Sun-protective glazing reimagined

Funktion, Energy Efficiency and Design: GM® ISO SUN

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Modern architecture emphasizes transparency, light, and expansive glass facades. However, the more glass surfaces are installed, the greater the impact of solar radiation on the indoor climate. This results in overheating, glare, and increased cooling energy requirements—especially in the summer. At the same time, requirements for energy efficiency under the Building Energy Act (GEG) and for indoor thermal comfort are rising.

Solar control glazing such as GM® ISO SUN is the answer to this challenge: It protects against overheating, reduces the use of air conditioning, and contributes to sustainable building operation through optimized physical properties.

How GM® ISO SUN Balances Comfort, Light, and Energy Efficiency

GM® ISO SUN uses state-of-the-art technology to selectively filter sunlight: A high light transmittance (tL) ensures bright, natural-looking rooms, while a low total solar energy transmittance (g-value) significantly reduces heat gain. Ideal g-values range between 0.2 and 0.4 while maintaining high light transmittance—a requirement that GM® ISO SUN meets in various versions.

Selectivity—the ratio of light transmission to heat gain—is another key factor. GM® ISO SUN achieves selectivity values of over 2—a sign of outstanding efficiency. Combined with a low U-value, valuable heating energy is saved even in winter.

Through various coating processes—e.g., magnetron coating with metals such as silver—both color-neutral as well as reflective or lightly tinted glass variants are possible. For designers, this offers maximum design freedom while simultaneously complying with all building code requirements (e.g., DIN EN 410).

What makes GM® ISO SUN the ideal sun-control glazing

GM® ISO SUN impresses with its versatile applications and technical features—especially for large window areas, sunrooms, roof glazing, or when external sun protection is not feasible.

The benefits of GM® ISO SUN:

  • Effective summer heat protection—interiors stay 2–5°C cooler.
  • High light transmission – daylight is preserved, glare is minimized.
  • Excellent selectivity – ideal for energy-efficient construction.
  • Can be combined with sound insulation, safety, and thermal insulation.
  • Suitable for renovation and new construction – also as laminated insulating glass with edge enamel.
  • Visually versatile – from color-neutral to colored reflective.
  • Certifiable according to GEG and EnEV – ideal for subsidized construction projects.

Special applications such as muntins in insulating glass or combinations with safety glass make GM® ISO SUN the ideal solution for demanding facade and window construction projects.

Effective heat protection & high energy efficiency

In addition to its wide range of applications, GM® ISO SUN plays a key role in maintaining a comfortable indoor climate year-round. This special glazing not only provides effective heat protection in the summer but also delivers high energy efficiency during the heating season. Read the following article to learn exactly how GM® ISO SUN helps improve living comfort and save energy:

GM® ISO SUN CLIMATE – Transparent. Efficient. Futuristic.

Particularly noteworthy is the GM® ISO SUN CLIMATE product line, which combines a transparent appearance with excellent insulation properties—ideal for sustainable building design. Glas Marte thus presents an innovative solar control insulating glass that meets the highest standards for energy efficiency, daylight utilization, and architectural design. Thanks to a special triple-layer silver coating, the glass allows approximately 50% of natural daylight into the room while simultaneously reflecting or absorbing up to 76% of solar energy.

This glass stands out for:

  • Low g-values (21–24%) combined with high light transmission (42–49%)—for maximum selectivity and optimal indoor comfort.
  • Excellent thermal insulation with a U-value of up to 0.5 W/m²K – ideal for passive houses and energy-efficient construction.
  • Bird-friendly thanks to very low external reflection (only 12%).
  • Uniform appearance with neutral interior reflection—no color cast, no glare.
  • Sound insulation up to 39 dB Rw,P when required through lamination (uniglas-sun-gm-climate-…).

The product line is suitable for double- and triple-pane insulating glass units and performs exceptionally well even in demanding applications such as:

  • South-facing glass facades
  • Window fronts and structural glazing
  • Large-scale elements up to 2,400 × 5,000 mm
  • Transparent glass-wood combinations

In addition, GM® ISO SUN CLIMATE is available in tempered form and can therefore also be used for increased safety requirements.

Design freedom for sustainable architecture

GM® ISO SUN CLIMATE offers architects and designers not only top-notch technical performance but also a high degree of design freedom—perfectly tailored to the requirements of sustainable, energy-efficient architecture. 

For more technical information and installation options, please visit the Glas Marte product page. We would be happy to advise you personally—please feel free to contact us.

More than just a view

Modern windows have long been high-tech components in buildings that combine numerous functions into a single element. Whether it’s thermal insulation, daylight utilization, ventilation, or security: Today, windows must meet the highest standards while also being aesthetically pleasing. Find out which features are in demand today and what really matters during the planning phase in the article “Functional Windows”—with a special focus on insulated glass and its versatile additional benefits.

FAQ

What materials are used to coat solar control glass?

Typically, ultra-thin layers of metal such as silver, tin, or chromium are used—usually on the outer pane—to ensure maximum protection and efficiency.

How does the g-value affect the energy efficiency of solar control glass?

A low g-value (0.2–0.4) means that less solar heat penetrates the building. This reduces the need for cooling and significantly improves energy efficiency in the summer.

What are the differences between the various types of solar control glass?

A distinction is made between coated glass, tinted glass, and combinations of the two. Tinted glass absorbs more light, while coated glass reflects more—depending on the application and design requirements.

How does selectivity affect light and heat transmission in solar control glazing?

High selectivity (value > 2) means plenty of light with minimal heat. This creates bright, comfortably temperate rooms without high energy consumption.

What country-specific regulations apply to sun-protective glazing?

In Germany, DIN EN 410 governs the measurement of light and energy transmittance. In addition, requirements under the Building Energy Act (GEG) and potential eligibility criteria—such as those of KfW—must be observed.

Why is built-in sun protection in insulated glass a good idea?

Solar control glazing can block over 80% of solar heat gain, thereby significantly helping to reduce indoor temperatures. Especially in the case of large glazed areas, efficient solar control prevents rooms from overheating—without significantly reducing the amount of natural light entering the space.

Which sun-protective glass options are in stock?

We carry solar control glass with a g-value range between 22% and 40%. Depending on your requirements, these options provide varying degrees of solar heat protection. For project-specific inquiries, we would be happy to provide you with a customized quote based on your desired g-value and configuration.

Can sun-protective lenses be combined with other features?

Yes. Modern solar control insulating glass units are often multifunctional. Depending on their construction, they can also provide thermal insulation, sound insulation, or meet safety requirements (such as burglary resistance or impact resistance). This makes it possible to meet complex building physics requirements with just one type of glass.

In what shades are your sun-protective lenses available?

Our solar control glass is primarily available in neutral tints—ideal for a clear, unobstructed view. Compared to the blue, green, or gray solar control glass commonly found on the market, neutral variants blend seamlessly into a variety of façade designs without any distracting color casts.

What is the g-value of conventional insulating glass—and how does solar control glass look different?

Standard thermal insulation glass without a sun-control function typically has a g-value of approximately 50%. In direct comparison, neutral sun-control glass with a g-value of about 30% appears slightly tinted, but offers a noticeable advantage in terms of summer heat protection. The visual effect is minimal, but the energy-saving effect is significant.