Natural Lighting Design Of Underground Atrium Space Based On Dynamic Light Environment Simulation

Underground buildings will play an increasingly important role in the future urbanization process.For underground space,natural lighting is of great significance,and introducing natural light into the underground space through atrium will effectively improve the overall light environment inside it.Most of the existing researches use the static light environment simulation method to evaluate the lighting level of the interior space of the building.However,it will be more effective and accurate for applying the dynamic light environment simulation method based on meteorological data to reflect the overall lighting level of the building in a complete time series.This paper aims to evaluate the lighting situation of the underground atrium space by dynamic daylight index.And a dynamic light environment simulation software--Daysim is introduced into this research to simulate the natural lighting situation in underground atrium space.Firstly,the commonly used light environment evaluation indicators are compared.The dynamic evaluation indicators fully consider the impact of building orientation,usage time and various actual weather conditions throughout the year.They are more comprehensive and systematic comprehensive indicators for evaluating the effective natural daylighting throughout the year.Therefore,this paper uses daylight autonomy?DA?and useful daylight illuminance?UDI?as the main evaluation indicators.The higher the values of DA and UDI,the better the dynamic light environment is.Through computer simulation,the effects of well index,section form and inner surface reflection coefficient of atrium on light environment in atrium space are explored.The results show that:?1?If the value of WI of atriums with different sizes is the same,the difference of dynamic daylight index is small,in other words,the dynamic light environment of the atriums is similar,witch verifies that the well index is still a very effective index in dynamic light environment simulation.When the value of WI is around 1.5²,the atrium space could get the best overall light environment.This result is more practical than the conclusion of most scholars?WI within 3?and takes full account of reducing glare.?2?In the situation that the value of WI is constant and the surface materials of the inner layers of the atrium are the same,the higher the reflection coefficient,the higher the average value of DF and DA₃₀₀,but the average value of the UDI_100-2000 increases first and then decreases;If the inner surface of the atrium is divided into upper and lower parts according to the floors?B1 to B3 and B4 to B6?,and the surface materials'reflection coefficient of the upper and lower parts are different,the average value of DA₃₀₀ in the atrium space increase when the difference in reflection coefficient get greater.And changes in the reflection coefficient of the upper part has a greater influence on the inner lighting environment than that of the lower part.?3?The section form of underground atrium space has great influence on its interior light environment.Among the three sections,the inverted pyramid atrium has the best overall light environment,the rectangular atrium has the second light environment,and the orthopyramid atrium has the worst light environment.