Best software for insulation effect on heating/cooling loads?
In planning an addition and retrofit to my home in Maryland, I have been working with a professional HVAC Manual J consultant. He has been using the Wrightsoft software to give me heating and cooling loads depending on various insulation scenarios. But we have arrived at an impasse with this software when attempting to look at exterior insulation.
My existing home is 8″ brick, and I am contemplating an addition with 8″ aerated autoclaved concrete (AAC). After adding R-12 to the exterior of the existing brick house, the Wrightsoft software predicts that the house will have exactly the same BTUh requirements whether I use plain 8″ AAC or add a further R-4 to the exterior of the AAC (to make the whole house R-12). Adding R-4 makes not a single BTU/hr difference – in the house as a whole and also room by room. I had also asked for heating and cooling load calculations for exterior R-16, R-20 and R-24 scenarios. The Wrightsoft software won’t allow these levels of insulation to be inputted. (It actually won’t even allow for attic insulation above R-35, so I can’t see the attic code-minimum level).
Is there a software that will give me the heating and cooling loads for these insulation scenarios, so that I can size the appropriate HVAC system?
Also, a code-related question: I have read in several places that I will need by 2006 IECC code to place the list of the house’s insulation levels in the electrical fuse box, but I also think I read once that I will also need to place the Manual J calculations for these insulation levels. Is this true?
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Replies
Richard,
Here's the Web page that lists support options for Wrightsoft users:
http://www.wrightsoft.com/training_support/overview.aspx
Questions about Wrightsoft software can be sent to the company by e-mail at this address:
support [at] wrightsoft [dot] com
I hope that someone from Wrightsoft will be posting an answer here soon; I have contacted the company and suggested they do so.
In the meantime, any experienced users of Wrightsoft software are welcome to provide advice and feedback.
Hi Richard,
Would you know what version of Manual J is being used? The latest version is 8, which I believe takes into consideration building science principles like exterior foam sheathing, tree shading, etc. I've had a Manual J done, calculating 4" polyiso on the outside of a house with nothing in the walls, and the results clearly reflected that insulation choice, so it's out there.
Wrightsoft's Right-Suite Universal is based on ACCA Manual J Eighth edition (MJ8). The AAC issue is due to MJ8 limitations. In MJ8, wall type 14C (AAC) provides for insulation levels only up to R-5. MJ8 uses tabulated data for constructions because cooling load depends on both U-value and mass. However, the MJ8 heating load calculation is strictly UA-deltaT. Right-Suite Universal provides a way to enter custom constructions with any U-value. Using this feature produces heating loads that conform to MJ8 and also reasonable cooling loads if used with care (although technically "beyond" what MJ8 covers).
Regarding attic insulation, MJ8 and Right-Suite Universal both support ceiling insulation up to R-50. Other attic configurations have lower maximum R-values. As with walls, the custom construction feature can be used if the built-in constructions are too limiting.
Please contact me directly if you have further questions.
Thank you, Martin and Avi.
Stephen - I am imagining you are from Wrightsoft. It sounds like the limitation lies in Manual J, even in the latest version 8. I take it Manual J doesn't include in its tabulations the possibility for a roof-deck R38 or the various external insulations I am interested in. I'm glad to hear there may be extrapolations that Wrightsoft can estimate for me, using the Right-Suite Universal customizable feature. I'll ask my consultant to see if he is using these; and if not, that he ask Wrightsoft for guidance.
reads like AI generated SPAM post... you know.. .that fuse box in a Manual J and all...
haha, ok, this makes me less scared that ai will take my job, but still, it's insidious that these things have been unleashed on the world in a pervasive way and as they get better, it will be more and more difficult to distinguish ai generated vs a real human.
next level anxiety question would be: at what point do we consider the content interchangeable...? (typed by a human)