Renovate or Replace Windows: How to Decide Correctly

January 5, 2023
  1. Condensation or chicken skin
  2. Reasons for a window renovation
  3. Reasons for a window replacement
  4. The five main advantages of new windows
  5. How much do new windows cost?
  6. Are there subsidies for new windows?
  7. Window know-how: The right frame
  8. Window know-how: The right glass
  9. Window know-how: Special case skylights
  10. Window know-how: Energy-saving potential

Windows have a lifespan of 20 to 50 years: Plastic or metal windows (30 to 50 years) last longer than wooden windows (20 to 40 years), but they require more frequent maintenance. Insulating glazing lasts 25 years. If you don't know how old the windows in your house or apartment are, find out with a simple test. Hold a lit candle up to the window and look closely at the pane:

  • If you see 3 flames, the window is triple-paned and no more than 15 years old. The glass and frame should still be in good shape.
  • If you see 2 flames, the window is double glazed and probably 15 to 30 years old. The frame should be in good shape, the glass should probably be replaced.
  • If you see 1 flame, the window is single glazed and probably 30 to 50 years old. The frame might still be in good shape, the glass would definitely need to be replaced.

Condensation or chicken skin

If, despite the candle test, you are unsure how old the windows in your house or apartment are, there are other clues as to whether or not they are still tight:

  • Condensation on the inside of windows is not uncommon, especially in the winter, but could be dangerous if the humidity is consistently too high. Mold feels right at home in damp wooden window frames, endangering your family's health in addition to the structure of the building.
  • Do you heat, but still freeze or shiver? It is possible that the heat escapes uncontrolled to the outside. Ask a window maker to check the windows with a thermal imaging camera for possible weak points. Where the thermal image of the camera turns red, heat is escaping.

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Reasons for a window renovation

You do not have to replace double-glazed windows or triple-glazed windows just because a moving part has failed to withstand the load. It is often worthwhile to have such damage professionally repaired by a window maker. For example, if a hinge is broken or the hardware needs to be replaced. It is also worth replacing window handles, rubber seals or hinge covers. If the damage is more extensive, window replacement often makes more sense than window renovation. Especially in the case of non-insulation glazed windows. Often, spare parts such as hardware or hinges are no longer available for such old windows.

Reasons for a window replacement

There are three reasons for window replacement besides energy saving potential: frame breakage, glass breakage and leakage.

  • Frame breakage: Smaller chipping can be repaired by any good window maker. However, if the window frame is cracked to the core or even broken, you will have to have the entire window sash (frame and glass) replaced.
  • Glass breakage: Theoretically, glass can be replaced. Double and triple glazed insulated windows are never as tight after replacement as they were before. Besides, glazing with installation costs more than a new window. Therefore, in case of glass breakage, the whole window sash is usually replaced.
  • Leakage: If you discover condensation between the panes, the window frame is leaking. Replacing only the rubber seal between the frame and the panes is rarely enough. Therefore, in case of leakage, you should have the whole window sash replaced.

Houzy Advice

Good to know

If you replace only one window in a house that is not yet insulated, for example in the living room, the window could become a cold bridge because it insulates better than the facade.

Houzy Hint


If you replace all the windows in a non-insulated house, the risk of mold increases. That's why replacing windows is the best time to think about energy renovation. It avoids heat loss, saves energy costs and pays for itself quickly.

Window maker sets windows
New windows reduce energy consumption, improve the indoor climate and protect against burglary or noise.

The five main advantages of new windows

New windows have many advantages. These are the five most important advantages, sorted alphabetically:

  • Burglary protection: New windows offer more resistance than old windows. Therefore, pay attention to the resistance class. For a window of resistance class RC2 a burglar needs only simple tools and three minutes time, for a window of resistance class RC3 he needs additional lever tools and already five minutes time.
  • Energy consumption: Replacing windows is a simple but effective way to reduce energy consumption, minimize CO2 emissions and optimize energy efficiency. With double instead of triple glazed windows you improve the thermal insulation value by about 80 percent to 0.5 to 0.6 watts per square meter Kelvin.
  • Indoor climate: Regular ventilation improves the indoor climate. Alternatively, there are windows with self-regulating ventilation systems or electronically controlled fans that optimize air exchange. If you have recently replaced your windows, you can retrofit them with a ventilation system with adjustable air vents.
  • Soundproofing: Triple-glazed windows provide better protection against noise than double-glazed windows. If you're sensitive to noise, don't sleep very deeply or live on a busy street, consider soundproof windows. They protect against noise up to 85 percent better than double-glazed windows.
  • Value retention: New windows enhance the value of your house or apartment. Many prospective buyers are willing to pay more if a property is more energy-efficient, safely protected and all rooms look more homely thanks to more daylight. In addition, windows with colored frames or narrow profiles change the image of the house.

