Comfort and Indoor Air Quality
Comfort is more than temperature. Humidity, air movement, filtration and ventilation all shape how a space feels.
Safety
What it is
Comfort is the condition where a person is not aware of being too warm or too cool. It depends on air temperature, the temperature of surrounding surfaces, humidity, air movement, clothing and activity level. HVAC equipment can influence the first four.
Mean radiant temperature
The average temperature of surfaces around a person. A cold window can make a room feel cool even at a comfortable air temperature.
Why it matters
Many comfort calls are not equipment failures. A room that feels cold may have a cold exterior wall, a drafty window, or a supply register throwing air across the occupant. Knowing what actually drives comfort keeps you from replacing working equipment.
| Complaint | Frequent cause | Where to look |
|---|---|---|
| Clammy in summer | Poor latent removal | Airflow too high, oversized equipment, short cycles |
| Dry and static in winter | Low indoor humidity | Infiltration, no humidification, very cold outdoor air |
| Cold drafts | Air movement across occupants | Register throw and placement, supply air temperature |
| One room off | Distribution | Duct sizing, balancing dampers, closed or blocked registers |
| Stuffy or stale | Insufficient ventilation | Outdoor air rate, HRV or ERV operation, filter loading |
Air quality basics
- Filtration removes particulate. Higher MERV filters capture more but add pressure drop, so filter area has to grow with rating.
- Ventilation dilutes indoor contaminants with outdoor air. Balanced ventilation with an HRV or ERV recovers most of the energy.
- Source control matters more than any filter. Combustion appliances, attached garages and moisture problems should be addressed at the source.
- Humidity control limits mold growth and dust mites at the high end and irritation at the low end.
Combustion safety comes first
Local requirements
Ventilation rates, filtration requirements and combustion air provisions are set by the codes and standards adopted in your area.
Practice & Mastery
- Comfort and Indoor Air Quality Troubleshooting Scenarios2
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