Replacing your windows is one of the more significant home improvements you can make, and it is entirely natural to run your hand across the new glass and wonder whether it should feel quite so cold. Many UK homeowners are surprised to find that their brand-new double or triple glazed windows still feel noticeably cool in winter, even after spending thousands of pounds on an upgrade.
New double or triple glazed windows feeling cool to the touch in a UK winter is generally normal and does not indicate a fault. Even a top-rated A-rated double glazed unit with a U-value of around 1.4 W/m²K will have an inner glass surface a few degrees below room temperature on a cold day, because glass conducts heat and no window eliminates this entirely. The key warning signs of a genuine problem are condensation between the panes, draughts around the frame, or frost forming on the inner surface, all of which should be reported to your installer and resolved under warranty at no cost to you. If you are concerned, ask your installer to confirm the U-value specification in writing and check that you have received a FENSA or CERTASS certificate, which is a legal requirement for replacement window installations in England and Wales.
- A cool inner glass surface in winter is normal even in A-rated double or triple glazed windows, as glass conducts heat and no window eliminates heat transfer entirely
- Check for condensation between the panes, frost on the inner glass surface, or draughts around the frame, as these are genuine faults your installer must fix under warranty
- Ask your installer for the U-value of your new windows — A-rated double glazing should achieve around 1.4 W/m²K or lower, and triple glazing around 0.8 W/m²K
- Contact your installer in writing within the warranty period if you suspect a failed sealed unit, as most reputable UK companies offer at least a 10-year guarantee on sealed units
- Use a draught detector or a lit incense stick near the frame edges to check for air infiltration, which is a clear sign of poor installation rather than normal glass conductance
- If you paid for triple glazing and suspect you received double glazing, request written confirmation of the specification from your installer and check the unit edge spacer bar
- Report any concerns to FENSA or CERTASS if your installer is unresponsive, as these are the main competent person schemes covering window installations in England and Wales
- Understanding Why Windows Feel Cold to the Touch
- Is It Normal for New Windows to Feel Cold
- The Main Reasons New Windows Feel Cold
- Frame Materials and How They Affect Surface Temperature
- Condensation, Cold Glass, and What Each Tells You
- How to Tell If Your New Windows Are Underperforming
- What to Look For When Choosing High-Performance Windows
- Verifying Your Installer's Credentials and Guarantees
- Simple Steps to Improve Comfort Around Cold Windows
New double or triple glazed windows feeling cool to the touch is generally normal and does not automatically indicate a fault or poor installation. Even a high-performance A-rated window will have an inner glass surface temperature several degrees below room temperature on a cold day, because glass conducts heat and no window eliminates heat transfer entirely. However, certain warning signs — condensation between the panes, draughts around the frame, or frost on the inner surface — do indicate a genuine problem that your installer should address under warranty.
This guide walks you through exactly what is normal, what is not, and how to tell the difference — so you can make informed decisions rather than spending weeks worrying about something that is working exactly as it should.
Understanding Why Windows Feel Cold to the Touch
The surface temperature of glass and the temperature of the air in your room are two very different things, and understanding this distinction is the foundation of diagnosing any window concern correctly.
Glass is a thermal conductor, meaning it allows heat to pass through it more readily than materials like brick or insulated plasterboard. Even when a window is performing well, the inner surface of the glass will be cooler than the surrounding wall on a cold day, simply because the outside air is constantly drawing heat through the pane. The question is not whether the glass feels cool — it almost certainly will in a British winter — but whether it feels excessively cold, and whether that coldness is accompanied by other symptoms.
Thermal transmittance, commonly referred to as the U-value, is the standard measurement used to describe how easily heat passes through a window. A lower U-value means less heat escapes, which means better performance. Current UK Building Regulations Part L require a whole-window U-value of 1.2 W/m²K or below for replacement windows in England. A single-glazed window, by contrast, typically has a U-value of around 5.0 W/m²K — so the glass on old windows would have felt genuinely cold, not just slightly cool.
It is also important to assess the glass and the frame separately. The glass pane itself feels cold for different reasons than the frame does, and each requires a different diagnosis. A uPVC frame might feel relatively warm while the glass feels cool, or an aluminium frame might feel colder than the glass on the same window.
