Build Test Solutions adopt HEAT3D technology

Build Test Solutions now offer  HEAT3D technology as a key part of their toolkit for Rapid U value measurements in Building energy performance monitoring, diagnostics, quality assurance & compliance testing solutions for the built environment.

Heat3D mobile app and FLIR ONE Pro on an iPhone

BTS Heat3D infrared thermography kit

Heat3D is designed to work on iPhones and iPads and uses a portable thermal camera to obtain results in a matter of hours as opposed to days or weeks using traditional techniques.


  • Heat3D iOS mobile app
  • Sensors, targets and equipment
  • FLIR ONE Pro thermal camera

You can read more about the BTS HEAT3D solution here:-

HEAT3D U value accuracy

HEAT3D has now been proved to measure U values accurately.  A third field trial was carried out using HEAT3D’s innovative and unique time lapse survey procedure which takes less than 1.5 hours resulting in U-value measurements across a whole wall surface. This improves upon two key limitations of the existing standard method using heat flux plates, the length of the measurements (ISO9869 requires at least 72 hours and two visits to site) and their limitation to only the small area covered by the sensor. Heat3D therefore enables a less disruptive, more insightful and cost-effective testing method. The measurements were compared with ISO9869 measurements of the walls taken at the same time.

The results are very positive, with a close and direct relationship between the measurements by Heat3D and by heat flux plates according to ISO9869. In total 42 Heat3D surveys were compared with an ISO9869 U-value measurement across 14 different walls. In 36 of the surveys the U-value measurement by Heat3D fell within the combined uncertainty interval of the ISO9869 measurement. There was very close agreement between the two methods for U-values above 0.2W/m

The surveys were carried out across a wide range of locations around England and Wales with one property measured before and after the application of additional external wall insulation.

A range of building ages were surveyed with the majority of tests carried out on cavity walls

A detailed validation report is available. For more information please email us at:-

HEAT3D heat flow accuracy

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).

First Field trial results

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.

Second field trial results

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.



HEAT3D and the Energy House

HEAT3D has been successfully tested in the unique Energy House facility at Salford University and proved to measure heat flow accurately. The Energy house is the only fully climate controlled research facility in the world.

The test walls were massively instrumented with calibrated Heat flux plates and thermocouples so HEAT3D’s results could be compared with the standards based values using current best practice ( ISO 9869 parts 1 & 2).

Energy house instrumentation

This is a HEAT3D thermal model captured from one of the surveys. You can view it in full AR mode in Safari on an iOS device with iOS 12 or later. Just tap on the the image to launch the iOS AR viewer.

HEAT3D captured IR model

Several significant novel improvements to the initial HEAT3D apparatus and method were made based on the experimental results. HEAT3D was then re-tested. The graph below shows the comparison between the heat flow measured by conventional heat flux plates (blue) and HEAT3D surveys (orange ) over a 2 week period with the Energy House driving varying heating and temperature regimes including a very artificial sunny day right at the end where the heat flow went negative. HEAT3D’s measurements tracked perfectly.

HEAT3D and HFP measurements over a 2 week testing period


Comparison of HEAT3D heat flow measurements with the calibrated Heat Flux plate ones