analysis of the influences of solar radiation and façade glazing ...

4.2 Comments and conclusions 102
Apart from that, a reduction of the glazing area lead to a decrease in the operate
temperature during the warm season, thus provided better thermal environment
quality in living spaces.
Furthermore, the analysis of the influence of the glazing system area on the
buildings energy demands showed that there is a linear correlation, described by
Eq. (3.1), between energy consumption for space heating and the window-to-wall
ratio.
� The next finding of this study was the determination of the relation between the
energy transfer and the windows’ height above ground level for the warm season as
well for the heating period – Eq. (3.2) and Eq. (3.3). Simulation results indicated
that the difference between the first and the last floor is high and equal to 31 % for
balcony-windows and up to 66 % for windows in winter month. The windows’
energy balance for the summer month showed that the difference between the first
and the last floor is quite small due to the sun's higher elevation above the horizon.
� The present work was also focused on the investigation of an intensive night
ventilation system during the warm months when the ambient temperature is lower
than inner air temperature. As it turned out, cooling by ambient air can be an
energy-saving solution. This ventilation system, coupled with external shading
devices, is sufficient to prevent living spaces from excessive overheating during the
entire warm part of the year. It was found that the amplitude between day and night
internal air temperatures is significantly higher for apartments with variable air
volume systems. Due to this effect, we can relatively quickly reduce and stabilize
the air temperature to a lower level inside living spaces. The difference between the
operate temperature in apartments with constant air volume systems and with night
cooling systems using the variable air volume flow increases from April to the first
half of June. This value stays approximately at the same level equal to 3.5°C for the
next period of the warm season. The maximum value differs from 4.1°C to 4.4°C
and the mean value differs from 2.7°C to 3.0°C depending on the apartment
location.
� Based on the results of the multivariate testing of the buildings’ energy
performance and thermal comfort conditions for warm seasons, we are allowed to
state that the window shade with the highest reflection surface mounted outside and
near the fenestration guarantees the best protection of gains from solar radiation.
� The results indicate that if we change the collector tilt angle from 25° to 60°, the
absorbed solar energy varies only about 10 % in the period of a year. However,
applying the extreme angles 0° (a horizontal position) and 90° (a vertical position)
leads to a significant reduction of the DHW systems efficiency. Energy conversion
decreases to 70 % of the maximal value in an optimal panel position for the angle
0° and for the angle 90° the same reduction reaches about 50 %. Simulation results