Some degree of coolness on the inner glass surface is physically unavoidable even in a well-performing window. The key question is whether the coldness is excessive, disproportionate to the weather conditions, or accompanied by draughts, condensation between the panes, or genuine discomfort when sitting nearby.
Practical tip — if you are concerned about your window’s performance, note the outdoor temperature when you do your check. A glass surface feeling cool when it is 2°C outside is very different from the same glass feeling bitterly cold on a mild autumn day.
Is It Normal for New Windows to Feel Cold
Yes — it is completely normal for new double or triple glazed windows to feel noticeably cooler than the surrounding wall, particularly during winter months, and this does not automatically indicate a fault with the window or its installation.
A well-fitted, A-rated double glazed window will still have an inner glass surface temperature that is several degrees lower than the room air temperature when it is cold outside. This is not a defect; it is simply the physics of how glass behaves. What has changed compared to your old windows is that the difference is much smaller than it used to be, and the draught and bone-chilling cold associated with poorly performing single or aged double glazing should be gone.
Triple glazed units, which typically achieve a whole-window U-value of around 0.8 to 1.0 W/m²K for the glass unit, will generally feel warmer to the touch than standard double glazing on the same cold day. However, even triple glazing will not feel warm in the way a solid wall does — it will simply feel less cold than double glazing, which in turn should feel much less cold than single glazing.
The following are the key warning signs that suggest something is genuinely wrong rather than normal behaviour:
- Visible condensation or misting between the panes of glass (not on the surface)
- A draught you can feel when holding your hand near the frame or glass
- Frost or ice forming on the inner surface of the glass in cold weather
- The window feeling as cold as your old single-glazed units did
- Cold air noticeably radiating from the frame perimeter rather than the glass centre
If none of those signs are present, the chances are high that your windows are performing as they should and you are simply adjusting to a new normal that, while improved, still involves some degree of surface cooling.
Practical tip — compare how the glass felt last winter with your old windows versus now. If the room is warmer, your energy bills are lower, and you are not feeling draughts, your new windows are almost certainly doing their job.
The Main Reasons New Windows Feel Cold
Several distinct factors contribute to cold-feeling windows, and identifying which one applies to your situation helps you decide whether to take action or simply adjust your expectations.
Thermal Bridging Through the Frame
A thermal bridge is a point in a building’s fabric where heat bypasses the insulation layer and escapes more rapidly — in the context of windows, this most commonly occurs where the frame meets the wall reveal, and where the spacer bar connects the two panes of glass. Different frame materials conduct heat at very different rates. Aluminium is a strong conductor, meaning heat moves through it quickly, which is why even thermally broken aluminium frames can feel noticeably cold at the edges on a winter day. uPVC and timber are considerably better insulators and will generally feel warmer to the touch.
Low-Emissivity Glass Coating Performance
Low-emissivity glass, commonly called Low-E glass, has a microscopic metallic coating that reflects long-wave infrared heat back into the room rather than allowing it to escape through the glass. This is what makes modern double glazing significantly more effective than older units. However, the glass still absorbs some cold from outside on very cold days. Soft-coat Low-E glass, applied using a magnetron-sputtering process, typically offers superior performance to older hard-coat versions and should be standard in windows installed today.
Gas Fill Degradation in the Sealed Unit
Modern double and triple glazed units are filled with argon or krypton gas between the panes, rather than simply air. These inert gases conduct heat less readily than air, which improves the U-value of the unit. If the hermetic seal of the unit has failed — due to a manufacturing defect or poor installation — the gas leaks out and is replaced by ordinary air or, worse, moist air. A unit that has lost its gas fill will perform significantly worse and feel noticeably colder. This is a fault that should be addressed under warranty.
Incorrect Installation Leaving Gaps or Poor Sealing
Even a perfectly specified window can underperform if it is not installed correctly. If insulating foam, packers, or draught seals were not properly fitted between the frame and the wall reveal, cold air infiltration around the frame can make the entire window area feel far colder than the glazing specification would suggest. This kind of cold tends to concentrate around the frame perimeter rather than across the centre of the glass, which can help distinguish it from a glazing unit fault.
