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Strange behavior of cooling, heating energy consumption and Blinds operation

asked 2015-03-20 06:51:30 -0500

Waseem gravatar image

updated 2015-07-11 10:41:40 -0500

Hi All,

I am trying to model blinds in EnergyPlus, I have setup Daylighting:Controls and have a schedule to operate blinds. However, when I try to simulate my building it gives readings that lighting energy increases when there was blinds (make sense) but it also gives results that heating and cooling energy consumption increase when there was blinds (This does not make sense to me). The blinds should be blocking solar gains and therefore there should be reduction in cooling energy, on the other hand it will also reduce heat loss and hence reduction in heating energy consumption.

I may be missing some small point but unable to figure it out at the moment. Any ideas? The location for weather file is UK and there is only one south facing window.

Thanks

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Less solar gains can result in increased heating. On the other hand it should reduce cooling. However, due to decreased available daylight your internal gains from artificial lighting are increasing, affecting both heating and cooling. Former should be decreased while latter should be increased. It can be difficult to find a balance between all these phenomena. In addition to this, a building thermal mass also affects cooling and heating requirements.

Ivan Korolija gravatar imageIvan Korolija ( 2015-03-20 06:59:37 -0500 )edit

Thanks, I agree. I missed the point before posting this question. I should have plotted lighting gains as well.

Waseem gravatar imageWaseem ( 2015-03-20 07:22:59 -0500 )edit
3

This reminds me of a lengthy and interesting discussion on the Yahoo EnergyPlus group last year. If the lighting load doesn't entirely account for the increase then you might take a look at that thread. https://groups.yahoo.com/neo/groups/E...

Jamie Bull gravatar imageJamie Bull ( 2015-03-20 09:30:30 -0500 )edit
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Waseem gravatar imageWaseem ( 2015-03-23 05:34:38 -0500 )edit

@Ivan Korolija Please repost your comment as an answer to this question so that is no longer shows as "unanswered". Thanks.

MJWitte gravatar imageMJWitte ( 2015-10-15 13:56:12 -0500 )edit

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answered 2015-10-15 14:16:49 -0500

Ivan Korolija gravatar image

Less solar gains can result in increased heating. On the other hand it should reduce cooling. However, due to decreased available daylight your internal gains from artificial lighting are increasing, affecting both heating and cooling. Former should be decreased while latter should be increased. It can be difficult to find a balance between all these phenomena. In addition to this, a building thermal mass also affects cooling and heating requirements.

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And any solar absorbed by the blinds will become an instant heat gain compare to solar that is absorbed in a wall or floor which results in a delayed load.

MJWitte gravatar imageMJWitte ( 2015-10-20 15:48:42 -0500 )edit
2

answered 2015-10-15 15:30:59 -0500

Archmage gravatar image

Another point to consider is that lighting power also serves as reheat. If the HVAC system is doing latent control and has reheat, it can happen that reductions in lighting lead to increased heating because the reheat coils need to work more.

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Asked: 2015-03-20 06:51:30 -0500

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Last updated: Oct 15 '15