Aluminium is in most ways the perfect material for constructing windows and doors: it is incredibly strong, light, weather proof and needs very little maintenance to provide years of reliable use. However, aluminium is also a very good conductor of heat, which means that on its own it provides very poor insulation against the winter weather and provides little protection from the summer sun.
Despite sounding like an unfortunate manufacturing defect, “thermally broken” aluminium windows and doors immediately solve this insulation problem by using a “thermal break” (sometimes known as a “thermal barrier”). This is a piece of material that doesn’t conduct heat at all, used to separate two materials or structures that do conduct heat. It acts as a barrier between the two to prevent heat transferring between them. In the case of aluminium windows, its main benefit is to prevent heat transferring from the inner frame to the outer frame – and to prevent the cold moving in from the outer to the inner.
So thermally broken aluminium windows and doors use a barrier in this way to improve insulation and energy efficiency. These days, the thermal barrier conducts up to 1,000 times less heat than aluminium, so it provides a tremendous reduction in heat loss and increases thermal performance. It also has the side effect of making your windows more soundproof, by dampening vibrations between the outer and inner frame