Analyzing Building Energy Consumption Using Area-Based Load Types in Revit Models

Now that we have our analytical boundaries drawn in, Revit can help us understand how much energy this building might use. We divided this building into several areas because each section will consume power differently. For example, this classroom area will have lights and power outlets and may only use one watt per square foot.

In contrast, we have a kitchen area that might be full of power-hungry appliances like a big freezer, ovens, and ranges. These appliances might mean the power density for this area is actually 100 watts per square foot. Big difference! That's 100 times the power usage of the classroom. So, all these areas combined will give us the total power consumption for the building.

Now, to jump into this, let's give ourselves more screen real estate. I’m going to close the System Browser if it's open, and I’ll open up a handout to help us understand the power densities for each of these areas. I’ll jump over to our PDF handouts section found in our Downloads folder, BIM 323 File Downloads, PDF Handouts, and then I’m looking for Analytical Areas.

I’ll open this up. You might ask, where does this information come from? It could come from our Electrical Engineer, or we might need to research this ourselves to determine how much power is consumed by each area. And every building is quite different. Imagine a data center or an industrial building, which would consume much more power per square foot.

But this is a good idea of power consumption for our classroom building. So let’s split the screen. I’ll drag Revit’s window across so we can see our little handout at the same time.

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Excellent! On the left, I have Revit opened up with the Electrical Analysis Level 1 floor plan. On the right, I’ve got the handout with the Analytical Areas.

Now I can start creating these areas. Let’s jump into the "Analyze" tab, then "Electric, " where we have "Area-Based Load." I’ll click that button and start by selecting this first classroom area.

I’ll click once. It might be tempting to keep clicking, but unfortunately, all that will do is add the areas together, and we don’t want that. We want to keep them separate, so I’ll click on "Finish Editing."

Now that I have this area, I hover over the blue plus and click once. That opens up the Properties window for that area. Here in Properties, I want to set the voltage.

So I look across and see that I have "General Classroom 1 watt per square foot." How do I know this area is "General Classroom"? If I go down to page 2, every area is labeled. So, "General Classroom."

"General Classroom 1 watt per square foot." So I’ll jump in, and where it asks me to set the area-based load type, it currently says "None." I’ll click the dot-dot, and this brings up all the different load type settings.

I’ll create a new one just for our project and call it "General Classroom." I’ll click "OK, " and I’ll set the power density to 1 watt per square foot. It’s currently set to "Load Classification of Appliance, " but most of this load will be coming from Lighting.

So let’s change that to "Lighting" and click "OK." The other settings are just fine: a Power Factor of 1, Lagging Power State, and Apparent Power Density, which will be calculated from the two above values.

We’ll click "OK, " and we now have 1 watt per square foot, and the voltage here is 480. Well, we notice from our sheet that it says 120, which is a more realistic voltage for the classroom and the outlets.

120 volts. Now, to get 120, we don’t need three phases of power. We just need one.

We’ll change our number of phases to 1 and scroll down to make sure we have everything else correct. Identity Data Name is "Area-Based Load." We can call this something more specific.

We can call it "L1 for Level 1" and then "Classroom" and it’s Area 1. So, I’ll put 1, and that’s it. It’s asking where it’s getting its power from, and for now, leaving it set to "None" is A-OK. We’re just getting the area defined, and then we’ll come back and distribute the power later.

So that’s one. I’ll go through and create an example for each, and then you can create some of these on your own to finish out Level 1 and Level 2. The next area we have is called "General Corridor."

So I’ll go back to "Analyze" and "Electric, " then "Area-Based Load." I’ll hover over this corridor right here. If you find the little X, it helps click there.

There’s the corridor. "Finish Editing." Now I’ve got another area.

I’ll click the little plus and, up at the top, I’ve got "Area-Based Load Type dot." I’ll create a new one again. So, I’ll create a new Area-Based Load.

In my handout, I’ll find "General Corridor, " so that’s the name "General Corridor, " and click "OK." The power density is half a watt per square foot, and I’ll click "OK." Now that’s set.

I need to set the voltage to 120, number of phases to 1, and I can give this a better name. I’ll call it "L1 Corridor." OK, now we’ve got this corridor.

Let’s take a look at our handout. We have a "General Restroom" right here. So, let’s create another area.

"Analyze, " "Electric, " "Area-Based Load." I’ll hover over the restroom, place the area, and click "Finish Editing." I’ll hover the blue plus, click, and now I can make edits to this one.

"Area-Based Load Type dot." You get the pattern now. We’ll create a new load type, and this will be "General Restroom."

And what do we have for restroom? 0.65 watts per square foot. "Six five." And we don’t want Appliance.

We want to change that to Lighting and click "OK." I think I forgot that part on the Corridor. It still says Appliance, but no problem.

I can change it here, and it will change it everywhere else. So, let’s do that right now while I’m thinking about it and click "OK." Now, I want to go back to Restroom.

