High quality energy efficient windows

Ever-increasing energy costs make thermal insulation more and more important for building owners.
Modern energy saving windows save up to 40 % on energy costs!

Heat loss from windows, balcony doors and patio doors

Windows can lose heat in a number of ways, starting with the area between the frame and the masonry or wall. Proper installation is one of the decisive factors here.

Reasons for heat loss

  • Poor installation
  • Inadequate glazing and insulation
  • Incorrect profiles

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Heat loss from windows, balcony doors and patio doors

The most popular materials for energy saving windows

The 3 most important energy saving factors

energy saving factor material and profile

Material & Profile

Choose energy efficient materials & profiles for the frame and focus on thermal insulation and energy efficiency. Especially vinyl windows, aluclad vinyl windows and wood-aluminum windows have an advantage here.

energy saving factor glazing


Reduce your energy costs with a triple insulating glazing. The advantages are lower energy costs, a better ecological balance and a better heat distribution in the room, plus the triple glass is offering a high sound insulation.

energy saving factor thermal edge seal

Thermal edge seal

Triple glazing in particular benefits from an effective edge seal (also known as a warm edge), which helps the window to insulate and reduces energy loss to a minimum. We are offering for our windows the best and most modern warm edge spacer, offered by Swisspacer, Alupro, Technoform, Fenzi and Lisec.

The most popular energy saving windows at a glance

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FAQ energy-saving windows

How does energy-efficient glazing work?

Energy-efficient glazing works by reducing the amount of temperature transfer between the inside and outside of a building through the windows. This is achieved through various techniques and technologies such as:

  • Double or triple glazing: This involves using two or three panes of glass with a gap of air or gas (usually argon or krypton) between them. The gap between the panes creates an insulating barrier that reduces the amount of heat transferred through the window.
  • Low-emissivity (low-e) coatings: These coatings are applied to the surface of the glass and reflect heat back into the room while allowing light to pass through. This reduces heat loss through the window and keeps the room warmer.
  • Warm edge spacers: These are used to separate the glass panes in a double or triple glazed window. The spacer is made of materials that are less conductive than traditional aluminium spacers, reducing heat loss through the edge of the window.
  • Gas fills: In double or triple glazed windows, argon or krypton gas is used to fill the gap between the panes. These gases are less conductive than air, reducing heat transfer through the window.

What is the warm edge?

A warm edge spacer is a component in a double or triple glazed window that separates the glass panes and maintains the spacing between them. The spacer is usually made of a material that has low thermal conductivity, which reduces the amount of heat lost through the edge of the window.

The name "warm edge" comes from the fact that the spacer reduces the temperature difference between the edge of the glass and the surrounding environment. This reduces the risk of condensation forming on the inside of the window, which can lead to issues such as mold and rot.

Warm edge spacers, are made of materials such as thermoplastic or silicone foam, which have lower thermal conductivity and improve the overall energy efficiency of the window.In addition to improving energy efficiency and reducing condensation, warm edge spacers can also improve the durability of the window. By reducing the stress on the glass caused by temperature changes, they can help to prevent cracks and other types of damage.

How is energy efficiency in windows measured?

Energy efficiency windows are measured using several different metrics, which help to quantify the amount of heat lost or gained through the window. Some of the most common metrics used to measure energy efficiency in windows include:

  • U-value: This measures the rate of heat transfer through the window, expressed in watts per square meter per degree Celsius (W/m²K). A lower U-value indicates better insulation and less heat loss.
  • Solar Heat Gain Coefficient (SHGC): This measures the amount of solar radiation that passes through the window and enters the building. It is expressed as a percentage, with higher numbers indicating more solar heat gain.
  • Visible Transmittance (VT): This measures the amount of visible light that passes through the window and enters the building. It is expressed as a percentage, with higher numbers indicating more light transmission.
  • Energy Star Rating: This is a certification system developed by the U.S. Environmental Protection Agency (EPA) to help consumers identify energy-efficient products. Energy Star rated windows meet specific energy efficiency criteria, including U-value, SHGC, and air leakage.

By measuring these metrics, homeowners and builders can compare the energy efficiency of different windows and make informed decisions about which windows to use in their building projects.

How much can be saved on energy costs with modern windows?

The amount of energy cost savings that can be achieved with modern windows depends on several factors, including the type of window, the size of the window, the climate, and the energy costs in the local area. However, in general, upgrading to energy-efficient windows can result in significant energy cost savings for homeowners and building owners.

Replacing single-pane windows with energy-efficient windows can result in energy cost savings up to - 40 % per year for a typical single-family home. The savings will depend on the climate zone and the specific characteristics of the windows, but these estimates give an idea of the potential savings.

