March 8, 2016

Breaking the ‘Upfront Cost Barrier’

Part One – Lucas Johnson’s long quest for the holy grail of high performance building

Port Townsend Passive House from Artisans Group

Port Townsend Passive House from Artisans Group

In his previous career as a green builder, 475’s West Coast Solutions Consultant, Lucas Johnson, was frequently asked to find better alternatives to spray foam and code-minimum membranes.  The goal was to find a cost effective assembly that delivered long-lasting Passive House level airtightness and robust vapor control that builds drying reserves utilizing non-toxic materials.

He agreed there were better options and researched many different systems, however, the failure was almost always upfront cost. Finding environmentally friendly high-performance building products that could beat the upfront cost barrier became Lucas’ holy grail.

In his consulting role as the in-house building scientist for Seattle’s Community Power Works program, Lucas got to observe different approaches to upgrading thousands of residential and commercial buildings. Again, standard membranes and spray foam continued to plague him and upfront cost would defeat the high performance options he presented.

When looked at from the long-term perspective, high performance components make the  most sense due to dramatically decreased maintenance, and overall health for both structure and occupants – before you even consider the energy reduction value. So, the challenge is: how does one defeat the upfront cost barrier to better building?

Lucas had the opportunity to transition from his consulting 2x6Walls_mentorole back into building Passive Houses for the design/building firm, Artisans Group, in the greater Cascadia region. It was in this role that he met 475 and finally discovered a high performance system that broke the upfront cost barrier. By using membranes and tapes that each served multiple utilities, enough labor could be saved to move beyond the conventional approach!

 

Below is a summary comparison of the conventional 2×6 wall system vs. the holy grail 2×6 wall system that Lucas discovered .


Conventional 2×6 wall system – $14,874 upfront

  • Exterior system of Tyvek, Tyvek tape, and Flexwrap
  • Interior system of drywall blocking, insulation netting, and 6mm PE
  • Both scenarios assume the same siding, rainscreen, and dense pack blown cellulose
  • This scenario presents risk of discomfort, higher energy bills, and most importantly, failure due to vapor closed materials combined with poor control of water vapor and air flow

Holy Grail 2×6 wall system – $14,293 upfront

  • Exterior system of SOLITEX MENTO 1000, TESCON VANA, and EXTOSEAL ENCORS at window sills
  • Interior system of INTELLO Plus, TESCON VANA tape, and service cavity battens
  • Both scenarios assume the same siding, rainscreen, and dense pack blown cellulose
  • This scenario presents best practices in delivering comfort, minimized energy bills, and the lowest risk of building failures

 

The key difference is the extra labor for wrapping all four sides of the windows, the complication of drywall blocking, and the installation of two interior membranes instead of just one. This isn’t an earth-shattering victory of being something like 15% below conventional cost; however, it is significant that high performance can be on par or slightly less than conventional, given a simplified and calculated design.

In other words, when a holistic view of labor and materials is taken, high performance can beat conventional upfront. This is core to 475’s reasoning behind giving away information for free. Our downloadable CAD Details and Construction Guide Books are worth something, we know. But we find that its far more beneficial for all involved to put it out there and suggest assemblies that simplify connections, while maintaining high performance standards, and work in the real world.

We realize every builder and every project is a particular situation, and this math doesn’t reflect every contingency and location. It does start a conversation on a way forward for those needing to break the upfront cost requirements. We get plenty of questions about installed cost, and our standard answer is: “It depends.” Because it does. But that’s not as helpful of answer as we wish we could give – so let this be a first stepping stone on a dialogue of installed cost. Lucas, and rest of the 475 team is happy to engage in discussion regarding how you feel about this comparison of upfront costs. Please share your thoughts in the comments section below!

In addition, in the following months, there will be more stories to follow summarizing how high performance can beat spray foam, XPS exterior insulation, and standard ventilation.

costcomparison

 

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