The methodology and software for the production of EPCs have a few unexpected consequences. Here are a few of the significant features to be aware of.
De-Stratification Fans.
The presence or absence of de-stratification fans in a heated workshop or warehouse space is probably the single most influential feature in the model. The rating always improves significantly when de-stratification is included. It can only be assumed that this reflects the improvement in actual performance where fans are installed.
Property Type.
This is an equally significant feature, but can be open to the subjective opinion of the assessor. For a typical (larger) unit in an industrial estate, three property ‘types’ or classifications are normally appropriate. These are ‘Industrial Process’, ‘Warehouse’ and ‘Workshop /Maintenance’. For identical building data, the variation of the ‘type’ between these three options will gave a large variation in EPC rating. Industrial will be significantly better, and workshop slightly poorer than warehouse.
The difference arises from the underlying assumptions about the heating, ventilation and lighting of the main space which is consistent with the activities described.
Air-Tightness
For a newer building, if an air-tightness certificate is available, use of the certified figure will usually make a significant difference.
Insulation
With regard to the fabric of the building, roof insulation is unsurprisingly the most significant. Where large areas of glazing are present this is also important.
Heating sources
Among the traditional and frequently encountered methods of heating, electric is significantly worse than all others. Heat Pumps (air-conditioning run as a heater) are the best. Unfortunately it is also common to find both of these serving an office area. Ill-advised occupants use the electric heating in the winter, and the air-con in the summer only for cooling. EPC rating and bills fall dramatically when the air-con is used to heat as well as cool.