Airflow characteristics of modulated louvered windows with reference to the Rowshan of Jeddah, Saudi Arabia.
The main aim of this research project is to assess the potential of the modulated
louvered windows (ML W) to provide ventilation as a cooling source to achieve thermal
comfort inside buildings. It presents an intensive analysis of the characteristics of airflow as
function of the various MLW parameters in order to provide designers with practical
information about the performance of MLW in the control of natural ventilation inside the
room. Some initial studies suggested the significance of adjustable horizontal louvered
windows, or the MLW as they are referred to in this research, as an effective technique for the
control of natural ventilation beside the other Environmental issues.
In Jeddah, Saudi Arabia, the shelter adaptation to the hot-humid climate was achieved
by employing a number of passive solutions, one of which, the MLW constructed in the
Rowshan, was considered a main elevation treatment. The Rowshan, a projected window
bay, covered in this study is constructed with adjustable louvers in a number of sashes
arranged in rows and columns to control and alter breeze to the desired level inside the room.
The Rowshan is also credited with controlling other environmental factors and is supposed to
reflect social necessities.
This thesis has investigated the airflow characteristics of the MLW with reference to
the Rowshan of Jeddah, Saudi Arabia. After reviewing the previous efforts and prediction
techniques concerned, the research has conducted a series of experiments including laboratory
and computation fluid dynamics (CFD) appraisal stages. The laboratory stage included the
evaluation of the pressure drop (L1J') and the velocity drop (v/ve%) characteristics across the
MLW. The pressure drop was examined under various airflow rates (Q) using the
depressurising test chamber technique. The velocity drop (v/ve%) was examined under
various prevailing wind conditions using the test chamber technique. This appraisal stage
covered also the room configuration and its contribution to this effect. On the other hand, the
CFD measurement has examined the viability of CFD coding to simulate airflow around the
reviewed MLW. The predicted results obtained from CFD were compared against those
obtained from the laboratory. Consequently, an intensive evaluation of airflow patterns of the
common Rowshan configurations, including the plain and projected Rowshans, employed in
leddah in conjunction with various outlet types was conducted.
From the literature review, it has been concluded that the MLW played a major role
in the provision and the control of natural ventilation in the traditional architecture of leddah,
Saudi Arabia. The various appraisal stages showed that parameters such as louver inclination,
aperture between louver blades and the free area of the MLW were more significant variables
than the depth of louver blades. Nevertheless, the major pressure and velocity drops were not
due to individual variable but rather to the combination of variables that would
comprehensively describe M and v/ve% across the MLW.
Practically, the design of the modulated louvered windows must give consideration to
those variables that play an important role in altering airflow characteristics inside the room.
It should also have an element of flexibility as this enables designers to approach their
window treatments with a number of choices whilst retaining similar ventilation
performances. Airflow velocities in a room containing an MLW result from an interaction of
louver geometry, room geometry and prevailing wind conditions. As far as the Rowshan
configuration was concerned, the plain Rowshan was generally better than the projected
Rowshan. Yet the flow in the living zone could be enhanced by correctly sizing the projected
Rowshan. Finally, CFD analysis has been successfully used to predict air velocities in the
region close to the MLW side.