View of Central Tower from roof of the Palace of Westminster (c) Houses of Commons
In informal conservations about my work at the Houses of Parliament I get frequently asked about the purpose of the gothic towers, spires and turrets. These conversations revealed that many people assume that they were added for architectural effect. Indeed people were astonished when I explained that they were Victorian ventilation shafts introduced for the extraction of hot air and smoke. Their position, dimension and form was shaped by functional requirements. One of the objectives of the research project is to develop a critical understanding of their design, function and effectiveness and how they were integrated within the wider ventilation system.
Over the past two years I have undertaken site visits with staff of the Parliamentary Estates Directorate and the Restoration and Renewal Programme team, looking at the ventilation towers. These have revealed that whilst the main features of these historic shafts have survived, many of the more intricate technical details was lost. The latter included, among others, sophisticated arrangements of wind-pressure sensitive louvres. In the project original sketches, construction details and written accounts are used to reconstruct the lost technical features and to gain an understanding of how the shafts were operated.
This is the first in a series of blog posts in which I will be writing about the design, history and function of individual ventilation shafts ‘adorning’ the roofline of the Houses of Parliament.
Dispelling the myth of the Central Tower.
Today I will be giving a brief introduction to the history of the Central Tower, the large gothic spire above the Central Lobby. This is not only largest tower that has been added to the Palace of Westminster for the purpose of ventilation, but it was also the only shaft that never fulfilled its intended purpose. It is the remnant of a grand, yet unrealised ventilation scheme developed by the physician David Boswell Reid between 1840 and 1846.
The original architectural plans submitted by the architects Pugin and Barry to the architectural competition in 1835 did not include a Central Tower. Their plans only had two towers, the Elizabeth Tower next to Westminster Bridge and the Victoria Tower opposite Westminster Abbey, and none of these had been introduced for ventilation purposes. The idea of applying principles of stack ventilation to this architectural scheme was not seriously considered until 1840, when Reid was formally employed and charged with the responsibility of developing a ventilation system following principles of stack-ventilation.
The original sketches, plans and letters produced in the 1840s show that Reid planned an extensive network of horizontal flues at roof level to convey the smoke and hot air from every room inside the Palace, including the two debating chambers, into one large tower. His objective was to utilise, as far as possible, the waste heat from people, smoke and gas fumes to drive the maintain the convective flow inside the Tower. Coke fires, located at the base of the shaft, were proposed as a backup to be used over period when the waste heat was not sufficient. However, it is to be highlighted. that the ventilation was not purely stack driven. The Central Tower was introduced to provide the motive power for the extraction of air and smoke, whilst the fresh air supply was provided through a separate system involving the use wind-cowls and steam-powered fans.
A decentralised strategy is adopted, 1846 and 1855.
In the autumn of 1846, following difficulties in establishing an effective collaboration between Reid and Barry, the idea of central ventilation system was abandoned, leaving the Central Tower without a purpose. Instead of using one large shaft Barry adopted a decentralised system that involved multiple ventilation shafts. The large network of air and smoke channels that was intended to terminate in the Central Tower was divided into a series of local networks, each provided with a separate ventilation shaft. The system of House of Commons, for instance, was equipped with a separate stone turret. Between 1846 and 1855 new ventilation towers were added gradually as the plan for the new decentralised ventilation system was emerging.
The plan below shows position of the main ventilation towers and the date at which they were introduced. Working with his own team of engineers, Barry gave these functional features the appearance of gothic turrets and towers, which gave the roofline its picturesque qualities.
Diagrammatic plan of Palace of Westminster, showing position of main ventilation towers. (Schoenefeldt 2016)
Although it was significantly reduced in size, the Central Tower was retained. Its use was the subject of lengthy discussions between Reid and Barry between. The final plan, approved by Barry in 1848, was to retain the Central Tower as a local up-shaft for the House of Lords only. Barry’s plan, however, was never realised. Instead the House was provided with different extract system in 1855, involving the use of the large shafts inside the Victoria Tower and a smaller shaft next to the Peers Lobby. As a consequence the Central Tower became a largely redundant feature. It only functioned as a minor outlet, used to extract hot air from the Central Lobby and fumes from the kitchens on the River Front. Most of the work was done by the smaller ventilation towers, which I will be discussing in the next few blogs.