Influence of Opposing Exterior Window Geometry on the Carbon Emissions of Indoor Lighting under the Combined Effect of Natural Lighting and Artificial Lighting in the City of Shenyang, China

Abstract

According to relevant statistics, the electricity consumption for lighting in university buildings accounts for 20 to 40% of the total energy consumption of the buildings. Lighting energy saving is a key influential factor in achieving a low-carbon campus construction. The electricity consumption for lighting is simultaneously affected by the utilization of natural daylight and artificial lighting schemes. Currently, there is a lack of research regarding the dynamic quantitative correlation between the geometric design of external windows affecting the utilization of natural daylight and carbon emissions. Also, research on the dynamic synergistic impact between natural light utilization and artificial lighting on carbon emissions has not been observed. Hence, there is a lack of quantitative carbon impact prediction and guidance in the early design and actual operation of such spaces. This study took the professional drawing space of a university in the severe cold regions of Shenyang as a prototype. Daylight factor (DF) and spatial daylight autonomy (sDA) were determined using Rhino + Grasshopper and Ladybug + Honeybee for window geometry. DIALux evo simulation was used to analyze the carbon emissions of space operation, followed by correlation analysis and multiple linear regression analysis using SPSS to determine the degree of influence of each window design parameter on the carbon emissions. The window-to-floor ratio (WFR), window-to-wall ratio (WWR), windowsill height (Hws), window width (Ww), and window height (Hw) had inhibitory effects on carbon emissions from daylight-responsive artificial lighting (C), and the influence of different orientations was different. Under the condition of an opposing window, the overall C trend of the professional drawing space was west < east< south < north, and the C of the morning period in each orientation was significantly lower than that in the afternoon period. Taking the frame structure system space with a floor-to-floor height of 4.2 m as an example, within the requirements of WFR and WWR, the C of the west-facing professional drawing classroom with 2.55 m for Hw, 0.75 m for Hws, and 9.6 m for Ww was the smallest. To a certain extent, opening large windows and opening high windows can reduce the C of the space.