Practical tip — if the cold feeling is concentrated around the frame edges rather than across the glass, installation quality rather than glazing performance is the more likely culprit. Request a visit from your installer to inspect the perimeter sealing.
Frame Materials and How They Affect Surface Temperature
The material your window frame is made from has a significant influence on how cold it feels to the touch, independent of the glazing unit itself. This is worth understanding both when choosing windows and when diagnosing a concern after installation.
| Frame Material | Thermal Conductivity | Typical Feel in Winter | Key Consideration |
|---|---|---|---|
| uPVC | Low | Slightly cool but not cold | Multi-chambered profiles outperform basic ones |
| Aluminium (standard) | Very high | Very cold | Not suitable for thermal performance without a break |
| Aluminium (thermally broken) | Reduced by break | Cold at edges, less so at centre | Better than standard but still cooler than uPVC |
| Timber | Low | Warmest of all frame types | Gaps or poor maintenance negate the advantage |
| Composite (timber core) | Low to medium | Generally warm | Performance depends on timber core thickness and quality |
uPVC frames are the most common choice in UK homes and perform well from a thermal perspective. uPVC is a relatively poor conductor of heat, which means frames do not typically feel as cold as the glass they hold. Multi-chambered uPVC profiles — those with multiple hollow sections within the frame — perform measurably better than basic single-chamber designs because the trapped air within each chamber adds insulation.
Aluminium frames are popular for their slim sightlines and modern aesthetics, but aluminium is one of the most thermally conductive metals used in construction. Even with a thermal break — a strip of low-conductivity material inserted within the aluminium profile — these frames will feel considerably colder than uPVC or timber on a cold winter day. This is not a defect specific to your installation; it is an inherent property of the material, and it is worth knowing before purchase rather than discovering after.
Timber frames offer the best natural insulation of any common frame material. Wood is a poor conductor of heat and timber frames typically feel the warmest to the touch. However, gaps at the joints, failed sealant, or poor maintenance can create cold spots and air infiltration that negate this natural advantage entirely.
Composite frames, which combine a timber core with uPVC or aluminium outer cladding, generally perform well for surface temperature. The thermal performance depends heavily on the thickness and quality of the timber core — a generous core will feel considerably warmer than a thin one surrounded by a substantial aluminium outer skin.
Practical tip — if you are planning a new window purchase and surface warmth matters to you, specify uPVC or timber frames and ask your installer about the number of chambers in the uPVC profile. More chambers generally means better thermal performance at the frame.
Condensation, Cold Glass, and What Each Tells You
Condensation on or around windows is one of the most common concerns UK homeowners raise, and the location of the condensation tells you almost everything you need to know about whether there is a problem.
External Condensation on the Outside Pane
Condensation forming on the outside surface of your new windows — particularly on clear, cold mornings — is actually a positive sign. It means the outer pane is cold because very little heat is escaping through the window from inside your home. The warm, moist outdoor air contacts the cold glass and deposits moisture on it, exactly as it does on cold car windscreens on damp mornings. This is a clear indicator that your window is performing well thermally. Homeowners sometimes find this counterintuitive, but external condensation is something to feel reassured by, not concerned about. why new windows get condensation on the outside explained
Internal Condensation on the Room-Facing Surface
Condensation forming on the inner surface of the glass — the side facing into the room — suggests the glass surface temperature is dropping below the dew point of the indoor air. The dew point is the temperature at which air can no longer hold all of its moisture and begins depositing it as water. This can indicate poor glazing performance, but it can equally indicate very high indoor humidity — for example in kitchens, bathrooms, or poorly ventilated rooms with many occupants. Before concluding the window is at fault, consider whether improving ventilation would resolve the issue. condensation on windows causes and solutions UK
Condensation Between the Panes
Condensation or misting visible between the two panes of a double glazed unit is always a fault and should never be treated as normal. It means the hermetic seal of the insulating glass unit (IGU) — the sealed assembly of two or three panes with gas between them — has failed. Once the seal fails, the inert gas escapes and moist air enters the space between the panes. The glass will feel noticeably colder, the misting cannot be wiped away from either surface, and the unit’s thermal performance will be significantly degraded. Contact your installer immediately and reference your warranty documentation, as this constitutes a manufacturing or installation defect.
