# Energy Vanguard Blog

Hey, HERS raters, what if I told you that you could get the volume of a multi-pitched roof for all of your home energy ratings without the need to calculate a single algebraic formula? Or, how about wall area? I know, I'm your new best friend, right?

Anyway, with Google SketchUp this is all possible. In fact there are a few more ways to use the program to help you complete all the calculations (e.g. area, volume and perimeter) necessary for a home energy rating, or any energy modeling exercise.

Building 3-D models in SketchUp is fairly simple once you learn a few of their basic shape drawing tools. For example, the model you will see in the following samples took less than a minute to create, and would be based on the take-offs made in the field, or from a set of plans.

Once the model is created, you can start getting the more complicated measurements, such as wall area, window area, and volume. All it takes is selecting the surface that you want and asking the program to calculate the measurement you need.

Here are a few screen shots of what it looks like:

1. Calculating wall area: Select the wall, right click, and then select 'Area>Selection.'

2. Calculating window area: Select all the windows of a certain orientation, right click, and then select 'Area>Selection.'

3. Calculating volume: Select the volume part of the home whose volume you want to know (e.g. roof, floor level), right click, and then select 'Volume.' Voila!

Once you've mastered this, which really would take only half a day, you can calculate all of the measurements necessary for a HERS rating in less than 30 minutes, depending on the complexity of the house. In fact, I've been able to do it in less than 5. Of course, this tool also helps with doing Manual J heating and cooling load calculations, which are just another form of energy modeling.

Sounds good to me. Not having to figure the volume or surface area of a hip roof would be awesome.
Posted @ Tuesday, March 15, 2011 7:45 AM by Jon LaMonte
Exactly, Jon! And, how about tray/coffered ceiling areas and houses with multiple ceiling heights in the same floor. You can make it all a single volume, and SketchUp will calculate it as one.
Posted @ Tuesday, March 15, 2011 7:53 AM by Chris Laumer-Giddens
Bingo! I've used this since it was made available by Google. Once a builder or architect knows you have this capability, you will be on the inside track. EnergyPlus already has an add-on that may be helpful for performance rating.
Posted @ Tuesday, March 15, 2011 7:54 AM by George Reynolds
IES also has a new performance analysis plug-in that we are experimenting with.
Posted @ Tuesday, March 15, 2011 7:58 AM by Chris Laumer-Giddens
IES Plug-in http://bit.ly/fxtA6Y
Posted @ Tuesday, March 15, 2011 7:59 AM by Chris Laumer-Giddens
Nice article, Chris! It's pretty amazing how SketchUp is finding so much application in so many different areas. Hope to see some EV plug-ins out there in 3DWH soon! ~John
Posted @ Tuesday, March 15, 2011 8:15 AM by John Poole
Great idea, John! I'll get to work on that, right away. Thanks!
Posted @ Tuesday, March 15, 2011 8:23 AM by Chris Laumer-Giddens
Actually, I meant contributed energy models / exemplars in 3D Warehouse. Any plug-ins I assume you'd post right here on your site. Aw, you know what I meant! It's still too early in the morning...

:-)
Posted @ Tuesday, March 15, 2011 8:32 AM by John Poole
I hard that! Did you have 7up instead of coffee this morning, too?

Anyway, once we're confident the results from these energy modeling plug-ins, we'll be sharing! I'm anxious to see how they compare with other programs.
Posted @ Tuesday, March 15, 2011 8:37 AM by Chris Laumer-Giddens
Great article Chris, is this training going to be online?
Posted @ Tuesday, March 15, 2011 9:46 AM by Brad Brinke
Yes, it will eventually become available online. Our first classes will be face-to-face, starting in Atlanta.
Posted @ Tuesday, March 15, 2011 11:00 AM by Chris Laumer-Giddens
I think the time-consuming part is measuring the building. Calculating areas not so much. With the added time to build the model, how does SketchUp save any time?
Posted @ Tuesday, March 15, 2011 9:00 PM by David Fay
Good question, David.

The biggest time savings with SketchUp is with complicated volumes (e.g. roofs, different clg heights, etc.).

It doesn't take long to get to a point with SketchUp that you can quickly produce a model from the take-offs in the field. Then, finding areas and volumes is just a mouse click.
Posted @ Wednesday, March 16, 2011 6:25 AM by Chris Laumer-Giddens
I'll have to give it a try. One more question: can you get the area of the thermal boundary (excluding attic and basement, for example) with a single click? In other words, can the SketchUp model include interior walls, ceilings and floors?
Posted @ Wednesday, March 16, 2011 7:56 AM by David Fay
Thanks for the post, anything that helps save time on the complicated volumes is a good thing
Posted @ Wednesday, March 16, 2011 8:00 AM by Carl D. Clark
"Sounds good to me. Not having to figure the volume or surface area of a hip roof would be awesome.
Posted @ Tuesday, March 15, 2011 7:45 AM by Jon LaMonte"

What, Jon? You don't like calculus?
Posted @ Wednesday, March 16, 2011 8:32 AM by Gareth Ables
Thanks Carl an Gareth.

David,
Yes, all you would need to do is create a model of just the thermal envelope volume, and take your measurements from that. Make sense?
Posted @ Wednesday, March 16, 2011 9:22 AM by Chris Laumer-Giddens
Boo! Hiss! Google didn't make a Linux version of SketchUp. Not yet, anyway.

At work we have to use Xactimate for most of our jobs, as required by the insurance companies that are paying for water damage drying or smoke damage cleanup in their customers' homes and businesses. It will calculate volumes, but I mostly work with the floor plan parts. Ceiling heights come into play for dehumidification calculations, but ceiling shapes are usually pretty simple.
Posted @ Wednesday, March 16, 2011 10:57 PM by Lee Thompson
Hi Lee,
Glad to hear about another software that makes calculation simpler. Do you ever have to get in to roof volume, and can Xactimate do that for you?
Thanks!
Posted @ Thursday, March 17, 2011 5:43 AM by Chris Laumer-Giddens