Elements and Perception:A Study of the Nighttime Environments of University Campuses based on the Evaluation of Safety Perceptions and Preferences
The nighttime environment is an important part of the infrastructure of university campuses.However,it lacks the exploration of human needs.There are relatively few studies on specific environmental elements and perceptions at the micro and medium levels.The impact of campus nighttime environment on users'safety perceptions and preferences warrants further investigation.In this study,a survey on environmental elements at 16 campus outdoor spaces in Suzhou during daytime and nighttime was carried out using the hierarchical sampling method,focusing on user safety perceptions and preferences.Horizontal and vertical illuminance were measured with an illuminometer,and the uniformity was calculated.Photographs were captured and the average luminance,maximum road luminance,and average ambient luminance of the environment were calculated using an illuminometer.In addition,color temperatures of lamps at the survey sites were measured using a SPIC-300 spectral color illuminance meter.Landscape experts were invited to evaluate the landscape characteristics and quantitative criteria of each survey site.Day and night photographs of 16 survey sites were captured.Moreover,subjective evaluations of respondents'safety cognition and preferences to survey sites were acquired using online questionnaires and color photographs.The correlation between light environment elements and safety perceptions was discussed quantitatively using the day-night difference method,thus further recognizing major environmental factors which influence the overall preference at night,as well as their thresholds.Finally,ranges of environmental parameters based on comprehensive perceptions were established.Results showed that the nighttime environmental renewal design of university campuses should consider the light environment,followed by the landscape features.Specifically,the average horizontal and road luminance were important factors that affected safety perceptions and preferences of users.Under conditions of comprehensive safety perceptions and preferences,the favorable average horizontal illuminance range was 13~17lx,and the favorable average road luminance range was 0.7~0.9 cd/m2.Moreover,a threshold of nighttime environmental elements with an average horizontal illuminance of 17~27lx and an average road luminance of 0.9-1.2 cd/m2 were considered to fulfill higher requirements.A high-quality university campus nighttime environment should be built based on user needs to stimulate campus vitality at night.It has become an important way to practice the concept of people-centered campus sustainable development.Limited by energy and the acceptance of respondents,the use of landscape photographs from too many perspectives were not suggested as the evaluation media,as this may cause certain deviations.In future,empirical studies should be carried out.More comprehensive evaluations may be made by combining physiological reactions or behavioral tests,such as eye movements or heart rates.This study provides data supporting the nighttime environmental renewal design at university campuses and their accurate implementation,thereby improving the subjective perception of users,and promoting the construction of a sustainable campus environment.