The Amount of Energy Consumption for Cooling
The examination of the cooling energy consumption performance in peak
hot weather conditions in Ilam (32.5 at its peak hot weather on
July) was done similar to that of the heating energy consumption.
Analysis results showed that Sample H had the highest amount of energy
consumption. Evidently, given the specifications listed in Table 2,
Sample H with a length, width and total area of 26m, 6m and
156m2, respectively, showed the worst energy
consumption performance in terms of both heating and cooling.
[CHART]
Figure 3.: The amount of cooling energy consumption of samples
during the peak hot period (average temperature of 32.5℃)
As previously expressed, following the selection of the eight building
samples in the first stage, the amount of energy consumption of the
samples during peak hot and cold periods and the wall transparency range
of 0-100 were calculated and shown as charts.
As can be seen in Figure 2, increase in wall transparency at the peak
cold period reduced the total energy consumption in Samples A, B, D, E,
G, and D; in addition, increase in wall transparency compared to dark
surfaces led to increased energy consumption. Such reduction and
increase in consumption considering wall transparency for Sample E are
shown based on Figure 2.
Chart 2 demonstrates that with increased total area of windows as the
transparency factor in building walls followed by increase in the
received solar energy, the heating energy of the house is somewhat
provided by the sun, resulting in lower energy consumption for heating.
With the lowest extent of transparency, Sample E had the highest amount
of energy consumption.
In contrast, increase in the extent of openings increased the amount of
energy waste and subsequently, energy consumption. As shown in Figure 2,
increase in the openings by a specific limit in all samples raised the
amount of energy consumption significantly.
Figure 3 represents the amount of energy consumption and building
performance during the peak hot weather across five selected samples.
According to the chart, increase in wall transparency raised energy
consumption. The reason behind this is that in hot seasons, increase in
the openings would raise the amount of received sunlight and
subsequently, more heat is received; in turn, this raises the amount of
energy consumption for cooling to lower the building temperature to a
desirable degree.
Here, the following question can be posed: What is the cause behind such
an increase in energy consumption in Sample E compared to the other
samples? To answer this query, Figure 2 should be compared with Figure
3; according to the former, the lower the extent of openings
(transparency) in the building, the lower the amount of received solar
energy. In this case, considering the difference in temperature between
day and night in the examined climate, the amount of received energy
during the day is lower than the energy wasted at night; as a result,
more energy would be required for heating. By increasing the
transparency (total area of openings), the amount of received solar
energy is increased by 10-20%; and through the gradual compensation for
the lost energy, the chart gained a similar procedure to other samples.
Nonetheless, Chart 3 shows that in the hottest day of the year with 10%
transparency accompanied by intense sunshine and insignificant
temperature difference between day and night, the temperature of the
building interior raised which necessitated a large amount of energy to
lower the temperature. Notably, the higher the difference between the
interior and exterior of a building, the more the energy exchanged
between the two environments; in such cases, more energy would be
required to reach the desirable temperature.
However, given the ratios between the building and total areas of
openings (transparency) in other samples, there is a proper proportion
between received and wasted energy; consequently, the energy consumption
of samples has a similar chart. In other words, lower ratio of openings
to the building volume in Samples A, C and B had a better performance
compared to Sample E in terms of received and wasted energy.
The other samples including D, G, F and H received more solar energy due
to larger surfaces of openings and west-east stretch (being in the
direction of sunshine).