What does insulated glass cost and what should you look out for?

1. Construction of double glazing

Double glazing consists of:

• Two panes of glass made of standard float glass (usually 4 mm thick)
• An air gap of approx. 6 to 12 mm between the panes of glass
• Aluminium spacer bar (often visible as a thin edge profile)
• Desiccant in the spacer bar to prevent condensation

Unlike HR glass, double glazing does not contain a heat-reflective coating or gas filling. As a result, the insulation value is limited.

2. Insulation value (U-value)

Conclusion: double glazing insulates much better than single glazing, but much worse than HR++ or HR+++ glass. Therefore, it no longer meets modern energy requirements.

3. Features of Insulating Glass

4. When to replace double glazing?

Replacement is recommended for:

• Condensation between the glass panes (leaky pane)
• Draft or cold complaints with windows
• Improving the sustainability of the home
• No HR quality mark visible on the spacer

Modern HR++ panes usually fit into existing rebates of double glazing, allowing for quick replacement without major structural modifications.

5. Costs and savings on replacement

* Depending on energy prices and home type. When using ISDE subsidy, the payback period is significantly reduced.

6. Subsidy for replacing double glazing

When replacing double glazing with HR++ or HR+++ glass, ISDE subsidy is possible, provided that:

• A minimum of 8 m² (HR++) or 6 m² (HR+++) is replaced
• The measure is combined with a second insulation measure
• Carried out by a recognized glazing company

Subsidy amounts:

• HR++ glass: approx. €23 per m²
• HR+++ glass: approx. €65 per m²

A quote via jeofferte.nl automatically takes this into account.

Summary

Thermopane is the classic form of double glazing, with limited insulation value and without modern techniques such as coating or gas filling. Although it was once an improvement over single glazing, it no longer meets the energy requirements for home improvement today. Replacement with HR++ glass provides noticeable energy savings, higher comfort, and lower heating costs. Via jeofferte.nl, you will quickly receive quotes for professional replacement, including advice on subsidies and execution.

1. Price per m² double glazing (2025)

The price depends on the thickness of the glass, dimensions, accessibility of the frame, and complexity of the installation. Small jobs are relatively more expensive due to fixed call-out fees and minimum labor costs.

2. Total price per housing type (indication)

These indications include delivery, dismantling and removal of old glass, assembly and finishing. Additional costs may apply for difficult accessibility or non-standard shapes.

3. Price breakdown double glazing

For homes older than 2 years, the reduced VAT rate of 9% on labor is applied, making the price more favorable.

4. Comparison with HR++ glass

Thermopane is cheaper, but insulates considerably less effectively. This means that the energy savings are limited, and the payback period is longer in practice than with HR++ glass.

5. Energy Saving and Payback Period

Thermopane glass therefore only offers a limited advantage over single glazing and is no longer recognized for subsidy schemes such as the ISDE.

6. Summary

• Double glazing will cost on average between €40 and €70 per m² in 2025, including installation and VAT.
• For a complete house, the total costs will be between €1,800 and €7,000, depending on the glass surface area and house type.
• The insulating value of double glazing is limited (U-value approx. 2.8 W/m²K) and is amply surpassed by HR++ glass.
• Double glazing is suitable for limited budgets, but has a long payback period and is not eligible for subsidies.
• For those who want to make their homes more sustainable with a return on investment, HR++ or HR+++ glass is usually a better long-term investment.

Via jeofferte.nl you can easily compare quotes from recognized glass companies for both double glazing and HR++ glass, with a clear price structure and professional advice.

1. Total costs per home type (HR++ glass)

* Subsidy based on the ISDE scheme when combined with a second insulation measure (such as floor, roof, or cavity wall insulation) and installation by a recognized professional company.

2. What is included in these prices?

• On-site measurement
• Custom HR++ glass (4-15-4, argon filling, coating)
• Removal and disposal of old glass
• Installation with finishing and sealing
• VAT (21% on materials, 9% on labor for homes ≥ 2 years old)
• Travel costs within the service area

3. Possible additional charges

A recognized glass company will only charge these items after assessment. Via jeofferte.nl, quotes are standardly specified on these points.

4. Cost example: corner house with 16 m² HR++ glass

• HR++ glass average: €135 per m²
• 16 m² × €135 = €2,160 total
• Subsidy (16 m² × €23) = €368
• Net investment: approx. €1,792
• Annual savings on gas: approx. €250 – €300
• Payback period: 6 – 8 years (depending on energy price)

Summary

The total costs for glass replacement in a home range on average between €750 and €4,100, depending on the home type and glass surface area. Thanks to subsidies (ISDE) and the reduced VAT rate on labor, the net investment can be considerably lower. Via jeofferte.nl, you can compare quotes from certified glass companies free of charge, including installation, finishing, and support with subsidy applications. This way, you know exactly where you stand.

