The likely increasing temperature predicted by UK Climate Impacts Program (UKCIP) underlines the risk of overheating and potential increase in cooling loads in most of UK dwellings. This could also increase the possibility of failure in building performance evaluation methods and add even more uncertainty to the decision-making process in a low-carbon building design process. This paper uses a 55-unit residential unit project in Cardiff, UK as a case study to evaluate the potential of thermal simulations to identify risk in the early design stage. Overheating, increase in energy loads, carbon emissions, and thermal bridges are considered as potential risks in this study. DesignBuilder (DesignBuilder Software Ltd., Stroud, UK) was the dynamic thermal simulation software used in this research. Simulations compare results in the present, 2050, and 2080 time slices and quantifies the overall cooling and heating loads required to keep the operative temperature within the comfort zone. Overall carbon emissions are also calculated and a considerable reduction in the future is predicted. Further analysis was taken by THERM (Lawrence Berkeley National Laboratory, Berkeley, CA, USA) and Psi THERM (Passivate, London, UK) to evaluate the thermal bridge risk in most common junctions of the case study and the results reveal the potential of thermal assessment methods to improve design details before the start of construction stage.