Volume element model for 3D dynamic building thermal modeling and simulation

We present herein the development, experimental validation, and application of a volume element model for 3D dynamic building thermal simulation. The 3D spatial domain in the VEM is discretized with lumped hexahedral elements using ray crossings and ray/triangle intersection techniques that yield sufficiently accurate geometric representation of a building. Subsequently, energy balance is applied to each element in the mesh, and the resulting system of ordinary differential equations is integrated in time to obtain spatiotemporal indoor temperature and relative humidity fields. In this work, we adjusted the model by comparing the simulated indoor air temperatures to the experimental measurements as we calibrated model parameters with high uncertainty. The adjusted model was validated using different experimental data sets, and the numerical results were in a good agreement with the measurements. We employed the validated model to conduct a case study in which the sensible heat gain and loss as well as the time lag were evaluated as functions of different envelope thermal masses. Results showed the trivial effect of floor thermal mass on heat gain, and the changes in sensible heat gain and envelope thermal mass were not linearly proportional, alluding the existence of an optimal envelope design. •We present vemBUILDING, a 3D dynamic building thermal simulation tool.•We elaborate the mathematical formulation and experimental validation of the tool.•Indoor temperature measurements were used to adjust and validate the model.•Heat gain, loss, and time lag were analyzed for different envelope thermal masses.•The change in building heat gain and thermal mass is not linearly proportional.