What Is Krypton Gas?

 

Krypton is a colourless and odourless noble gas with the chemical symbol Kr and atomic number 36. It occurs naturally in very small quantities in the atmosphere and is chemically unreactive under ordinary conditions.

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Its low thermal conductivity makes it useful as an insulating gas within sealed glazing units.

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The gas is enclosed between the panes during manufacture and cannot be seen or detected by the homeowner. The product specification or manufacturer’s documentation should confirm whether a unit contains argon, krypton or another gas.

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How Does Krypton Double Glazing Work?

 

A sealed double glazed unit contains two panes separated by a spacer bar. The cavity between them is filled with dry air or an insulating gas.

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Gas filling reduces heat transfer across the space between the warm internal pane and the colder external pane. Low-emissivity glass works alongside the gas by reducing radiant heat transfer through the unit.

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A typical high-performance krypton unit may include:

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• Two or three panes of glass

• One or more low-e coatings

• Krypton-filled cavities

• Warm-edge spacer bars

• Insulated perimeter seals

• A thermally efficient frame

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The complete combination determines the window’s performance rather than the gas alone.

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Krypton Versus Argon Double Glazing

 

Argon remains the standard choice for most domestic double glazing because it offers a practical balance of availability, thermal performance and cost.

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Krypton has better insulating properties within narrower spaces. Pilkington identifies krypton as particularly beneficial where the space between panes is limited, while Lawrence Berkeley National Laboratory reports that its optimum cavity thickness is approximately 6mm.

 

Argon usually performs more effectively in wider conventional cavities.

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This makes krypton particularly useful in:

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• Narrow-cavity double glazing

• Slim heritage-style units

• Triple glazing with two restricted cavities

• Frames with limited glazing depth

• Specialist high-performance windows

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A standard double glazed window with a conventional cavity may gain less practical benefit from krypton, particularly when compared with its additional cost.

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Krypton-Filled Triple Glazing

 

Triple glazing contains three panes and two separate cavities.

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Where the overall thickness of the window is limited, each cavity may be too narrow for argon to perform at its best. Krypton can provide stronger insulation within these reduced spaces.

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Research by Lawrence Berkeley National Laboratory shows that switching from argon to krypton in carefully designed narrow-cavity triple glazing can produce a substantial improvement in insulating performance.

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However, the result depends on:

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• The width of both cavities

• The gas-fill percentage

• The number and position of low-e coatings

• The glass thickness

• The spacer system

• The frame

• The size and opening style of the window

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Simply describing a window as krypton-filled does not provide enough information to judge its overall performance.

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Krypton-Filled Windows and Low-E Glass

 

Krypton controls conductive and convective heat movement within the cavity. Low-e glass reduces radiant heat transfer.

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For this reason, krypton gas-filled windows normally combine the gas with one or more low-emissivity coatings. Gas filling alone cannot compensate for an inefficient frame or basic glass specification.

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When comparing products, ask for:

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• The whole-window U-value

• The centre-pane Ug-value

• The recognised Window Energy Rating

• The low-e glass specification

• The krypton-fill percentage

• The width of each cavity

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A whole-window figure is more useful than a centre-pane result because it includes the thermal effect of the glazing and surrounding frame.

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Are Krypton Windows More Energy Efficient?

 

A correctly designed krypton unit can achieve better thermal performance than a comparable argon unit where the cavities are narrow.

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However, krypton does not guarantee that one complete window will outperform another. A well-designed argon-filled window with better low-e glass, an insulated frame and careful installation may perform more effectively than a poorly specified krypton window.

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Pilkington confirms that insulating-glass performance can be improved through a combination of low-e coatings, argon or krypton gas, triple glazing and warm-edge spacer technology.

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The supplier should therefore provide certified figures for the exact product being offered rather than relying on a general description of the gas.

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Are Krypton-Filled Units Worth the Cost?

 

Krypton is more expensive than argon, so it is generally used where the design requires its particular performance advantages. Lawrence Berkeley National Laboratory notes that krypton can be the best option for small glazing gaps but is more costly.

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The additional expense may be justified where:

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• A very low U-value is required

• Triple glazing must fit within a restricted frame depth

• Heritage frames require slimmer sealed units

• The property is being upgraded to a demanding energy standard

• Reducing the overall unit thickness is important

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For an ordinary replacement-window project, argon-filled low-e double glazing may provide better value.

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Ask the installer to show the actual improvement in U-value and energy rating before paying extra for krypton.

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Are Krypton-Filled Windows Widely Available?

 

Krypton glazing is available, but it is less common than argon-filled double glazing.

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Major glass manufacturers recognise krypton as an insulating-glass option, particularly for restricted cavity widths and high-performance units. However, not every fabricator or installer routinely supplies it.

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Before ordering, confirm:

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• That the quoted manufacturer can produce the required units

• The expected krypton-fill level

• The unit thickness

• The delivery period

• The replacement-unit availability

• The sealed-unit guarantee

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This can be especially important for unusually sized or specialist windows.

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Does Krypton Improve Sound Insulation?

 

Krypton is principally selected to improve thermal insulation. It should not be treated as an acoustic upgrade on its own.

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Noise reduction is more dependent on glass thickness, using panes of different thicknesses, acoustic laminated glass, cavity design, frame seals and installation quality.

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Where reducing outside noise is important, request a tested acoustic specification rather than choosing windows solely because they contain krypton.

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What Happens If the Sealed Unit Fails?

 

Krypton must remain enclosed within a properly manufactured sealed unit.

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If the perimeter seal fails, insulating gas can gradually escape and moisture may enter between the panes. Visible misting or condensation within the unit is a common indication that the seal has broken down.

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A failed unit can normally be replaced while retaining the existing frame, provided the frame remains in good condition.

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Check whether the guarantee covers:

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• Failure of the sealed unit

• Condensation between the panes

• Replacement glass

• Labour and installation

• The length of cover

• Transfer to a new homeowner

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The paperwork should also identify the original glazing specification so that any later replacement can be matched correctly.

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Questions to Ask Before Choosing Krypton Gas Double Glazing

 

Before accepting a quotation, ask:

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• Why is krypton being recommended?

• What cavity width is proposed?

• Is the unit double or triple glazed?

• What krypton-fill percentage is specified?

• Which low-e glass is included?

• What is the centre-pane Ug-value?

• What is the complete window U-value?

• How does it compare with the argon alternative?

• What additional cost does krypton add?

• Which guarantees cover the sealed unit?

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The quotation should contain clear product details rather than simply referring to premium or energy-efficient glazing.

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Find Suitable Krypton-Filled Windows

 

Krypton-filled units can provide excellent insulation where narrow glazing cavities or demanding thermal targets make conventional argon units less suitable. For most homes, however, krypton should be considered as part of the complete window specification rather than an essential upgrade.

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APN Double Glazing can connect homeowners with experienced local installers who can compare argon, krypton, double glazing and high-performance triple glazing.

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Get in touch for expert advice and a free, no-obligation quote for energy-efficient replacement windows.