The difference is how many sashes open: a single-hung window has a fixed upper sash and a movable lower sash; a double-hung window lets both sashes slide vertically. That affects ventilation choices and, on models with tilt-in hardware, how you can clean the glass. It does not tell you which window is more energy efficient—the ratings and installation matter more.
How the sashes work
Both styles have an upper and a lower sash. On a single-hung window, the lower sash moves and the upper sash stays fixed. On a double-hung window, both sashes move. The names describe sash operation, not whether the glass is single- or double-pane. Pella and Andersen use this distinction in their explanations.
Ventilation: when two openings are useful
A single-hung window ventilates through its lower opening. With a double-hung window, you can open the lower sash, the upper sash, or both, depending on the product. Opening the upper sash may let warm air escape while cooler air enters below, but actual airflow depends on conditions inside and outside the room. Follow the operating instructions for the specific window.
Cleaning: check the tilt feature on the exact model
Some window sashes tilt inward, allowing you to clean exterior glass from indoors. A double-hung window may let both sashes tilt, but tilt-in or tilt-wash hardware is not standard on every model. Single-hung models also vary in their materials and tilt features. Check the manufacturer’s specifications for the exact product before assuming you can reach both exterior surfaces from inside.
#1 Best Overall
- Reliable Window Opening Control - Designed as an effective window opening control device, these window sash vent stops help limit how far your window sash can open. Ideal for improving everyday window stoppers security in homes, apartments, and light commercial spaces.
- Upgraded Durable Nylon Construction - Made from high-strength nylon composite, these window stoppers offer better durability than standard plastic window parts. Built to resist cracking and wear, making them a dependable choice for long-term window hardware use.
- Universal Fit for Vinyl Windows - Each window sash stop fits a standard adaptor slot size of 1.875" X 0.285", making it compatible with many vinyl double hung windows. A practical solution for vinyl window replacement parts and everyday window stops needs.
- Clean White Finish for Any Window Style - The neutral white design blends easily with most window frames, including PVC, painted wood, or aluminum. Works seamlessly with various window treatment hardware and keeps your windows looking uniform.
- Easy Installation & 6-Pack Value - Snap-in design allows quick install or removal. For easier handling, using needle-nose pliers is recommended. This 6-pack set helps replace multiple window sash components at once—perfect for maintaining consistent window hardware across your home.
Cost: single-hung is often less, but there is no universal price difference
Manufacturers generally attribute lower prices for single-hung windows within a comparable product line to their fewer moving parts. That is a relative tendency, not a reliable dollar estimate: dimensions, frame material, glass package, finish, and installation scope all affect the total. Compare quotes for windows with the same specifications rather than applying a fixed premium to double-hung windows.
Energy performance: compare ratings, not the style name
Neither “single-hung” nor “double-hung” is an energy-efficiency rating. The U.S. Department of Energy’s Federal Energy Management Program says fenestration savings vary by climate. Compare the actual product’s certified U-factor and solar heat gain coefficient (SHGC), as well as its frame, glazing, air sealing, and installation. ENERGY STAR explains that a lower U-factor means better insulation, while a lower SHGC blocks more solar heat; which balance is desirable depends on climate. Check the ENERGY STAR product guidance and current certified product listings when choosing.
Rank #2
- Complete Set: Each purchase includes 4 sets of white window sash locks with 16 screws, meeting your replacement and security needs
- Durable Material: Made from high-quality alloy with a corrosion-resistant coating, these locks are designed for long-lasting use and are resistant to wear and damage
- Universal Compatibility: The sash lock mounting holes are spaced 2.4 inches apart, making them suitable for most sliding windows and doors, whether vertical or horizontal
- Easy Installation: Simply drill holes with a 3mm drill bit and secure the lock with the provided screws for a quick and straightforward installation process
- Versatile Application: Designed for use with wood, aluminum, and vinyl window frames, these sash locks work well on both single and double sliding windows, enhancing the security of your home or office
ENERGY STAR’s guidance lists typical window ranges of 0.10–0.60 for U-factor and 0.15–0.60 for SHGC. These are broad typical ranges, not targets for every home or climate. FEMP’s December 2021 guidance, using 2020 dollars and modeled assumptions, said ENERGY STAR-qualified residential windows save money if priced no more than $2 per square foot above less-efficient models, and that best-available models save up to $4 per square foot. Those figures are not current retail-price guarantees or a direct comparison of hung-window styles. See FEMP’s window guidance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which style fits your project?
