Replacement Window GuideDouble-hung and casement are the two operating styles most homeowners compare. The NFRC consumer guide describes double-hung windows as having two sliding sashes and casement windows as hinged units that swing open, and the two seal air very differently. This Old House prices casement at about 529 dollars and double-hung at about 551 dollars per installed window. The sections below attribute each claim to its source.
How each style operates
The NFRC consumer guide describes double-hung windows as having two sliding sashes, where the top sash can be lowered and the bottom sash can be raised. That lets you open the top, the bottom, or both.
The same guide describes casement windows as hinged on the sides of their sashes, opening by swinging out or in, typically by turning a crank. The difference in how they open drives most of the practical tradeoffs that follow.
Air sealing and energy efficiency
The biggest performance difference is how each seals. GreenBuildingAdvisor notes that the many sliding seals in a double-hung window tend to leak more air than the compression-type seals used in casement windows. A casement sash presses against the frame when the crank pulls it shut, forming a compression seal.
Because frame material and glazing also shape efficiency, the NFRC consumer guide reminds buyers that frame properties significantly influence total window performance. In either style, look at the NFRC air leakage rating, which the same guide describes as the volume of air that can infiltrate, where a lower number means less leakage.
Ventilation and airflow control
The two styles ventilate differently. Because a double-hung window has both an upper and lower sliding sash, the NFRC consumer guide's description of the top lowering and the bottom raising means you can vent warm air out the top while drawing cooler air in the bottom.
A casement, being hinged and swinging fully open, exposes nearly the whole opening to catch a breeze. Neither is universally better; double-hung gives finer control over where air enters, while casement opens the widest for maximum flow.
Cost comparison
On price, the two styles are close. This Old House lists casement windows at about 529 dollars and double-hung windows at about 551 dollars per installed window in its 2026 data.
For context, This Old House places single-hung as the most budget-friendly style at about 474 dollars, so both casement and double-hung sit in the middle of the style range rather than the extremes. Material and glass package will move the final number more than the choice between these two styles.
Which works for egress openings
In bedrooms and basements, the window must meet emergency escape rules regardless of style. Building Code Trainer, citing IRC Section R310.2, states that emergency escape and rescue openings require a minimum net clear opening of 5.7 square feet, or 5.0 square feet at grade-floor level.
The same source lists a minimum net clear height of 24 inches, a minimum width of 20 inches, and a sill no higher than 44 inches above the finished floor. A casement can swing fully clear to hit the net-opening target in a smaller frame, while a double-hung only opens half its height at once, which is worth checking against these numbers before you choose.