Sharp JX-9400 Informations techniques télécharger pdf (Page 124)

indoor environment quality and health or paying attention to possible damages

to buildings. If a decrease of thermal comfort was implicitly accepted, cases of

mould growth, increased indoor pollution and health hazards were not

expected but often observed. Since then, the idea that saving energy in build-

ings decreases the indoor environment quality still prevai ls.

Of course, some energy conservation opportunities such as low internal

temperature or too low ventilation rates may degrade the indoor environment.

These should therefore either be avoided, or accepted only in case of emergency

and for a limited period of time.

Some other energy saving measures should be used only in conjunction with

others. For example, retroﬁ tting windows in poorly insulated dwellings leads to

a risk of mould growth, and improving the envelope airtightness without taking

care of ensuring and controlling a minimum ventilation rate may decrease

indoor air quality.

Table 5.4 lists, in the ﬁrst column, various uses of energy in buildings.

Known ways to save energy are presented in the second column, and eﬀects

of these energy saving measures on comfort or indoor environment quality

are presented in the third column. It can readily be seen that there are many

cases where energy saving measures, when well designed and executed,

improve indoor environment quality.

Several recommendations, resulting from experience and recent surveys

performed within European projects (Bluyssen et al., 1995; Roulet et al.,

2005) are given below.

Method

The method used to scientiﬁcally support these recommendations is described

in detail in Jaboyedoﬀ et al. (2004). A typical oﬃce building equipped with full

air conditioning and cold ceiling, including heat recovery, was simulated using

an appropriate computer program. The heating, ventilation and air condi-

tioning (HVAC) system is shown in Figure 5.18.

The three-storey building is of heavy construction and well insulated with

low-e, clear glazing. The oﬃce rooms are oriented south with 53 per cent glazed

area. The internal temperature can be controlled using either air conditioning

or hydronic heating and cooling.

Numerous simulations were perfo rmed for diﬀerent climates: northern

(Oslo), central (London and Zu

rich) and southern Europe (Rome), and the

following variants were calculated:

outdoor air supply: 15–50 m

/hour and per person;

relative humidity of supply air to room: 50 per cent and no humidiﬁcation;

eﬃciency of heat recovery: 0 (no heat recovery), 0.75 and 0.85;

inﬁltration: 0.5 and 1.0 air changes per hour;

set point for cooling: 248C, 288C and no cooling;

ventilation: 24 hours a day or during working hours only (7 am to 7 pm);

natural ventilation – using windows – instead of mechanical ventilation.

Measurements and Measures Related to Energy Eﬃciency in Ventilation 103

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