Summary: Cost-Effectiveness Analysis of the Residential Provisions of the 2015 IECC for the State of Utah (Pacific Northwest National Laboratory (June 2015)
Methodology
- 96 building energy models using EnergyPlus v8
- Incremental costs from several sources with local construction cost multiplier based on standardized methodology
- 5% interest rate, 30-year mortgage, 10% down payment
- Compared 2015 IECC vs “Utah IECC”
Prescriptive Building Thermal Envelope changes to the 2015 IECC vs “Utah IECC”
- increased attic insulation (CZ 3, CZ 5)
- improved skylight, window and door efficiency values (CZ 3, CZ 5, CZ 6)
- increased wood frame wall, and basement wall insulation (CZ 3, CZ 5, CZ 6
Other changes Analyzed
- Improved insulation for return air ducts in attics
- Demand-activated controls for recirculating systems
- Outdoor Air Temperature Setback Control for Hot Water Boilers
- Reduced air leakage rate
- Reduced duct leakage
- 75% high efficiency lighting
Economic Analysis: 2015 IECC is Cost Effective
- The incremental cost to the builder ranges between $1,089 and $3,332 (depending on the building plan and location)
- Reduces energy costs by $297/year or 23.9% on average
- Home buyers realizes “positive cash flow” within 2 years (annual energy savings are greater than the higher down payment and mortgage costs when these costs are rolled into a 30-year mortgage)
New “Energy Rating Index” Performance Path
- New voluntary “Energy Rating Index” performance was not analyzed
- The ERI is supported by the Leading Builders of America as a more cost effective way to building energy efficient new homes