Meeting energy efficiency codes
The City of Louisville has adopted the 2024 International Energy Conservation Code (IECC) and Colorado's Electric-Ready and Solar-Ready requirements. These standards help improve energy efficiency, reduce utility costs, and support sustainable building practices.
Who has to meet these codes?
Energy code requirements apply to:
- New residential construction
- New commercial construction
- Residential additions and major remodels
- Commercial additions and tenant finish projects
- Mechanical and electrical system replacements, when applicable
Residential requirements for new homes
New homes must comply with the 2024 IECC and include:
- Whole-house ventilation
- Blower door testing
- Duct leakage testing
- Electric-ready infrastructure
- EV-ready parking requirements
- Compliance with minimum insulation and window performance standards
New homes must also achieve an Energy Rating Index (ERI) score of 50 or less, verified by a certified RESNET energy rater.
Minimum residential insulation requirements
The following insulation values are commonly required for new residential construction:
| Building Component | Minimum Requirement |
|---|---|
| Above Grade Walls | R-30 or R-20 & R-5 ci |
| Below Grade Walls | R-21 / R-19 cir |
| Floors | R-38 |
| Non-Heated Slab on Grade | R-15 for 4 ft. + R-5 under full slab |
| Fenestration U-Factor | .30 |
| Fenestration SHGC | .33 |
| Skylight U-Factor | .50 |
| Skylight SHGC | .40 |
| Heated Water Pipes | R-3 |
| Heated Air Ducts | R-8 |
Window and door assemblies must also meet applicable U-factor and Solar Heat Gain Coefficient (SHGC) requirements established by the adopted energy code.
Additional resources
For questions regarding energy code compliance, please contact the Building Safety Division at 303-335-4584.