# Thread: Plumbing Schedule - Formulas

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## Plumbing Schedule - Formulas

I've hit a wall trying to create a schedule that automatically determines your minimum plumbing fixture counts based on the IBC. I've searched the forum and can't find this particular answer but know many of you must have gotten this far.

Here it is:

Plumbing code defines # of required fixtures per use group. For example, Use Group A-1 requires 1 Male Watercloset per 125 occupants.

So, first I created a key schedule that defines the associated rules for each use group (see attached).

Then I assigned a key (use group) to each area on my area plan.

Then I created a schedule that totals the number of occupants for each use group type and divides that by the associated # from the key schedule. (see attached).

But, when I get to Use Group B, I hit a wall I can't figure a workaround for.

The requirements for that group are not simply 1 in 125, but "1 per 25 for first 50 occupants and 1 per 50 for remaining occupants exceeding 50". Ugh.

If there is no workaround, we'll simply export a schedule to excel that tallied the # of occupants per use group - that in itself is a big help.

Thank you,

David
PBC+L Architecture
Asheville

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## Re: Plumbing Schedule - Formulas

Originally Posted by dlancor

But, when I get to Use Group B, I hit a wall I can't figure a workaround for.

The requirements for that group are not simply 1 in 125, but "1 per 25 for first 50 occupants and 1 per 50 for remaining occupants exceeding 50". Ugh.

Thank you,

David
PBC+L Architecture
Asheville

Hello David-

Its definetely doable in the Revit schedule, with an If statement.

if(OCC < 50), NUMBER/25, (((NUMBER-50)/50)+2)

Youre basically saying: If the occupancy is less than 50, use the formula "Number / 25", and if the Occupancy is greater than 50 (in this syntax im saying "not less than 50"), use the combination "first 50 people / 25 (i just used the integer 2), + the remaining / 50.

Does that work for what you need? Youll have to substitute your parameter names in...

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## Re: Plumbing Schedule - Formulas

Aaron,

Yes, that does make sense - Thank you. The problem is that I don't know where to put that formula.

The Key Schedule will not accept that as a value, as opposed to say 150, because formulas in a key schedule cannot contain parameters.

In excel, you could place that formula precisely in the 'Use Group B" and "Required Male Waterclosets" cell, but with schedules you need one rule that applies to all rows....

Is that right?

Thank you,

David

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## Re: Plumbing Schedule - Formulas

Im not quite understanding your schedules and what youre trying to achieve, but i *think* how i would do it is use the key schedule to determine values for parameters... Lets call they VARIABLES. Then the VARIABLES, depenind on the key schedule, would get input in to the formula i wrote, which would be in the actual schedule itself. For instance:

if(OCC < 50), NUMBER/VARIABLE1, (((NUMBER-50)/VARIABLE2)+2)

I would have the variable numbers (what youre dividing the total number of people by) to be affected by the key schedule, and have this actual formula in the schedule the key is being used for. The SCHEDULE KEY would be driving VARIABLE 1 and VARIABLE 2, the number of occupants per WC or lav.

Making sense?

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## Re: Plumbing Schedule - Formulas

Aaron,

Yes, what you describe is what I've done. The Key schedule determines VARIABLE1, which is associated with a certain use group (KEY) assigned to each area.

Got that. The way the schedule is set up at the moment is that it then returns "Required Male Waterclosets" as OCC/VARIABLE1. This works when the code simply requires 1 per 125. In these cases VARIABLE2 is not needed.

When the code requires what you and I have been discussing, I would need to create VARIABLE2 and I would need to enter
if(OCC<50), OCC/VARIABLE1, (((OCC-50)/VARIABLE2) +2)

The problem you see is that I can't enter both forumlas in the same spot on the schedule! The second formula will not work in the simple 1 in 125 situation.

Unless perhaps I set up an embedded if statement that looked something like this...
if(VARIABLE2>0), (if(OCC<50), OCC/VARIABLE1, (((OCC-50)/VARIABLE2) +2)), OCC?VARIABLE1)

Would this work? I'll go try it.

David

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## Re: Plumbing Schedule - Formulas

Aaron,

Thank you!

I had to fix the syntax a little bit, but the formula worked. The introduction of Variable 2 was key - thank you.

David

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## Re: Plumbing Schedule - Formulas

David-

I think i may be misunderstanding how you needed it to compute. What i was trying to write (albeit, i was ni a hurry), was an if statement that would use OCC/VARIABLE1 if the OCC value was less than 50.

Because of the if statement, you would never enter "OCC/VARIABLE1" in the Required Male Waterclosets. The If statement will return that value if the OCC is less than 50.

But even though im missing the boat on what you were trying to do, it sounds like you got it already.

I love formulas in Revit. With this forums help, i have it doing most of our Egress calcs, and warning uss if calcs are not accurately represented on our plans.

IMHO, this type of data leveraging is hugely necessary. An egress plan at 1/32" = 1'-0" makes it difficult to notice that a demise wall has shifted 4", or 8"... But that DOES affect the Egress calcs. Being able to do them automatically with the model data is very significant in situations like that...

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## Re: Plumbing Schedule - Formulas

Hi All,

At the risk of raising an old thread from the dead... I too am encountering an issue with revit calculating required plumbing fixtures from room generated occupant loads.

Here's the issue:

My floor has several rooms, and Area / 100 sf per person = 205 persons.

If I run IPC plumbing counts manually, that should result in 6 toilets total, or 3 per gender.

I created a calculated value parameter, that runs this equation:

This formula works great if I have one big room, with 205 persons. BUT... I have several small rooms. And Revit seems to run this equation for each room individually. Consequently, the schedule tells me that I have way more fixtures, than are actually necessary.

The problem is that this equation does not scale on a per room basis. If it was a straight multiplication equation, such as (1 per 125 people) then it would scale on a per room basis.

I'm afraid I know the answer... But can I have Revit apply this equation to the grand total number, not the individual room values?

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## Re: Plumbing Schedule - Formulas

Use the formula on an Area plan that treats the entire floor planas one large area...

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## Re: Plumbing Schedule - Formulas

Use the formula on an Area plan that treats the entire floor planas one large area...
Thanks Arron. Yes that will work... Until I have more than one, detached area on the same floor plan. Still no way to access the totals for formulae, eh?

BC

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