(2) what assessment she has made of the performance of the software model iSBEM that has been launched in support of the new building regulations L2; and if she will make a statement.
The simplified building energy model (SBEM) was developed to conform to the emerging European standards for energy calculations and therefore it has incorporated those energy flows for which procedures have been developed in the draft European Standards (prENs).
The impact of thermal mass on energy demand is included in the energy calculation as far as its impact on normal heating and cooling strategies are concerned. SBEM does not address night cooling strategies because this is difficult in a monthly calculation method like SBEM. It was always recognised that certain design features would not be included in early versions of SBEM, and that is why the Government included in the overall national calculation methodology the option to use more detailed hourly simulation models, which can address features such as night cooling. This means that options exist whereby any design strategy can be assessed in terms of its contribution at achieving compliance with part L.
The SBEM calculation method has been developed in close discussion with industry who have been provided with beta test versions and invited to test the tool and provide feedback on their experience. The tool has also been used on a number of case studies in both this country and abroad.
Passive heating techniques are recognised in the Government’s standard assessment procedure (SAP) for the calculation of energy efficiency. It is intended to use SAP in the code for sustainable homes, and accordingly the code will give credit for passive heating techniques.