Abstract
This chapter proposes an approach to thermal comfort that increases occupant pleasure and reduces energy use by connecting architecture's material and environmental dimensions. Today's dominant thermal comfort model, the predicted mean vote (PMV), calls for steady-state temperatures that are largely unrelated to building design decisions. A more recent alternative approach, the adaptive thermal comfort (ATC) model, ties comfort to outdoor conditions and individual experience. Yet reliance on HVAC technology to provide building comfort hampers how such ideas are integrated into building design. This chapter outlines the historical background of the PMV and ACT models to understand the current status of thermal comfort research and practice. It then uses four recent buildings to outline how the insights of adaptive comfort research can be translated to bespoke comforts through spatial, material, formal, and other design strategies.
TopIntroduction
Architecture improves the weather. That is, the indoor climate created by buildings is intended to increase human health, productivity, and happiness while decreasing disease and discomfort. We are more comfortable inside than out. Yet, given comfort’s fundamental role to architecture, architects typically outsource its creation to mechanical engineers, who in turn base their designs on the Predicted Mean Vote (PMV) comfort standard. This standard restricts comfort to a narrow band of temperature and humidity that requires significant amounts of energy to maintain.
Global climate change is heightening our collective consciousness of comfort. It is becoming increasingly difficult to separate stable interior climates from changing exterior ones. This growing awareness of comfort has led some building researchers to question the dominant PMV approach. The Adaptive Thermal Comfort (ATC) model is a promising step in this direction. ATC holds that, by allowing indoor climates to change in ways that reflect outdoor ones, the design team can improve building comfort and reduce energy use. ATC currently exists largely as a building standard. Its observations have yet to be embraced by architects as design opportunities to shape building environments. Similarly, ATC researchers have not fully considered how the formal, spatial, and material intelligence architects bring to the design process can further advance the goal of a more comfortable, less energy-intensive architecture. This chapter connects ideas from adaptive comfort research to examples of building design. It demonstrates how architects can consciously improve the weather in ways that relate architecture’s material dimensions to its environmental ones.
The 20th-century engineering definition of comfort focused the attention of building professionals on a narrow yet politically effective definition of comfort. This limited definition became a discursive vehicle for naturalizing comfort into a matter of technical and legal fact captured in building standards and embodied in the buildings they governed. Yet, when seen historically, comfort appears as a sociotechnical concept that links cultural norms, expectations, and differences on one hand with technical and natural systems on the other. This history shows that the concept of comfort is a rich locus of ideas that is both fundamental to architecture and part of larger interdisciplinary debates. Comfort reflects how the built environment affects health and creates pleasure. It manifests cultural conventions, from temperature preferences and seasonal traditions to notions of privacy and gender identity. It reflects important technical developments that have accelerated since the 19th century and architectural traditions that have faded during this same period. Perhaps most importantly for the challenges facing architecture today, building comfort reflects the social construction of energy use (Shove, 2003). As such, understanding how comfort came to be what it is today provides insights into how it can continue to evolve to address today’s unique challenges.
Key Terms in this Chapter
Predicted Mean Vote (PMV) Comfort Model: Developed by comfort researcher P. O. Fanger, the PMV comfort model equates comfort with the heat balance between a body and its immediate environment. It is based on the four environmental variables of dry bulb temperature, relative humidity, mean radiant temperature, and air velocity, as well as the two personal variables of activity level and the insulation value of clothing. It is typically associated with cool, dry still air provided by air conditioning in which people are largely sedentary and wearing typical business attire.
Heat Balance: A mechanistic approach to comfort based on the idea that when the heat produced by metabolism is balanced with a room’s air temperature and humidity, people feel comfortable.
Spatial Alliesthesia: The experience of different thermal stimuli on parts of the body as captured by the folk expression describing comfort as resulting from “warm feet and cool head.”
Climate Chamber: A windowless room in which temperature and humidity can be precisely set and independently controlled. Also called air conditioned , environmental , or psychrometric chambers.
Predicted Percentage Dissatisfied (PPD): An estimation of how many people will find PMV comfort conditions thermally satisfactory. Danish comfort researcher P. O. Fanger, who developed the PMV comfort model, considered conditions acceptable when 80% or more of occupants were satisfied with the building’s interior climate. Importantly, such satisfaction reflected a condition of thermal neutrality, where building occupants did not object to interior environmental conditions, rather than one of thermal pleasure.
Temporal Alliesthesia: The experience of temporary variations in thermal experiences over relatively short periods of time, such as moving from a patch of shade into the sun on a winter walk, or rounding a street corner and stepping into a cool breeze on a humid summer day.
Adaptive Responses: Factors that affect thermal comfort beyond the body’s heat balance with the surrounding environment. There are generally considered to be three adaptive responses: behavioral adjustment, physiological acclimation, and psychological expectation. The response recasts building occupants as active agents in shaping their comfort rather than as passive recipients of comfort conditions.