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Hey Ed, What Is J SHR?

In this edition of "Hey Ed," Ed talks about what J SHR is.

Hey Ed, what is JSHR? JSHR is another one of these acronyms. I love acronyms, LOL. Another acronym that we see in our industry. JSHR, the J stands for manual J, and sensible heat ratio is the SHR part. Houses have most houses, normal houses, 80% of the country or more, have a sensible gain and a latent gain. You do have areas and desert type or what they refer to as arid climates that might not have any latent gain, but they will still have a JSHR. The numbers will just be higher. So using just generic numbers. We have to be sitting in my home right now. I know my lower door number. I know my load calc. My house came in right around three tons, and it had a .92 sensible heat ratio, meaning 92% of the gain was sensible, and then that remaining 8% was latent. If you took my house and dropped it in Arizona, say you would see a house that would most likely load out somewhere around a 98, a .95 to .967 sensible heat ratio, where the majority, if not almost all, of the gain on a design day, is going to be sensible. The latent load is not coming from outside. It’s drier outside on those warm days than it is inside, but you got people, I mean, we are perpetually exhaling, and H2O is coming out when we do that. Cooking bathrooms, those kinds of things, are going to add to the latent load in a structure. This is very fundamental information. This is a topic that is only going to help you in your path to being a good HVAC person. And that’s the way I see it.

Ed Janowiak is the Manager of HVAC Design Education at ACCA.

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