1. Standard Price structure for glass replacement

A complete glass quote consists of several components. Below is an example of the price distribution for a standard HR++ glass installation:

For homes older than 2 years, the reduced VAT rate of 9% applies to the labor portion, while materials fall under 21%.

2. Key price-determining factors

The final price is influenced by a number of technical and practical factors:

1. Glass type and composition

More layers, films or coatings increase production costs and therefore the price per m².

2. Dimensions and shape

• Standard rectangular panes are cheaper than panes with deviating shapes (round, oblique, trapezoidal).
• Large panes entail higher costs due to heavier materials, handling and transport.
• Small orders (e.g. 1 pane of 0.5 m²) are relatively expensive due to fixed start-up costs (€100 – €150 minimum rate).

3. Assembly conditions

4. Urgency and special planning

• Emergency replacement (within 24 hours): surcharge of 10% to 25%
• Emergency provision (plexiglass or temporary closure): €150 – €300 extra
• Weekend or evening placement: €50 – €125 surcharge

5. Number of panes and scale

The more panes that are placed at the same time, the lower the cost per m²:

3. Subsidy and tax advantage

The gross offer price can be reduced by using schemes such as:

ISDE subsidy (only for HR++ or HR+++ glass)

Reduced VAT rate

• 9% VAT on labor costs for homes older than 2 years
• Is automatically applied in recognized glass offers

4. Example: Price structure for 12 m² HR++ glass (terraced house)

Summary

1. What are storm windows?

A storm window is an additional pane of glass that is installed on the inside or outside of an existing window, with an airtight air gap in between. The effect is comparable to double glazing: heat loss is limited, noise is reduced, and the glass surface feels less cold.

There are both fixed storm windows and removable variants, depending on the use and installation situation.

2. When are secondary glazing units suitable?

Secondary glazing units are particularly interesting in the following situations:

• Monuments or historic buildings where original windows must be preserved
• Wooden frames with a limited profile where HR++ does not fit
• Rental properties or temporary use
• Budget constraints: lower investment than full glass replacement
• Need for noise reduction in urban areas or near railways

They are generally not suitable for situations where safety glass or fire resistance is required.

3. Types of secondary glazing

Glass in secondary glazing is usually single glazing (float glass or safety glass), sometimes also acrylic (plexiglass) for lightweight or temporary applications.

4. Insulation value and performance

Secondary glazing does not provide the same insulation value as HR++ glass, but it is a big step forward compared to single glazing.

5. Cost indication for secondary glazing (incl. VAT and installation)

The costs depend on the type of frame, material (glass or plexiglass), mounting technique, and accessibility.

6. Advantages and disadvantages

Advantages:

• No intervention in original frames (suitable for monuments)
• Fast installation, even in occupied situations
• Sound reduction in addition to thermal insulation
• Lower cost than glass replacement
• Seasonal use possible (removable variants)

Disadvantages:

• Limited insulation value compared to HR++ or HR+++ glass
• Visually less sleek when placed on the inside
• No subsidy possible via ISDE
• Regular maintenance required when placed outside

7. Combination with other measures

Storm windows can be part of a broader insulation package, especially in situations where traditional glass replacement is not possible. Consider, for example:

• Internal wall insulation for monuments
• Draft excluders and gap sealing
• Floor insulation or roof insulation as a supplement to preserving windows

Summary

Secondary glazing is a practical and affordable alternative to glass replacement in specific situations, such as for monuments, temporary solutions, or frames where HR++ glass does not fit. The investment is lower than for full glass replacement, but the insulation value is also more limited. There are no subsidies available for secondary glazing, but they can contribute to improved comfort, sound insulation, and lower heating costs. Via jeofferte.nl, you can also compare providers who supply secondary glazing, including custom advice and installation, if desired.

1. What is the difference between thermopane and HR++ glass?

Thermopane is classic double glazing with an air gap, without coating or gas filling.
HR++ glass has an insulating coating and a cavity filled with noble gas (often argon), making it significantly better at insulating.

2. Can I get a subsidy for double glazing?

No, double glazing is not eligible for ISDE subsidies.
Only HR++ and HR+++ glass is recognised by the government as sufficiently insulating to receive a subsidy, provided it is installed by a recognised glazing company and combined with a second insulation measure.

3. Is thermopane glass still available?

Yes, thermopane is still available and is occasionally used for:

• Smaller projects with a limited budget
• Windows in unheated spaces (shed, storage room)
• Replacement in existing wooden frames that cannot accommodate HR++

For living spaces and energy-efficient applications, HR++ or better is always recommended.

4. When is thermopane glass due for replacement?

Replacement is recommended in case of:

• Condensation between the glass panes (leaky window)
• Outdated seal or leakage
• Drafts or heat loss at the window
• Improving the sustainability of the home (e.g., when improving the energy label)

Most thermopane panes have a lifespan of approx. 20–30 years.

