Empirical Analysis of the Thermal Performance of Phase Change Material-Integrated Building Walls for Passive Cooling in Maiduguri

Passive cooling through incorporation of phase change materials in building envelope components exploits latent heat storage to reduce peak indoor temperatures and shift thermal loads in hot climate buildings, reducing air conditioning energy demand. This study empirically analyzes the thermal performance of phase change material-integrated wall panels in an experimental room constructed at the University of Maiduguri campus, Borno State, North East Nigeria, in comparison with a reference room of identical geometry using conventional sandcrete wall construction. Paraffin wax with a melting point of 28 degrees Celsius and latent heat of 220 kJ/kg was selected as the phase change material based on measured local ambient temperature profiles and encapsulated in macro-capsule form within 40 mm wall board panels. Instrumented with 24 thermocouple sensors, heat flux sensors, and data loggers, both rooms were monitored continuously for 60 days during the dry season peak cooling period. Indoor air temperature, wall temperature profiles, and heat flux through walls were analyzed to quantify thermal lag, peak temperature reduction, and total daily heat gain. Results demonstrate a mean peak indoor temperature reduction of 3.8 degrees Celsius and a thermal lag increase of 2.4 hours in the phase change material room relative to the reference room. Daily cooling energy savings equivalent to 18 percent of a 1 kW air conditioning unit load were estimated. The study develops a transient heat transfer model for the phase change material wall system validated against measurements and performs sensitivity analysis on phase change material melting point selection for the Maiduguri climate. Keywords: phase change material, passive cooling, building envelope, thermal performance, Maiduguri