Frost on the Inner Surface
Frost or ice forming on the inner surface of a window is a serious performance failure. In a window sold as double or triple glazed, this should not happen under normal UK winter conditions. If you observe this, contact your installer immediately and reference your FENSA or CERTASS installation certificate. what to do if your new windows are not working properly
Practical tip — take a photograph with a timestamp if you observe condensation between the panes or frost on the inner surface. This documentation will support any warranty claim you need to make.
How to Tell If Your New Windows Are Underperforming
If you are not sure whether your windows are performing as they should, there are several straightforward checks you can carry out yourself before involving your installer.
- Check your FENSA or CERTASS certificate — all replacement windows installed by a registered company in England and Wales must be self-certified under a competent person scheme. Your certificate confirms the installation meets Building Regulations and specifies the U-value compliance. If your installer has not provided this document, request it immediately — you are legally entitled to it and it confirms the specification you paid for.
- Request the window energy rating or U-value data — windows in the UK are rated A++ to E by the British Fenestration Rating Council (BFRC), which is the independent body responsible for assessing and certifying window energy performance. An A-rated window should deliver measurable energy savings compared to older double glazing. If your installer cannot supply BFRC rating documentation or a whole-window U-value figure, that is a red flag worth pursuing.
- Conduct the hand test — hold your hand 2 to 3 centimetres from the inner glass surface on a cold day. You should not be able to feel a draught or a stream of cold air. If you do, air infiltration is occurring around the frame or through a failed seal, and the installation should be formally inspected.
- Use an infrared thermometer — non-contact infrared thermometers are widely available for under £20 and allow you to measure surface temperatures without touching anything. On a cold day, measure the centre of the glass, the edge of the glass near the spacer bar, the frame, and the surrounding wall. A significant temperature drop from the glass centre to the glass edge can indicate a poor-quality or damaged spacer bar, which is a thermal bridge that reduces the effective U-value of the unit.
- Compare with a known reference point — if one window feels markedly colder than another of the same type and specification in the same house, this is a strong indicator that the colder one has a problem specific to that unit or its installation, rather than simply being normal behaviour for the product.
Practical tip — write down the readings from your infrared thermometer measurements before contacting your installer. Specific figures are far more useful than descriptions like “it feels cold” when making a warranty claim or requesting an inspection.
What to Look For When Choosing High-Performance Windows
If you are still in the planning stage or considering replacing windows that are underperforming, the following steps will help you specify windows that genuinely deliver on thermal comfort as well as energy savings.
- Ask for the whole-window U-value, not just the glass unit U-value — the centre-of-glass U-value will always look more impressive than the whole-window figure, because it excludes the frame and the edge of the glass near the spacer. Always ask specifically for the whole-window U-value and confirm it meets or betters the 1.2 W/m²K Building Regulations requirement for England.
- Look for the BFRC energy label — an A or A+ rating from the British Fenestration Rating Council indicates the window has been independently assessed and its performance figures verified. Installers who cannot provide BFRC-rated products or equivalent third-party documentation should be viewed with caution.
- Ask about the spacer bar — the bar that separates the two panes of glass at the edge of the unit is a significant thermal bridge. Standard aluminium spacer bars conduct heat readily and cause cold edges. Warm-edge spacer bars, made from polymer, foam, or stainless steel rather than standard aluminium, significantly reduce this thermal bridge, lower the risk of edge condensation, and improve the overall U-value of the unit. Always specify warm-edge spacer bars.
- Specify soft-coat Low-E glass — confirm that the glazing includes a soft-coat Low-E layer. Soft-coat, also known as magnetron-sputtered coating, is applied in a vacuum and typically offers superior thermal performance to older hard-coat Low-E glass. It is more fragile and must be protected within the sealed unit, but this is standard practice for all reputable manufacturers.
