Environmental Engineering Reference
In-Depth Information
and cooling strategies on the airflow pattern in an office was investigated
by applying mixing ventilation [21] as well as those results indicating
the effect of supply conditions on the airflow pattern [16]. The ventilation
performance represents the capabilities of the airside design for providing
a clean space. The effect of the heat and contaminant source location on the
ventilation performance is also important. Optimum ventilation perfor-
mance is achieved when these sources are located near the exhaust open-
ing [22]. In healthcare applications, the air quality is generally influenced by
airborne and contaminant generation, especially in critical sites such as the
isolation and surgery rooms. Several studies have investigated airborne par-
ticle control in operating rooms using numerical techniques [23-26].
7.3.3.4 Closure
Air movement efficiency is mainly based on two factors: the air pressure
relationship with the other neighbourhood spaces and the airside design.
Differential air pressure can be maintained only in an entirely sealed room.
Therefore, it is important to obtain a reasonably close it of all doors and seal
all walls and floor penetrations within pressurised areas. This is best accom-
plished by using weather stripping and drop bottoms on doors. The opening
of a door between two areas instantaneously reduces any existing pressure
differential between them to such a degree that its effectiveness is nullified.
When such openings occur, a natural interchange of air takes place between
the two rooms due to turbulence created by the door opening and closing
combined with personal ingress/egress.
7.3.4 Energy-Efficient Building Design
7.3.4.1 Introduction
In the early 1970s, the energy crisis forced the development of conservation
strategies in a variety of industries. Sustainability and energy efficiency
continue to be strong issues in this time of limited resources. Therefore,
the implementation of energy-conserving strategies in HVAC systems must
be balanced with occupant comfort and health. A few guidelines gave spe-
cific recommendations about energy saving in HVAC systems, but these
recommendations do not meet all requirements and design varieties. Indeed,
in hot and humid climates, outdoor conditions play an important role in the
energy consumption.
7.3.4.2 Problem Identification: Pyramid Concept
Until now, the guidelines and design standards have not provided restricted
utilisation strategies for the conditioned air in spaces. This results in inef-
ficient systems and expensive energy invoices. In some critical facilities,
such as hospitals, HVAC designers face the problem of balancing healthy
