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Within the City of London the ventilating systems range from the simple arrangements such
as the room with its openable window with an air shaft communicating directly to the open air
together with a single heating unit, to mechanical systems of:-
(a) Through passage of atmospheric air which, after some form of treatment is used in
the offices and then exhausted to atmosphere — in other words, fresh air is used;
(b) Varying degrees of recirculation of air taken from atmosphere — treated and then
recirculated continuously, fresh air being introduced only to make up any air lost from the
spaces in use, which constitutes almost 100% recirculation.
The inspection of various installations using recirculation, and discussions with engineers
and designers, support the opinion that the majority of existing plants are capable of being adjusted
to 100% fresh air with, no doubt, an increase in the cost of running the plants to control
temperature.
There would appear to be greater consideration needed in building design to the control of
heat loss/gain and the glazing and size of windows in offices, and more flexibility in ventilation
unit size, i.e. small units instead of one large unit, in order to facilitate the control of conditions
in different parts of a large office block.
As there is no legal requirement for prior approval of office development to meet the requirements
of the Offices, Shops and Railway Premises Act, 1963, there seems to be insufficient
appreciation by architects, designers and ventilating engineers of the fact that when the office
is occupied it must comply with the requirements of the Act.
During the year the question of prior approval was dealt with simply by making it known to
professional people and owners that they were welcome to visit the Guildhall and discuss their
projects whilst in the planning stage. Towards the end of the year a steady stream of technical
advisers were being interviewed on all the provisions of the Act.
Conditions appeared to vary between the following extremes:-
(a) That a building and its services should be constructed and maintained to meet all
the requirements of the employee; or
(b) That the employee is secondary in consideration to building construction, especially
where economy is stressed.
The Act is to make fresh provision for securing the health, safety and welfare of persons
employed to work in office or shop premises. This has been interpreted, and it is hoped correctly,
to mean that people should have the primary consideration.
When it came to the question of ventilation in high rise development, it was found that where
tall buildings are erected with fixed windows and every effort is made to effectively seal the
building from fortuitous entry of external air, the pertinent points were: (I) Are there any ventilation
standards? (2) If so, how were they arrived at and on what data were they based.
With fixed windows, the occupant of the rooms has to endure or enjoy what form of ventilation
is provided. There is a general impression, fondly held on the part of the public at large, that all
mechanical ventilation is good, and owners of property do not seem to question the true effectiveness
of any mechanical ventilation installed.
In the absence of any standards known to have a scientific basis the question was posed as
to what is adequate ventilation. Along with this problem was considered the problem of what is
fresh air.
The view is expressed that recirculation of vitiated air is undesirable and furthermore it
would still seem to be the intention of the Act to ensure that adequate supplies of fresh air or
artificially purified air shall be available to the occupants. What constitutes the proper means
of meeting these requirements seems to raise many conflicting views and the grounds on which
some of these varying standards are proposed appear to be of a dubious nature. We are, therefore,
left with a distinct feeling of unease that the "person" is not receiving the prime consideration.
In these circumstances, we have come to the conclusion that, to maintain conditions which
promote the well-being of the staff, ventilation by means of fresh air or artificially purified air,
supplied at the rate of not less than 3,000 cubic feet per person per hour, would be considered
suitable in any room in which persons are employed to work.
It is suggested that the surroundings should be such that an employee can work without any
impairment to his health or well-being and not merely survive. In practice it is sometimes found
that a building is erected with openable windows but the staff are not allowed to open them.There
is a recirculatory air heating system for temperature control which would be out of balance if the
windows were open. In such situations the ventilation is by recirculation, even though physically
the windows can be opened.
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