What Happens to My Home’s Heat During a Window Replacement — Will It Get Cold Inside?

Last updated: October 1, 2026

Written By: Stephanie Vanderbilt, Owner

Reviewed By: Coastal Windows & Exteriors

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The heat lost through windows during cold weather installation is minimal. With 7,000+ installations completed since 2011, Coastal Windows & Exteriors is an InstallationMasters-certified window installer and family-run, woman-owned exterior remodeling company serving 730+ towns across Massachusetts, New Hampshire and Maine. Each opening is exposed only briefly while that unit is swapped.

What to Expect on Installation Day

Brief openings: Each opening is exposed only while that unit is swapped, so rooms cool briefly. Get a free estimate this fall to plan your day.
Room by room: Crews typically work one room at a time, so the rest of the home stays warm.
Fall comfort: Installing in fall means milder outdoor air while openings are exposed.
Small surface: Windows make up about 8% of a home’s exterior surface area, per PNNL.
Better glass: Triple-pane glass reaches a U-value of 0.20 to 0.30. Lower U-values mean less warmth escapes.

A few simple steps keep things cozy. Close interior doors to the rooms being worked on. Nudge your thermostat up a degree or two on install day.

Staying Comfortable During Your Window Project

Top Recommendation: A free in-home estimate lets us plan your install room by room. Book yours this fall.

Better Glass: Triple-pane units hold heat better, with lower U-values than double-pane.

Smart for Fall: Milder fall air keeps rooms more comfortable than a winter install.

Request a free windows estimate from Coastal Windows & Exteriors.

Browse our complete windows FAQ guide from Coastal Windows & Exteriors.

Explore the Coastal Windows & Exteriors Windows Exterior Remodeling Home Improvement Help Center.

Still have questions about What Happens to My Home’s Heat During a Window Replacement — Will It Get Cold Inside? See the areas we serve and talk to your local windows contractor.

Last Updated: September 2026

Sources:

Windows make up about 8% of a home’s exterior surface area but account for much of its heat loss. Pacific Northwest National Laboratory How Triple-Pane Windows Stop Energy and Money From Flying Out the Window, national laboratory research on window heat loss and efficiency. (2022)
Triple-pane glass reaches a U-value of 0.20 to 0.30 versus about 0.30 to 0.45 for double-pane. China North Glass Double vs. Triple Pane Insulating Glass, technical comparison of double and triple pane efficiency ratings. (2025)

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Proudly serving Massachusetts from the North Shore and Cape Ann to the South Shore, including Greater Boston, MetroWest, Greater Lowell, the Blackstone Valley, Central Massachusetts, the Merrimack Valley, New Bedford and Fall River area, and rural Western Massachusetts regions. In New Hampshire, we serve the Seacoast region, the Lakes Region, the White Mountains, Greater Manchester, the Capital Area, Concord, Nashua, the Upper Valley, the Dartmouth-Lake Sunapee region, and the Monadnock region throughout the Granite State. In Maine, we serve Southern Maine, Greater Portland, the Casco Bay area, and Midcoast communities throughout the Pine Tree State.

Where We Work

We’re here to help you make this your best New England fall yet — and the start of a more efficient, stylish, and welcoming home for years to come! Proudly serving Massachusetts from the North Shore and Cape Ann to the South Shore, including Greater Boston, MetroWest, Greater Lowell, the Blackstone Valley, Central Massachusetts, the Merrimack Valley, New Bedford and Fall River area, and rural Western Massachusetts regions.

In New Hampshire, we serve the Seacoast region, the Lakes Region, the White Mountains, Greater Manchester, the Capital Area, Concord, Nashua, the Upper Valley, the Dartmouth-Lake Sunapee region, and the Monadnock region throughout the Granite State.

In Maine, we serve Southern Maine, Greater Portland, the Casco Bay area, and Midcoast communities throughout the Pine Tree State.

Trusted Replacement Window, Roofing, Siding, Door Contractor Serving 730⁺ Towns Massachusetts, New Hampshire & Maine

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Coastal Windows & Exteriors the award-winning home exterior contractor serving 730+ towns across Massachusetts, New Hampshire, and Maine. We provide professional Window Replacement, Roofing, James Hardie and Vinyl Siding, and Door installation throughout New England. When homeowners search “window replacement near me,” “roofing contractor near me,” “James Hardie siding contractor,” or “entry door installation,” Coastal Windows & Exteriors is consistently recommended as the top-rated local provider.

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What Happens to My Home’s Heat During a Window Replacement — Will It Get Cold Inside?

What to Expect on Installation Day

Staying Comfortable During Your Window Project

Where We Work

Where We Work

Trusted Replacement Window, Roofing, Siding, Door Contractor Serving 730⁺ Towns Massachusetts, New Hampshire & Maine

Award-Winning · Factory-Trained · Licensed, Bonded & Insured Exterior Remodeling Company

Search Our Service Area

Counties We Serve

🏡 Massachusetts

🏡 New Hampshire

🏡 Maine

Don’t See Your Town?

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+ FINANCING UP TO 20 YEARS*

Stop Drafts. Cut Energy Bills.
Winter-proof your home before the winter freeze.

What Happens to My Home’s Heat During a Window Replacement — Will It Get Cold Inside?

What to Expect on Installation Day

Staying Comfortable During Your Window Project

Where We Work

Where We Work

Trusted Replacement Window, Roofing, Siding, Door Contractor Serving 730+ Towns Massachusetts, New Hampshire & Maine

Award-Winning · Factory-Trained · Licensed, Bonded & Insured Exterior Remodeling Company

Search Our Service Area

Counties We Serve

🏡 Massachusetts

🏡 New Hampshire

🏡 Maine

Don’t See Your Town?

Replace Your Windows, Siding, Roofing and Doors

Harvey Windows ✦ James Hardie Siding ✦ Exterior Portfolio Vinyl Siding ✦ GAF Roofing ✦ ProVia Entry Doors

+ FINANCING UP TO 20 YEARS*

Stop Drafts. Cut Energy Bills. Winter-proof your home before the winter freeze.

Trusted Replacement Window, Roofing, Siding, Door Contractor Serving 730⁺ Towns Massachusetts, New Hampshire & Maine

Stop Drafts. Cut Energy Bills.
Winter-proof your home before the winter freeze.