Environmental performance of naturally ventilated library buildings in Bauchi, Nigeria

Abstract

Naturally ventilated libraries (NVLs), which have been in existence since 1948 in Nigeria, are common types of library buildings in Africa that depend on wind flow through window openings for ventilation. Their propagation was propelled by chronic shortages and unreliable electric power supply. However, there is limited information about the indoor environmental quality (IEQ) performance of NVLs which is essential for the health, comfort and productivity of library users. The objective of this research is to investigate indoor environmental performance of NVLs with the aim of promoting their use. Post Occupancy Evaluation (POE) was carried out in four academic NVLs in Bauchi to assess their indoor environmental performance. The study used a 3-way interaction concept to form an integrated assessment of passive characteristics, environmental conditions and library users’ perception to achieve the objectives of the study. A mixed mode approach was used as the methodology. A range of data collection techniques were used namely: observation and walk through, interview, physical measurement of IEQ variables and a survey questionnaire distributed to 593 respondents. From the observation, the result shows that cross ventilation is the dominant ventilation system prevailed in the case study buildings. The spatial configuration of the study spaces was in line with cross ventilation principles. A neutral temperature of 27.70°C and thermal comfort range of 27.20°C to 28.28°C were identified in the study halls. Multivariate statistical analysis of Structural Equation Modelling (SEM) inferred from the NVLs indoor environmental performance model showed that indoor environmental conditions has a direct and significant effect on the indoor performance. The NVLs indoor environmental quality performance model has a large effect size of 0.45. No complaint was expressed from the library users about excessive environmental discomfort. The outcomes of the three objectives established that the indoor environmental quality performance of NVLs is comfortable to the users. The study concludes that the NVL buildings in Nigeria are acceptable and patronized by the library users. Therefore, the use of NVLs should be maintained and promoted. The research also proposes design recommendations for NVL’s policy makers and aid architects and building design professionals in promoting low-energy library design.