Bifold doors should not necessarily make a room colder if they are properly installed and fitted with high-quality double glazing. In fact, bifold doors can actually improve the thermal efficiency and energy efficiency of a room by letting in natural light and reducing the need for artificial lighting, as well as providing ventilation when needed. However, if bifold doors are poorly installed or fitted with low-quality glazing, they may be less energy-efficient and could contribute to drafts and heat loss.