Replies

1. GBA Editor
   Martin Holladay | Oct 30, 2014 11:35am | #1

   Rick,
   The first step to designing a net zero house is to choose an energy modeling program. Your energy model will allow you to experiment with different wall R-values and ceiling R-values until you hit on a cost-effective approach.

   If you have an idea of the R-value of your walls, you can begin to think about the best way to build your walls.

2. 
   dowens825 | Nov 04, 2014 07:55am | #2

   I, too, am interested in net-zero for a new home in SW Michigan. Don't really like the idea of spray or rigid foam, so double-stud walls with non-OSB sheathing was the direction of my thinking after reading here for the last couple of months. Read this question and response with real interest, and immediately did a search of the site for 'energy modeling program' to learn more. Was quite surprised to find that the top match was an article by Martin Holladay entitled "Energy Modeling Isn’t Very Accurate ". Not quite sure what to do with this information! Wondering if Rick was able to move forward with this, or if Martin could offer a little more specific information on how to choose an energy modeling program.

3. GBA Editor
   Martin Holladay | Nov 04, 2014 10:19am | #3

   Dave,
   For more information and advice on choosing energy modeling software, see Energy Modeling Software.

   In that article, I wrote:

   "If you’re ready to investigate energy-modeling software but aren’t yet ready to spend hundreds of dollars, start with one of the free programs such as eQuest, HEED, or HOT2000. After fooling around with free software, you may decide that you want to integrate energy modeling into your regular work routine; at that point, you will probably appreciate the advantages—especially, the improved technical support—that comes when you purchase REM/Design or a similar program.

   "Most residential builders would rather pay a consultant to perform energy modeling than learn to use the software themselves. 'Mike Duclos does most of our modeling when we need it, using REM/Rate or PHPP,' says Paul Eldrenkamp, a Boston-area builder and published author. 'If you do enough modeling on enough projects, you eventually develop a good intuition about what you need to do on any given project to reach a general level of performance. Once you have that intuition in place, the modeling becomes less useful. In fact, the modeling sometimes proves to be less accurate than the intuition. But the modeling is an indispensable step in gaining the intuition.'”