National Calculation Methodology (NCM) - Scottish Government
National Calculation Methodology (NCM) - Scottish Government 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
egarded as being mechanically ventilated. Any boosted supply rate required to limit overheating must be ignored in the notional and actual buildings. If the mechanical ventilation system only operates in peak summer conditions to control overheating, and during normal conditions ventilation is provided naturally, then the space must be regarded as naturally ventilated, and the mechanical ventilation system can be ignored in both the notional and actual buildings. 39. If a zone is naturally ventilated, the modelling strategy must provide for enhanced natural ventilation in the notional building to prevent overheating. If this is not done, heat will build up and artificially depress the demand for heating the next day, thereby making the energy target unrealistically harsh. For DSMs 13 , the following modelling strategy must be used in the notional building. The strategy must increase the natural ventilation rate to 5 ac/h whenever the space temperature exceeds the heating set-point 14 by 1 K. This enhanced ventilation must cease immediately once the space temperature falls below the heating setpoint. By maintaining the increased natural ventilation until internal temperatures fall to the (high) heating set-point, the temperatures at start-up next day will be neither artificially high nor low. 40. Humidity control is ignored in both the notional and actual buildings. 41. The following fuel must be used for space and water heating services in the notional building: a. Where mains gas is available on site (even if it does not supply any heating services in the actual building), mains gas must be used in the notional building to supply both space and water heating. b. Where mains gas is used for any space or water heating in the actual building, mains gas must also be used in the notional one. This means that if mains gas is used for heating, but another fuel is used to supply hot water (or vice versa), then in the notional building, gas must be used for both services on the basis that it is available. c. Where neither paragraph 41.a nor paragraph 41.b applies, oil must be used for space and water heating services in the notional building. d. For the purposes of this guide, the ‘main heating fuel’ should be taken as the fuel which delivers the greatest total thermal output (space or water heating) over the year. If there are multiple devices served by the same fuel, the relevant total thermal output is the sum of all the outputs for the devices served by that fuel. 13 Such an approach is not needed in SBEM since the form of the model means that there is no feedback between overheating on one day and the energy demands on the next. 14 This guidance assumes that the zone heat output is zero when the heating set-point is exceeded. If models use a proportional band to modulate heating output, the heating set-point in this context should be regarded as the temperature at the top of the proportional band, not its mid-point. 15
- Page 1 and 2: Directorate for the Built Environme
- Page 3 and 4: Contents. Contents 3 List of Tables
- Page 5 and 6: BER Building Emission Rate BSD Buil
- Page 7 and 8: 2 Approved Software Tools. 5. Non-d
- Page 9 and 10: of building or building features. T
- Page 11 and 12: Building Fabric 26. The U-values in
- Page 13: Methods that use flow networks are
- Page 17 and 18: d. The electricity used by fossil-f
- Page 19 and 20: . For other spaces, divide the illu
- Page 21 and 22: Table 6: Carbon dioxide emission fa
- Page 23 and 24: 4 Energy Performance Certificates (
- Page 25 and 26: 5 Input Data to Approved Tools. 74.
- Page 27 and 28: d. Any fuel used in generating the
- Page 29 and 30: Table 8: Measurement and other conv
- Page 31 and 32: pressure filtration is also defined
- Page 33 and 34: Building Type Description 16 Non-re
- Page 35 and 36: Activity Type Description 33 Generi
- Page 37 and 38: Construction and Glazing Databases
- Page 39 and 40: ID Category Construction Name 518 P
- Page 41 and 42: ID Category Construction Name 565 P
- Page 43 and 44: 101. It may also be that more compl
egarded as being mechanically ventilated. Any boosted supply rate required to<br />
limit overheating must be ignored in the notional and actual buildings. If the<br />
mechanical ventilation system only operates in peak summer conditions to control<br />
overheating, and during normal conditions ventilation is provided naturally, then<br />
the space must be regarded as naturally ventilated, and the mechanical ventilation<br />
system can be ignored in both the notional and actual buildings.<br />
39. If a zone is naturally ventilated, the modelling strategy must provide for enhanced<br />
natural ventilation in the notional building to prevent overheating. If this is not<br />
done, heat will build up and artificially depress the demand for heating the next<br />
day, thereby making the energy target unrealistically harsh. For DSMs 13 , the<br />
following modelling strategy must be used in the notional building. The strategy<br />
must increase the natural ventilation rate to 5 ac/h whenever the space<br />
temperature exceeds the heating set-point 14 by 1 K. This enhanced ventilation<br />
must cease immediately once the space temperature falls below the heating setpoint.<br />
By maintaining the increased natural ventilation until internal temperatures fall to<br />
the (high) heating set-point, the temperatures at start-up next day will be neither<br />
artificially high nor low.<br />
40. Humidity control is ignored in both the notional and actual buildings.<br />
41. The following fuel must be used for space and water heating services in the<br />
notional building:<br />
a. Where mains gas is available on site (even if it does not supply any heating<br />
services in the actual building), mains gas must be used in the notional building<br />
to supply both space and water heating.<br />
b. Where mains gas is used for any space or water heating in the actual building,<br />
mains gas must also be used in the notional one. This means that if mains gas<br />
is used for heating, but another fuel is used to supply hot water (or vice versa),<br />
then in the notional building, gas must be used for both services on the basis<br />
that it is available.<br />
c. Where neither paragraph 41.a nor paragraph 41.b applies, oil must be used for<br />
space and water heating services in the notional building.<br />
d. For the purposes of this guide, the ‘main heating fuel’ should be taken as the<br />
fuel which delivers the greatest total thermal output (space or water heating)<br />
over the year. If there are multiple devices served by the same fuel, the<br />
relevant total thermal output is the sum of all the outputs for the devices served<br />
by that fuel.<br />
13<br />
Such an approach is not needed in SBEM since the form of the model means that there is no<br />
feedback between overheating on one day and the energy demands on the next.<br />
14<br />
This guidance assumes that the zone heat output is zero when the heating set-point is exceeded. If<br />
models use a proportional band to modulate heating output, the heating set-point in this context<br />
should be regarded as the temperature at the top of the proportional band, not its mid-point.<br />
15
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