Multi-Storey modeling of residents’ exposure to heat in the urban canopy model TEB

The Urban Heat Island (UHI) effect describes the phenomenon whereby, during the nighttime, cities experience higher temperatures than the rural surroundings. This phenomenon amplifies indoor and outdoor heat stress for city residents during heat waves, which are becoming more frequent and intense as a result of climate change. Several factors determine the indoor temperature experienced by the occupants of buildings, including the building’s solar exposure, the materials used in its construction, and the storey on which it is located. For instance, during heat waves, people living on the upper storeys of buildings suffer greater thermal discomfort, which can lead to an increase in morbidity. To evaluate indoor comfort, the urban processes at the city scale (e.g. UHI) and the building‑level processes must be simulated simultaneously. This is achieved by coupling an Urban Canopy Model (UCM) with a Building Energy Model (BEM). Consequently, this work focuses on improving the BEM included into the Town Energy Balance (TEB) urban climate model, with the goal of better assessing indoor heat stress and city‑wide heating and cooling energy consumption. A significant improvement is the implementation of a multi‑storey energy balance model that represents indoor air temperature, specific humidity, and mean radiant temperature across the building storeys. All processes that were once modeled as averages over the entire building are now modeled storey‑by‑storey. For instance, shutter operation and window opening are simulated separately for each storey.

The improved TEB‑BEM is validated by comparing its results with newly conducted measurements from the VERTIC (Vertical Evaluation of Residential Indoor Comfort) campaign. The measurement campaign is conducted in a single, unoccupied building (a former student residence) that features two sets, West and East-facing, of four vertically stacked bedrooms. Continuous recordings of air temperature, relative humidity, mean radiant temperature, and conductive heat fluxes through the envelope are taken for each room throughout a full year in Toulouse. The meteorological forcing data required for TEB simulations is also collected. The results from the VERTIC campaign, launched in October 2025 and still in progress, will be presented with a particular emphasis on the differences between temperature and thermal comfort on different storeys (e.g. ground storey compared to top storey). The evaluation results for the improved TEB-BEM will also be presented.

Ultimately, this research will increase our understanding of how urban climate affects occupants’ thermal comfort and building energy demand while delivering decision‑support tools that enable cities to design effective adaptation strategies for climate change challenges.