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QUB/e: Validation of a transient method for determining whole building thermal performance and building element U-values in situ under actual operating conditions

Sougkakis, Vasileios; Wood, Christopher; Meulemans, Johann; Gillot, Mark; Cox, Tom

Authors

Vasileios Sougkakis

Christopher Wood

Johann Meulemans

Mark Gillot

Tom Cox

Abstract

Growing evidence in recent years has suggested that a difference exists between the design and the as-built thermal performance of UK dwellings. This difference commonly known as the ‘performance gap’ may have serious implications on the UK government’s emissions reduction targets. Determining the theoretical design thermal performance of whole dwellings (Heat Loss Coefficient, HLC) and building elements (U-value) can be straightforward; however in situ measurements of actual thermal performance can be much more difficult to achieve. Several methods have been developed to measure these properties in situ with the most common usually involve quasi-steady state conditions that necessitate long testing periods. The duration of such tests is deemed impractical from a building access perspective and wider uptake has therefore not been achieved.
The QUB/e method, developed by Saint-Gobain, is a dynamic method used to experimentally measure in-situ the thermal performance of a building in order to determine the whole dwelling HLC and U-values. The method is an advancement on the usual quasi-steady methods as it has the benefit of being able to be performed typically in a single night without occupancy. Validity of results has been demonstrated in a climate chamber under controlled conditions in a previous work. In this work, validation of the QUB/e method is performed under actual operating conditions by conducting a series of measurements on a daily basis in a modern well-insulated property located at the University Park Campus, University of Nottingham. Results were compared to those obtained with quasi steady-state measurements; the HLC was compared to that obtained with a coheating test and the U-values with those obtained by means of the procedure as per BS ISO 9869-1:2014 average method. Good agreement was found for both the HLC (7.5% relative difference between the two methods on average) and the U-values (in most cases the relative difference of the quasi-static and dynamic methods was approximately 2% while in one instance it was 12.5% on average), thereby increasing confidence in the ability of the QUB/e method to provide reliable results and highlights its potential to test the actual performance of buildings.

Start Date Aug 21, 2018
Publication Date Aug 21, 2018
Book Title SET 2018: 17th International Conference on Sustainable Energy Technologies

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