Modern electric storage heaters, if classified as ‘high heat retention’ can benefit from a more favourable rating of some performance aspects when assessed using SAP2012 (The Government’s standard assessment procedure for energy rating of dwellings).
To qualify as high heat retention, products have to be tested and show 45% heat retention when tested in accordance with EN60531:2000 (as stated in SAP 2012 clause 9.2.8). This requires a ventilated calorimeter of particular size calibrated for heat loss under various conditions.
BSRIA has a calorimeter with associated instrumentation at the BSRIA North premises to determine the heat retention. The results and report generated can be submitted to BRE, who administer SAP on behalf of The Department for Business, Energy and Industrial Strategy (BEIS) for inclusion within their product listing.
The test methods from the European standard used are:
Clause 8.1 - Continuously charge in the minimum discharge condition in the test corner until the charging control switched off automatically for the first time. Energy consumption is stated as the continuous nominal charge. Charging time is the continuous charging period in hours and minutes.
Clause 10 - Repeat of clause 8.1 within the test calorimeter with the calorimeter ventilation rate set using the calibration curves. When the storage heater achieves the same value as that in the continuous charge acceptance test the charge is stopped and heater is switched to give minimum discharge. Heat loss is calculated using the pre-determined calibration curves, with the heater discharging for 16 hours.