Upgrading to energy-efficient windows can also increase the value of the property. Home-buyers are increasingly interested in energy-efficient features, and properties with energy-efficient windows and other features may command higher prices on the real estate market.

Overall, the energy cost savings that can be achieved with modern windows will depend on a range of factors, but in general, upgrading to energy-efficient windows is likely to provide significant financial and environmental benefits.

How much do energy saving windows cost?

The cost of energy-saving windows can vary depending on several factors, including the type of window, the size of the window, the features of the window, and the installation costs. In general, energy-saving windows are more expensive than traditional windows, but the cost can be offset by the energy cost savings and other benefits over time.

When considering the cost of energy-efficient windows, it's important to also factor in the potential energy cost savings. While the exact amount of savings will depend on a range of factors, such as the local energy costs, the climate, and the specific features of the windows, energy-efficient windows can result in significant energy cost savings over time. In addition, energy-efficient windows can provide other benefits, such as increased comfort, improved indoor air quality, and increased property value.

Overall, while energy-efficient windows may be more expensive upfront than traditional windows, the long-term financial and environmental benefits make them a smart investment for many homeowners and building owners. It's important to carefully research the options and choose windows that provide the best combination of energy efficiency, durability, and affordability for your specific needs.

Which windows are suitable for passive house?

Passive house windows are an important component of passive house design, as they play a critical role in reducing energy consumption and maintaining indoor comfort. Passive house windows are designed to meet strict energy efficiency standards, with a focus on minimizing heat loss and maximizing solar gain. Here are some of the types of windows that are suitable for passive house construction.

Most of the windows and doors that Neuffer is offering can achieve Passive House Values requirements by using energy efficient glass, high insulation profiles and modern materials. We also have profiles that have already passed the Passive House Institute test, and are certified as Passive House Components:

  • Energeto 8000
  • Energeto 8000 ED
  • TwinSet Enegreto 8000 ED
  • Eco Idealu
  • Eco Plano

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How does Energy Efficient Glazing work?

The largest portion of any window is the glass surface. Therefore, it has the greatest potential for both loss and savings. Historically, windows featured only a single pane of glass and energy could easily move from one side to the other. The area near windows was usually cold compared to the other side of the room and the panes themselves were cold to the touch.

Then came double glazing and today triple glazing. Using multiple panes of glass creates an insulating gap, often filled with an inert gas such as argon. The additional panes and air gaps serve to trap heat inside and prevent energy from moving from the inside to the outside.

Gas fillings such as argon, krypton and xenon are less conductive than air, meaning it is even harder for heat to move through it.

Double-glazed windows may be sufficient for mild climates but triple-glazed is increasingly the norm.

Finally, sealing the insulated glass units with warm edge spacers is critical to ensure that the gas does not escape and no moisture enters. The spacer is also made of thermally optimized material which helps prevent energy from moving from pane to pane via the spacer.

Low-E Coatings

In addition to the glass itself, special coatings can be added to influence the amount of infrared radiation (i.e. heat) allowed to pass through the glass. This is known as low-e or low-emissivity.

In colder climates, it is often applied to the interior so that heat is deflected back into the home whereas in warm areas, the opposite is done to minimize internal heat gain.


How Energy Efficiency is Measured: U-values

The heat transfer coefficient, referred to as the "U-value" or "U-factor", measures the amount of heat transferred through components of a building. Simply put, that means how much cold or heat moves from the outside to the inside of your home. Just as your home has many parts, each of which perform differently, so too do windows and doors. Both the window frame and glazing have individual values that make up the overall U-value. Like jackets, the difference between an old window and new one is similar to that of a thin windbreaker and a thick down jacket.

U-values are given in W/m²K (Watt per m² Kelvin). The lower the number, the better the insulation. A U-factor of 0.6 W/m²K is one of the best possible today.

The following make up the overall U-value of a window:

  • Uf - heat transmittance coefficient of the frame
  • Ug - heat loss through the glazing
  • ψg - energy loss through the spacer (warm edge)
  • Uw describes the u-factor of the overall window

R and G-Values

The G-value measures how much solar heat (infrared radiation) is allowed in through a specific part of a building. Therefore, a low value indicates that a window allows a very small percentage of solar heat to enter. This may be desirable in hot climates but not in cooler ones.

High R-values are good. Low U-values are good and a balanced G value is the best for most climates.

The R-value is the measure of thermal resistance. The higher the R-value is, the better that material prevents heat transfer.

Over 150 years of experience in window construction

Neuffer Fenster + Türen GmbH, located in the Swabian capital Stuttgart, was founded on January 13, 1872 by Ludwig-Ulrich Neuffer, so the company can look back on almost 150 years of experience in door and window construction in the private and commercial sector and guarantees the highest level of trustworthiness through various certifications.

Experience in window construction
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