- Consider triple glazing for cold rooms or exposed elevations — if you have a north-facing room, a room above an uninsulated garage, or a property in Scotland or another colder region, triple glazing is worth considering. It typically achieves a whole-window U-value of around 0.8 to 1.0 W/m²K and will feel noticeably warmer to the touch than double glazing in cold conditions. The additional cost is roughly 20 to 30 per cent above equivalent double glazing. triple glazing vs double glazing is it worth it UK
- Verify installer accreditation — only use FENSA or CERTASS-registered installers for replacement windows in England and Wales. In Scotland, ensure compliance with Section 6 of the Scottish Building Standards. You can verify FENSA registration at fensa.org.uk and CERTASS registration at certass.co.uk.
| Window Type | Typical Whole-Window U-value | Approximate Cost (3-bed semi, all windows) | Inner Glass Feel in Winter |
|---|---|---|---|
| Standard double glazing (argon, basic Low-E) | 1.4 to 1.6 W/m²K | £3,500 to £6,500 | Noticeably cool |
| A-rated double glazing (argon, soft-coat Low-E, warm-edge) | 1.0 to 1.2 W/m²K | £4,500 to £8,000 | Cool but significantly less than above |
| Triple glazing (argon or krypton, soft-coat Low-E, warm-edge) | 0.8 to 1.0 W/m²K | £6,000 to £11,000 | Mildly cool, warmer than double glazing |
| Old single glazing (for reference) | 4.8 to 5.8 W/m²K | Not applicable | Very cold, often with draught |
Practical tip — always get at least three quotes and ask each installer to specify exactly the same product in writing so you are comparing like with like. Cost variations between quotes often reflect differences in glazing specification rather than simply profit margin.
Verifying Your Installer’s Credentials and Guarantees
Knowing who to turn to if something goes wrong is just as important as understanding what the problem is. The UK has clear schemes in place for this, and using them protects you legally and financially.
FENSA and CERTASS
FENSA (Fenestration Self-Assessment Scheme) and CERTASS are the two government-authorised competent person schemes for replacement glazing in England and Wales. A registered installer self-certifies that the work meets Building Regulations, eliminating the need for a separate local authority building control inspection. After installation, you should receive a certificate that is registered with the scheme. This certificate is important when you sell your home, as solicitors will request evidence of Building Regulations compliance for any replacement windows fitted. Verify your installer’s registration at fensa.org.uk before work begins.
TrustMark
TrustMark is the government-endorsed quality scheme covering home improvement tradespeople, including window installers. TrustMark registration means the business has been assessed for technical competence, customer service, and trading practices. It does not replace FENSA or CERTASS compliance for glazing, but it provides an additional layer of consumer protection, particularly for dispute resolution. Look for the TrustMark logo on installer websites and verify registration at trustmark.org.uk.
Warranty and Guarantee Coverage
Reputable window installers offer guarantees on both the glazing units and the installation workmanship, typically ranging from 5 to 10 years on sealed units and similar periods on frames and hardware. If a sealed unit fails within the guarantee period — evidenced by condensation between the panes, significant cold spots, or visible damage — you are entitled to a replacement unit at no cost. Keep your installation paperwork, including the FENSA or CERTASS certificate, the installer’s written guarantee, and any product specification documents, in a safe place from day one. window installer guarantees and warranties what UK homeowners need to know
Escalating a Complaint
If your installer is unresponsive to a warranty claim, both FENSA and CERTASS offer dispute resolution services for their registered members. You can also contact TrustMark if the installer is registered with the scheme. For larger financial disputes that cannot be resolved directly, the Consumer Rights Act 2015 provides a legal basis for claiming that goods or services were not of satisfactory quality or fit for purpose — which is relevant if windows were sold with a specific U-value specification that they are demonstrably not achieving.
Practical tip — do not sign off completion of an installation on the day of fitting if you have not received your FENSA or CERTASS certificate number and written guarantee documentation. Reputable installers will provide these without hesitation.
Simple Steps to Improve Comfort Around Cold Windows
Even well-performing windows can create a sense of cold in a room, because cool glass radiates cold to the surrounding air — a phenomenon known as radiant cooling, where the body loses heat to a cold surface even without direct contact. There are practical steps you can take to reduce the discomfort associated with this, without compromising ventilation or the window’s performance.
