This project focused on five neighborhoods within the greater Phoenix area, Arizona, USA. Phoenix is the U.S. metropolitan area "with the highest summer temperatures (National Oceanic and Atmospheric Administration 2012), averaging 74 days per year with daily maximum air temperatures at or above 40 °C. These high temperatures are shown to be associated with the highest risk for heat-related morbidity (Petitti et al. 2015) which can be particularly dangerous for the most vulnerable low income populations (e.g., Declet-Barreto et al. 2015). Moreover, the desert Southwest is warming faster than most US regions and is projected to warm at a high rate in the coming decades (Karl et al. 2009; Walsh et al. 2014), with the temperature change in the hottest days projected to increase approximately 5.5–8.5 °C under a high emissions scenario (Luber et al. 2014)." Neighborhoods were selected to provide contrasts in urban geography and form, socioeconomics, demographics, and vegetative cover.

Eighty participants were recruited to participate in this study and asked to carry iButton temperature sensors for a week in September. These sensors recorded a time series of experienced ambient temperatures, both indoors and outdoors. This IET time series approximates each participant's personal heat exposure (Basu and Samet 2002, Kuras et al. 2016).

Recruitment took place during September of 2014 and occurred via flyers distributed on the street by the research team, study information bulletins posted in neighborhood businesses, and emails sent out through Homeowner Associations. Study approval was obtained from the Institutional Review Board at Arizona State University prior to participant recruitment, with written informed consent received from all participants. Participants were diverse in terms of age, income, housing type, and gender.

The study took place from 20:00 September 13 to 20:00 September 20, 2014 to capture IETs under warm season conditions. Each research participant was equipped with a Thermochron iButton (DS1921G-F5#), a small and light mobile sensor (<20 mm diameter, <7mm thickness, 3.3 grams) that measured and recorded instantaneous air temperature at 5 minute intervals during the study week (EDS 2012; Sullivan 2009). IETs were converted to 4-hour averages for each participant.

Participants completed an optional background survey that asked questions about age, race, gender, occupation, income, educational attainment, housing status, home cooling strategies, and orientation toward the neighborhood.

Daily surveys consisted of four segments and were completed at the end of each day. First, participants noted any period of time during which they were not carrying their iButton. Participants were instructed that, if they were not carrying their iButton, they should leave the sensor at home in a shaded area, not too close to a heat-emitting appliance. Indicated time periods were excluded upon retrieval of the iButtons. It is possible that participants underreported the amount of time that they did not carry their iButtons, in which case indoor air temperatures was oversampled. Second, participants ranked both how hot or cold they were as well as their personal comfort in the place they spent the majority of their time during the previous night (roughly 11pm-7am). This same question was repeated for the time spent inside during the day and again for the time spent outside. Third, participants estimated the number of hours they spent outside. Fourth, participants described their day in terms of their overall experience with temperature and included any notable activities or observations, prompted by examples such as, "a scorching hot day, a rigorous run or bike ride, refreshing ice cream, a broken air conditioner, or a trip to the pool."

Activity logs were optional surveys for participants that occurred once on a weekday (Tuesday, Wednesday, or Thursday) and once on the weekend (Saturday or Sunday). During each of two 5-10 minute phone calls, a researcher asked the participant for a full, detailed schedule of his or her entire day and previous night, organized by fifteen-minute intervals. Researchers would ask about the participant's thermal comfort during various activities and whether the participant was indoors or outside.

At the conclusion of the study week, members of the research team met with each participant to retrieve his or her daily surveys, background surveys, and iButtons and conduct an optional exit interview. Interviews consisted of multiple sections including experience in and perception of the neighborhood, heat and general access to cooling resources, such as air-conditioning, parks, and pools, and the drawing of a neighborhood "heat map," including usual routes, favorite and least favorite places, and areas that felt physically hot and cool during the warm season.