Environmental Engineering Reference
In-Depth Information
7.3.2.3 Status Quo
At present, most research recommends experimental and numerical simu-
lation as the perfect tools to obtain the optimum design. The optimisation
procedure of the HVAC airside design depends on the predictions of the
air temperature distribution based on the simulation of different paramet-
ric designs using experimentally verified numerical tools. The influence of
various ventilation strategies and vapour generation rate on the character-
istics of temperature and moisture distribution is investigated [12,13]. The
vast majority of the available thermal comfort data pertains to sedentary or
near-sedentary physical activity levels typical of office work. The body of
available data does not contain significant information regarding the com-
fort requirements of children, the disabled or the infirm.
Airside design and room furnishing were found influential in order to
ensure a comfortable environment, especially in the displacement ventila-
tion configuration [14]. The airflow velocity influence was investigated, and
it was found that acceptable velocity could be as high as 0.35 m/s in the occu-
pied zone [15]. The configurations of the conditioned space affect the comfort
level as well as the space applications, such as healthcare facilities, which are
so complex [16,17]. The correct specifications of outdoor ambient conditions
affect thermal loads, as shown in Figure 7.1, and consequently, the comfort
level [18]. Some research recommends changing the focus on the effect of
building envelope to reduce the thermal load to enhance the thermal com-
f or t [1,19 -21].
7.3.2.4 Closure
The comfort conditions depend on many factors beyond the indoor air tem-
perature, relative humidity and airflow velocity. Comfort conditions depend
also on the air distribution pattern and the air movement [20], but the effect
of these factors can be considered close to the air quality more than the com-
fort level. Indeed, the comfort criteria affect the air quality and the energy
conservation in the ventilated and conditioned spaces, as shown in the
following sections. The relation between the comfort and air quality is an
interchange or a mutual relation.
7.3.3 Air Quality
7.3.3.1 Introduction
Most guidelines consider that the air quality is the result of a collaborative
effort among environmental conditions (those presented in the introduc-
tory section). Indeed, in the present literature, the air quality is specified by
a collaborative effort of the pressure relationship, air movement efficiency
and contaminant concentration. These conditions play an important role in
