What is a casement window?

A casement window opens on side hinges. The National Fenestration Rating Council (NFRC) Manual section 2.2.1 explains that virtually its entire window area can open, while sliders open less than half. Compare the hinge position and usable opening area when describing the replacement you want.

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By InstaBids editorial team with AI research agents. Updated 5 November 2026

What this means for your home project

Before removal begins, compare the delivered windows with your order and look for both ENERGY STAR and NFRC labels; resolve mismatches first. (source)
Request a written window schedule listing the exact U-factor and SHGC for each unit, so the contract records both performance measures. Source: ENERGY STAR, read 2026-11-05.
For original windows in a pre-1978 home, request a removal scope that addresses lead-paint dust and chip containment. Source: ENERGY STAR, read 2026-11-05.
Have the installer leave each NFRC sticker with you as the record of the window installed. Source: ENERGY STAR, read 2026-11-05.
Before handover, try each casement crank and note any difficulty opening it for the installer to address. Source: ENERGY STAR, read 2026-11-05.

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What is the difference between casement and awning windows?

Use NYC’s glossary and the NFRC comparison to identify the opening style before describing a replacement (read 2026-11-05). “Casement: A window sash that is hinged on the side.” (source) “Hinged windows include casements, awnings, and hoppers—hinged at the side, top, and bottom, respectively.” (source)

Are casement windows always more energy efficient than sliders?

NFRC separates a general sealing advantage from overall performance; U-factor measures insulation and SHGC means solar heat gain coefficient (read 2026-11-05). “For operating fenestration products, the type of operation has little direct effect on the U-factor or SHGC of the unit, but it can have a significant effect on the air infiltration and ventilation characteristics.” (source) “Hinged windows such as casements, awnings, and hoppers generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame, permitting the use of more effective compression-type weatherstripping.” (source)

What are major casement windows cost factors?

ENERGY STAR identifies age-related removal precautions that can change the work included in a casement replacement scope (read 2026-11-05). “Remember, if your home was built before 1978 and the original windows are replaced, the installer should follow lead paint protocols during the removal of the old windows to ensure lead paint chips and dust are not spread around your house or outside on the ground.” (source) “Following lead paint clean-up protocols is good for your home because they require the installer to catch any lead paint chips that fall during removal of the old windows, to clean up the site with extra care when the job is completed, and to dispose of the old windows correctly.” (source)

How to choose the best casement windows for a residential or commercial project?

Compare ENERGY STAR’s performance measures alongside the frame requirement in NFRC Simulation Manual section 2.3.1 when selecting a unit (read 2026-11-05). “Hinged windows require a strong frame to encase and support the projecting sash.” (source) “The U-factor range for windows is typically between 0.10 and 0.60.” (source) “The lower the number the more the window will insulate.” (source) “The SHGC range for windows is typically between 0.15 to 0.60.” (source) “The lower the number the more heat is blocked.” (source)

Replacing a casement window: what happens on installation day?

ENERGY STAR gives a before-and-after sequence for checking delivery and operation, helping you recognize unfinished installation work (read 2026-11-05). “When the installer arrives, the first thing you should do (before any of your current windows are removed) is to check if the windows to be installed are the ones you ordered and that they include both ENERGY STAR and NFRC labels.” (source) “Before the installer leaves, open and close each window to ensure they are not twisted or installed unevenly.” (source) “Casements should crank open easily and vertical and horizontal sliding windows should slide easily.” (source) “Inspect the caulking on each window to be sure there are no gaps, and all the work is neatly done.” (source)

Sources

Glossary: Casement — New York City Landmarks Preservation Commission; read 2026-11-05.
THERM7 / WINDOW7 NFRC Simulation Manual, sections 2.2.1 and 2.3 — National Fenestration Rating Council; published July 2024; read 2026-11-05.
High Performing Windows or Storm Windows — ENERGY STAR; read 2026-11-05.