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.

from the desk of Energy Vanguard's architect dude

Views: 1367

Tags: SketchUp, energy, home, raters, ratings

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Comment by Ryan Moore on April 25, 2011 at 11:27am
I've just started using SketchUp for my takeoffs and am also finding it very useful.  Being a newbie at it, I would be interested in learning any tips from you folks out there.  One concern I have it that a SketchUp model from an architect will result in erroneous measurements because the wall heights are exterior, not interior as would be calculated for a HERS rating.  I'm guessing it's a simple matter of changing the height of the block(s), but wonder if anyone else out there has a good way of dealing with this.
Comment by Jim Peck on March 31, 2011 at 12:50pm
Way nice!  I need to use this more.
Comment by Doris Ikle on March 31, 2011 at 8:27am
This will be a great help in improving accuracy of estimating energy savings. Too often floor space is used when volume or wall size should be used.  Seal-up savings in particular are greatly over-estimated because the size of the envelope is not taken account of in "estimating" air-changes/hr. after the seal-up. Thanks for a much needed tool.
Comment by Chris Laumer-Giddens on March 21, 2011 at 12:14pm
Yes, it is! The more I use it the more I realize just how useful.
Comment by John Poole on March 21, 2011 at 12:07pm
SketchUp is an amazingly useful tool!

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