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Sensible vs Latent cooling - What do they mean?

Written by Geoff Brown | Jul 6, 2023

In this episode of FAQ with AGIQ, we're going to talk about the two types of cooling or heating that I'm sure you've heard about, but you may not understand yourself... and it's important that you do.


Episode Transcription:
In this episode of FAQ with AGIQ, I want to talk about the two types of cooling, or heating that I'm sure you've heard about. I'm sure you've heard an engineer or manufacturer, or a contractor talk about… but you may not understand yourself, and it's important that you do.

Sensible and latent cooling. Sensible cooling is - Think about it in a way you can sense it. It's the temperature change on an air stream.

Latent cooling is the removal of water from an air stream. Latent heat is the water in that in that air stream. And so, again, sensible cooling is the cold that comes out of an air conditioner. Latent cooling is the water that comes off that coil, or the dew that forms on a cold glass on a hot day.

Similarly, latent, and sensible heating can exist. So latent heating is evaporation or humidification happening in a room. It's not the temperature of the air that changes, but it's its moisture content. And sensible heating is exactly what you'd expect. It's hotter air coming off something. It's the heat coming off your light. It's the heat coming off people in your space.

So now that you understand the basics of what those mean, there's a lot of things that intertwine here that make this a little more exciting. So, you've got sensible cooling that happens and it reduces the moisture content. Well, that moisture came from somewhere. That latent cooling happened because of latent heating happening elsewhere in your system. Latent heating happens from your plants.

Your plants transpire, people evaporate moisture, they sweat, they breathe. That's latent heating in your space. The interesting part with plants in particular is those plants suffer sensible cooling when they're heating latently. So, they evaporate in your space. They provide latent heat to your space, but they cool your space at the same time through evaporative cooling. What that means is, ultimately, you're going to have sources of sensible heating and sensible cooling in your space and you're going to have sources of latent heating and latent cooling in your space.

And you need to ensure that all of those, your latent heat and your latent cooling sum to zero. Whatever those sources are, and there's a whole bunch of them, but whatever those sources are, they sum to zero. And same on the sensible heating and cooling side. That system needs to sum to zero so that you can have a stable room temperature.

That's the long and short of it. But sensible heat or cooling is what you can sense. It's the temperature latent heating or cooling is latent heating is adding moisture to your air. Latent cooling is removing it. You're going to hear people talk about it. It's air conditioning and humidification or dehumidification. That simple.

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