107. Mushrooms in Net-Zero Home with Bill Spohn

Most home tours happen on move-in day, when everything's shiny and nobody's tested anything yet. This one is different — Bill Spohn and his wife built a net-zero, airtight, modular "Pretty Good House" outside Pittsburgh, and they've lived in it for six years.

So what actually happened? A factory installation mistake led to a rotted subfloor and — yes — mushrooms growing under the shower. Two windows still won't seal in winter (there's blue painter's tape involved). The AC failed once from a bad install, not a bad heat pump. And yet Bill says he's more pleased with the house now than the day they moved in — quiet, comfortable, and still net-zero on an annual basis.

We talk about what six years of real living reveals that a spec sheet never will: the honest tradeoffs of going airtight, why he skipped a battery backup, the well and septic saga that almost derailed the build, and what he'd actually tell someone considering this path today.

Bill also runs BetterHVAC.org, a free nonprofit directory connecting homeowners with contractors who understand building science — not just HVAC in isolation.

Resources mentioned:

• spohnhome.com — Bill's build story and blog
• betterhvac.org — free contractor directory
• trutechtools.com — Bill's business, home performance testing tools
• Building Performance Institute — credentialing body for home performance contractors
• Solar United Neighbors — nonprofit that runs local solar co-ops to help homeowners get better group pricing

Timestamps:
00:00 Introduction
00:31 Bill's background and motivation
02:06 The concept of passive house
03:04 Designing for energy efficiency
04:51 Achieving airtightness
06:17 Ventilation solutions
10:29 Challenges in construction
12:53 Achieving net-zero energy
17:07 Living in the home
20:16 Tips for building energy-efficient homes