Sensible heat is the heat energy that causes a change in temperature of a substance but doesn’t modify its state. For instance, when a heating system warms up the air, a change in temperature occurs without changing the phase. This is the heat that you can sense and feel and can be measured by a thermostat or a thermometer. Sensible heat plays a key role in maintaining indoor climate, making it an important part of heating and cooling processes.
Sensible Heat vs. Latent Heat
Sensible heat refers to the heat energy that changes the temperature of a substance without changing its phase.
Latent heat is the opposite of it. It alters the physical state of a substance without impacting its temperature. It changes the state of a substance from liquid to gas, from solid to liquid, etc. In HVAC, latent heat refers to the energy absorbed or released when the moisture content in the air changes, such as during humidification or dehumidification, without changing the air’s temperature.
In HVAC systems, you will find both sensible and latent heating working together. For instance, during the cooling process, when heat is removed from the air (sensible heat), moisture is also removed through condensation (latent heat).
If an HVAC system removes only sensible heat, the air may feel cool but remain sticky due to high humidity. On the other hand, if it removes too much latent heat without addressing sensible heat, the space may feel dry and uncomfortable.
Both sensible and latent heat play key roles in achieving a balanced climate that provides consistent comfort throughout your home.
Sensible Heat Capacity
In HVAC, capacity refers to a system’s ability to remove heat from a space. Sensible heat is the HVAC system’s cooling capacity expressed in tons. Latent heat capacity refers to the unit’s ability to remove moisture from the air.
Sensible Heat Ratio
The sensible heat ratio (SHR) is the percentage of total capacity dedicated to lowering temperature, with the remaining capacity used for controlling humidity levels. HVAC contractors use the SHR, along with home size, climate, and other factors, to accurately size a system for optimal comfort.
