Study On Natural Lighting In The Reading Space Of Xuzhou University Library Based On Light Comfort

As the most important learning and scientific research place for teachers and students,the light comfort of its reading space has an extremely important impact on teachers and students.Natural light can not only create a more comfortable and healthy light environment than artificial light sources,but also reduce energy consumption.With this as the background,this thesis focuses on Xuzhou area,aims to meet the light comfort of readers,summarizes the current status and problems of natural lighting in the library,and applies shading,reflection and light guidance measures to the design and transformation of the natural light environment of the reading space of university libraries.The thesis focuses on three questions.First,the first question is explored: how to evaluate the spatial light environment of Xuzhou University Library.Through literature combing,research on current status,theory,indicators and simulation software is carried out.The static evaluation indexes: lighting coefficient(DF)and dynamic evaluation indexes: effective natural lighting time percentage(UDI)and all-natural lighting time percentage(DA)were selected as the evaluation indicators of light comfort in this thesis,and Dali2023 was determined as the simulation software of the light environment in this thesis.Secondly,the second question was studied: what is the current situation of natural lighting in the reading space of Xuzhou University Library.Field investigation was conducted in 10 libraries of Xuzhou universities,typical reading spaces were selected for natural light environment measurement,and readers were surveyed on questionnaires.(1)The measured light coefficient shows that the lighting coefficient near the window is as high as 11.38%,which is easy to produce glare;(2)The illumination at the far window is low,which cannot meet the lighting requirements;(3)Analysis of questionnaire reliability validity showed that the questionnaire α coefficient of Wenchang Campus and Jingwen Campus Library exceeded 0.8,and the reliability of the questionnaire was good;the KMO value was 0.859 and 0.837,respectively,and the questionnaire validity was strong.(4)Only 35.32% of readers are satisfied with the current reading space light environment,and42.39% of readers believe that the most important problem to be solved in the current reading space is glare.Then answer the question three: how to optimize the design of the reading space light environment of Xuzhou University Library.A typical model of the reading space of Xuzhou University Library was established,and the factors that affected the light environment were selected to be simulated.The simulation results are:(1)in the case of double-sided lighting,the best orientation of the reading space is 10° east by south and 5°west by south,respectively;In the case of single-sided lighting,the best orientation is 15°east south and 5° west south.(2)In the case of double-sided lighting,the bay should not be larger than 30.6m;in the case of single-sided lighting,the larger the bay,the better.(3)Under the condition that other factors remain unchanged,the floor height has little impact on the lighting of the reading room.(4)The size of the side window has a great influence on lighting,and the window width should not be greater than 3.9m in the case of double-side lighting;when the window height is 2.1m,the light environment is more comfortable.In the case of single-sided lighting,the window width should not be less than3.6m;when the window height is 2.7m,the light environment is more comfortable.(5)Through the simulation of five kinds of glass with different light transmittance,it is found that in the case of double-sided lighting,the light transmittance is 0.57(shading Low-E glass)is appropriate;in the case of unilateral lighting,the light transmittance of glass cannot be lower than 0.75(light blue glass).(6)In the reading room with double-sided lighting,vertical shading should be used,and the length of the visor should be 0.8m;in the case of unilateral lighting,it is not recommended to add shading components.(7)In the case of a certain number of light guides,the best arrangement is 3× 4,2× 6,4× 3 and 1×12.(8)In the case of double-sided lighting,when the length of the external reflector does not exceed 1m,the longer the length,the more comfortable the light environment,and the installation angle is 20° best;The length of the built-in reflector is 0.9m optimal.In the case of single-sided lighting,the length of the external reflector should not exceed 0.3m,the installation angle should be 20°,and it is not recommended to install the built-in reflector.Finally,based on the research of the above three problems,a representative library reading space is selected for design transformation and verification,and three lighting auxiliary measures are added to the target building: sun visor,reflector and light guide.The software simulation found that the average DF after the renovation remained within the comfort range,and the problem of excessive illumination near the window was significantly improved.The average value of the DA450 lx did not change much;The UDI100-2000 lx average increased from 30.3% to 38.3%,an increase of 26.4%.The 1:30scale model after the transformation was experimented under the artificial sky dome,and it was found that it was consistent with the software simulation results,which proved the necessity and effectiveness of the design transformation.