Why is the zone sensible cooling not zero even if the natural ventilation and the cooling design air flow rate is off?

asked 2022-08-25 08:17:01 -0500

Maria1688
1 ●1

updated 2022-08-25 11:56:09 -0500

Aaron Boranian

13830 ●76 ●24 http://bigladdersoftware.com/

I would like to check out all the influencing factors on the "zone sensible cooling". Therefore I first wanted to switch everything of so that the sensible cooling is zero. I switched of the "Model infiltration". Furthermore I set the "Cooling design air flow rate (m³/s)" to 0. However, if I run the simulation there is still in the Heat Balance a "Zone sensible cooling" and also System Looads for total cooling. Which settings do I have to set that there is no "zone sensible cooling"?

answered 2022-08-28 23:00:41 -0500

Kaue Queiroz
13 ●1 ●3

Im not a E+ user, so maybe Im not the best source to help you, however, in IES even if you zero your HVAC system components, you still get your sensible cooling/heat loads in a sense of the cooling/heat DEMAND needed to maintain your zone at the set points set to zone’s thermal template. So, if I understood your question correctly, turning off your design airflows will not zero your energy demand for the zone. Zeroing the infiltration as you mentioned certainly has an influence to cooling loads but you still have heat transfer through envelope (conduction), internal heat gains that add to your cooling load etc…so this is probably what you are seeing there and why.

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The heat transfer through the envelope is a good objection. However, my zone has a volume of around 70 m³ and the exterior wall has an area of 11.8 m². The floor, the ceiling as well as all the other walls are adiabatic. There can only be a heat transfer across the exterior wall of 11.8 m². The "zone sensible cooling" is -0,10 kW. Isn't this to much for just the heat transfer across the exterior wall?

Maria1688 ( 2022-08-29 03:26:23 -0500 )edit

Check your internal heat gains such as occupancy, lighting, equipment - they all add sensible cooling load too

Kaue Queiroz ( 2022-08-30 10:58:30 -0500 )edit

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Why is the zone sensible cooling not zero even if the natural ventilation and the cooling design air flow rate is off?

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Why is the zone sensible cooling not zero even if the natural ventilation and the cooling design air flow rate is off?