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eﬀectiveness of the ventilation in appropriately distributing the air in the venti-

lated space or in evacuating contaminants emitted at a given location can be

assessed using the methods described in Chapter 3.

When applied in the air handling unit, such measurements can be

performed simultaneously with measurements of airﬂow rates, thus reducing

the amount of work required. In a single measurement campaign, the mean

age of the air in the ventilated space, the eﬃciency of the ventilation system,

the supply, exhaust and recirculation ﬂow rates can be measured as well as

the air leakage in both directions through the building envelope.

Airtightness

The building envelope should be reasonably airtight to ensure the eﬃciency of

a mechanical ventilation system, and this system itself should have airtight

ducts in order to distribute the air appropriately throughout the ventilated

space. Chapter 4 describes the measurement methods. The general methods

are described ﬁrst and their application to the building envelope can be

found in Chapter 4, ‘Airtightness of buildings’, while the application to air

ducts or ductworks are in Chapter 4, ‘Measurement of airtightness of a duct

or network’.

Energy eﬃciency

To comply with a sustainable development policy and also to reduce the emis-

sion of greenhouse gases, energy eﬃciency of any system should be improved.

This can be achieved without the use of systems powered by non-renewable

energy. In our case, a mechanical ventilation system could be applied to an

appropriate building design, allowi ng natural ventilation. However, this is

not always possible, and in some cases – for example in cold or hot countries

where heat recovery on indoor air actually allows energy savings – may even

be counterproductive.

Therefore, the mechanical ventilation systems should be designed, built,

commissioned and maintained with the aim of ensuring good indoor air quality

at reduced energy use. Chapter 5 proposes various methods, checklists and

propositions to measure, check and improve the energy eﬃciency of ventilation

systems and components. They include:

eﬃciency of heat recovery (‘Hea t exchange eﬃciency’);

eﬀectiveness of heat exchangers(‘Heat exchangers’);

fan power eﬃciency (‘Energy fo r ventilation’);

energy eﬀects of indoor air quality measures (‘Energy eﬀects of IAQ

measures’).

Contaminants in air handling units

Unfortunately, in practice major so urces of indoor air contaminants are

components in air handling units and ventilation systems (Bluyssen et al.,

Introduction xix

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