Service Hot water Usage

asked 2017-12-08 09:35:09 -0600

hoffmann1320
251 ●2 ●7

updated 2017-12-10 09:48:28 -0600

I am designing the hotwater fixtures for a project that uses lav sinks at 1 gpm and a kitchenette sink at 1.5 gpm. I input those values into the water use equipment peak flow rate value. I am seeing unreasonably high water usage for the building in the 300k gallons per year range, even with a flow fraction schedule of .008 for only 1 hour a day for 5 days a week. If i reduce the water equipment peak load to .1 and .15 the value starts to make sense.

What other parameters are affecting the water usage that is making this water usage value be too high when the water use equipment peak flow rate is what the design calls for? Is there an input for gallons per person that I am not seeing?

Thank you for your input.

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What software are you using? Also are you seeing a more than 10x decrease in water consumption when you decrease the peak flow rate by 10x? Also how many fixtures to you have? just one of each or mulitple of each?

David Goldwasser ( 2017-12-08 11:18:06 -0600 )edit

Open Studio (1x) 1.5gpm (11x)- 1 gpm

When I decrease the peak flow rate by ten it reduces by 10x, but i also had to reduce the flow fraction scedule to only run for one hour at .01 a day for 5 days a week. The pump power when I do this goes to 0 because the flow fraction schedule is essentially nothing

hoffmann1320 ( 2017-12-08 11:22:19 -0600 )edit

Are you saying you see less water consumption when your flow fraction is 0.01 vs .0.008? That would seem odd. In both cases only non zero value for 1 hour a day? On side note each sink isn't getting used much, less than a minute a day of run time?

David Goldwasser ( 2017-12-08 11:56:43 -0600 )edit

https://drive.google.com/open?id=1cr0...

here is the link to the file in a compressed zip file it might be easier to just look at the file itself

hoffmann1320 ( 2017-12-08 12:04:23 -0600 )edit

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answered 2017-12-10 13:29:45 -0600

Avi
4320 ●2 ●11

updated 2017-12-12 02:56:39 -0600

Out of the EnergyPlus report that was found in your model subfolders : image description So the yearly water consumption is about 5 m^3 which translates to about 1320 Gal. I am not sure where were you looking to get the 300K gals per year.

OK, if anything your model produce lower water consumption than it should:

260 weekdays * 60 minutes * 0.0099 (your fraction use in the model) (111 gpm+1.5 gpm = 12.5) = 1930.5 The reason for that is that only 8 out of your 12 WaterUse:Equipment objects are assigned to spaces that are assigned to thermal Zones. I belive that if you assign thermal zone to each space in your model then you will get the right water usage.

When OS translate the model to IDF it is not translating those objects that are not located within a thermal zone. I am not sure why OS does that without throwing any warnings. It might be an issue. My be someone can step in and explain that.

Comments

That is because I already changed the peak flow rate of the fixtures to .1 and .15 and the flow fraction schedule to 1 hr a day at .008 as the fraction for that value

hoffmann1320 ( 2017-12-11 08:25:07 -0600 )edit

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