National Calculation Methodology (NCM) - Scottish Government

More documents

Recommendations

Info

3 Compliance with Building Regulations. 19. Compliance with Standard 6.1 of Section 6 requires that a new non domestic building must show, by calculation, that it is designed to limit carbon dioxide emissions. This is achieved by demonstrating that the building as designed will have emissions no greater than a Target Emission Rate (TER), i.e. the Building Emission Rate (BER) is less than or equal to the TER. 20. The TER is based on the performance of a “notional building” and the following procedure must be followed in order to establish the TER. This approach is adopted to avoid the need to define system models appropriate to different types of building. It also ensures a consistent approach to the target setting process. Definition of the Notional Building 21. As specified in the guidance under Standard 6.1 of Section 6, the notional building must have the same size, shape, and zoning arrangements as the actual building, with the same conventions relating to the measurement of dimensions (see table 8 below). 22. Each space must contain the same activity (and therefore the same activity parameter values) as proposed for the equivalent space in the actual building. The activity in each space must be selected from the list of activities as defined in the NCM Activity Database (see paragraph 75 and Chapter 6 of this guide). 23. The notional and actual buildings must be given the same orientation and be exposed to the same weather. For DSM software 7 , the notional building must be subject to the same site shading from adjacent buildings and other topographical features as are applied to the model of the actual building. 24. Whatever servicing strategy (heating, ventilation, cooling) is specified in a zone in the actual building must also be provided in the corresponding zone in the notional building. Note that in some zones, heating need not be provided, even though the NCM Activity Database specifies a heating set-point. For example, the actual building may contain an unheated stairwell or atrium space. The corresponding zones in the notional building must also be unheated. However, if heating were provided to either of these spaces in the actual building, then heating must correspondingly be specified in the notional building, and then both buildings must heat those spaces to the heating set-point specified for the zone type in the NCM Activity Database. 25. Any building services system not covered by Section 6 must be ignored in both the actual and notional buildings. 7 This does not apply to SBEM where external shading is not modelled.
Building Fabric 26. The U-values in the notional building must be as specified in Table 1. Taking into account guidance in BR 443 8 , all U-values should be calculated in accordance with BS EN ISO 6946: 2007, where the U-values calculation methods are inclusive of repeating thermal bridges. The reference constructions conforming to these Uvalues are identified in Table 1 by their reference identities. In addition, the general guidance beginning at paragraph 78 must be followed. Table 1: U-values of construction elements in the notional building Exposed element U-value (W/m 2 K) Database reference IDs Pitched † roofs 0.16 236 Flat roofs 0.25 291 Walls 0.30 295 Ground and other exposed floors (see paragraph 30) 0.25 248 Windows * and rooflights 2.2 ‡ See Table 3 External personnel doors 2.2 480 Vehicle access and similar large doors 1.5 261 Internal walls 2.0 307 Internal windows 3.85 481 Internal floors viewed from room above 1.25 355 Internal floors viewed from room below 1.23 315 † o o A pitched roof is one with a pitch greater than 10 and less than or equal to 70 . Any part of a roof with a pitch greater than or equal to 70 o is considered a wall. ‡ This U-value relates to the performance of the unit in the vertical plane. The U-value must be adjusted for slope as detailed in section 11.1 of BR 443. * Glazed doors are treated as windows (see Table 8 below). 27. In addition, the U-values of display windows must be taken as 5.7 W/m 2 K in both the notional building and the actual building. 28. Smoke vents and other ventilation openings such as intake and discharge grilles must be disregarded in both the notional and actual buildings, and their area substituted by the relevant (i.e. immediately surrounding) opaque fabric (roof or wall). 29. Non-repeating thermal bridge heat losses for each element (including windows, etc.) must be accounted for by using the ψ (psi) values specified in clause 6.1.4 of Section 6. Note that the U-values as given in Table 1 do not include any allowance for heat losses through non-repeating thermal bridges, and so the calculation tool must make the adjustment explicitly. 8 Conventions for U value calculations, BRE, 2006. 11
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: of building or building features. T
Page 13 and 14: Methods that use flow networks are
Page 15 and 16: egarded as being mechanically venti
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

National Calculation Methodology (NCM) - Scottish Government

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?