Urban microclimate prediction prior to dynamic building energy modelling using the TEB model as embedded component in TRNSYS

Abstract

This paper is a contribution towards the link between urban microclimate and building energy modelling using the Town Energy Balance model TEB as a new component embedded into the non-stationary building energy model TRNSYS. A number of comparative features between TEB and TRNSYS motivated this work, which includes commensurate time processing speed, similarity in describing the building facets, comparable inputs and simulation time scope, and the versatile modular architecture of TRNSYS. The paper describes the parameter tabs, inputs and outputs of TEB-Type 201, which offers (i) a user-friendly graphical interface, (ii) short time for data pre-processing with consistency check of inputs, (iii) versatility in selecting and storing outputs in small-sized files and (iv) easy installation. Besides illustrating the capabilities and practicality of this new component, an extensive sensitivity analysis highlights in a hierarchical form the main decisive urban and building parameters responsible in the formation of urban canopy heat or cool islands. The anthropogenic heat, the canyon geometry (aspect ratio, roof plan density) as well as the thermo-physical and radiative properties of the building envelope (thermal insulation, thermal inertia, albedo, emissivity) considered individually or in combination with each other appear to have clear effects on the formation of a microclimate in-canyon on the one hand, and in the magnitude and frequency of canopy heat or cool island episodes at daily and monthly basis on the other hand. The warming of canyon air is heavily influenced by the combination of high urban density (deep canyons and high plan density), high level of anthropogenic heat and weak thermal insulation. Low emissivity, no or low anthropogenic heat, better thermal insulation and low thermal mass favour the cooling of the canyon. These findings reveal the decisiveness of urban and building design choices on the outdoor thermal environment and hence on the energy demand for heating and cooling indoors. As outlook, the paper also notes the necessity of a synchronised coupling of urban canopy and building energy models.