- SHEFFIELD
Head Office:
- SWINDON
Southern Regional Office:
- BARNSLEY, COLCHESTER,
- DERBY, HEREFORD,
- MANCHESTER, NORTHAMPTON,
- SALISBURY, SURREY & YORK
Regional Bases:
Frequently Asked Questions
Energy Information Pack >Free Advice and Quotation >
What is NCM?
The National Calculation Method for the EPBD (Energy Performance of Buildings Directive) is defined by the department for Communities and Local Government (CLG). The procedure for demonstrating compliance with the Building Regulations for buildings other than dwellings is by calculating the annual energy use for a proposed building and comparing it with the energy use of a comparable 'notional' building. Both calculations make use of standard sets of data for different activity areas and call on common databases of construction and service elements. A similar process is used to produce an 'asset rating' in accordance with the EPBD. The NCM therefore comprises the underlying method plus the standard data sets. More details can be obtained at the following link:
What is SBEM and iSBEM?
SBEM stands for Simplified Building Energy Model. SBEM is a computer program that provides an analysis of a building's energy consumption. SBEM estimates the monthly energy use and carbon emissions of a building. iSBEM is the Interface tool for the Simplified Building Energy Model developed for CLG in compliance to the EPBD.
Can iSBEM be used in Scotland and Northern Ireland?
iSBEM can now be used for compliance with Building Regulations Part F in Northern Ireland. The iSBEM_v2.0.c is now suitable to use with the Scottish Building Regulations Section 6.
What is the notional building?
This is defined in the Advisory Documents. In essence, it is a building of the same size, shape and use as the actual building, but with U-values etc that are just compliant with the 2002 regulations.What are the improvement factors required for different ventilation strategies?
| Building services strategy for the actual building | (a) Improvement factor |
(b) LZC benchmark |
Heated and naturally ventilated |
0.15 |
0.10 |
|
Heated and mechanically ventilated |
0.20 |
0.10 |
|
Air conditioned |
0.20 |
0.10 |
The overall improvement on the CO2 emissions of the building required is a function of the improvement factor and the LZC (Low and Zero Carbon Technologies) benchmark. For example, the improvement factor for an air conditioned space would be (1 - 0.2) x (1 – 0.1) = 0.72 x Cnotional. Therefore a 28% improvement is required over the 2002 standard.
When is SBEM not appropriate?
Buildings that encompass properties which vary non-linearly over periods of an order of an hour, may not be able to be accurately modelled using SBEM. Similarly buildings which encompass large atria may also present problems. In these instances it may be more appropriate to use a thermal simulation package.
For a block of flats should SBEM be used for the common areas (corridors and reception)?
Each flat is a separate dwelling and must
be assessed using SAP (the
relevant guidance is in ADL1A). However, the common areas in the
flats are not classified as dwellings. As stated in ADL1A paragraph
14, the appropriate approach to compliance depends on whether the common
areas are heated or unheated. If the common areas are heated,
the guidance in ADL2 should be applied using SBEM.
Limiting U-Values
Table 4 Limiting U-value standards (W/m2•K)
Element |
(a) Area- weighted average |
(b) For any individual element |
Wall |
0.35 |
0.70 |
Floor |
0.25 |
0.70 |
Roof |
0.25 |
0.35 |
Windows, roof windows, |
2.2 |
3.3 |
Pedestrian doors |
2 |
|
Vehicle access and similar large doors |
1.5 |
|
High usage entrance doors |
6.0 |
6.0 |
Roof ventilators |
6.0 |
6.0 |
What are the requirements for Existing Buildings?
Domestic
Extensions
For
extensions there are three potential ways to comply with L1b.
Option 3. Show emissions for the actual dwelling plus actual extension is better than the actual dwelling plus notional extension using SAP.
Option 1 and 2. require alternative calculations.
Material change of use
For
material change of use there are two theoretical ways to comply with L1b
Option 1. Paragraph 61 L1b demands an energy rating certificate. This demands a SAP calculation i.e. using option 2. It is not clear therefore under what circumstances it would be appropriate to use option 1.
Option 2. Calculate whole building CO2 emissions using SAP.
Non Domestic
Extensions
A
large extension is treated as new build if it has an area larger than 100m² AND greater than 25% of the existing floor area. There are
three potential ways to show compliance.
Option 3. SBEM calculation.
Option 1 and 2. require alternative calculations.
Material change of use
For
material change of use there are two theoretical ways to comply with
L2b
Option 2. SBEM calculation
Option 1. Alternative requirements to demonstrate compliance
Can BREEAM Offices assessments be carried out on both new and existing office buildings?
Yes, non occupied or occupied, as follows:
New build or refurbishment: design & procurementExisting office (occupied): management & operation
What BREEAM Rating can I achieve?
PASS, GOOD, VERY GOOD OR EXCELLENTWhen should I contact a BREEAM Assessor?
At the concept design stage (or as early as possible in the design process) an assessor should be involved to ensure the performance of the building is maximised for least capital cost.
Why is Energy Important?
The CO2 emitted from the operation of buildings in the UK accounts for
over 50% of the total UK CO2 emissions. If you include CO2 from manufacturing.
