Heat3D

Heat3D directly measures building energy loss and U-Value quickly and cheaply, making energy saving opportunities visible and quantifiable.

Background

The thermal behaviour of old buildings is very poorly understood and existing models and assumptions about U values have proved to be very inaccurate in assessing their performance. The performance of new buildings is often underestimated or neglected during its construction and operation. It is well known in the building industry that there is very often a significant difference between the predicted energy requirement using calculated U values and the actual building performance, it can be over 40% out.

A heat flux meter (HFM) is typically used to determine the U-value, a key parameter for assessing the thermal quality of the building envelope in steady-state conditions. However, this non-invasive test takes at least 72 hours to execute, the accuracy is  rarely better than 28%, and it is not reliable for non-homogeneous building elements. An alternative technique is based on infrared thermography (IRT). Although it is generally used for qualitative analysis, quantitative internal IRT methods can be adopted for in-situ measurement of the U-value based on physics models of radiation and convective heat transfer.

The Heat3D solution uses a development of the quantitative internal IRT method, combining two new and cheap technologies to provide a low cost handheld instrument offering a quick and highly visual measurement of the heat flux through a building surface in Watts, along with its U value. These measurements can then be used to provide quantitative input to future domestic EPCs (Energy Performance Certificates), to allow before and after measurement of U values during refurbishment of existing buildings to improve insulation, and to check a new building’s performance meets predicted/designed U value expectations.

The Heat3D Device and Operation

An iOS device running the Heat3D application is paired with a FLIR One Infrared camera module. The Heat3D application captures and displays the 3D model of the room being measured using the iPhone or iPad camera and Apple’s ARKit framework. The FLIR One camera captures and overlays the IR thermography image of the walls and surfaces on the model capturing the temperature at each IR pixel. The ambient inside temperature is measured using a blackbody radiator (black cardboard with a QR code on it) positioned inside the room (typically several cm from the wall surface). The incident radiant temperature on each wall is measured using the temperature from a crumpled silver foil square attached to the wall (again with a QR code on it) Tref. These are captured and recorded using the Heat3D app and FLIR One camera as the room is scanned. The outside temperature of the surface is measured using the ambient temperature outside, again with the FLIR One camera or a thermocouple. The wall emissivity can be measured by comparing the IR temperature of a black piece of card closely attached to the wall surface and the temperature of the wall surface.

The heat flow and U value is then calculated for all the points on each wall and displayed on the visual model. A value for the cost per Kw of heat energy can be used to display the cost of the heat going through the wall.

The total Heat Flow and averaged  U value of each wall is also calculated and displayed on the model. The 3D models also capture the room dimensions (wall areas, heights and room volume). GPS location, orientation, date, time and local weather conditions can also be captured at the same time. All associated data can be saved, shared and viewed again later. The captured 3D models could be integrated with a BIM (Building Information Model) to provide an overall building assessment.

There is a short 1 minute video demonstrating how to use HEAT3D with the FLIRONE Pro camera here:- https://youtu.be/a4eXaoUoLzM

Acknowledgements

Research and development of the prototype Heat3D solution has been part-funded by an Energy Game Changer award from Innovate UK.

Contact Information

For a copy of our technical white paper, further discussion or to arrange a demonstration of the Heat3D solution, please contact:

Steve Bennett
Electric Pocket Limited

Email: steve@electricpocket.com