Two sets of field trials have been run comparing HEAT3D’s measurements with standard ISO 9869 heat flux plate ones. The first using an early version of HEAT3D before the investigations carried out at the Energy House. The second set afterwards, incorporating several significant innovations and improvements to HEAT3D’s methods and apparatus based on the results of the R&D.
Field trials on twenty-five walls were run on multiple properties ranging from an 18th century farmhouse, solid brick Victorian terraced through to new-build eco houses with U values ranging between and 0.1 and 2 W/m2K.
Both HEAT3D and standard ISO 9869 heat flux measurements were performed over a period of 2 weeks at each site. The locations are shown on the map below.
This graph shows the results from the first field trial using the early version of HEAT3D. The results showed poor agreement in terms of HEAT3D’s heat flow measurement accuracy and repeatability compared to the calibrated heat flux plates (HFP).
Several novel breakthroughs were made in solving HEAT3D’s measurement accuracy problems from the results of the first field trial and R&D at the Energy House. The next graph shows the results from the 2nd set of field trials using the latest version of HEAT3D with these improvements. The error bars for both the HEAT3D and Heat Flux plate values are also shown. There is an almost perfect alignment within the limits of measurement accuracy.
The innovations from the R&D work have dramatically improved HEAT3D’s accuracy and repeatability for measuring heat flow. HEAT3D can now measure heat flow to a proven accuracy of 5% for a 20W/㎡ heat flow. This is the same order as that obtained using industry standard Heat Flux plates such as the Hukseflux HFP01.