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NC-2009 EAp2:Minimum Energy Performance

Gas vented fireplace

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Carlos Vazquez
Consulting Engineer
Carlos A. Vazquez, PE
LEEDuser Basic Member
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I have a project were there is a 24,000 Btuh gas vented fireplace. Is a wall device mostly radiant heater (70-75%) with a glass panel which does not have a fan. All combustion air is taken from outdoors and vented to outdoors again through a roof vent. I found a performance standard ANSI Z21.88-2009 and other versions for this kind of device. In ASHRAE 90.1-2007 and 2010, the minimum efficiency standards in chapter 6 are for warm air furnaces and combination of warm air furnaces / air conditioning units.

Therefore, shall I model this kind of device as a process load, with equal efficiency in the proposed and baseline energy model? Or is any baseline performance in the ASHRAE standard for this kind of device?

 

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Mon, 10/09/2017 - 22:26

This is not really covered by 90.1. It sounds like a sort of a space heater for this area. It is not really process however because it provides space conditioning. So I would model it identically as a space heating source that is not a process load.
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Carlos Vazquez
Consulting Engineer
Carlos A. Vazquez, PE
LEEDuser Basic Member
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Tue, 10/10/2017 - 01:43

Thank you Marcus. Your answer leads me to another question. The building is less than 25,000 sq-ft. The rating system is LEED v3. The climate zone is 2A. The heating sources are an air handler with electric resistance, VRF heat pumps, and the gas fireplace only for a single zone. This gas fireplace will seldom do something for heating. My initial simulation shows that it will only be turned-on a couple of days, one hour per day in the morning during December and January. So, the heating source is predominantly electric resistance and VRF heat pumps. At first sight, looks like I have to model the baseline with System 3 - PSZ from table G3.1.1A and G3.1.1B. Or can I justify to use System 4 - PSZ-HP based on the very low demand for the fossil fuel heating source?
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Tue, 10/10/2017 - 15:03

I think a system 4 is appropriate. The fireplace is a sort of rarely used space heater it sounds like so I think the fair comparison is to just model it identically especially since the usage is minimal.
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Carlos Vazquez
Consulting Engineer
Carlos A. Vazquez, PE
LEEDuser Basic Member
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Tue, 10/10/2017 - 17:16

Thank you Marcus. I just made another simulation for the proposed building turning off the radiant heater, and my unmet heating hours remained very low as well. So looks like it is something that is not essential for maintaining comfortable temperatures. Thank you for your feedback.

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