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Cambridge Building Energy & Environment Portal

Equipment needed for V1 lab.


Task (as outlined in main handout on Environmental Measurement)

One blower door kit, one hot-wire and one rotating-fan anemometer are available. The anemometers must first be calibrated (typical speeds less than 1 m/s) by a timed walk in still air over a measured distance (or in some other way you can invent). Means of determining the direction of air flow will also be needed.

First use the anemometers to make a rapid survey of air movement in the lecture room. Identify any significant inflows and outflows (e.g. with different combinations of windows and doors open. Attempt to estimate the number of air changes per hour. Then concentrate on a chosen detail – air movement near a window, or near a hot radiator etc. Identify any differences in air velocity with height (e.g. measuring air velocities at ankle height and head height) and note the occupant response. Record your results in appropriate diagrams.

Use the blower door kit to perform the airtightness test at a range of pressures. Plot the pressure difference vs. the flow rate on a logarithmic scale and from this obtain values of the flow coefficient and the flow exponent that are particular to the room under test. It will then be possible to quantify Q50 (the air flow rate in m3/h through each m2 of building fabric at 50Pa) and n50 (the number of air changes via the building fabric per hour). Compare air- change measurements with published standards on ventilation. Note that the blower door test will be performed with the demonstrator Miss Alessandra Luna-Navarro(, who will be in touch to make the necessary arrangements.

Comment on the causes and significance of any noteworthy observations, and on the performance and suitability of the instruments.