Window Selection for Sun Valley and Idaho Mountain Communities

Mountain homes face window challenges that valley homes don't. According to the Efficient Windows Collaborative, extreme cold, high altitude, and intense sun exposure require premium window specifications.

The Mountain Difference

According to climate data, mountain communities like Sun Valley, McCall, and Stanley experience:

• Winter lows frequently below 0°F
• Temperature swings of 40°F+ in a single day
• Increased UV intensity at elevation
• Heavy snow loads (relevant for skylights)

Recommended Specifications

According to ENERGY STAR and NFRC guidance:

| Specification | Recommended | Why |
|---------------|-------------|-----|
| U-factor | ≤ 0.20 | Extreme cold demands premium insulation |
| SHGC | 0.35-0.50 | Capture passive solar heat |
| Frame | Fiberglass | Best dimensional stability |
| Glazing | Triple-pane | Meaningful comfort improvement |
| CR | ≥ 60 | Prevent condensation/frost |

Triple-Pane: Worth It Here

While triple-pane windows may have questionable ROI in milder climates, according to Lawrence Berkeley National Laboratory, they provide clear benefits in extreme cold:

• Interior glass stays within 3-5°F of room temperature
• Virtually eliminates cold drafts near windows
• Prevents condensation even at -20°F exterior
• Long heating seasons amplify savings

Altitude Considerations

According to NFRC guidance, high altitude affects insulated glass:

• Pressure differential can stress seals
• Specify windows manufactured for your elevation
• Work with installers experienced in mountain installations

Passive Solar Opportunity

Mountain homes often have excellent solar exposure. According to the Efficient Windows Collaborative:

• Higher SHGC on south-facing windows captures free heat
• Can reduce heating costs by 5-10%
• Combine with thermal mass for best results

The Bottom Line

Mountain homes justify premium window specifications. Triple-pane with low U-factor and higher SHGC provides meaningful comfort and efficiency improvements in extreme climates.

*For complete guidance, see: [Climate Zone Window Selection](/guides/climate-zone-window-selection-idaho)*