Heat waves in Berlin, Germany -- Climate projections
Final Report Abstract
We developed the urban parametrization scheme DCEP-BEM and implemented it into the regional climate model COSMO-CLM. The new BEM component considers indoor conditions including heating and cooling. It is thus able to calculate the energy demand for heating and cooling, and the anthropogenic heat emitted into the atmosphere depending on the outdoor conditions such as incoming solar radiation and air temperature. We successfully evaluated the model with outdoor and indoor measurements in Berlin (Germany). In particular during the studied winter period, the consideration of anthropogenic heat from buildings proved to be crucial for a realistic computation of the urban heat island intensity. DCEP-BEM can be applied to arbitrary meteorological conditions and urban forms. In our project, we studied the impact of different air conditioning (AC) systems on the outdoor thermal environment in Berlin during a summer period in 2018. We investigated two locations where the AC outdoor units were installed: either on the wall of a building (VerAC) or on the rooftop of a building (HorAC). We found that the latter had an overall smaller impact on near-surface air temperatures. We compared the AC energy consumption at different locations and noted that the daily average AC energy consumption per floor area was of about 35 % higher at an urban site than at a suburban site due to urban heat island and different building configurations. We also identified that the AC energy consumption decreased considerably as the target indoor temperature increased. Furthermore, we studied how a rather coarse regional climate model can be used to estimate average values of the microscale heat stress parameter mean radiant temperature (Tmrt ). To this end, we developed an approach to diagnose this parameter within DCEP-BEM, and compared results with measurements and results from a microscale model. Overall good agreement was found between both models. While nighttime values of DCEP-BEM were closer to measurements than the other model due to the dynamic calculation of the surface temperatures within DCEP-BEM, Tmrt during the afternoon hours modeled with DCEP–BEM was underestimated compared to the other model. Further, excluding vegetation, higher values for nighttime Tmrt were found in the densely built-up city centre than in the suburbs with more open structures, while the city centre had lower values for Tmrt during midday.
Publications
- (2020). “Impact of Air Conditioning Systems on the Outdoor Thermal Environment during Summer in Berlin, Germany”. In: Int. J. Environ. Res. Public Health 17.13
L. Jin, S. Schubert, M. Hefny Salim, and C. Schneider
(See online at https://doi.org/10.3390/ijerph17134645) - (2021). “Estimation of mean radiant temperature in cities using an urban parameterization and building energy model within a mesoscale atmospheric model”. In: Meteorologische Zeitschrift
L. Jin, S. Schubert, D. Fenner, M. Hefny Salim, and C. Schneider
(See online at https://doi.org/10.1127/metz/2021/1091) - (2021). “Integration of a Building Energy Model in an Urban Climate Model and its Application”. In: Boundary-Layer Meteorol. 178, pp. 249–281
L. Jin, S. Schubert, D. Fenner, F. Meier, and C. Schneider
(See online at https://doi.org/10.1007/s10546-020-00569-y)
