Minimum Energy Efficiency Standards MEES
Case Study- benefit of using Dynamic simulation (DSM) to calculate EPC ratings and comply with MEES
Most EPC are calculated using the Simplified Building Energy Model (SBEM) which models the building using relatively simple algorithms based on monthly averages. The more sophisticated Dynamic Simulation Software (DSM) uses an annual weather files which allow more accurate modelling of solar gains and daylighting. This is particularly beneficial for cooling dominated buildings where there is significant self shading or shading from surrounding buildings.
The case study compares the EPC rating calculate using DSM with that using SBEM for a 1980s deep plan office with central courtyard with buildings on three sides with a constant volume HVAC system and fluorescent lighting fitted with magnetic ballasts.
The EPC rating calculated using DSM is F129 compared with G198 using SBEM, a whole band better. When the lighting is upgraded to LEDs with occupancy and daylight sensors the EPC rating calculated using DSM is E115, meaning the building complies with MEES, while the rating calculated using SBEM is two whole bands lower at G160.
The benefits of the more accurate modelling using DSM become apparent when we examine the CO2 emissions. Firstly DSM more accurately calculates the benefits of daylight sensors to dim the lights when there is sufficient daylight. Secondly DSM also allows for the reduced solar gains from shading. Both effects lead to reduced use of electricity leading to lower CO2 emissions and a better EPC rating.
Landlords, recalculating the EPC rating using DSM instead of SBEM may be sufficient for the building to comply with MEES without the need to invest in improvement measures.
The full case study can be downloaded here