Although we think of an air conditioner or a heat pump in cooling mode as cooling the home, both systems actually remove heat. If you’re shopping around for a new air conditioner or heat pump system, you may have heard a bit of talk about sensible heat and latent heat.
But what do these two terms mean? Let’s start with sensible heat.
By Anne Fonda
A simple sensible heat definition: Sensible heat is the heat you can feel or sense that can be measured by a thermometer or thermostat. Examples of sensible heat in your home would include:
A simple latent heat definition: Latent heat is the heat energy required to cause a substance to change state. (Liquid to gas, liquid to solid, for example). Latent heat cannot be sensed by a thermometer.
Latent heat in the HVAC industry refers to heat that results from an increase or decrease in the moisture in the air.
You may also hear or read the terms sensible capacity and latent capacity as you explore HVAC cooling units. Sensible capacity is the unit’s cooling capacity and refers to the capacity in tons required to lower the temperature. Latent capacity is the unit’s capacity to remove moisture from the air.
Total capacity combines the two.
The sensible heat ratio (SHR) is the percentage of capacity that goes towards cooling/lowering the temperature (the rest goes toward controlling humidity). An HVAC contractor will use the SHR, the size of your home, your climate, and many other variables to provide accurate system sizing for your home.
To get the specifics of how SHR works in system sizing, visit HVAC School.
Set your thermostat to a temperature that will keep you warm in the winter and cool in the summer. Your furnace, heat pump, or air conditioner will add or remove sensible heat – creating a temperature change you can measure.
Air conditioners and heat pumps remove moisture from the air as they cool. Single-stage units may struggle to remove enough moisture when the outdoor humidity is high. Upgrading to a variable-speed system or adding a whole-house dehumidifier can provide the humidity control you need.
Set your humidity level with a humidistat or whole-house dehumidifier to remove latent heat caused by water vapor from the air. Many smart thermostats have built-in humidistats to help you control excess humidity. That old saying – “It’s not the heat, it’s the humidity” rings true. If the air is too humid with latent heat, you’ll feel uncomfortable even if the indoor temperature is 72 degrees.
The Environmental Protection Agency (EPA) recommends an indoor humidity level between 30% and 55% for ideal comfort. A humidity level of 60% or above is considered high humidity and can allow mold growth
Questions about how to balance latent heat vs sensible heat for home comfort? Contact your local Trane dealer for an assessment and product recommendations.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Kimberly Sexton, Senior Systems Engineer
HVAC capacity is the production capability of a heating or cooling unit. Air conditioning capacity and heating capacity are measured in tons or BTUs.
Discover the importance of correct HVAC sizing for efficient home heating and cooling. Consult with your local Trane dealer for expert guidance.
A humidistat, also known as a humidistat control or hygrostat, is a humidity monitoring tool that helps keep your home at the optimal level of humidity.
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