This chapter describes the testing facilities which were
available for the duration of the Project. These were
split into two sections; laboratory and site facilities. In this way, airflows could be measured with and without the extraneous effects of the weather.
4.1 Laboratory Facilities Double Chambers
The laboratory facilities were located in the Department of Building, Sheffield City Polytechnic. These consisted of a double chamber facility, comprising two airtight rooms each of internal dimensions 2.6m x 3.0m x 3.89m ( height x length x width ). The chambers are shown in Fig. 4.1 , over the page.
The two rooms were separated by a partition wall, into which was fitted a door of dimensions 1.98m x 0.76m ( height x width ) , together with its door frame and architrave. The door was fitted by a qualified tradesman, and was deemed to be a good fit.
not used for
exhaust. environmental
cha mber tests
iO partition wall design chamber inlets compressor conditioning units
Figure 4.1 View of double chamber facility Air Supply and Extract
Each side of the double chamber had an independent, air supply and exhaust system. Air was supplied to each chamber via two ceiling diffusers; operated -by
electrically controlled fan. The rates of supply was
controlled by an iris damper within the connecting ductwork; measurement was provided by pressure tappings
from a pitot-static tube. The maximum rate of supply
to each room was 390 m~3/h ( 12.9 ach ). Air was
extracted via a grille at floor level within both rooms and was operated by electric fan, the air being exhausted to the outside environment. The rate of extract was controlled by a butterfly valve within the ductwork. Flow measurements were made by pressure tappings from a pitot static tube; the maximum rate of extract in both rooms was 505 m~3/h ( 16.7 ach ).
Temperature Control; Environmental Side
One side of the double chambers, dubbed the environmental
side, contained a recirculatory air handler unit. This
was located outside, on top of the chamber roof. The
closed loop ductwork consisted of an inlet and outlet, located in the ceiling of the chamber. The air handler unit was controlled by an IBM microcomputer, which could hold the temperature within the room to ± 20 c, with an accuracy of ± 0.5 c.
Temperature Measurement; Environmental Side
Temperature was measured in the environmental side using copper/constantan thermocouples fed to a Farnell model FCO 11, 10 channel digital thermometer. Two were used, both placed in the centre of the room, at 60cm and 120cm above the floor. The quoted manufacturer's accuracy was to within 0.1 c, for temperatures of between 0 c and 100 c.
Temperature Control Design Side
The other side of the double chamber, dubbed the design side, contained a single thermostatically controlled 2 kw convector heater placed on the wall furthest from the door. This was because most domestic radiators are wall mounted; it was also thought that this position would create the most representative artificial airflow pattern, possibly imposing itself upon the natural airflow patterns through the door. Temperatures of up to + 35 c could be generated and held; initial tests indicated that this could be held to an accuracy of ± 2 c.
Temperature Measurement Design Side
The remaining eight channels of the digital thermometer were fed to thermocouples in the design side. These were again placed in the centre of the room, and arranged in a vertical fashion, at 3 0 cm intervals from floor level. In this way, the effects of temperature gradients with height could be measured.
Leakiness of Double Chamber Facility
To assess the leakiness of the double chamber facility, a single tracer gas decay ( section 2.1.1 ) test was done, this enabled a room airchange rate to be determined. All the possible leakage routes were sealed up, these included the service inlet holes, and the air supply and extract grilles. The data from this series of tests are shown in
Appendix B.
Leakiness of Environmental Side
The background leakage for the environmental side was found to be between 0.035 and 0.046 air changes per hour. With the air handler ducting open to the chamber, the air change rate was found to be 0.76 air changes per hour. This apparently closed loop ducting thus proved to be very leaky.
Leakiness of Design Side
The background leakiness for the design side was found to be 0.026 air changes per hour
4.2 Site Facilities
Choice of Site
The site chosen for the duration of the Project, was a
single dwelling house. It was a deliberate policy to
concentrate on just one house. In this way, the possible parametric effects of different house types i.e. whether it was terraced or semi-detatched etc, individual building components i.e. different window or door types, location, terrain and shielding, would be reduced to single set, particular to the chosen site. Work of this kind has been undertaken by several workers, including Warren, who has measured the effect of house type on airchange rates (31) , and McGrath, who has measured the effect of
different individual building components on the air change rate (32).
Location of Site
The site location was Norfolk Park, Sheffield, England. The house stands within its own grounds, the front facade
facing South East. Mature trees, reaching above eaves
height, surround the front and left-hand side of the house. The general location is however, within a built up residential area. The site was within 5 minutes drive from Sheffield City Polytechnic, and so logistical problems were reduced to a minimum.
Type of House
The chosen building was a detatched dwelling house, built
circa 1895. This was constructed of stone, with walls
0.36m thick. The roof was slate with a pitch of
approximately 3 5 degrees, ventilation being purposely