Fitting well-lined curtains or thermal blinds that reach the floor and sit close to the glass creates an insulating air gap between the cold surface and the room. This can make a noticeable difference to perceived warmth in a bedroom or living room on cold nights. However, closing curtains over radiators placed under windows traps heat behind the curtain and reduces its effectiveness — ideally, position a sofa or seating away from large window walls if radiant cold is a concern.
Ensuring your home is adequately ventilated — particularly in kitchens and bathrooms — reduces indoor humidity, which in turn reduces the likelihood of condensation forming on the coolest surfaces in the room, including glass. Trickle ventilators on window frames should be left open, not taped shut, even in winter. Modern windows are designed to work with background ventilation, not against it. window ventilation trickle vents should you keep them open
According to the Energy Saving Trust, draught-proofing gaps around window frames and ensuring good quality seals are maintained can contribute meaningfully to both comfort and energy efficiency in a home. If you can feel air movement around your window frames, this is a relatively quick and inexpensive fix that can be addressed with draught-proofing strips before considering whether the installation itself needs attention.
Practical tip — if your new windows came with trickle ventilators and you have closed them to reduce cold air, consider whether this is contributing to condensation in the room. The small amount of ventilation they provide is designed to manage moisture, not significantly reduce room temperature.
In summary, cool-feeling new windows are almost always normal rather than problematic, and the sensation typically reflects the genuine physics of glass in a cold climate rather than a fault in the product or installation. The signs that matter — misting between the panes, draughts, frost on the inner surface, and glass that feels as cold as your old single glazing — are specific and relatively easy to identify. If you see none of those signs, the most useful thing you can do is compare your energy bills, check your room temperatures, and allow yourself to recognise that your new windows are, in all likelihood, doing exactly what they were specified to do.
Frequently Asked Questions
is it normal for new double glazing to feel cold inside in winter UK?
Yes, it is entirely normal for new double glazed windows to feel cool to the touch on the inner surface during a British winter. A well-performing A-rated double glazed unit typically achieves a centre-pane U-value of around 1.4 W/m²K, which still allows some heat loss and means the inner glass can be several degrees below room temperature. The glass only becomes a concern if you notice draughts, condensation between the panes, or frost forming on the inner surface.
why is my new triple glazing still cold to touch?
Triple glazed windows significantly reduce heat loss compared to double glazing, but the inner glass surface will still feel cool rather than warm on a very cold day. A quality triple glazed unit should achieve a U-value of around 0.8 W/m²K, meaning the inner surface temperature will be much closer to room temperature than older windows, but not identical to it. If your triple glazing feels as cold as your old single glazing did, request the unit specification in writing and ask your installer to carry out a thermal assessment.
condensation between double glazed panes on new windows what should I do?
Condensation between the panes means the sealed unit has failed and the inert gas fill, usually argon, has been lost, allowing moisture to enter the cavity. This is a manufacturing or installation fault and is covered under your installer's sealed unit warranty, which reputable UK companies typically offer for 10 years. Contact your installer in writing immediately and request a replacement sealed unit at no cost, keeping a record of all correspondence in case you need to escalate to FENSA or CERTASS.
how do I know if my new windows were installed correctly UK?
A correctly installed window should have no detectable draughts around the frame, no cold spots concentrated at the edges rather than across the centre of the glass, and should come with a FENSA or CERTASS certificate issued automatically after installation. You can test for draughts using a lit incense stick or a draught detector moved slowly around the frame perimeter. If your installer has not provided a competency scheme certificate, contact FENSA or CERTASS directly, as failing to register a replacement window installation in England and Wales is a breach of Building Regulations.
can I get a refund or free repair if my new windows are faulty UK?
Under the Consumer Rights Act 2015, goods must be of satisfactory quality and fit for purpose, meaning a faulty sealed unit or poor installation within six years of purchase gives you the right to a repair, replacement, or partial refund. Most UK window companies also offer separate installer workmanship guarantees of two to five years and sealed unit guarantees of up to ten years. If your installer refuses to act, you can escalate to their trade association, such as the Glass and Glazing Federation, or pursue a claim through the small claims court for disputes under £10,000.
