A heat pump can hold the thermostat perfectly and still leave the homeowner uncomfortable.
That is the warning in a new August 26 ACHR News analysis from building-performance specialist Nate Adams, who argues that dehumidification deserves significantly more attention as homes move toward high-efficiency electrified HVAC.
Temperature Isn't the Whole Load
HVAC systems deal with two different problems.
Sensible load changes temperature.
Latent load removes moisture.
A system can satisfy one without adequately handling the other.
That becomes particularly noticeable during mild but humid weather, when the home needs moisture removal without much sensible cooling.
High-Efficiency Equipment Can Create New Challenges
Modern variable-capacity systems often run differently from conventional equipment.
When properly designed, they can deliver excellent comfort.
But equipment selection based primarily on heating capacity or efficiency ratings can overlook humidity performance.
The result can be a house sitting at the correct thermostat setpoint while still feeling sticky.
Contractors May Need Dedicated Dehumidification
In some climates and building types, HVAC design may need to consider a dedicated whole-home dehumidifier instead of expecting the cooling system to handle every latent-load condition.
This becomes especially relevant as homes become tighter.
Less uncontrolled outside-air leakage saves energy, but moisture introduced through ventilation, occupants and normal building operation still has to go somewhere.
Comfort Is More Than Degrees
For decades, HVAC sales have largely revolved around temperature and energy efficiency.
Building science is making the definition broader.
Temperature.
Humidity.
Air quality.
Ventilation.
All of them influence comfort.
The next high-performance HVAC system may need to control moisture just as intentionally as it controls temperature.
