Measured Energy Performance- Behind the Scenes

Measured Energy Performance- Behind the Scenes

Measured Energy Performance is our service that can help evaluate and monitor the performance of your retrofit projects. Measured Energy Performance (MEP) utilises accurate measurements of the Heat Transfer Coefficient (HTC) of the property in question, along with an RdSAP-style survey in order to produce a more accurate EPC rating for a property.

Property survey

Before any monitors are installed, a survey of the property is conducted. Details on the physical geometry of the property, its construction and details on the heating system are taken in order to produce an RdSAP assessment of the property. The thermal performance of the building is based upon the age of the property, in accordance with Appendix S of SAP. Therefore, the actual performance of the property may not be accurately accounted for; some properties will inevitably perform better, and some will perform worse than is estimated from RdSAP.

House survey

Retrofit Monitoring

Once the survey has been completed, the sensors are installed. These are small, battery-powered sensors that record the temperature and humidity within the property. Four of these are used in the property, covering the kitchen, bathroom, bedroom and living room, in order to get an average across the property. Once these are in place, meter readings of both gas and electric are taken, and the initial site visit is done. The sensors must be left in place for at least three weeks during the heating season (October to March inclusive), as a temperature differential is required between the internal and external environment that cannot be guaranteed during the summer.


Following the monitoring period, the sensors are collected (along with taking final meter readings), and the HTC of the property is produced. This HTC is used in our bespoke software, which allows us to manipulate SAP beyond the normal software interface, in order to see how the actual HTC impacts upon the EPC rating. A report for the property, in the style of a traditional EPC, is then issued, demonstrating the rating that the property would have if the measured HTC is used instead of that calculated by SAP; a more accurate representation of the performance of the property in reality.


MEP is most effective when used as an evaluative tool for retrofit projects. Using two monitoring periods, before and after retrofit works take place, offers a method to measure the HTC of a property rather than rely upon the SAP software, which may not always reflect reality. Comparison of the HTC, as well as the EPC rating of the property before and after retrofit works are conducted produces quantitative data, invaluable for demonstrating the outcomes of retrofit works in a way that simple questionnaires simply cannot. Putting hard evidence behind claims of improvements is crucial in any professional environment, and retrofit projects are no different; MEP can be used as a part of meeting the PAS 2035 requirements for monitoring and evaluation.

Want to find out more about MEP?

We will be running a number of sessions where you can find out more about MEP and start offering the service yourself. Register your interest here.

Article published 29/11/21

Elmhurst Energy Services Ltd. 16, St Johns Business Park, Lutterworth, Leicestershire, LE17 4HB

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