Lesson 1 – Why Comfort Complaints Exist Even When HVAC Is Working
Lesson Objective
Understand why occupants complain even when the HVAC system is operating as designed, and why “temperature is correct” is not enough to guarantee comfort.
The Common HVAC Myth
Many HVAC engineers believe that if the room temperature is correct, comfort is achieved. In real buildings, this assumption fails repeatedly.
Occupants often complain even when measured temperatures are within the design range. This happens because comfort is a combined human response, not a single technical variable.
Comfort vs System Performance
An HVAC system can meet cooling loads, airflow rates, and control setpoints, yet still create discomfort. From the engineer’s point of view, the system works. From the occupant’s point of view, the space feels wrong. Both views can be true at the same time.
Example 1 – “Temperature Is Fine, But…”
In an open office, the thermostat reads 24°C and remains stable all day. However, employees near the façade complain about feeling cold, while interior occupants feel warm. The HVAC system is blamed, but the real issue is radiant temperature from the façade and poor zoning, not the cooling capacity.
Why Complaints Appear After Handover
Most comfort complaints do not appear during design or construction. They appear after occupancy, when people sit still for long periods, use the space differently than assumed, and interact daily with air movement, noise, and surfaces. Comfort problems are often operational and spatial, not calculation errors.
Example 2 – Meeting Room Complaints
A meeting room is sized correctly for peak occupancy. During short meetings, it feels acceptable. During long meetings, occupants complain of stuffiness and headaches. The cooling load is correct, but air distribution and ventilation effectiveness are not sufficient for the actual usage pattern.
The Human Factor
Comfort perception varies between individuals. Age, activity level, clothing, and sensitivity all play a role.
HVAC systems are designed to satisfy most occupants, not everyone. Problems arise when expectations are not aligned with what the system can realistically deliver.
Example 3 – One Complainer, One System
In a shared office, one person constantly complains while others are satisfied. The system is adjusted multiple times without success. The issue is not the HVAC system, but individual sensitivity combined with lack of local control.
Key Insight
Comfort complaints are rarely caused by a single failure. They are usually the result of multiple small issues acting together: zoning, air movement, radiant effects, noise, and expectations.
Key Takeaway
When occupants complain, the correct question is not “Is the HVAC system working?”
The correct question is “Which comfort factor is being ignored?”
Reflection
Think about the last comfort complaint you dealt with.
Was it really a temperature problem — or something else?