ZEMCH 2015 - International Conference Proceedings | Page 755

Preference votes (%)

slightly warm (+1) (see Figure 3). Based on ASHRAE 55 standards (2004), a response in the central
three categories of the ASHRAE scale expresses satisfaction and more than 80% acceptability in
the three central categories of ASHRAE scale is enough to consider the indoor environment to
be comfortable which in this case is based on the thermal sensation votes. In addition, around
60% of the students in classroom S wanted No change on their thermal environment and more
than 50% of them in Classroom N preferred a cooler environment (Fig.3). The average indoor air
temperature during the teaching hours on the survey day was less than 21°C in Classroom S and
was more than 25°C in Classroom N. Based on this study, most of the students in both classrooms
felt neutral but the significant number of students preferred cooler environment when the indoor
air temperature is around 25°C and wanted No change when it was around 21°C. It should be
mentioned that the heating systems were always on during the cold season and as a result most
of the students in classroom N wanted cooler environment although most of them felt in three
central categories of the ASHRAE scale. Also the airtightness of Classroom S was slightly low as
the windows were not sealed enough which caused air leakage and as a result the average indoor
air temperature was less than Classroom N. Based on the questionnaire studies in this research,
the initial minimum comfort temperature in February set to be 21°C as the significant number of
students wanted no change and felt neutral at this temperature.
70.00%
60.00%
50.00%
40.00%
30.00%
20.00%
10.00%
0.00%

Cooler (-1) No change (0) Warmer (+1)
McIntyre scale
S
N

Figure 3: Thermal sensation votes and Preferences vote in classrooms S and N on 9th Feb 2011

Simulation Analysis
In order to assess and improve the indoor thermal performance of the classrooms based on the
passive design strategies and students’ thermal comfort satisfactions, thermal simulation analysis
was performed using DesignBuilder, buildings thermal simulation tool. The simulation analysis
was carried out for the field studies’ classrooms for one week in February 2011. The field studies
results were incorporated to the simulation model, DesignBuilder, to evaluate the current thermal
performance of the school buildings. Later various passive design strategies were applied to the
simulation model and the impact of these strategies including orientation, glazing, and thermal
mass as well as thermal insulation on indoor air temperature was analysed by revising the case
study model to identify the optimal solution.
Orientation
An appropriate building orientation can decrease the use of mechanical heating and cooling systems and, as a result, reduce the overall buildings’ energy consumption. It is important to consider
the connection between the geographical features of the site and the building itself in order to
create an accurate passive building (Light House Sustainable Building Centre and Guido 2009).
Building orientation has an impact on the heat gains of the building, as a result of the variety
of solar radiation at different angles (Givoni 1998). To analyse the impact of the orientation on
the indoor environment of this case study school building, a simulation analysis have been per-

Passive design strategies on indoor comfort of school buildings in hot-dry climates

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