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When assess airﬂows in buildings?

Ventilation performance should be checked early to detect potential problems

and to optimize the overall performance of the ventilation system. This includes:

appropriate airﬂow rates;

negligible leakage and shortcuts;

high ventilation eﬃciency;

high fan eﬃciency;

clean air and so on.

This check should be performed:

when commissioning the ventilation system in order to control that the

system is built according to the speciﬁcations;

if there are indoor air quality problems to help in ﬁnding the causes;

before refurbishing the system in order to accurately know where there are

potential problems, which should be cured by the refurbishing.

Available methods to assess airﬂow rates and

related quantities

This section brieﬂy presents the methods described in the book in order to

guide the user in the choice of the appropriate method. The section also

proposes adapted methods for diﬀerent purposes and gives a general guideline

for planning measurements.

Airﬂow rates in buildings and in handling units

Chapter 1 describes in detail the method of using tracer gases for as sessing

airﬂow rates betwe en indoor and outdoor spaces, and between indoor spaces.

Such measurements may be useful to check if the ventilation is suﬃcient.

The method also allows checks to assess if the airﬂows follow deﬁned paths

from room to room, as required in some buildings, such as laboratories hand-

ling dangerous substances.

Similar methods, described in Chapter 2, test if airﬂow rates in air handling

units correspon d to the design values, and detect possible leakage or parasitic

airﬂows in such units. Such measurements are also useful to check the power

eﬃciency of fans (see Chap ter 5, ‘Energy for ventilation’) and energy eﬃciency

of heat exchangers (Chapter 5, ‘Heat exchange eﬃciency’).

Age of air and ventilation eﬃciency

The longer the air stays at a given location, the larger will be its concentrations

of various contaminants. The age of the air, i.e. the time spent in the building

since the outdoor air entered it, can be measured using trac er gases. The

xviii Ventilation and Airﬂow in Buildings

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Sharp JX-9400 Technical Information Seite 19