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Hey Ed, How Do You Take Solar Gain Into Account on a Heat Loss?

In this edition of "Hey Ed," Ed discusses how to account for solar gain

Hey Ed, how do you take solar gain into account on a heat loss? On a heat loss. Oh, you don’t. It’s a freebie. There’s other things when it comes to a heat loss that we don’t take credit for. But before I get to those, I need to address the sunshine part. How bright is the sunshine at midnight in January? It’s not. So why would we take it into account? We can’t take credit for something that doesn’t happen 24 hours out of the day. There are other things that we don’t take credit for. The people that are in the house, we don’t take credit for them. You got our blower motor we were talking about before. We’re not going to take credit for that. These bright lights that are shining in my face right now. We don’t take credit for those on a heat loss. Heat gain? Absolutely. But not on a heat loss. So if you want to get your heat loss calculations more accurate, maybe you’re doing some heat pump work. You want a size to the heat loss, but the heat loss appears to be exaggerated. It’s not exaggerated. It’s historically the way whether reason manual J or other methods, these additional sources of heat have always been not ignored, but they are not accounted for in the heat loss. You want to account for them? Get one of those things that measures the wattage coming into your service panel. Take the wattage, multiply it by 3.412, and now you know how much heat is being not taken into account on your heat loss. I think that’s a good idea. That’s the way I see it.

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

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