Implementation of a building energy model in an urban canopy parameterization

The generation of heat in the buildings, and the way this heat is exchanged with the exterior can play an important role in urban climate. In this contribution, a Building Energy Model (BEM) is developed and implemented in an Urban Canopy Parameterization (UCP) for mesoscale models. BEM accounts for: diffusion of heat through the walls, roofs, and floor; ventilation; radiation exchanged through windows; longwave radiation exchanged between the indoor surfaces; generation of heat due to occupants and equipments; air conditioning and heating. Buildings of several floors can be considered and, from the processes mentioned above, the time evolution of indoor air temperature and moisture are estimated for every floor. The links between BEM and UCP are as follows: UCP (and the mesoscale model in general) gives to BEM the outdoor air temperature (needed for the ventilation and the estimation of the wall temperature) and the radiation reaching the wall for the computation of the amount of radiation entering in the building through windows (in the UCP used in this study a radiation is computed for every floor and for every specific orientation of the street). On the other hand, BEM gives to the UCP the wall temperature (needed to estimate the sensible heat flux from the wall), the heat flux due to ventilation, and the heat flux due to processes linked with the generation of energy within the building (e. g. air conditioning). Results obtained with BEM are compared to results obtained with a more sophisticated (and more CPU time consuming) model usually employed in architecture. The expected results of this study are to:

• Improve the capability of mesoscale models to simulate urban canopy climate (urban heat island processes, etc.).

• Allow the estimation of meteorologically related building energy consumptions (e. g. due to air conditioning in summer, or heating in winter).

In conclusion this work is a step towards a modeling tool that can account for the complex interactions between urban climate, air pollutant dispersion, and energy demand of buildings. Such tool can be an important support to urban planners.