RE-DEFINING AND DELIVERING THERMAL COMFORT IN BUILDINGS

This briefing by RMI describes a shift from traditional air temperature-centric building design to a targeted approach based on six variables of thermal comfort. Using the Rocky Mountain Institute's Innovation Center as a case study, the document explains how integrating these variables through the Predictive Mean Vote (PMV) metric and Integrated Project Delivery (IPD) can reduce energy use and support net-zero goals, while detailing the technical and contractual strategies needed to manage the associated risks of passive design.

• Traditional building design relies on an air temperature-centric approach that is considered ineffective, expensive, and inefficient. A more targeted strategy focuses on six variables that drive occupant thermal comfort: air temperature, air velocity, activity level, clothing level, surface temperature, and humidity.
• The ASHRAE 55 comfort standard utilizes a formula to translate the six comfort variables into a single output known as the predictive mean vote (PMV). This metric allows designers to specify a building's comfort level as a percentage of people who will be comfortable; for example, a PMV of 0.5 suggests 90% of occupants will feel comfortable.
• RMI applied this comfort-centric approach at its 15,610 sq. ft. Innovation Center in Basalt, Colorado, to achieve net-zero energy goals. The design shifted from monolithic central systems to smaller, targeted systems—such as external blinds for radiant needs and ceiling fans for airflow—complemented by personal comfort tools like user-adjustable windows and heated/cooled chairs.
• Implementing multiple targeted systems introduces significant complexity in system integration and commissioning. RMI found that proprietary control systems often conflict with central strategies, leading to 'fighting between systems' and increased operational troubleshooting. RMI recommends using a third-party master integrator for future projects to manage these technical and scope implications.
• To manage the risks of passive design and the absence of oversized central systems, RMI used Integrated Project Delivery (IPD) to align incentives and a risk-sharing framework. RMI explicitly assumed the liability for occupant comfort if the specified design parameters (PMV of 0.5) were met, while the design and construction teams were responsible only for meeting those conditions.
• RMI mitigated the financial and performance risks of passive systems by creating a contingency plan that included conceptual designs for 'plan B' backup capacity. This involved sizing ducts, panels, and conduits from the start to allow for easy future upgrades if the initial low-capacity systems proved insufficient.
• Effective thermal comfort in passive buildings requires a shift in commissioning and occupant engagement. Commissioning must move from testing individual equipment to long-term building-tuning to understand system interactions. Occupants must be active participants, which RMI encouraged through games that taught users how to adjust systems to achieve different PMV levels.

APA

McClurg, C. (2016). RE-DEFINING AND DELIVERING THERMAL COMFORT IN BUILDINGS. RMI. https://rmi.org/app/uploads/2017/03/Insight-brief_Thermal-Comfort-V7_FINAL-FOR-RELEASE.pdf

Chicago

McClurg, Chris. RE-DEFINING AND DELIVERING THERMAL COMFORT IN BUILDINGS. RMI, 2016. https://rmi.org/app/uploads/2017/03/Insight-brief_Thermal-Comfort-V7_FINAL-FOR-RELEASE.pdf.

Wikipedia

{{cite report |last1=McClurg |first1=Chris |title=RE-DEFINING AND DELIVERING THERMAL COMFORT IN BUILDINGS |publisher=RMI |date=May 2016 |url=https://rmi.org/app/uploads/2017/03/Insight-brief_Thermal-Comfort-V7_FINAL-FOR-RELEASE.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{mcclurg2016redefining, author = {McClurg, Chris}, title = {{RE-DEFINING AND DELIVERING THERMAL COMFORT IN BUILDINGS}}, institution = {RMI}, year = {2016}, month = may, url = {https://rmi.org/app/uploads/2017/03/Insight-brief_Thermal-Comfort-V7_FINAL-FOR-RELEASE.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }