Versatile lab-scale test rig for experimental analysis and heat transfer modelling of thermally activated building systems

Thermally activated building systems (TABS) constitute an energy efficient building conditioning solution through the combination of low-exergy space heating and cooling and thermal energy storage (TES) features. Their implementation is, however, complex, due to the number of factors involved in their design and operation. Mathematical models are useful to overcome this, but require validation, while experimental setups to study sensible TES can be bulky and difficult to handle. In this work, a homogeneous concrete slab and a multilayer concrete-sand-gravel slab are built and activated with constant heat flow. Both slabs are experimentally tested and their thermal behaviour is modelled through a 1D finite difference method (FDM). Results demonstrate that materials such as sand and gravel can be used to provide relevant experimental data for TABS heat transfer model validation through a versatile lab test rig. A 1D FDM proves to be a simple, accurate method to predict the thermal behaviour of the slabs during transient peaks in charging and discharging processes as well as during steady-state operation, given that most of the time absolute errors remain below the measurement uncertainty thresholds. Finally, this paper sets a basis to support future experimental work on sensible TES and provides data for further model validation.