Storm Windows vs Replacement Windows

A storm window is a second window added to an existing one, either outside or inside, to cut drafts, heat transfer and noise. For an older home with sound original windows, a good storm window can be the cheaper, gentler upgrade. When the original windows are rotted, broken or beyond repair, replacement is usually the better call.

In New Orleans there’s a local wrinkle. Historic district rules limit exterior storm windows on the street side, so interior storms and repair are the options the HDLC’s guidelines point to.

At TurnKey Window we repair and replace windows in older homes across the New Orleans area. If you’re weighing the two, reach out for an assessment or call (504) 226-6201.

Key takeaways

Storm windows are attachments added to an existing window to protect it from weather and improve energy performance, according to a PNNL and DOE program guide.
In a PNNL field test, exterior low-e storm windows cut heating energy 10.5 percent and cooling energy 8.0 percent.
The same program guide estimates a low-e storm window at about $10 per square foot, or roughly $150 for a 3 by 5 foot window.
In hot climates, low-e storms with lower solar heat gain do more for cooling bills.
The New Orleans HDLC does not permit exterior storm windows at locations visible from the street, but it points to interior storm windows as a way to improve historic windows.
Replacement makes more sense when frames, sills or sashes are too far gone to repair.

What counts as a storm window

The Storm Window and Insulating Panel Utility Playbook, from Pacific Northwest National Laboratory and the Department of Energy’s storm window campaign, defines storm windows as attachments added to an existing window to protect it from weather and improve energy performance.

It describes two main types. Exterior storms mount outside the primary window. Interior storms and insulating panels mount inside, and while they don’t shield the old window from the elements, the playbook says they still improve energy efficiency, air sealing, comfort and outdoor noise reduction.

Exterior storm windows protect the original sash and sill from rain and sun as well as adding insulation.
Interior storm windows fit inside the existing window and leave the exterior look unchanged.
Low-e storm windows add a low-emissivity coating, which the playbook says substantially decreases heat transfer through the window.

Storm windows are not hurricane windows

The name confuses people here. A storm window in the energy sense is a thermal and weather layer, not impact protection. The New Orleans HDLC’s Guidelines for Windows and Doors treat hurricane protection separately, pointing to shutters, pre-fitted panels and fabric storm panels.

If what you need is protection from wind-borne debris, look at impact-rated products instead. Our impact-resistant windows page explains how those work.

Do storm windows really work

For energy, the evidence is solid. PNNL tested exterior low-e storm windows over double-pane, clear-glass, aluminum-frame windows in a matched pair of lab homes. Its report on the Lab Homes study found average savings of 10.5 percent in the heating season and 8.0 percent in the cooling season.

Extrapolated over a typical year, that came to an estimated 10.1 percent annual energy savings, with a simple payback of 5 to 7 years. The report adds that homes with leakier older windows would likely see more savings than the test homes, whose primary windows were already well sealed.

Drafts are part of the story too. The PNNL playbook says case studies show modern storm windows cut overall home air leakage by an average of 10 percent, and that for older homes with old, leaky storms or none at all, that can be a big contributor to savings and comfort.

If you’re picturing the heavy, stuck storm panels of decades past, the playbook addresses that directly. It describes modern storm windows as operable, affordable and better looking than older storms.

For noise, the Federal Highway Administration’s noise reduction factors give light-frame buildings about 20 dB of reduction with ordinary closed sash and 25 dB with storm windows. The same FHWA guidance calls a 5 dB reduction readily perceptible.

What that means in a hot, humid climate

New Orleans sits in climate zone 2A, hot-humid, according to the Department of Energy’s Building America guide to climate regions. That changes which storm window helps most.

The PNNL playbook says savings depend heavily on region, and that cooling savings are more favorable in hot-summer regions when the low-e storm has lower solar heat gain. It also notes the lab test used high solar gain glass, which it calls ideal for northern climates, so ask for a lower solar heat gain product here.

Existing window	Modeled cooling savings per window, climate zone 2	Modeled gas heating savings per window, climate zone 2
Single-pane wood frame	49.4 kWh	4.7 therms
Double-pane wood frame	33.5 kWh	1.5 therms

Those modeled figures come from the PNNL playbook, averaged across two home types and both interior and exterior storms. Of the two, the single-pane wood window gains the most.

New Orleans Casement Windows Installers

Storm windows vs replacement windows compared

Here’s how the two options stack up on the points most owners of older homes care about.

