Multi-Criteria Evaluation of a Library’s Indoor Environmental Quality in the Tropics

The indoor environmental quality of a library greatly affects the comfort and productivity of its users while preserving the materials. Despite the high energy consumption of HVACs in libraries, achieving acceptable thermal conditions, acceptable acoustics, and sufficient daylight levels for users remains a challenge. There are limited studies on the IEQ of educational buildings, especially regarding the current situation of libraries. It is important to conduct further studies to define design guidelines promoting indoor environmental conditions. The main objectives of this study were to investigate the IEQ of a campus library to recommend retrofitting strategies. The IEQ parameters in the rare collection room, which houses special collections, and in the library hall were assessed using a full-scale measurement, with eight HOBO data loggers and sensors deployed in various locations to monitor IEQ. A comparison of the results with the standards revealed that rare collection room was unsuitable for maintaining rare collections, as the average indoor air temperature exceeded 21.2 °C, which is beyond the threshold limit. Additionally, the relative humidity ranged from 51.3% to 55.8%, which is marginally high. To provide acceptable indoor conditions, this study recommends retrofitting strategies for the exterior walls, such as using cement plaster with a low thermal conductivity. In the library hall, the reading zone was found to be thermally uncomfortable. The air velocity was below the range of 0.15 ms−1 to 0.50 ms−1 recommended by MS 1525. The average CO2 level was 479.5 ppm, with some points registering an increase of up to 588 ppm. The noise level in the library hall ranged between 43 dB(A) and 61 dB(A), while the light intensity was below 300 lux in the reading area, which is not within the acceptable range. This study suggests improvement solutions, such as implementing an air temperature between 24.5 and 26.5 °C for higher thermal comfort and increasing the window-to-wall ratio to utilize natural daylight. These findings provide insights into the design of new libraries and the renovation of existing ones, ensuring that libraries continue to serve as vibrant centers of knowledge and learning for generations to come.