چکیده:
To effectively design daylight in buildings, daylight availability data are necessary. Although there is a great potential for daylight energy in Iran, its use has been hampered by the absence of measured data. In this paper the illuminance data on the vertical south facing surfaces of Tehran were estimated using the IESNA model. For this propose an illuminance measuring set was used in order to measure the vertical illuminance for standard times over 17 days at one minute intervals from 9 a.m. to 4
p.m. Then, the measured data were compared with the IESNA model calculated data. A regression model between measured and calculated data was developed, which showed an acceptable linear correlation (r2=0.9535). Also mean hourly and monthly vertical illuminance was obtained from the new equation between measured and calculated data for a whole working year. To estimate daylight availability, Iso- Klx lines for working hours and frequency curves for vertical illuminance on south facing surfaces were produced.
خلاصه ماشینی:
Also mean hourly and monthly vertical illuminance was obtained from the new equation between measured and calculated data for a whole working year.
To estimate daylight availability, Iso- Klx lines for working hours and frequency curves for vertical illuminance on south facing surfaces were produced.
To estimate daylight variations in Tehran, the mean hourly and mean monthly illuminance on a south facing vertical surface were measured using a correspondent linear model obtained throughout a whole working year.
Measured data is presented as follows: - First the results obtained from the equations for average vertical illuminance on south facing surface for every month in the full working year.
Mean hourly and monthly illuminance on a south facing vertical surface for a whole working year in Tehran )View the image of this page( Considering the climatic calendar of Tehran, to decrease energy consumption in buildings, the use of solar energy and direct solar radiation is necessary for five months of the year (November to March) while in other months of the year, preventing direct solar radiation into interior spaces of buildings is recommended (Tahbaz, 2008, p.
Iso- Klx lines for varying vertical illuminance levels averaged according to working hours and months <H2>CONCLUSION</H2> In this paper the illuminance on south facing vertical surface was estimated using the IESNA method in order to obtain a developed regression model and daylight availability in Tehran.
By using these data, frequency curves for vertical illuminance and indirect solar illuminance were obtained which show daylight availability in Tehran for hot and cold months in a working year.