Sustainable Construction A Life Cycle Approach in Engineering

onmental changes. As architectural means, the buildings‟ skin must protect them from the environmental
conditions and keep a mild and comfortable atmosphere inside for the human beings
in order to make them feel themselves good. So it must be detailed carefully. In this concept
of detailing the skin of the building, the energy coming from the sun plays an important
role. Its rays are wanted to enter the building in cold days while they are tried to be escaped
from in hot days. The skin of buildings is generally composed of walls and roof . One of the design
possibilities in this sense is the shading elements‟ design because walls contain windows
within them. Due to the fact that windows let the sunshine get through them, they overheat the
interior.
For the radiation control, solar radiation should be kept out in summer while it should be let
in through the windows as much as possible in winter. “For any given locality the climatic conditions,
mainly the temperature, give an index for outlining cool and warm periods which can
be designated as the “underheated” and “overheated” periods. The “overheated” period is the
one when shading is needed.” (Olgyay & Olgyay, 1973, p.16) And the one when solar radiation
is necessary in the interior is the “underheated” period.
As Olgyay & Olgyay stated (1973), “the effect of climatic elements on the human physiology
can be graphically charted” (p.20). In Figure 1, the bioclimatic chart is given. The x-axis is the
relative humidity while the y-axis is the temperature. Also shading, radiation, air movement,
moisture are shown. At higher temperatures, wind is required and the velocity of the required
wind is stated on the chart. If the humidity is high, required wind velocity is also shown on the
chart. In the comfort zone, people feel themselves comfortable. Below this zone there is the
shading line (at around 21,1 ºC). Above this line, wind and shading is required while below the
line, solar radiation is necessary to feel comfortable. This shading line is important since it determines
the “Underheated zone” and the “Overheated zone”. Underheated zone is under the
shading line and overheated zone is above it. Shading is necessary above the shading line at
overheated zone.
With the use of the meteorological data, the average values are found for the city in question.
These average values are converted into curves in a coordinate system whose x-axis shows the
days of the year and y-axis shows the hours of a day. When the graphics which show the average
temperature curves and average relative humidity percentage curves are collided with keeping
the shading line in mind, a shading line that is dependent on time is achieved. Therefore
two areas are defined, one is between the shading lines (this gives the overheated period), and
the other gives the underheated period. The times in these periods are then converted into solar
time and they are placed in the sun-path diagram. The sun-path-diagram of Izmir is achieved as
shown in Figure 2. (Zeren, 1967, pp.23-31)
The overheated period and the underheated period are transferred to the sun-path-diagram as
in Figure 2. The dark area is the overheated period where shading is necessary but it has two
tones: the darker and the lighter area. The curved lines indicate two days of a year where the
sun is at the same altitude in the sky. The darker area of the overheated period means that shading
is required at both of the corresponding days. The lighter area shows the days when only
one of these two days (usually the autumn days) needs shading. The non-shaded areas of the diagram
show the days when no shading but radiation is required. The sun-path-diagram changes
according to the latitude. Therefore a special sun-path-diagram is prepared for each latitude. In
order to determine where shading must be done and where mustn‟t, sun-path-diagram and mask
are used together. This process is called as “Shading Analysis”.
Sun-path diagram: The path which the sun follows is projected onto a horizontal plane in
the sun-path diagram as seen in Figure 2. In this diagram, the outer circle is the horizon, and the
observer stands at the center. “The curved lines indicated by days and months of the year
represent the sun-paths on the dates shown. Lines „radiating‟ from the North Pole indicate the
hours. Between the hour lines are lighter lines indicating twenty-minute intervals” (Olgyag &
Olgyay, 1973, p.40).
Mask: The mask which is seen in Figure 3 is placed on the sun-path-diagram which is seen
in Figure 2, according to the orientation of the facade in question. Their centers should intersect.
The 90-90º line of the mask represents the facade of the building in question. The mask is
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