by • November 14, 2012 • Building Science, Insulation & Air Sealing, UncategorizedComments (5)9266

Austin TX Deep Energy Retrofit Remodel

I’m working on a whole house remodel project with Dick Clark Architecture and we didn’t originally intend this to be a deep energy retrofit.  The clients wanted to update the kitchens/baths, give it a more modern floorplan, and upgrade the systems to more efficient models.  The goals when we build are always:  Beautiful, Durable, Healthy, Efficient.  But, as we talked more with the clients we realized that a very low HERS score was pretty easy to achieve given our already high standard of construction.  If you aren’t familiar with the Home Energy Rating System it’s basically a performance score that takes into account all the energy related factors of a building.  Orientation, Shading, Insulation values, Window performance/location/sizing, Roofing, Hot Water Heating, etc.  So a HERS score of 100 is given to a house that meets current code for efficiency.  A score of 0 would be a house that is a net zero energy home meaning it makes all the energy it uses for the year.  My guess is that this house prior to our remodel would have scored about 150-175 if we had scored it on HERS index before we started.  In this video I’ll show you the 6 steps we took to achieve an incredible score of HERS 48!  This is a very low score and is not easy to achieve.
  The take away from this if you are planning a remodel is this:
Must Do’s:
-Conditioned Attic
-Full spray foam if it’s 2×4 construction
-High Efficiency HVAC & Metal Ducts
-Strict Air Sealing
Please Do’s:
-Exterior Roof top rigid foam (2″ is my current recommendation for Texas roofs)
-Exterior Rigid Foam on the walls.  (3/4″ minimum recommended)
-Mitsubishi Variable Refrigerant Flow HVAC

-Matt Risinger principal of Risinger Homes in Austin, TX 

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  • We want to stone veneer the outside of our new house (building) and not use brick. If we cover the outside like you show with 1” foam boards, how would we attach the mesh and stone with that foam board?

  • You’ll need to use a commercial wall tie that screws into the studs through the foam board. It’s a pretty standard detail on commercial buildings and you should be able to buy them at a Masonry Supply yard that sells to commercial contractors. You could also try WhiteCap supply. Best, Matt

  • As usual, great work Matt. I wish quality building could catch on more here in FW as it has in Austin. I’m wondering what you think about Zip systems R panels… I have not looked at cost vs. OSB/wrap/foam but it sure looks like a great product.

    • @Lance: I’ve seen that insulated Zip product and it’s pretty promising. I planned to try it on a project last month but got cold feet. #1. I’m hesitant to rely on “tape” for my drainage plane. I was planning to use Zip AND Tyvek over top as my drainage plane. The zip would air seal very well, but I don’t like that you can’t lap the seams like a traditional house wrap. #2 The issue I came across with considering the insulated Zip is that the insulation is sandwiched between OSB and 2x studs. This means a longer fastener and some potential for loss of shear capacity. It’s currently not code approved for shear capacity so you’d need an engineer to sign off on this and/or use let-in bracing or another shear method. I like the concept, but I wasn’t willing to take the risk. Seems easier and less risky to follow a tried method of Tyvek Drainwrap then rigid insulation on top. Best, Matt

  • I found your blog recently while researching ideas for energy improvements we want to make to an 1970s home that we recently purchased as a fixer-upper. I really want to move the ducts into the conditioned space – probably using soffits and lowered hall ceilings. The A/C closet, air return and thermostat are all located at one corner of the house and I think those should be more centrally located also. Who should I consult to get advice on these types of improvements?