May 2, 2016

The Returns From Indiana Are In: 0.4 ACH50 For The Win!

Warkentien 2015-08-03 12.05.12

Vertical furring strips make a vented rainscreen

Cruz, Clinton, Trump, Sanders…Warkentien? Dave Warkentien lives in Indiana and recently earned winning numbers: 0.4 ACH50.   He also got winning returns on power usage: at negative 457kWh for the first three months of 2016 (and that’s after accounting for two electric cars usage of 655kWh). We haven’t seen numbers like that since the SURE House won the DOE Solar Decathlon.

The wins are all the more remarkable as the house is located in Mishawaka, near Lake Michigan, and gets its fair share of snow and clouds.

How did he do it?  Focus on high-performance goals, with integrated design and construction – utilizing advanced components and assemblies.

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Service Cavity minimizes penetrations

For the advanced roof and double-stud wall assemblies SOLITEX Mento 1000 is the outboard vapor open and airtight WRB with back vented rainscreens.  Inboard is INTELLO Plus vapor intelligent and airtight membrane – in combination with a service cavity.   TESCON and CONTEGA tapes were used inside and out, along with KAFLEX and ROFLEX gaskets – providing essential continuity that the Pro Clima systems approach (pdf) uniquely provides.

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ROFLEX gasket at pipe penetration

Dave voted the electric party line; with no wood stove, using Mitsubishi mini splits instead, and no gas cooking, using an induction cooktop with ventless hood.  High efficient heat recovery ventilation and Passive House compatible windows, SunFrost refrigerator and all LED lighting help drive down the loads while assuring comfort and health.
With 8kW of solar panels on the roof, not only did the production power the all electric configuration but powered Dave’s Tesla too.

See the local TV news story here.  From our perspective it’s a winning ticket.


Warkentien Forest Ave house and car (1)

The Winning Ticket: INTELLO and Tesla.


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5 Responses to The Returns From Indiana Are In: 0.4 ACH50 For The Win!

  1. Stephen Sheehy May 10, 2016 at 10:11 am #

    Impressive statistics, but that is one unattractive house. (475 note: beauty is in the eye of the beholder. Please refrain from voicing unnecessary subjective commentary)

    • Mark Pollard May 11, 2016 at 7:51 am #

      Agreed regarding the aesthetics. The plain jane ranch seems to be held in high esteem in the Midwest. Which leads me to this critique, with a simple box it is really surprising the ACH50 was not lower. There are inboard and outboard air control layers, combined with the full accoutrements of the Pro Clima system for gasketing andstoo gapping. Seems like the blower door should have come in at least half that. The article does not say what brand of windows and doors were used but from the pictures it looks like a lot of fixed units and small tilt/turns, or casements. Is this the source of the majority of the leakage?

      I tend to scoff at using an interior air control layer since it is way too hard to detail well. Electrical boxes, utility penetrations, partition walls, floor assemblies all interrupt the continuity. From a vapor control standpoint, it seems pretty unnecessary in a double stud assembly with plywood, not OSB, and an exterior vapor open membrane. GWB does a great job of slowing the outward vapor drive in the winter and also allowing it to come back to the interior when the vapor drive reverses. Plywood’s permeability increases as moisture content and RH increase, and cellulose has an amazing ability to hold, distrubute, and release vapor (hygric buffering and hygric redistribution). Accumulation shouldn’t be a problem, with the exception of the coldest climate zones.

      I applaud 475 for their commitment to energy conservation, but we shouldn’t forget they are a retailer. This should be first and foremost in the reader’s mind while perusing these articles. Potential customers should be well versed in building science before buying energy conservation products from any retailer. You do not want to end up with unnecessary layers of redundancy.

      • Ken May 11, 2016 at 8:39 am #

        Thank you for the comment. A couple of clarifications:

        0.4 ACH50 is a very tight number, particularly on such a modest sized home – only folks who have completed a bunch of Passive House level constructions successfully could think to plan to hit such a low number. For a novice effort 0.2 would be absurdly airtight on this home.

        We don’t mind skepticism about the approach of an interior air barrier, but the approach is based on sound building science. See our blog post:

        GWB is not a vapor retarder.

        The enclosures we are recommending are not meant to probably be safe, walking on the edge – they are meant to have drying reserves and resilience that makes for long lasting robustness.

        Airtightness inboard and outboard of the insulation layer is not redundant. Surrounding the insulation in airtightness is a fundamental approach to optimization of that insulation.

        We appreciate the dialogue.

        • Mark Pollard May 11, 2016 at 11:21 am #


          I was in no way disputing .4 ACH50 is not a great result. It’s outstanding! Congrats to the homeowner, he is getting a legacy home. My contention is with the kit of parts used, it seems the number should have been lower. It is unclear from the article whether the homeowner built the house or a GC. If it was a GC, new to the world of high performance building or not, it just feels like the number should be lower. The kit of parts almost commands this. Infiltration via doors and windows? Humbleness aside, my first three DER projects achieved .3-.4 ACH50 on 1900-era homes with exterior air control only, funky envelopes, and very minimal foam. This was done with off the shelf parts from a local lumber yard and a very novice crew.

          I take issue with your use of citing your own website as a source. In the blog you cite, there are no links to back up the information presented other than links to other blogs on the 475 site.

          I was very careful to not call drywall a vapor retarder. Primer with two coats of latex, typical, it returns a wet cup perm rating between 10 and 20. Pretty good vapor control in my opinion.

          The big guns of building science all shy away from advocating for the use of interior vapor retarders unless there is a known source of high moisture; soil gas, inadequare ventilation, and major air leaks. New construction high performance homes have preplanning set in place to address vapor accumulation; vapor/water control layers, mechanical ventilation, and occupant education/awareness. If one or more of these fail, a structure is in trouble. It doesn’t matter if there are multiple ways to control vapor, failure is failure. Simply adding an interior vapor/air membrane does nothing if the occupants crank up the indoor RH and defer maintenance of the exterior claddings.

          You stated:
          “Airtightness inboard and outboard of the insulation layer is not redundant. Surrounding the insulation in airtightness is a fundamental approach to optimization of that insulation.”

          Other than very small convective loops between the insulation and interior wall cladding, how is the performance of the insulation being significantly degraded? Either through accelerated energy loss or excess vapor transport? The mechanisms are not present. The stack effect is negated through the use of an exterior air barrier and vapor has been addressed in pre-construction planning.

          My argument is simple, the assembly you are highlighting is this articles has an unnecessary layer of control that added significant expense in materials and labor. A small increase in cost to the exterior air/vapor/water control layers would yield equitable results. But at the end of the day, it’s not my house or my money.

          I really commend 475 for being advocates of foam free construction and high performance assemblies. Being a retailer and source of building science information is a bit like having a vice president who happened to have been employed by a defense contractor, kind of a conflict of interests.

          • Ken May 11, 2016 at 11:46 am #


            We never advocate doing anything in isolation – everything is a system of some sort – certainly air and vapor control is.

            The Building Science Corporation’s Thermal Metric Study and Joe Lstiburek himself point to the essential utility of inboard and outboard airtightness. See another blog post – this one with links to external sources:

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