This paper presents a preliminary case study of climate-adaptive designs for urban multi-family buildings at early stage, to allow thermal comfort and minimum energy use from today to the last part of 21st century. The generated future climate data combined with comfort model assessment has been proposed as a new way including future climate scenarios in preliminary building design for two representative sites, in Rome, Italy and Stockholm, Sweden. The existing vulnerability to the expected climate conditions from psychometric analysis indicates that: (1) the climate trend in Rome would gradually lead to more failures in the majority of conventional adaptive design measures, as the cooling and dehumidification demands would rise from 5.3% to 23.6%, while the heating and humidification demands would decrease from 27% to 16%; (2) the climate trend in Stockholm would result in an increased comfort period by exploiting more adaptive design measures, since the heating and humidification demands would be reduced from 67% to 53%. However, the cooling and dehumidification demands would increase slightly from 0% to 1.5%. Accordingly, four main key risks are identified: 1) overheating would become a rising increasing public health threat for buildings in Rome that rely exclusively on natural ventilation; 2) open questions remain for the design team in the area of correct cooling load selection, additional space for the future installation and the effectiveness of current cooling device etc.; 3) occasional heat waves and gradual rising humidity levels are expected to be a vulnerable topic for conventional lightweight building in Stockholm; 4) buildings with a heavy heating load would tend to have greater cooling demand, especially those with poor ventilation resources or greater internal gains. In conclusion, it is suggested that envelope optimization, whichever climate type, is one of the most efficient and effective adaptation measures towards future climate conditions.