Reframing the Frame of Reference – Using 2-Dimensional Software to Model 3-Dimensional Elements

This presentation initially took place at the 2020 Canadian Building Enclosure Symposium.

There are several means of estimating the thermal performance of building envelope components: good old-fashioned spread sheet calculations, 2-dimensional and 3-dimensional modelling software, and hot-box laboratory testing.

In many cases, a good old-fashioned spread sheet may be sufficient for the task at hand. In some cases, 2-dimensional and 3-dimensional thermal modelling programs may be more appropriate and can provide a cost-effective alternative to hot-box testing. 2D software is an uncomplicated and affordable tool. By employing relatively simply measures (which will be described in the paper), it can accurately represent 3D assemblies. 3D software, in comparison, is a costlier, more complex tool, requiring a higher level of effort by the modeler. Regardless of the software, the accuracy of the model depends heavily on the expertise of the modeler and in all cases, hot-box testing should be used as the benchmark for determining the ‘right’ answer.

This paper aims to demonstrate that when effective means of using 2D software to model 3D elements are applied, both 2D and 3D software, when referenced back to hotbox tests, can produce accurate results, with relative errors in the same order of magnitude. So, while 3D software may be useful, it is not always necessary.

Janette Meyrick

WSP Canada, Ottawa, Ontario, Canada

Janette works with the WSP Building Sciences team in Ottawa, specializing in thermal analysis and coordinating hygrothermal monitoring programs for heritage masonry buildings. She manages WSP’s national Centre of Excellence for Building Physics and Modelling, a national team that connects building physics and modelling business across the country, supporting teams by sharing knowledge, managing internal company processes and documents, and promoting industry reputation. She is a designated Building Science Specialist (BSS).

Janette’s 2D thermal modelling experience spans NFRC window certification simulations, condensation risk analyses, whole building R-value calculations, thermal bridge evaluations, and comparative studies of thermally broken building components.