Do you still have single glazing in your home? Then you lose a lot of heat through your windows. Single glazing feels cold, causes condensation more quickly and often gives an unpleasant draft feeling. Fortunately, you can replace single glazing in various ways, without always having to install new frames immediately.
The short rule: usually replace single glazing with HR++ glass if your window frames are suitable. Does HR++ glass not fit? Then vacuum glass is often a good alternative. Are you installing new window frames? Then you can also consider triple glass. In this article we explain what options you have, what you should pay attention to and when which glass fits best.
Why replace single glazing?
Single glazing consists of one pane of glass. As a result, it hardly retains heat. In winter, the inside of the glass becomes cold and heat quickly escapes to the outside. You often notice single glazing:
- cold windows
- draft feeling
- high heating costs
- condensation on the inside
- wet windowsills
- cold trap at large windows
- outside noise
- little comfort at the window
The difference after replacement can be significant, especially in living rooms, bedrooms and kitchens. The room feels warmer, even if the thermostat is not set higher.
What can you install instead of single glazing?
There are several options to replace single glazing. Which one is best depends on your frame, budget, insulation needs and the appearance you want to maintain. If you want to keep single glass, for example in an interior door or behind an installation, you can order it as clear float glass to size or installation glass to size.
| Option | When interesting? |
|---|---|
| HR++ glass | Most often chosen for existing window frames |
| Vacuum glass | For narrow or old window frames |
| Triple glass | With new window frames |
| Monument glass | For characteristic or monumental buildings |
| Laminated insulating glass | When safety is also important |
| Insulating glass with grille | If additional ventilation is required |
Rule of thumb: HR++ glass is the default choice. Vacuum glass is the alternative if HR++ does not fit. You should especially consider triple glazing with new window frames.
Option 1: replace single glass with HR++ glass
HR++ glass is the most practical choice for many homes. It insulates much better than single glazing and often fits into existing window frames, sometimes with adapted glazing beads. HR++ glass consists of two panes of glass with an insulating cavity between them. That cavity usually contains argon gas. The glass also has a coating that reflects heat back in.
Advantages of HR++ glass:
- good insulation
- more affordable than triple glass or vacuum glass
- often suitable for existing window frames
- a lot of comfort gain
- less cold
- less condensation on the inside
- possible subsidy
- widely applicable
HR++ glass is especially suitable if your existing window frames are still good and have sufficient space for thicker glass. Want to know more? Read what exactly HR++ glass is or assemble your window directly at compose insulating glass.
Does HR++ glass fit in every frame?
No. HR++ glass is much thicker than single glass. Single glass is often 4 to 6 mm thick, HR++ glass is usually about 24 to 28 mm thick. That's why you need to check whether the frame has enough space. NB:
- rebate depth
- space for glazing tape
- space for glazing beads
- kit room
- condition of the wood
- weight of the window
- hinges on rotating windows
- ventilation of the frame
With wooden frames, covering slats or nose slats can sometimes help to place HR++ glass neatly. With plastic and aluminum frames you are more dependent on the existing profile. Are you unsure whether thicker glass will fit? Read thicker insulating glass in an existing frame.
Option 2: replace single glass with vacuum glass
Vacuum glass is a good option when HR++ glass is too thick for your existing frame. It is much thinner than HR++ glass, but still insulates very well. Vacuum glass consists of two sheets of glass with a very thin vacuum space between them. Because there is almost no air between the glass plates, heat loss is greatly reduced.
Vacuum glass is especially interesting for:
- old wooden frames
- narrow rebates
- monumental buildings
- characteristic houses
- window frames that you want to keep
- situations where HR++ glass does not fit
- renovations while maintaining appearance
The disadvantage is that vacuum glass is usually more expensive than HR++ glass. Still, it can be interesting if it means you don't have to install new window frames. View the vacuum glass range or read the comparison vacuum glass versus HR++ glass.
Option 3: replace single glazing with triple glazing
Triple glazing consists of three glass plates and two insulating cavities. It insulates very well, but is thick and heavy. Triple glazing is especially interesting when you also install new window frames. Then you can immediately choose frames that are suitable for thicker and heavier glass.
Triple glass is suitable for:
- new construction
- new window frames
- complete renovation
- very well insulated homes
- homes with low temperature heating
- maximum energy performance
Triple glazing is often less practical in existing old window frames. It is usually too thick and heavy. Read when triple glazing is and is not useful or put it together at composing triple glazing.
