The UK-China research project Low carbon climate-responsive Heating and Cooling of Cities (LoHCool) investigates enhanced indoor summer comfort in the 9 Billion m2 of building stock of the challenging Hot Summer and Cold Winter (HSCW) zone of China. The HSCW region lies South of the Huai River-Qin Mountain line below which central heating and cooling are deemed 'not required'. If this central government direction is relaxed, a significant carbon penalty could arise if the existing building stock is sealed and air conditioned to Western standards. LoHCool investigates the alternative strategy of increasing the existing stock's resilience to climate through low energy, low technology adaptation. The approach is applied here to typical slab building forms in Hangzhou and Chongqing in the East and West of the HSCW zone. Internal thermal conditions are simulated using the dynamic thermal model EnergyPlus calibrated using field data. Insofar as ventilation is a critical component of the adaptation schemes proposed, the local wind environment of the case study buildings is simulated using an advanced large eddy simulation model, Fluidity. Out of these diagnostic analyses, adaptation schemes are configured, specified and modelled, and found to significantly increase comfort with viable payback periods although supplementary cooling will be required as the century advances.