Heat-coping strategies and bedroom thermal satisfaction in New York City

Abstract

There has been little research into the thermal condition of the sleeping environment. Even less well documented and understood is how the sleeping thermal environment is affected by occupant behaviors such as the use of air-conditioning (AC) and electric fans, or window operations. In this paper we present results from a questionnaire survey administered to assess summertime bedroom thermal satisfaction and heat-coping strategies among New York City (NYC) residents. Specifically, we investigated current AC usage in bedrooms and examined alternate cooling strategies, cooling appliance usage patterns, and the motivations that drove these patterns during the 2015 summer. Among survey respondents (n=706), AC was the preferred heat-coping strategy, and for 30% of respondents was the only strategy used. Electric fan use and window opening were deemed ineffective for cooling by many respondents. Indeed, less than a quarter of all respondents ever opened windows to alleviate heat in their bedrooms. In general, people utilized strategies that modify the environment more than the individual person. Unsurprisingly, the frequency and overall use of AC were significantly associated with greater bedroom thermal satisfaction; however, setting AC to a lower temperature provided no additional benefit. In contrast, more frequent use of electric fans was associated with lower thermal satisfaction. In addition, 14.7% of all respondents did not have AC in their sleeping environment and 5.8% were without any AC at home. Despite the high penetration of AC ownership, usage cost was still a major concern for most. This work contributes to a better understanding of bedtime heat-coping strategies, cooling appliance usage patterns, and associated thermal satisfaction in NYC. The findings of this study suggest resident AC usage patterns may not be optimized for thermal satisfaction. Potential alternative cooling approaches could be explored to better balance maximizing thermal comfort while reducing energy consumption and environmental impact.

Keywords: Air conditioner; Electric fan; Questionnaire survey; Sleeping environment; Thermal comfort; Windows.

Figure 1

Number of days per year with a maximum temperature or heat index of at least 90/95/100°F measured at the La Guardia Airport weather station (data source National Weather Service)

Figure 2

Respondents’ bedtime heat-coping strategies for summer 2015

Figure 3

Influencing factors behind chosen and unused heat-coping strategies

Figure 4

Effect sizes of Mann-Whitney U test pairwise comparisons with bootstrapped 95% confidence intervals for statistically significant variables

Figure 5

Comparisons of respondents 65+ and respondents who were retired against respondents <65, and respondents not retired (OR=1); * p<.05, ** p<.01, *** p<.001, **** p<.0001; ^ means the Pearson’s Chi-Square statistic was significant but standard residuals in individual cells were not (i.e. barely significant therefore interpret with caution)