The climate is changing. In October 2023 the Dutch meteorological institute KNMI published realistic climate scenario’s for 2050 and 2100, based on analyses of several climate models, previously used for IPCC assessments. Furthermore these scenarios have been converted to a detailed dataset for the near future, the years 2033 and 2050, in a format that fit the standards for use in building design. By these new datasets, the impact of the climate change can be assessed on thermal comfort and cooling needs in buildings, people’s health and the risk of overheating. This article discusses the consequences in existing buildings. This requires a revision of the current assessment for simulating thermal comfort. It is concluded that more attention is required for location-specific circumstances, whereby the urban heat island must be taken into account. This exploratory study already provides many insights into the consequences of the future climate for the built environment. However, this knowledge is in development. Further research is required. The calculated simulation results based on the future climate scenarios are so high that attention must be paid in standards and policy-advise to heat-resistant measures in buildings, whether or not mandatory via the building code. Attention should not only be paid to thermal comfort during daytime, but also during the night period. A higher outside temperature during the night leads to poorer thermal comfort and even health risks in buildings during the summer night period. It is necessary to adapt guidelines, standards and building codes to this new reality.