ASHRAE Journal - January 2022 - 58

TECHNICAL FEATURE
Although following a similar approach to their
experiments in the 1920s, the NPL had to produce a
much larger and technical complex model, capable
of simulating both air movement and atmospheric
temperatures. It was used to simulate the thermal
conditions within the seating areas, and how this was
affected by the direction, speed and temperature of
the air entering through the nozzles at both levels. It
was equipped with miniature ductwork, electric fans
and air nozzles for the supply and extraction of air,
including fresh air nozzles in the ceiling and below
the galleries (Figure 8).
The models included furniture, such as the Speaker's
chair, table and the benches; electric light bulbs, covered
with aluminium cones, were installed on top of the
benches to simulate the heat input from MPs' bodies.
During the tests the scientists used smoke for tracing
the general airflow pattern and scientific instruments
including hot-wire anemometers and electric thermocouples
to take accurate measurements of the temperature
and velocity of the air currents in 20 different
positions.
The primary objective of the tests was to scientifically
evaluate and refine Faber's proposal from a thermal
perspective, focusing on internal air movement as a key
factor. In letter from June 1948 Faber stressed that it was
physiological, rather then technological criteria that
were setting " limits to air speeds, " and the test were used
to prove that air blown in " horizontally above the heads
could not be felt. " 39 These tests were to guarantee that
the new arrangement would not expose MPs to currents
at speeds in excess of 100 fpm (0.5 m/s), which is the rate
at which air movement becomes noticeable.
The design was refined following an iterative
approach, in which schemes were tested and gradually
adjusted. The investigations took into account the affect
of architectural aspects, such as position, number and
dimension of air outlets, as well as operational aspects,
such as system settings and alternative control regimes.
The first tests revealed that the original configuration
of ceiling outlets produced currents in excess of
100 fpm (0.5 m/s) at head level, and in subsequent tests
they were gradually enlarged, by extending them from
originally two to all four sides of the chamber. This
allowed the same volume of fresh air to be introduced
at lower speeds. At gallery level the intensity of the currents
was reduced by adjusting the original flow rate
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settings, which was not permitted to exceed 6,000 cfm
(2832 L/s).
One of the findings was that it was advisable to supply
air simultaneously from both sides, but that the direction
of the supply should be alternating between the two
sides.40 and that the supply air had to be 57°F (14°C) to
maintain a temperature of 62°F (17°C) to 64°F (18°C) at
floor level.41
These inquiries into the operational aspects formed
part of Faber's wider plans to achieve a dynamic and
responsive system, taking into account changes in
internal user activity and external weather conditions.
In the historic chamber the responsiveness of
the system relied on staff observing and manually
controlling and monitoring procedures. In the new
chamber Faber introduced a semiautomated monitoring
and control network, which was equipped with
an array of electric sensors, permitting the temperature
and velocity of the incoming and outgoing air
to be continually monitored,42 and the control engineers
also surveilled changes in attendance with the
aid of a periscope.1
In 1950, shortly before the House of Commons was formally
reopened, the operational regimes were further
tested and refined inside the actual chamber through
a series of trial sittings. These and later trials inside
the chamber have been examined in another article,
published in Building and Cities.43 To recreate the conditions
of a crowded chamber, contingents of several
hundred guards were engaged to take the place of MPs.
A further performance evaluation, led by Bedford, was
also undertaken four years after its completion. These
involved the analysis of recorded climate data, airflow
tests as well as the review of personal feedback received
from MPs about their experience of the new climate,
which were used to make adjustments to the operational
settings.
Conclusion
This paper has shown that design of the post-war
debating chamber was the outcome of a long-standing
inquiry into issues of thermal comfort that had begun
inside the historic chamber and lasted over 30 years. In
retrospect the House of Commons could be interpreted
as a field for scientific and technical research, bringing
together scientists, engineers and occupants to engage
with specific challenges associated with environmental
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