Option 4: replace single glass with monumental glass
With monumental or characteristic homes you sometimes want to preserve the old appearance. Standard HR++ glass may then be too thick or not match the appearance of the building. Monument glass or thin insulating glass can be a solution.
This is interesting for:
- monumental buildings
- historic window frames
- stained glass
- old wooden windows
- protected cityscape
- homes where the appearance is important
Vacuum glass is also often considered for monumental window frames, because it is thin and yet insulates well. Always check which rules apply to monuments before replacing glass.
Option 5: replace single glass with laminated insulating glass
Sometimes you not only want to insulate better, but also improve safety. For example, with windows that start low to the floor or glass next to doors. Then you can opt for insulating glass with a laminated glass plate. Laminated glass consists of two layers of glass with foil in between. If broken, shards stick to the foil, making it safer than regular glass. Toughened glass is also possible as a safe glass plate in the superstructure.
Laminated insulating glass is wise for:
- low windows
- windows to the floor
- side lights next to doors
- front doors
- children's rooms
- glass along stairs
- situations with a risk of falling through
Please note: HR++ glass is not automatically safety glass. Safety must be selected separately in the glass structure. View the safety glass or read the difference between tempered and laminated glass.
Option 6: replace single glazing with ventilation grille
If you replace single glazing with better insulating glass, your home will become more dense. That is good for heat loss, but moisture must still be able to escape. A ventilation grille can therefore be wise. Ventilation grilles are especially useful in:
- bedrooms
- living rooms
- kitchens
- bathrooms with window
- rooms with condensation problems
A grille is usually placed above the glass, which lowers the window. When measuring, you must take the glass deduction from the grille into account. So think about ventilation before ordering; adding a schedule afterwards is usually not easy. View the ventilation grilles or read how a ventilation grille in glass works.
Replace single glass without replacing frame
In many cases you can replace single glazing without installing new window frames. This is often cheaper and less drastic than complete frame replacement. This is possible when:
- the frame is still good
- there is no wood rot
- the rebate can be adjusted
- the glass technically fits
- the window can support the extra weight
- glazing beads can be replaced
There are often more options available with wooden frames than with plastic or aluminum frames; wood can be adjusted more easily. However, you should always check carefully whether the frame is suitable. A bad frame with new glass remains a weak spot.
When should you replace the frame?
Sometimes just replacing glass is not enough. New window frames are wiser when the existing window frame is bad, rotten or technically unsuitable. Frame replacement is often better for:
- wood rot
- poor gap sealing
- sagging rotating parts
- too little rebate depth
- weak hinges
- poor insulation value of the frame
- old aluminum frames without thermal break
- complete renovation
- wish for triple glazing
Are you installing new window frames? Then you can immediately choose HR++ glass, triple glass or vacuum glass, depending on your insulation purpose.
How much difference do you notice after replacement?
The difference between single glazing and modern insulating glass is often large. Especially in winter, you will immediately notice that the glass feels less cold. You may notice:
- less draft feeling
- less cold
- less condensation
- warmer glass surface
- more comfortable room
- less noise from outside
- lower heat demand
With large windows or glass that you sit close to, the comfort difference is extra clear. Curious about the insulation value of your new glass? Calculate it with the U-value calculator.
Does new glass help against condensation?
Yes, better insulating glass often helps against condensation on the inside. The inner window remains warmer, so moisture precipitates less quickly. But condensation is not only caused by bad glass. Ventilation also plays a major role. Condensation on the inside can be caused by:
- cooking
- shower
- wash dry
- too little ventilation
- high humidity
- cold bridges
- insufficient heating
New glass helps, but good ventilation remains important. Condensation on the outside of HR++ glass or vacuum glass is usually not a problem; that is often a sign that the glass insulates well. You can read more about this in condensation on windows: inside, outside or between the glass.
Is replacing single glazing good for sound?
New insulating glass can reduce noise, but not every insulating glass is automatically sound-resistant. Do you especially want less noise from outside? Then please note:
- glass thicknesses
- asymmetrical glass structure
- laminated glass
- special sound foil
- gap sealing
- frame quality
- ventilation grilles
A standard HR++ window can provide an improvement compared to single glazing, but special sound-resistant glass is sometimes better when dealing with traffic noise.
Can you get a subsidy?
