Application of Passive Solar Design Principles in New Residential Developments in Sokoto State: A Professional Review

Sokoto State presents one of Nigeria's most thermally demanding residential climates, characterised by extreme dry season temperatures, intense solar radiation, and dust-laden Harmattan winds, making passive solar design an essential rather than optional dimension of responsible residential architectural practice in the region. This study professionally reviews the application of passive solar design principles in new residential developments constructed between 2019 and 2024 in Sokoto metropolis, examining the degree to which design decisions reflect informed passive solar strategy. Building documentation analysis was conducted for thirty new residential buildings spanning private developer housing, government housing, and individually commissioned residences. Design assessment evaluated building orientation relative to solar path, window-to-wall ratios by facade orientation, shading device provision, thermal mass strategy, cross-ventilation provision, and cool roof treatment. Site visits conducted temperature measurements confirming as-built thermal performance. Interviews were conducted with twelve architectural practitioners active in Sokoto and five developers regarding design decision drivers and constraints. Results indicate that only eight of thirty reviewed buildings demonstrated systematic passive solar design application across the majority of assessed criteria. Building orientation was inappropriate in sixty-three percent of cases, with major glazed facades facing west and generating severe afternoon heat gain. Shading devices were absent in seventy-seven percent of west-facing windows. Thermal mass was underutilised, with lightweight concrete block construction prevalent. The study recommends the development of a Sokoto State residential design climate guide and a passive solar design module for CPD offered by the NIOB North West chapter. Keywords: passive solar design, residential architecture, Sokoto State, thermal climate, passive cooling.