1835: Purified supply air heated in winter and cooled in summer in the Houses of Parliament
This innovation is given a more thorough account than others, as it embraces such a large part of the technical development in the field. Once more, though not for the last time, the Houses of Parliament in London are at the centre of attention.
The previous year, the House of Commons and the House of Lords had been destroyed by fire and temporary buildings had been quickly erected to accommodate members until a new permanent building was completed. The task of creating a good indoor climate, right next to the stinking River Thames, was given to the Scottish scientist and inventor David Boswell Reid, who was known for his advanced ventilation solutions in laboratory environments. The temporary building for the House of Commons was fitted with an innovative fire-driven ventilation system that removed the polluted indoor air through hatches in the ceiling of the debating chamber. This airflow created an under-pressure, drawing in outdoor air from the old palace gardens, where the air was regarded as being reasonably clean. It was then led to a space underneath the chamber where it could be purified, heated, cooled and humidified. Hot gas lamps, installed behind panes of glass close to the air vents in the ceiling, helped increase the extraction flows. In this way, the hall could be lit without introducing heat or fumes.
The air was purified in different stages, with soot and other particles being removed first using a filter in the form of a 70-square-metre sheet of damp cloth. After filtration, the air was cleaned by allowing it to flow through a spray of ordinary clean water and then through a spray of lime water. The acidity of the air was then neutralized using ammonia after which it was finally disinfected using chlorine. Before the purified and moisturised air was introduced into the chamber, through a myriad of apertures in the floor, it could be either heated or cooled by letting it flow over loops of piping containing hot or cold water. In order to avoid draughts caused by the jets of air, the floor was covered with a roughly patterned horse-hair carpet.
Depending on how cold it was outdoors, unheated and heated air would be mixed in the correct proportions to achieve a comfortable indoor temperature. During mild weather, the piping was not used at all and, during warm weather, cold town water was used to cool the supply air. On occasionally very hot days, the air was allowed to flow over blocks of ice to cool it before being purified. In the summertime, preventative cooling of the chamber was carried out at night.
The plant operators were instructed to strive to achieve an indoor temperature of just over 16 °C when the chamber was not in use and never more than 21 °C in session, which, by today’s standards, would be regarded as quite cool. The temperature was continually monitored using a thermometer, which now and again made an appearance through the holes in the floor.
The volume of the air flow was regulated via a nearly 5-square-metre valve in the extract air duct. This was manually adjusted up to 100 times per session depending on the indoor and outdoor temperatures, the wind conditions, and the number of members in the chamber.
Even if the ventilated floor was sometimes blamed for causing cold feet, Reid’s solution became a widely acknowledged success and “members of the House of Commons can now pursue their senatorial duties without a sacrifice of either health or comfort.”