Storm Windows for Historic Homes: Efficiency Without Replacement

Storm windows offer historic homeowners a way to dramatically improve energy efficiency without replacing original windows. According to the National Park Service, storms are often the most appropriate efficiency upgrade for historic buildings.

How Storm Windows Help

According to the U.S. Department of Energy:

Storm windows create:

• Additional air gap for insulation
• Reduction in air infiltration
• Protection for original windows from weather
• Barrier against condensation

Performance Impact

According to DOE and NPS research:

| Configuration | Approximate U-Factor |
|---------------|---------------------|
| Single-pane alone | 1.0 |
| Single-pane + storm | 0.50 |
| Single + storm + Low-E film | 0.40 |

Storm windows can reduce heat loss by 25-50%.

Storm Window Options

According to NPS guidance:

Exterior Storms

Traditional wood storms:

• Period-appropriate appearance
• Can be custom-made to match profiles
• Require seasonal installation/removal (if not divided)
• Good protection for primary windows

Aluminum triple-track:

• Most common modern option
• Combined storm and screen in one unit
• No seasonal changes needed
• Less period-appropriate appearance

Interior Storms

Advantages:

• Invisible from exterior
• Don't alter historic appearance at all
• Can be removed easily
• Work where exterior storms aren't possible

Options:

• Magnetic mount acrylic panels
• Track-mounted rigid panels
• Shrink-film temporary (seasonal)

Historic District Considerations

According to NPS standards:

Generally acceptable:

• Interior storm windows (not visible from exterior)
• Exterior storms matching original window color
• Storms that don't obscure decorative elements
• Removable installations

Generally not acceptable:

• Storms that significantly alter appearance
• Tinted or reflective glass
• Storms that cover architectural details
• Permanent alterations to original windows

Cost Comparison

According to industry estimates:

| Option | Cost per Window |
|--------|----------------|
| Interior magnetic | $50-150 |
| Interior track-mounted | $100-250 |
| Exterior triple-track | $150-300 |
| Custom wood exterior | $200-400 |
| Low-E retrofit film | $50-100 |

Compare to replacement: $400-2,000 for custom wood or high-quality vinyl

The Bottom Line

Storm windows provide significant energy improvement at a fraction of replacement cost while preserving original windows. According to NPS, they're often the most appropriate solution for historic homes.

*For complete guidance, see: [Historic Window Restoration](/guides/historic-window-restoration)*