Assessments of the surface cover within cities indicate that paved surfaces – roads, parking lots, sidewalks and driveways – make up anywhere from 12 to 44% of developed areas. These dense, often dark, and impervious surfaces are considered one of the leading factors in urban heat island (UHI) formation. Metropolitan Phoenix, Arizona, located in the Desert Southwest of the United States is one of the fastest growing urban centers in the US and has experienced an average increase in minimum temperatures of 8% over the last 30 years. The US Environmental Protection Agency (US EPA) and the US Green Building Council (USGBC) suggest open grid, permeable pavements as viable strategies for mitigating both climate and storm water runoff impacts of pavements. The actual benefit and performance of these types of pavement alternatives has yet to be quantified and their physical behavior fully understood in the literature. This study describes the construction and monitoring of one such pavement, GravelPave™ at a large parking lot located in Gilbert, Arizona. The researchers aimed to quantify the surface energy balance, impact on thermal comfort and heat stress index, and storm water runoff and infiltration rates of six different designs utilizing this alternative pavement material. The results of this investigation will represent the first quantification of the storm water and UHI mitigation performance of this type of pavement system in a hot arid climate. The findings can be used by city planners, architects, and engineers in future low impact development projects.