National Calculation Methodology (NCM) - Scottish Government

c. If the total area of these elements is less than the appropriate allowance from
clause 6.1.4 of Section 6, the balance must be made up of windows or
rooflights as appropriate.
d. If the total area of the copied elements exceeds the allowance from clause
6.1.4 of Section 6, the copied areas must be retained, but no further area of
windows or rooflights added. As noted in paragraph 28, smoke vents and other
ventilation openings must be ignored in both the notional and actual buildings.
e. The areas shown in clause 6.1.4 of Section 6, represent the areas of openings
in the wall or roof and comprise the area of the glass plus the frame. The
windows must have a frame factor of 0.1 (i.e. 90% of the area of the opening is
glazed) and rooflights a frame factor of 0.3 (display windows have a frame
factor of 0.1).
36. In addition, the following rules apply:
a. In the notional building, pedestrian and vehicle access doors must be taken as
being opaque, i.e. with no glazing.
b. No glazed area should be included in basements. In semi-basements, i.e.
where the wall of the basement space is partly above ground, the percentages
in clause 6.1.4 of Section 6 must include the above-ground part, with no
glazing allowance for the below-ground part.
HVAC 12 System Definition
37. Each space in the notional building will have the same level of servicing as the
equivalent space in the actual building. In this context, “level of servicing” means
the broad category of environmental control, i.e.
a. Unconditioned (i.e. neither heated nor mechanically cooled)
b. Heated only with natural ventilation
c. Heated only with mechanical ventilation
d. Air-conditioned (i.e. heated and mechanically cooled)
e. Mixed-mode cooling, where cooling operates only in peak season to prevent
space temperatures exceeding a threshold temperature higher than that
normally provided by an air-conditioning system. This can be accompanied by
either natural or mechanical ventilation.
38. A space is only considered as having air-conditioning if the system serving that
space includes refrigeration. Night cooling using mechanical ventilation is not airconditioning.
If the same mechanical ventilation system that is used for night
cooling is also used to provide normal ventilation, then the space should be
12 Heating Ventilation and Air Conditioning.
14