5. How do I recognize double glazing in my home?

• Two layers of glass with an aluminum edge (spacer)
• No indication such as “HR”, “HR+” or “HR++” on the edge
• No colorful reflection in the glass
• Possible indication “Thermopane” on the edge (older types)

If in doubt, a glass company can easily check this for you.

6. What does it cost to have double glazing installed?

The average price in 2025 is between €40 and €70 per m², including installation and VAT.
For a complete terraced house with approx. 20 m² of double glazing, you will pay approximately €2,500 – €2,800, depending on accessibility and the shape of the panes.

7. How much can I save by replacing double glazing with HR++ glass?

When replacing 20 m² of double glazing with HR++ glass, you save on average:

• Gas savings: approx. 130 m³ per year
• Cost savings: approx. €150 – €200 per year
• Payback period: approx. 7 – 9 years, shorter with subsidies

8. Does the entire window need to be replaced if I want to renew the glass?

No, in most cases only the glass can be replaced.
As long as the frame is still in good condition, replacing the glass is sufficient (provided the rebate is deep enough for HR++ or HR+++ glass). For outdated frames or limited space, replacing the entire window may be necessary.

9. Is thermopane glass safe enough for doors or low windows?

No, not always. In situations where there is a risk of injury (such as doors, floor-level windows, or stairwells), safety glass is mandatory according to the NEN 3569 standard. This means:

• Laminated glass or
• Tempered glass

A glass company will include this in the quote as part of the structural requirements.

10. Is it more advantageous to have multiple panes replaced at the same time?

Yes. The larger the project, the lower the average price per m².
For 1 small pane, fixed costs are relatively high (start-up, transport), whereas for 10–20 m², the price per m² decreases. A combined request via jeofferte.nl often leads to lower rates per pane.

Summary

Thermopane glass is still available, but no longer meets current insulation standards. When replacing, HR++ or HR+++ glass is almost always chosen due to better efficiency, available subsidies, and higher insulation value. Do you have questions about your specific situation? Via jeofferte.nl, you can compare quotes from accredited glass companies without obligation, with a clear price structure and tailored technical advice.

1. Recognizing double glazing in existing homes

Many homes built between approximately 1975 and 1995 are standardly equipped with double glazing. You can recognize double glazing by:

• Two layers of glass with an air gap, without visible coating or film
• Aluminum spacer without HR marking (like “HR++”)
• No heat-reflective sheen in backlight
• Sometimes recognizable by the imprint “Thermopane” on the edge

If the glass shows condensation between the glass layers, it is a leaky pane – which necessitates replacement.

2. Why double glazing is often replaced

Although double glazing is an insulation step up from single glazing, there are reasons to replace this type of glass:

• Limited insulation: U-value of approx. 2.8 no longer meets modern requirements
• No subsidy possible: No ISDE subsidy for replacement or installation
• Old glass seal aged: Leaks and cracked panes are common
• Savings when replacing with HR++: More comfort and lower heating costs
• Increase in property value: Better energy label score and sales position

When replacing glass as part of sustainability efforts, thermopane is therefore rarely the best option.

3. Applications where thermopane is still used

As of 2025, thermopane glass is still occasionally used in situations such as:

• Simple interior doors or storage windows where insulation value is less important
• Replacement in existing window frames where HR++ is technically not suitable
• Budget-driven projects with minimal investment space
• Temporary solutions or rental properties without renovation plans

For permanent application in living spaces, HR++ or better is generally recommended.

4. Important when replacing: standards and safety

When replacing double glazing with another type of glass, the current structural requirements and safety standards must also be taken into account:

A recognized glass company is aware of this and will include it in the quote.

5. Combination with frame renovation or painting

When planning frame replacement or exterior painting, it is logical to simultaneously replace outdated double glazing with HR++ or HR+++ glass. This offers:

• Less work afterwards (one-time scaffolding setup)
• Better airtightness and insulation
• Aesthetic upgrade of the frame
• More efficient installation (existing glass does not need to be removed separately)

Especially with wooden frames older than 25 years, a combined approach is often more cost-effective.

6. Subsidy only when replacing with HR++ or HR+++ glass

As previously indicated, double glazing is not eligible for a subsidy, but:

• Replacing double glazing with HR++ is eligible for subsidies, provided that:
• A minimum of 8 m² is replaced
• It is combined with a second insulation measure
• The work is carried out by a certified company

The ISDE subsidy then amounts to approximately €23 per m² of HR++ glass.

Summary

Thermopane glass is an outdated type of glass that is still found in older homes but no longer meets modern insulation requirements. Replacing it with HR++ glass provides immediate benefits in terms of energy, comfort, property value, and subsidy options. When choosing to replace glass, it is important to also consider safety standards, the structural condition of the frames, and whether or not to combine it with other renovation work. A quote through jeofferte.nl gives you transparent insight into all costs, technical possibilities, and subsidy rights – fully tailored to your home.