1810: Heated supply air in winter and cool supply air in summer
In the then hyper-modern William Strutt Infirmary (later Derbyshire General Infirmary, now London Road Community Hospital) in England, a fire-driven ventilation system was installed that could supply the building with warm air in winter and cool air in summer. The ventilation stacks were fitted with revolving cowls to increase efficiency. Supply air was introduced via 70-m-long tunnels in which the temperature was relatively constant all year round. If necessary, in winter, this air could be post-heated in stoves situated on each floor. It is also worth mentioning here that the ventilation system was not the only technically advanced installation in the hospital. Other innovations included automatically flushing toilets, adjustable beds with foot heaters, washing machines and a transportation system via which wet washing was moved to drying rooms on rail-bound drying racks. William Strutt was an English businessman and innovator.
1821: Calorifiers used to heat supply air
In Germany, a fire-driven ventilation system was developed using so-called calorifiers. Later on, these also became very popular in other countries. This was actually a heating system based on airborne heat, with ventilation as an added bonus. In principle, the system comprised a stove being placed in an air intake. The surface of the stove was enlarged by using a folded mantel. Calorifiers were mostly used in large public buildings such as churches, military barracks and hospitals. However, their high surface temperatures made the heated air smell of burnt dust. The technology was used as late as the first part of the 1900s, though the calorifiers were then often fitted with fans.