You may be able to receive a subsidy for replacing single glazing with HR++ glass, triple glazing or vacuum glass. Conditions apply. NB:
- the glass must meet insulation requirements
- you need to replace enough square meters
- the installation must be done professionally
- you need an invoice
- you need proof of payment
- a reporting code is often required
- you must apply within the correct period
Do you want to apply for a subsidy? Then have it checked in advance whether the chosen glass meets the conditions. Read the details in ISDE subsidy for insulating glass.
How do you measure single glazing for replacement?
Don't just measure the old window. It is better to measure the rebate of the frame. The old window may have been installed incorrectly or too small.
- Where possible, remove a glazing bead or check the rebate.
- Measure the width in three places.
- Measure the height in three places.
- Use the smallest size.
- Subtract the appropriate placement clearance.
- Check the rebate depth.
- Check which glass thickness fits.
- Record everything in millimeters.
For standard glass in a frame, you often subtract 8 mm from the width and height. You must apply an additional glass deduction for ventilation grilles. An extensive manual can be found in measuring glass.
What happens during installation?
When replacing single glazing, the old glass is usually removed first. The frame is then prepared for new insulating glass. Assembly often goes like this:
- Remove old glazing beads or putty.
- Carefully remove the single glass.
- Clean the frame.
- Repair wood rot or damage.
- Check whether the rebate is suitable.
- Place glazing tape and glass blocks.
- Install new glass.
- Install glazing beads.
- Seal with suitable glazing sealant.
- Checking connection and drainage.
You can order materials such as glazing beads, glazing blocks, glazing tape and sealant from glass articles.
With HR++ glass, vacuum glass and triple glass, good placement is important for lifespan and insulation value.
Can you replace single glazing yourself?
Replacing a small single window is technically possible for handy handymen. But replacing single glass with insulating glass is more difficult. NB:
- insulating glass is heavier
- the size must be exactly correct
- the frame must be able to be adjusted
- incorrect placement can cause leaking glass
- glazing must be placed tension-free
- subsidies usually only apply to professional installation
Do you want to apply for a subsidy? The glass must then usually be installed by a construction or installation company. Installing it yourself is usually not an option.
Common mistakes when replacing single glazing
- Thinking that HR++ glass always fits — HR++ glass is much thicker than single glass; always check the rebate depth.
- Measure the old window only — Measure the rebate of the frame, not just the old glass.
- Leave bad frames in place — New glass in a bad frame still causes problems.
- Forgetting Ventilation — Better insulation without ventilation can cause condensation and mold.
- Do not choose safety glass in high-risk areas — Low windows and glass next to doors often require safety glass.
- Want to install triple glazing in old window frames — Triple glazing is usually too thick and too heavy for old window frames.
- Check subsidy conditions too late — Do you want a subsidy? Check in advance whether the glass and mounting are satisfactory.
Selection aid: which glass do you choose?
| Situation | Best choice |
|---|---|
| Existing frame with enough space | HR++ glass |
| Old wooden frame with little space | Vacuum glass |
| Monumental house | Vacuum glass or monument glass |
| New window frames | Consider triple glazing |
| Low window or door | Laminated insulating glass |
| Lots of condensation | HR++ glass + ventilation |
| Lots of noise | Soundproof insulating glass |
| Limited budget | HR++ glass |
| Maximum insulation | Triple or vacuum glass |
Checklist before replacing single glazing
- Is the frame still in good condition?
- Is there wood rot?
- How deep is the rebate?
- Does HR++ glass fit?
- Could vacuum glass be better?
- Are you installing new window frames?
- Is safety glass necessary?
- Do you want ventilation grilles?
- Do you want to apply for a subsidy?
- Is it professionally installed?
- Have glass thickness and weight been checked?
- Are the dimensions recorded in millimeters?
- Has the old sealant or putty been completely removed?
- Is the ventilation in the house sufficient?
Conclusion
Replacing single glazing is one of the most noticeable improvements to your home. You lose less heat, experience less cold and get more comfort at the window. For many existing homes, HR++ glass is the best choice, as long as the frame has enough space and is in good condition. Does HR++ glass not fit? Then vacuum glass is often a good alternative, especially for old or narrow window frames. Are you installing new window frames or completely renovating? Then you can consider triple glazing.
When choosing, don't just pay attention to insulation. Also check rebate depth, glass thickness, weight, ventilation, safety glass and subsidy conditions.
Read more or get started right away? View the insulating glass range, compare vacuum glass with HR++ glass or read how to replace double glazing. Ready to order? Compose your window with custom glass.