Spray Foam vs. Fiberglass: A Tale of Two Homes

Transforming Energy Efficiency

In a groundbreaking project by Habitat for Humanity in Denton, TX, two identically designed homes were built side by side with one key difference: their insulation materials. This unique setup provided a real-world comparison of energy efficiency between spray foam insulation and traditional fiberglass insulation combined with a solar board. The findings from this comparison offer valuable insights for homeowners considering insulation options.

The Project Setup

Both homes, constructed in 2007, feature the same floor plan and orientation but differ significantly in their insulation approaches. One home was insulated using 3.5 inches of Sealection open-cell foam in the exterior walls (R-Value of 13) and 5.5 inches in the roof deck (R-Value of 21), creating a closed attic assembly. This setup places the air handler and ductwork within the thermal envelope, significantly reducing the thermal load on the HVAC system and allowing for a smaller HVAC unit.

The other home utilized traditional fiberglass insulation in the walls and attic floor, achieving an R-Value of 13 in the walls and 38 in the attic floor, with a solar board on the roof deck. Despite these specifications, the fiberglass insulation does not encompass the HVAC system within the home’s thermal envelope.

Energy Efficiency Outcomes

The results were stark. Monitoring equipment installed in both homes measured temperature, humidity, and electrical usage, revealing significant differences in energy consumption and cost. The spray foam insulated home showed drastically reduced air leakage, over 14 times lower than its fiberglass counterpart, translating to 95% less air leakage overall.

Energy consumption figures underscore the efficiency of spray foam. The fiberglass-insulated home used an average of 2248 kWh per month at a cost of $258.03, while the spray foam-insulated home consumed just 883 kWh at $105.41. This amounts to a substantial monthly saving, with total energy costs nearly 60% lower in the foam-insulated home.

Real-World Implications

These findings illuminate the profound impact that insulation type can have on a home’s energy efficiency. Spray foam insulation not only offers superior air sealing properties but also enhances the overall efficiency of heating and cooling systems. The reduced energy usage not only leads to lower utility bills but also contributes to a smaller environmental footprint, a critical consideration in today’s energy-conscious climate.

For homeowners and builders alike, this project serves as a compelling demonstration of how advanced insulation technologies like spray foam can lead to long-term savings and sustainability. It’s a clear example that in the world of building and insulation, material choices can have dramatic impacts on both costs and comfort.