How much do new windows cost?

The cost depends on the frame material, window size and glazing. Good window makers charge 100 to 120 Swiss francs an hour. Expect to pay 600 to 1,000 Swiss francs or more (including installation) for a triple-glazed insulating window:

  • Plastic from 600 Swiss francs
  • Wood from 850 Swiss francs
  • Plastic and aluminum from 850 Swiss francs
  • Aluminum from 1,000 Swiss francs
  • Wood and aluminum from 1,000 Swiss francs

A double-glazed window costs about 100 Swiss francs less. If you want to make a rough estimate of the cost, count on 350 to 500 Swiss francs per square meter of window area for double-glazed windows and 400 to 600 Swiss francs per square meter of window area for triple-glazed windows. Options such as tilt and turn hardware, better soundproofing or safety glass will cost extra, as will the time it takes to get there and back. On the other hand, the cost of professional disposal of the old windows is usually included in the price of window replacement.

Houzy Advice

Good to know

Windows with one sash cost less than windows with two sashes, simple casement windows are cheaper than windows with turn or tilt fittings.

Are there subsidies for new windows?

No. If only the windows are renovated in a non-insulated house, the humidity rises and collects as moisture in the masonry instead of as condensation on the window. This creates mold, which threatens the fabric of the building. This is why the subsidy programs generally only finance window replacement as part of overall energy renovations (see measures M-10 to M-15 in the harmonized subsidy model of the cantons from 2015 - available only in German).

Replace windows - wood-aluminum frame
Windows made of wood and aluminum cost more than wooden or plastic windows, but they last longer and are cheaper to maintain.

Window know-how: The right frame

Aluminum, wood or plastic? The decision depends on your budget, taste and house. The materials are equal in terms of burglary protection, energy consumption, indoor climate and sound insulation. Thus, the materials for window frames differ:

  • Wood windows last 20 to 40 years and should be maintained every 10 years. Wood is a renewable resource and therefore has the best environmental balance. On the other hand, wooden frames require more maintenance, especially on the outside. Their surfaces can be painted with RAL or NCS colors or glazed according to the color chart.
  • Plastic windows last from 30 to 50 years and should be maintained every 6 to 8 years. They are inexpensive and are reinforced with galvanized steel reinforcement in the frame and sash and can be painted or foiled. Opt for recyclable polyvinyl chloride (PVC) if you choose plastic.
  • Wood-aluminum and vinyl-aluminum windows are technically up-to-date and easy to maintain. Their surfaces and aluminum shells can be painted with RAL and NCS colors or according to color chart. They cost more than pure wood or plastic frames, but they last longer and are cheaper to maintain.

Window know-how: The right glass

The choice of windows is simple. Since the late 2000s, all windows in Switzerland have been triple-glazed as standard. They reduce the heat transfer of the gas in the spaces between the panes, therefore have a higher thermal insulation value (U-value) of 0.5 to 0.6 watts and insulate just as well as a solidly insulated wall. Triple-glazed windows insulate about 80 percent better than double-glazed windows, which were standard until the late 2000s. That's why new windows are a simple, effective and comparatively inexpensive measure to improve the energy efficiency of older houses or apartments.

Houzy Advice

Good to know

Minergie windows are more energy-efficient than other windows because the space between the three panes is filled with inert gases and therefore no heat can escape. The higher energy efficiency compensates for the additional costs comparatively quickly.

Window know-how: Special case skylights

Skylights are more stressed than other windows because they are more exposed to wind and weather. That's why they only last about 25 years and should be serviced every 6 to 8 years. You should also check them thoroughly at least once a year for cracks and damage to the frame, rotted wood frames, gaps between frame components, fogged windows, and brittle or missing seals. If you have the facade and roof insulated, you should also replace the skylight(s) so that the whole building envelope is perfectly insulated from the point of view of building physics.


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Window know-how: Energy-saving potential

Many homeowners replace windows to improve energy efficiency and save money on the bottom line. A window renovation with insulating windows of energy efficiency class A has an energy saving potential of 5 to 10 percent. If you enlarge the windows on the sunny side, you optimize the energy balance because you gain more energy thanks to the larger area of sunlight than you lose through heat loss. If the house or apartment has not yet been renovated for energy efficiency, you should think about it before replacing the windows. Thanks to new windows, a new heating system and better exterior insulation, you can save up to 60 instead of 5 to 10 percent energy. Use our energy calculator to check the energy efficiency class of your house or apartment, simulate the impact of energy renovations, analyze the savings potential and calculate the investment costs, taking into account any subsidies.

Talk to a professional if you are unsure whether to renovate or replace windows. In our strong partner network, you will find certified window makers from your region whom we recommend to you with a clear conscience. They will also advise you on energy-related issues.

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