Design of heat-resilient housing in hot-arid regions

Abstract

Extreme heat events in urban areas increasingly challenge the capacity of electrical distribution systems to serve building cooling equipment under peak loads and, when power is interrupted, the thermal response of buildings that can delay the onset of dangerously high indoor temperatures. The design of new buildings and their operation can mitigate the risks of intense heatwaves, but architects and planners face a myriad of choices about what measures to select, and how best to estimate their individual and collective performance. To aid the design and operation of heat-resilient buildings, this paper takes a multidisciplinary approach that is novel in two key aspects. First, it evaluates the individual and aggregated impact of factors associated with architectural and urban design, equipment technologies, and human behavior. Second, its valuation metrics include the magnitude of peak electrical load, appropriate for assessing active measures aimed at reducing peak power, and the time after a power outage for indoor temperatures to reach levels associated with heat stress, an indication of the efficacy of passive (no power) measures. The application of the method in the Middle East North Africa (MENA) region, where growing populations and demand for space cooling make it particularly relevant, relies on knowledge of building codes and local construction practice. Single-factor testing shows that pre-cooling produces the largest reduction in peak electrical load during a simulated four-day heatwave, followed by building adjacency, maximum temperature set point and equipment loads. A combination of all considered factors reduces peak power by 70% and shifts the reduced peak to a later hour. In response to a power outage, the incorporation of architectural factors (roof, wall and window thermal resistance above code minima, increased thermal mass, reduced glazing solar heat gain coefficient and window shading) reduces the time above a Heat Index of 28 °C (caution) in a week-long test period in which the power failure occurs at hour 40 from 119 to 53 h. The presented methodology applies broadly to other building types and to regions affected by very hot weather.