Cooling Effects and Human Comfort of Constructed Wetlands in Desert Cities: A Case Study of Avondale, Arizona

Abstract

Heat continues to be a hazard in the desert southwestern USA. This study presents the results of a preliminary microclimate field survey in two Avondale, Arizona, neighborhoods developed with artificial wastewater-treatment wetlands and one adjacent desert neighborhood. The preliminary field study reported here measured morning, near-noon, and afternoon air temperatures and, together with other observed variables, calculated mean radiant temperatures (critical to human comfort) at 28 locations across three neighborhoods on a sample day in September of 2018. The aim was to determine cooling effects of blue/green environments and identify benefits for residents. Overall results for September indicate 1–3 °C cooling, which is understandable for this time of year at summer’s end. Mean radiant temperature results are substantially different at lake sites versus dry neighborhood sites (by some 5–20 °C), likely due to the presence of fewer lateral radiant fluxes and cooler exposures at lake sites compared with dry neighborhoods. Cooling benefits likely provide year-round outdoor comfort compared to desert-landscaped communities. The authors reinforce the conclusion that recycled water and treatment systems can reduce local heat island conditions and aid in combating extreme heat in the desert southwest. This study also shows that constructed wastewater-treatment wetlands in desert cities support sustainable residential developments.