for the BSD.
This can be applied to any building (irrespective of size) although there are
some constraints, as discussed in Chapter 7 of this guide. Such constraints are
for example, where representation of certain building features require some
approximation, entailing additional demands of the assessor’s input time and
effort; and
b. Approved Dynamic Simulation Models (DSMs). These are applicable for any
building unless an individual DSM’s approval specifically excludes certain types
8