Isotherm Building Science

The numbers · Michal Matyjasik's own house · 1,400 sf · all-electric · Climate Zone 5B

Design heating load and assembly R-values of the house Isotherm's principal built in Grand Junction, CO

Each value is printed with its unit, the condition it holds at, and whether it was measured, calculated or rated.

Design heating load

8,350 Btu/h

Whole house at 20 °F outdoor

Calculated

Roof assembly

R-105.5 effective

Unvented; 5 in closed-cell spray foam over 19 in dense-pack cellulose

Calculated · parallel path

Wall assembly

R-26.1 effective

2×6 at 24 in o.c., wet-spray cellulose, ZIP R-9 sheathing; 22 % framing

Calculated

Floor

R-10 + R-10 skirt

Insulated slab-on-grade; perimeter, and a 4 ft skirt below grade

As built

What Isotherm does

We answer physical questions about a building from building plans, published values, measurements, or derived from first principles, with our proprietary software.

About

Michal Matyjasik, PhD

PhD in biochemistry, CU Boulder, 2019. Owner-builder, self-GC of his own high-performance, all-electric house in Grand Junction, CO, Climate Zone 5B. Building science learned through execution: envelope assemblies, closed-cell spray foam, water-resistive-barrier detailing, whole-building energy modeling, HVAC sizing and Manual J.