A thermostat can reach its setpoint while a person remains uncomfortable. Investigate the conditions at the occupied position before treating the displayed number as proof of comfort or of a failed cooling system.
Literature summary: thermal comfort depends on air temperature, radiant surroundings, air movement, humidity, clothing and activity. A warm window or cool surface can change heat exchange with a person even when the nearby air temperature is unchanged.
Comfort models combine several inputs and apply within defined conditions. Mean radiant temperature represents the combined radiant surroundings; one infrared reading of one surface is not a measurement of that complete environment.
Decision example — If discomfort follows direct afternoon sun while a shaded comparison position has similar air temperature, investigate shading and radiant exposure alongside airflow. That pattern is a testable lead, not proof that cooling capacity is adequate or inadequate.
Field method
What to record and compare
Record place, time, weather, occupancy, instrument and operating state. Keep observations separate from explanations.
01
GCT field method 1 — Record the occupied position, time, complaint and a nearby comparison position. Ask for the person’s experience without collecting unnecessary medical or personal details.
02
GCT field method 2 — Record air temperature in °C, relative humidity in %, air speed in m/s when measured, sunlight and nearby warm or cold surfaces. Identify sensors and their locations.
03
GCT field method 3 — Note ordinary activity and clothing only to the extent needed to interpret comfort. Label assumed model inputs rather than presenting them as measurements.
04
GCT field method 4 — If a comfort model is used, retain its version, method, applicability checks, inputs and uncertainties. Do not turn its output into a claim that everyone is comfortable.
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GCT field method 5 — Try one authorized, safe change such as shading or a suitable airflow adjustment; repeat at comparable time and use. Record the response, including no improvement.
New source links and claims reviewed November 4, 2026. A source explains the stated mechanism; it does not diagnose a particular building or endorse ICY.
Health and Safety Executive
Thermal comfort: six environmental and personal factors
Air temperature, radiant conditions, air movement, humidity, clothing and activity jointly affect comfort; UK guidance used for physical principles, not a worldwide legal temperature rule
Read the primary sourceUniversity of California, Berkeley — Center for the Built Environment
CBE Thermal Comfort Tool
Comfort models require environmental and personal inputs; Model applicability and input assumptions must be checked; a tool result is not a site assessment
Do not remove required protective clothing, defeat ventilation or expose people to heat or cold for a comparison test. Follow local safety procedures and seek qualified assessment when hazardous exposure is possible.
