Calculating Occupancy Load in AutoCAD with Tables and Formulas Using the 2024 Building Code Standards

Now let's take a look at calculating the occupancy load using the tools that AutoCAD provides. What is the occupancy load? If you've ever been in a public building, you might have noticed somewhere over a door, there is a little sign that says max occupants, and it says how many people can be in a given facility. Now the code dictates this, and again, different cities use different code, but for our example, we're taking a look at the 2024 International Building Code, and we'll notice that for business areas, there is a load factor.

What does that mean? We have to do math. We have to take the total square footage and divide by this load factor to calculate the occupants. Well, AutoCAD can help us do that.

So here in our plan, let's start the table command, t-a-b-l-e, table, and we want to set this up. We want to make a couple of changes. The first number of columns needs to be just two, and data rows, I think we'll be okay with four, and we don't need a header row, so our second row cell style can be changed to just data.

So title, data, data, and then click okay, and you might notice it's super tiny. Just go ahead and click one time on your plan to place it. Click and click away from it, and if we zoom in, we'll see that table.

It's super tiny, super cute. We'll click on it, and we'll type in sc for scale, enter, and click on the top left corner. Click one time, and our scale factor, we will do 48.

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How did I come up with 48? That's because we're using quarter inch scale on our drawing, so we multiply 4 times 12. So 12 inches, quarter inch, we get 48, enter, and now it's big. We'll zoom back out, and there it is.

It's kind of just on top of our plan. We'll move it around later. Right now, it's okay.

So first, we want to give it a title, so double click right in the top, and the title is, we'll see if we have room for this, Occupancy Calculation. Let's just do Occupancy Calc, period. That's going to be big enough.

All right, Occupancy Calc. Now we need to go through all of our data. Now it looks like it gave us a header row anyways, whether we wanted one or not.

Let's see, we can right click, and can we delete this row? Delete. Yes, we can. So that's a way to get rid of that header row.

If it gave you one anyways, right click and delete that row. Okay, for our first one, we have to know our square footage, so we'll type that in, square footage, and then we need to have our occupancy type. A quick little note, you might say, well, this is how we do occupancy every time.

Well, with the code, it's always different. For example, look at airport terminals. There's baggage claims, baggage handling, they all have different occupancy load factors.

So this can get really complicated really quick, but in our case, it's all a business occupancy. So this will work out pretty well, knowing that if you're going to do a more complicated building, you'll have a bigger and bigger table and more math. But this is the basic foundation of how this works.

Occupancy type, the next one here is our load factor. Occupancy, we'll just abbreviate that, load factor. And last but not least, the magical number we're getting to is our actual occupancy.

Okay, so those are all of our rows, and now we need to do the math. The square footage, what is the square footage of our building? A couple ways to calculate it. Luckily, this building is super easy.

It's three bays of 20 feet this way, so 60 feet, and then two bays of 20 feet this way, so 40 feet. 20 × 60 is 2,400 square feet, so we'll type in 2,400. And the occupancy type, we know we're going to choose business.

You can do business areas or just type in business, business. And our occupancy load factor we're getting from the code, so that's 150 gross, 150. And here's where AutoCAD really shines.

It can do the math for us to determine the occupancy. We'll double click in that cell on the bottom right, and we'll type in an equation. We can just simply type in the equal sign, equals, and then we have to type in what the cells are.

So the square footage is B2, so it's B and then 2 right there, so column B, row 2. And then do some math. We'll do divided signs. Well, it's a slash on our keyboard for divided by, and then the next cell is column B, row 4, so B4.

That's it, and enter. And there's our occupancy. We can have 16 people in this space.

Now if we don't like the trailing zeros, we can change that if we'd like. We can click on it one time, and then up at the top we're looking for something called cell format and data format. Click the data format and go to custom table cell format.

And we'll notice that we're in decimal number, and just click the additional format button, and we want zero suppression. Click on trailing and okay. So again, that's decimal number, additional format.

We'll see if that worked. Okay, and it did. It got rid of our trailing zeros.

If that doesn't work for you, no sweat. Zeros are fine. They don't hurt anybody.

Let's be a little bit cleaner. Now notice in AutoCAD that that number 16 is kind of highlighted. It lets us know it's a calculated value.

And if we double click there again, we can get back to that formula. It's still there. Okay, pretty cool, right? All we need to do now is to update our column widths.

Let's see, I'll click on square footage and change its width down. Grab the blue dot. There we go.

Just kind of tighten it up here. That looks decent. And then this one, we will tighten it up.

It can be a little tricky. Sometimes you have to make sure like snaps and things aren't working. And just zoom in to kind of get to what we want.

Now I notice I have a couple that are extra big rows. All I have to do is just drag them up, and it fixes it. Just drag them up arbitrarily, and it gets back to the correct row.

All right, so that's it. The last note I would say is I wouldn't sweat everything here. Like things don't always get the perfect formatting.

We're not working in like Excel or Google Sheets here. So you have to kind of be okay with it not being absolutely perfect. But what is perfect is our calculation.

That's what matters for the code. Now we'll just select this and move it. M for move.

I'll just put it down below the open office right there. Occupancy calc. And that's it.

It's a great time to save.