National Calculation Methodology (NCM) - Scottish Government

7 Suitability of Calculation Method.
96. Selection of the software tool to be used for a particular project will depend on a
number of issues. These issues may apply to any software used for these
purposes, not only to the use of iSBEM 31 /SBEM.
Availability of Tools and Competence of Users
97. First, the choice of software tool will depend on whether the tools that are
available are within the competence of the users – ideally the users have
successfully undertaken training on use of the chosen tool and have further
practical experience of its use. Formal accreditation in the use of the tool, whilst
not essential, is beneficial. It may be that the user has already used one of the
DSM tools or a CAD 32 package that interfaces with one of the software tools for
design work, so that the bulk of the input has already been undertaken; this will
mean that it is preferable to continue to use the tool that the project has already
been started on.
98. Where the project requires that the software should be used outside the standard
scenarios, for instance inputting a system that is not on the standard drop-down
menus, it is important that the user should understand and be competent to
extend the software in such ways. The user should also be prepared to document
and justify any extraordinary uses of the software to an auditor or verifier in
relation to compliance issues.
99. It is important that there should be consistency in the rating of similar buildings,
otherwise the credibility of the rating procedure is undermined. When software
tools are used and assessors follow a standard set of conventions to minimise
differences that may arise from interpretation, it should be possible to ensure that
consistent results are obtained. On the other hand, using software that does not
have such conventions governing its use may allow inconsistencies between
assessors. Consistency may diminish if the simulation depends on user
interpretation to set appropriate inputs.
The Complexity of the Building and its Services
100. The more complex a building and its building services, the greater the possibility
that it may not be simulated accurately by a user. This is because data entry may
depend on the vigilance and competence of the user to enter all necessary
parameters reliably, and whether any checks on this can be made using the
chosen software (e.g. if it produces a graphical representation to compare with the
actual building).
31 Interface to SBEM.
32 Computer-Aided Design.
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