Factor	Storm windows	Replacement windows
Cost	About $10 per sq. ft., or about $150 for a 3 by 5 foot window, per the PNNL playbook	Higher, and the PNNL playbook points to the affordability of storms compared to full replacement
Energy savings	10.5% heating and 8.0% cooling in PNNL’s lab test over double-pane windows	Depends on the product you’re replacing and the new unit’s ratings
Original windows	Kept in place	Removed
Historic districts	Interior storms suggested by the HDLC; exterior storms not permitted where visible from the street	Must match the original closely, and vinyl or aluminum is not permitted to replace historic wood at street elevations
Fixes rot or broken parts	No, the old window still needs repair	Yes
Noise	FHWA factor rises from 20 dB to 25 dB on light-frame buildings	Depends on the glass package

Historic district rules in New Orleans

If your home is in a local historic district, the HDLC’s guidelines shape this decision more than anything else. The commission reviews all alterations to and replacement of visible exterior windows.

On storm windows, the guidelines are direct. The HDLC does not permit exterior storm windows or doors at locations visible from the street.

At the same time, the guidelines say a good carpenter or handy homeowner can generally repair a historic wood window and install an interior storm window to improve thermal performance. They also say the HDLC strongly encourages repair and selective part replacement before full replacement.

Street-facing historic wood windows: repair plus an interior storm is the path the HDLC describes.
Side and rear windows not visible from the street: more options may be open, so check with HDLC staff.
Missing or unrepairable historic sash: the HDLC recommends wood replacement sash with details matching the rest of the building.

When storm windows are the better choice

Storm windows make the most sense when the original windows are in decent shape. Think of them as a way to add performance without giving up what’s already there.

Your original wood windows are solid, operate well and just need glazing or paint work.
You live in a historic district and want to keep street-facing windows original.
You want lower energy bills and fewer drafts on a tighter budget.
You’d like a quieter house without replacing every window.

When replacement windows are the better choice

Replacement wins when the existing windows can’t be saved or are holding the house back. Our post on the top signs it’s time to replace your windows covers the warning signs in more detail.

Frames or sills are soft and rotting through.
Sashes are missing, broken or painted shut beyond repair.
Glass seals have failed on many double-pane units at once.
You want something storms can’t add, like impact-rated glass.

If replacement is the answer, our window replacement page explains how a project runs, and our custom windows page covers made-to-fit units for older openings.

double hung window

How to decide for your house

A quick walk around the house usually points you one way or the other. Work through these steps before getting quotes.

Check your district. Find out if you’re in a local historic district, since that changes what’s allowed on the street side.
Inspect every window. Press on sills and bottom rails, test each sash and look for broken glass or failed seals.
Sort them into groups. Sound windows are storm candidates, while rotted or broken ones are repair or replacement candidates.
Pick the storm type. Interior storms keep the exterior look, while exterior storms also shield the old sash from weather.
Ask for low-e with lower solar heat gain. PNNL’s playbook says that’s what drives cooling savings in hot climates.
Price both paths. Compare storms plus repair against replacement, window by window.

Working on ladders to measure or inspect upper-floor windows is risky. Leave that to a professional if you’re not comfortable up high.

Frequently asked questions

What is considered a storm window?

A storm window is an attachment added to an existing window, either outside or inside, to protect it from weather and improve energy performance. That’s how the PNNL and DOE storm window playbook defines it.

Do storm windows really work?

Yes. In PNNL’s lab home test, exterior low-e storm windows cut heating energy 10.5 percent and cooling energy 8.0 percent, and the FHWA credits storm windows on light-frame buildings with about 5 dB more noise reduction than ordinary closed sash.

Are storm windows cheaper than replacement windows?

Usually. The PNNL playbook estimates a low-e storm window at about $10 per square foot, or roughly $150 for a standard 3 by 5 foot window, while replacement covers a whole new unit and its installation.

Can I put storm windows on a historic house in New Orleans?

Interior storm windows are the path the HDLC describes for improving historic windows. Its guidelines do not permit exterior storm windows at locations visible from the street.

Are storm windows the same as hurricane windows?

No. Storm windows are a thermal and weather layer, while hurricane protection means impact-rated windows, shutters or storm panels, which the HDLC’s guidelines cover separately.

Get a straight answer on your windows

We’ll look at each window, tell you which ones can be saved and which ones need replacing, and give you a free estimate. You’ll get a plan that fits the house and the budget.

Storm Windows vs Replacement Windows for Older Homes