The Calculation Method for Light Climate Parameters Based on Sun-Lighting Efficiency and the Comparative Analysis of Light Climate in Hanoi and Moscow

The main source of daylight is the Sun. The EarthТs atmosphere scatters its light due to the air, water vapour, ice particles (at high altitudes), dust, various gases, and other contaminants that appear in the air as a result of human activities. This forms a daylight diffuse (scattered) component, which is a data basis for calculation of daylight in buildings. This basis has its own features for a given region. This article shows a calculation of sun-lighting efficiency in Vietnam. We obtained a variation of horizontal daylight illuminance in Hanoi (21.03∞N). Comparing it with the variation of horizontal daylight illuminance in Moscow (55.70∞N), we can see a high level and a distribution uniformity of outdoor illuminance in Vietnam. The maximum levels of diffuse illuminance and total illuminance in Hanoi are 45.2 and 58.52 klx; the maximum levels of diffuse illuminance and total illuminance in Moscow are 28.3 and 53.1 klx. Besides, illuminance levels in winter months are much higher for Hanoi than for Moscow. This can be explained by different latitudes of these cities and by the Sun motion.