Multi-Level Modelling of residents’ exposure to heat

Urban areas experience elevated nighttime temperatures in comparison to their rural
surroundings, a phenomenon known as Urban Heat Island (UHI). This phenomenon
exacerbates the heat stress experienced by urban dwellers during heat waves, which are
becoming more prevalent and intense due to climate change. The indoor temperature and,
consequently, the heat stress experienced by occupants within residential structures is
contingent upon several factors, including: the solar exposure of the structure, the materials
utilized, and its specific floor level. For instance, top-floor apartments experience greater
solar exposure. To better assess the indoor heat stress and optimize energy consumption for
heating and cooling at the city scale, the focus of this paper is on improving the Building
Energy Model (BEM) integrated into the Town Energy Balance (TEB) urban climate model.
A key enhancement involves the implementation of a multi-storey energy balance for more
accurate representation of temperature variations across building levels.
BEM currently treats buildings as a single, homogeneous thermal zone, which limits its
ability to capture temperature distribution and energy use between storeys. The enhanced
model differentiates individual floors, considering their functions, such as commercial spaces
or residential units, as well as unique boundary conditions, including increased solar exposure
on upper levels. The model solves prognostic equations for indoor temperature and humidity
at each level, and it integrates a refined representation of the building envelope, including
thermal bridges, to improve heat exposure estimates and energy demand predictions. The
TEB-BEM model is evaluated at the building and urban scales through comparisons with
EnergyPlus simulations and data from urban measurement campaigns. Ultimately, this study
will contribute to a better understanding of the impact of urban climate on the thermal
comfort of inhabitants and building energy consumption, thus providing decision-making
tools to help cities adapt to the challenges of climate change.