Investigation of Thermal Comfort Perceptions and Adaptive Behaviour in Office Buildings in the North Central Zone

Thermal comfort in office buildings in Nigeria's North Central zone is a critical workplace quality determinant that directly influences worker productivity, energy consumption, and overall occupant wellbeing, yet empirical investigation of comfort perceptions and adaptive behaviours in this specific climate and building context is largely absent from the literature. This study investigates thermal comfort perceptions, adaptive comfort behaviours, and their relationship to building design characteristics in twenty air-conditioned and naturally ventilated office buildings in Abuja, Lokoja, and Minna. Environmental monitoring using calibrated sensors recorded operative temperature, relative humidity, mean radiant temperature, and air velocity at workstation positions during a six-week summer period. Concurrent comfort surveys following the ASHRAE 55 protocol were administered to four hundred office workers, collecting perceived thermal sensation votes, comfort ratings, and records of adaptive actions taken. Physical building documentation recorded cooling strategy, envelope construction, window area, shading provision, and orientation. Adaptive comfort modelling applied the EN 16798-1 adaptive comfort standard, which accounts for outdoor running mean temperature, alongside ASHRAE 55 adaptive comfort limits. Results indicate that naturally ventilated office workers demonstrate significantly wider thermal acceptability ranges than air-conditioned workers, consistent with published adaptive comfort theory, with acceptable ranges extending two degrees Celsius beyond ASHRAE 55 limits in naturally ventilated settings. The most common adaptive behaviours were window opening or closing (sixty-seven percent), clothing adjustment (fifty-four percent), and position relocation (thirty-eight percent). The study argues for performance-based comfort standards calibrated to Nigerian office building types. Keywords: thermal comfort, office buildings, North Central Nigeria, adaptive behaviour, occupant survey.