why use heat loss measurement?
Our research has shown measurement to be more accurate
The MEASURED project team carried out a government-funded study where the measured and BS EN12831 calculated heat loss was compared for 56 homes of different sizes, types and ages. The calculated heat loss only matched the measurement to within its uncertainty margin for 30% of homes, this means that for 70% of homes a heat pump would be incorrectly sized using a BS EN12831 heat loss calculation.
How BS EN12831 incorrectly estimates the true heat loss
The average absolute difference between the calculated and measured heat loss was 35%, with a range of 36% undersized to 144% oversized. There was a significant bias towards overestimating the heat loss, with 59% of houses having an overestimate which would lead in turn to an oversized heat pump. An oversized heat pump would incur higher capital costs, estimated to be 10% on average for the heat pump alone in this sample, greater likelihood of a requirement to replace heat emitters with consequent cost and disruption, and possibly lower running efficiency over time.
There were also 13% of houses for which the heat loss was undersized by a heat loss calculation, for these houses there would be a risk that the specified heat pump wasn't sufficient to keep the house warm during the coldest periods.
Quicker & Easier
In our field trial, installers found heat loss measurement easier and quicker to carry out than heat loss calculations, in addition to adding greater accuracy and confidence in the design process.
Simple to Integrate
Elmhurst have developed a BS EN12831 Heat Loss Calculator which allows the simple entry of a measured Heat Transfer Coefficient to calibrate the calculation for better accuracy of room-by-room heat loss for emitter sizing, as well as overall space heating requirement.
The report below contains detailed information & results of the study that the measured team have carried out.
Heat Measurement Report v003.pdf