Guess what?
Some energy modeling programs can't tell the difference between
NRG block and conventional walls. That just means that you may
be getting bad information that can cause you to waste money and energy.
An energy model may allow you to input an NRG wall, and also input
a conventional wall with insulation on the building interior. However,
just because you can input different walls, doesn't mean the model
can tell them apart.
We went through this a couple years back with one of the world's largest
retailers. They told us that, according to their energy models, there is no
difference between their R-14 wall system (which was a perlite filled cmu)
and the NRG wall.
They were using a DOE2 based system that gave them that bad information.
Based on that one eensie beensie bit of misinformation, they can lose a
hundred million dollars over the next ten years. Hey, it's only money, right?
For the architect and engineer who may use the e-QUEST/DOE2 programs to
compare mass wall systems, you need to realize that the results may not reflect
the careful research produced at Oak Ridge National Lab, which you can find
links to on this site.
To determine if your energy modeling program works correctly, you can do a test. Run a simulation with two R-12 mass walls in an Arizona climate zone (where the difference in thermal performance should be very significant). Simulate one wall made up with 2" rigid EPS interior insulation, and a 10" exterior heavyweight cmu with partially grouted cores; the second wall, have an interior portion with a 6" partially grouted heavyweight cmu, with 2" EPS rigid EPS middle layer, and a 4" partially grouted heavyweight cmu as the wall exterior.
If there is no significant difference between predicted heating and cooling loads for these walls, then your energy modeling program does not accurately differentiate between isolated (conventional) and insulated thermal mass walls (NRG).
Take advantage of NRG's on-line, on-demand course that provides more detailed information on the topic of adding energy efficiency by adjusting the insulation configuration in mass walls. It includes excerpts from, and links to, the relevant Oak Ridge National Lab research reports.
Use this information to design more energy efficient buildings.
|
|