| Decision | Single-hung | Double-hung | What to verify |
|---|---|---|---|
| Sash operation | Lower sash moves; upper sash is fixed. | Both sashes move. | Confirm the configuration on the specific model. |
| Ventilation | Air passes through the lower opening. | You can open the upper sash, lower sash, or both, depending on the product. | Consider whether the room benefits from two opening positions. |
| Cleaning access | Upper sash may require exterior access; tilt options vary. | Both sashes may tilt for indoor cleaning. | Check tilt-in or tilt-wash features for the exact series and material. |
| Relative cost | Generally lower within a comparable product line. | Generally higher within that line. | Compare the same dimensions, materials, glass package, finish, and installation scope; no general dollar difference is established. |
| Energy performance | Not determined by style alone. | Not determined by style alone. | Compare certified U-factor and SHGC for your climate, along with air sealing and installation. |
Choose double-hung if an upper opening or easier indoor cleaning is useful, and confirm the model’s tilt hardware if cleaning access is a deciding factor. Single-hung may suit a project where one opening is enough and a lower relative price or simpler operation is preferred.
Quick Recap
Best Value
- Ideal Use: Replaces worn, loose, or missing sash locks on single- and double-hung vinyl windows to restore security and proper operation
- Dimensions & Compatibility: Fits windows with flush-mounted meeting rails and 2-1/16 in. mounting hole centers on both the lock and keeper
- Materials & Components: Durable diecast zinc construction with a white-painted finish; includes one lock, one keeper, and mounting fasteners
- Key Features: Cam-action design pulls the sash and keeper together for a tighter seal, improved insulation, and reduced drafts
- Fit Guidance: Designed for compatible vinyl window systems and is not universal; verify dimensions and hole spacing before purchasing
Rank #4
- You Will Receive: 10 pcs F 2590 replacement sash locks and 20 pcs self-tapping screws, providing everything needed for convenient installation and multiple window latch replacement projects
- Premium Material: The F 2590 windows replacement sash lock made of high-quality alloy with corrosion-resistant painted coating, offering strong durability, reliable performance, and long-lasting use
- Secure Locking Function: Our window locks designed to firmly pull window sashes together, helping reduce window movement, improve sealing, and enhance overall home security
- Easy Installation: Designed with 2-1/4" mounting hole centers for quick alignment and simple installation, allowing easy replacement of old or broken window sash locks without special tools
- Versatile Window Compatibility: This F 2590 sash lock fits single‑hung, double‑hung vertical sliding windows and some horizontal aluminum sliding window frames, ideal for multiple household window replacement scenarios
Rank #3
- WINDOW SASH LOCK – This window sash lock includes one cam-action latch with fasteners and can be used on a variety of aluminum-framed sliding windows. The lock does not use a separate keeper, instead, the latch engages into the fixed rail to lock the window.
- REPLACEMENT PART – Use this window sash lock to replace old or broken window locks to maintain security in your home.
- EASY INSTALLATION – Installation is quick and easy, and the sash lock can be used on vertical, single and double hung aluminum sliding windows. These locks will also fit some horizontal, aluminum-framed sliding windows.
- DURABLE – Made of diecast zinc with a white painted finish, this sash lock is strong, durable and made to last.
- SIZING - This sash lock has 2-1/4” mounting hole centers with a 3/8” latch projection that engages into the fixed rail of the top sash.
What to check before replacing windows
- Confirm opening dimensions and the proposed installation method.
- Compare frame and glazing options and the product’s certified ratings for your climate.
- Check for drafts, deteriorated sills or sashes, or windows that no longer open—conditions ENERGY STAR identifies as possible reasons to consider replacement. See ENERGY STAR’s replacement guidance.
- If the home was built before 1978, discuss precautions for possible lead paint with the installer before replacement work begins; see the same ENERGY STAR guidance.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
