Frequently Asked Questions - Energy - SAP, EPC, DEC & SBEM

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:

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.

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.

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.

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.

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.

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.

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.

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

Yes, non occupied or occupied, as follows:

PASS, GOOD, VERY GOOD, EXCELLENT OR OUTSTANDING.

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.

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. Building Energy Certification - FAQ's

Yes, whenever a building is constructed, sold or rented out, a certificate detailing its energy performance must be made available. This can either be to the owner or, by the owner, to the prospective buyer or tenant. No certificate may be older than 10 years.

Only individuals who:
• prove competence through examination with their chosen assessment tool
• demonstrate their competence, either by a recognised qualification from an awarding body or approved prior experience and learning equivalent to the National Occupational Standard requirements
• maintain appropriate professional indemnity cover
• maintain Continuous Professional Development
• participate in the accreditation body’s quality assurance scheme

Yes, there are three levels of accreditation. An assessor must work within the limitations of their qualification. The levels are:
• Level 3 - simple existing non-dwellings; small buildings such as converted houses or doctors surgeries
• Level 4 - new and existing non-dwellings: e.g. office buildings
• Level 5 - new and existing non-dwellings involving complex natural ventilation strategies and/or large glazed atria

Results and certification can usually be produced within one week of receipt of all information and an official order.