LEED · Second Brain

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Thermal Comfort

Definition

Thermal comfort concerns the combined effects of indoor temperature, thermal radiation, humidity, air speed, occupant activity, and clothing. Standard 55-2023 states that these factors are to be considered together rather than as isolated setpoints. ASHRAE 55 p. 4

Why It Matters

Current BD+C includes a Thermal Environment option within Occupant Experience, connecting thermal conditions with seasonal change, occupant transitions, different activity levels, and opportunities for adjustment. BD+C p. 164 BD+C p. 166

Current O+M evaluates occupant experience and satisfaction with the indoor environment through a survey pathway, providing an operational feedback boundary rather than a separate design-compliance path in the cited page. O+M p. 78

Authority and Version Scope

  • BD+C: Verified against the November 2025 published rating system, which explicitly references Standard 55-2023 with errata. BD+C p. 166
  • ID+C: Source-gated. The April 2025 launch guide describes a parallel thermal-environment option, but it is guidance rather than current published authority. ID+C guide p. 324 ID+C guide p. 326
  • O+M: The cited current rating-system page verifies an occupant-experience survey boundary; it does not establish a separate Standard 55 design option. O+M p. 78
  • Technical standard: The restricted local document is confirmed as ANSI/ASHRAE Standard 55-2023, superseding the 2020 edition. ASHRAE 55 p. 1

LEED v5 Requirements

BD+C

The Thermal Environment option requires occupied spaces to meet Standard 55-2023 with errata and asks the design to investigate project thermal conditions, including seasonal change, overcooling, transitions between environments, and different occupant activities. BD+C p. 166

The option sits within the broader Occupant Experience credit and is one selectable pathway rather than a standalone prerequisite. BD+C p. 164

ID+C

Source-gated: the April 2025 launch guide presents a Commercial Interiors Thermal Environment option that references Standard 55-2023 and similar occupant and seasonal considerations. It is not promoted to a current published ID+C requirement. ID+C guide p. 324 ID+C guide p. 326

O+M

The current O+M Occupant Experience Performance credit uses an occupant survey to assess satisfaction with the indoor environment during the reporting period. The cited page does not isolate thermal comfort as a separate compliance calculation. O+M p. 78

MEP and Piping Application

Vault-authored engineering interpretation

The applications below are HVAC design and verification practices, not additional LEED requirements.

  • Translate occupancy, activity, envelope exposure, solar loads, and space use into thermal zones before selecting terminals and controls. ASHRAE 55 p. 4 BD+C p. 166
  • Coordinate air temperature, radiant effects, humidity, and air movement rather than treating thermostat setpoint as the complete comfort outcome. ASHRAE 55 p. 4
  • Provide appropriate occupant adjustment or differentiated zones where project use and the selected LEED pathway support them. BD+C p. 166
  • Verify sensors, sequences, balancing, and representative operating conditions through commissioning and post-occupancy feedback. Standard 55 identifies design documentation and measurement of existing environments as distinct verification activities. ASHRAE 55 p. 4

Engineering Workflow

  1. Define occupied spaces, tasks, schedules, clothing and activity assumptions, and relevant environmental factors. ASHRAE 55 p. 4
  2. Develop zoning, load, terminal-unit, air-distribution, and control strategies responsive to those conditions. BD+C p. 166
  3. Document the Standard 55 method and the project assumptions used to evaluate occupied spaces. ASHRAE 55 p. 4
  4. Test sensors, control responses, and representative environmental conditions during commissioning. ASHRAE 55 p. 4
  5. Use occupant feedback as operational evidence and investigate patterns by zone, time, and condition before changing controls. O+M p. 78

Documentation and Evidence

  • BD+C requirement evidence: Standard 55 compliance documentation and the project explanation of seasonal, transitional, and activity-related thermal conditions. BD+C p. 166
  • O+M evidence: occupant survey results and reporting-period records under the selected current O+M pathway. O+M p. 78
  • Engineering evidence: zoning diagrams, load assumptions, control narratives, sensor calibration, trend reviews, balancing records, and issue logs can support traceability without becoming new LEED requirements. ASHRAE 55 p. 4

Technical Standards

  • ANSI/ASHRAE Standard 55-2023 is the confirmed local edition and the edition explicitly named by current BD+C. ASHRAE 55 p. 1 BD+C p. 166
  • Its scope combines environmental and personal factors and distinguishes design compliance from measurement and evaluation of existing environments. ASHRAE 55 p. 4
  • This note does not reproduce comfort limits, equations, or tables from the restricted standard.

Relationships

Version and Interpretation Notes

  • Current BD+C directly references Standard 55-2023; ID+C uses the same edition only in the captured launch guide and therefore remains source-gated. BD+C p. 166 ID+C guide p. 326
  • O+M occupant feedback is an operating outcome measure and must not be presented as proof of a BD+C Standard 55 design pathway. O+M p. 78 BD+C p. 166

Deferred Source Gaps

  • Current published LEED v5 ID+C Rating System.

Source References

Published Rating Systems

Addenda and Interpretations

  • None used.

Reference Guides

Technical Standards

Foundational Sources

  • None used.

Draft or Context Sources

  • None used.

Review Questions

  1. Which environmental and personal factors define thermal comfort in Standard 55?
  2. How does the BD+C Thermal Environment option differ from O+M occupant feedback?
  3. Why is thermostat setpoint alone an incomplete comfort description?
  4. Which Standard 55 edition is confirmed and used here?
  5. Why must ID+C remain source-gated?

Recent notes

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