All the settings are still good. Click "OK." Now, we have the kitchen up at the top, our big power burner. So, I’m going to go up to "Analyze, " "Electric, " "Area-Based Load, " hover right here over the kitchen, click once, "Finish Editing."

I’ll click the kitchen, "Area-Based Load Type dot, " and I need to create a new one. Or I could just duplicate it. That works as well.

If I duplicate, then I have to rename it "General Kitchen." It saves us the step of setting the classification. I just need to change the wattage.

For "General Kitchen, " I’m at 100 watts per square foot. So, I’ll click "OK." Now I’ve got the kitchen.

Next, I want to set the cafeteria. So, I’ll again go to "Analyze, " "Electric, " "Area-Based Load, " hover over the cafeteria, click "Finish." I’ll select that area by hovering the blue plus symbol, and now I’ll set the "Area-Based Load Type dot."

I’ll duplicate again. I liked doing that. Let’s do that again.

Duplicate. Rename. We’ll call this "Cafeteria."

From our handout sheet, we see that "General Cafeteria" is 0.45 watts per square foot. Maybe we have some really efficient lighting in there, and it doesn’t need a ton of power. We’ll say "OK."

Alright, we’ve got a couple of other unique rooms here: the gym and the office.

So let’s do those next. "Analyze" tab, "Electric, " "Area-Based Load." I’ll hover over the gym.

Click once. Click "Finish." Hover over that plus.

I’m going to have to hit "TAB" on my keyboard to select it. "Area-Based Load Type dot." And we’ll duplicate again.

And rename "General Cafeteria." This one will be called "Gymnasium." The power density for the gymnasium, we are deciding that it will be 0.65 watts per square foot. Click "OK."

And the voltage: 120. Number of phases: 1. We’ll give this a name: "Level 1 Gymnasium."

And apply. Now we’ll go to one more. "Electric, " under "Analyze, " "Area-Based Load."

Here we go. We’ll set, click this library, and we’re going to call this an office load.

The load doesn’t always have to match the room name because we’re picking this whole area. There’s a library, storage room, some office-type spaces, and a corridor. But it all has the power density.

So, we’ll set that here. We’ll duplicate again. And we’ll rename this "Office."

"General Office" is 0.5 watts per square foot. And we can say "OK." We’ll set the voltage again to 120.

And that comes again from our cheat sheet right here. And our phases to 1. We’ll give it a nice name such as "L1 for Level 1." And this, we know it’s the library, so we can call it the library. Click "Apply."

And finish editing. We’re all set. Those are the different types we have in the whole building.

Everything else can be a classroom or an office. So, what we can do now is, if I missed any steps, I can click back on these spaces. For example, the kitchen.

And I might have forgotten a couple of things, like it still says 480 volts. I’ll make it 120 with one phase.

Everything is parametric in Revit, so I can come back and update these at any time. We’ll call this "Level 1 Kitchen." Apply.

Grab this Cafeteria next. This is "Level 1 Cafeteria." Let’s jump up to our voltage: 120.

Number of phases: one phase. Let’s double-check the restroom here. It also needs to be 120 volts.

One phase. Name can be "Level 1 Restroom." We’re populating all this information here in Revit.

Our general corridor we already got as 120. What do we have left on Level 1? It’s just more classrooms. Unfortunately, with these area-based loads, we cannot copy, mirror, or even create similar.

We just have to create more. I’ll let you create your own classrooms. I’ll do one to share that it’s a little bit easier this time because once we set up those area-based load types, we can just reuse them.

So here’s Classroom 2. We’ll finish editing first. Hover over it. Get to the properties.

"Area-based load type." We don’t have to create another one. We can just select the general classroom again because we’ve already created it.

We’re just using that same type again. We also have to set the voltage to 120, number of phases to 1, and give it a name that makes more sense. So, "Level 1, Classroom 2." We have Classroom Area 1, Classroom Area 2. Apply.

And so, this could be Classroom Area 3, Classroom Area 4, and Classroom Area 5, all starting with Level 1. Let’s jump up to Level 2 now. I should say up to Level 2. Open up that view. Level 2 is recycling all of these types yet again.

So, all I have to do is come back and set my area-based load. For example, we’ll start with the restroom. Click right there.

Finish editing. We already have that type because we used it on Level 1. I select it, and I just click the dot-dot and select the general restroom type we already created and click "OK." Set the voltage and the number of phases.

Give it a better name. Now that we’re on Level 2, I’ll say "Level 2, Restroom." Apply.

So, that’ll be "Level 2, Restroom." We’ve got "Level 2, Corridor." Let’s start over with the classroom.

So "Level 2, Classroom 1." "Level 2, Classroom 2." "Level 2, Classroom 3." "Level 2, Classroom 4." And we have "Level 2, Office." And that will wrap it up. I’ll let you create those areas on your own.

Now that we have these areas created, our next step will be to create a distribution system to bring power into the building and distribute it to these various areas.