Wednesday, February 19, 2014

Comfort Vs. "Cool": Thermal Comfort & Clothing Variability in Schools

Thermal comfort in schools is impacted by a variety of factors, and this was discussed somewhat in a previous post: Culture and Thermal Comfort. But beyond HVAC system problems as well as the differences in perceived temperature control, activity levels and physiology between students and adults (and between men and women), the variation between student and adult thermal comfort ratings are partially due to the typically greater variability in student clothing compared to adult clothing (particularly during the warmer months and for high school students). One’s perspective of acceptable clothing is shaped by peers and family, school policy, and society in general. Clothing is also used as a means of establishing “group” identity as well as signaling membership in that “group.” For teenagers who are still maturing and experimenting with who they eventually want to be and what “groups” they want to belong to, clothing is part of that experimentation, both in terms of clothing type and the amount worn (Harmon 2012).

Because the varying insulative properties of clothing also affect thermal comfort, when a large segment of the facility population has a wide range of clothing styles subject to frequent changes, it becomes more difficult to maximize thermal comfort. One potential means of addressing this beyond the building itself, is to encourage everyone to keep layers of clothing available. The goal is an occupant population that will add or reduce layers of clothing as individually needed and more uniformly respond to exterior weather conditions in terms of percentage of exposed skin, but still allow expression through clothing choices and styles (Harmon 2012).

This is a reasonable response to widely varying clothing styles because we know that occupants in general are more likely to adjust their clothing in response to changing thermal conditions as opposed to keeping them constant (Schiavon and Lee 2013). However, in K-12 environments this is complicated by socio-economic status (perhaps more so than in other environments) because low SES students may not have the financial resources to obtain multiple layers of clothing. In addition, energy models commonly assume a clothing insulation value of 0.5 clo for the cooling season and 1.0 clo for the heating season, with an abrupt change from one to the other as the seasons transition. But we know that clothing is not constant (and can be highly variable among the building population). Studies (Lee et al. 2013; Lee and Schiavon 2013; and Schiavon and Lee 2012, 2013) have shown that energy models making use of more dynamic models of clothing insulation result in improved thermal comfort, smaller HVAC equipment sizes and lower energy consumption.

References

Harmon, M. (2012) Creating Environments that Promote Efficiency and Sustainability: Anthropological Applications in the Building/Construction Industry. Proceedings from the 2012 ACEEE Summer Study on Energy Efficiency in Buildings, pp 7-75 - 7-87, http://www.aceee.org/files/proceedings/2012/start.htm

Lee, J., H. Zhang and E. Arens (2013) Typical Clothing Ensemble Insulation Levels for Sixteen Body Parts. Indoor Environmental Quality (IEQ), Center for the Built Environment, Center for Environmental Design Research, UC Berkeley, http://escholarship.org/uc/item/18f0r375.

Lee, K. H. and S. Schiavon (2013) Influence of Two Dynamic Predictive Clothing Insulation Models on Building Energy Performance. Indoor Environmental Quality (IEQ), Center for the Built Environment, Center for Environmental Design Research, UC Berkeley, http://escholarship.org/uc/item/8sx4w8mn.

Schiavon, S. and K. H. Lee (2012) Dynamic Predictive Clothing Insulation Models Based on Outdoor Air and Indoor Operative Temperatures. Indoor Environmental Quality (IEQ), Center for the Built Environment, Center for Environmental, Design Research, UC Berkeley, http://escholarship.org/uc/item/3338m9qf

Schiavon, S. and K. H. Lee (2013) Influence Of Three Dynamic Predictive Clothing Insulation Models On Building Energy Use, HVAC Sizing And Thermal Comfort. HVAC Systems, Center for the Built Environment, Center for Environmental Design Research, UC Berkeley http://escholarship.org/uc/item/3sx6n876.

No comments:

Post a Comment