Keller minimal windows®

Keller minimal windows® redefines the boundary between indoors and out. Designed and manufactured in Luxembourg, these precision-engineered aluminum sliding systems offer floor-to-ceiling transparency with virtually invisible framing—perfect for projects that demand unobstructed views and seamless transitions.

At GlasHaus Windows, we specialize in bringing Keller’s minimalist elegance to high-end residential and commercial architecture across Colorado and the Mountain West.

Where Design Meets Craft.

minimal windows® 4+

minimal windows®4+ offers ultra-slim, triple-glazed sliding or fixed units designed for expansive glass façades—maximizing natural light, uninterrupted views, and a seamless indoor-outdoor connection. This system also includes the minimal windows® pivot door, which carries the same signature slim design and precision engineering to create striking entrances with effortless functionality.

The minimal windows® 4+ allows architects to create expansive glass façades with heights of up to 6 meters and individual sashes weighing up to 1,000 kg. This flexibility opens up endless design possibilities for modern, minimalist architecture.
In line with the latest building standards, the 4+ system is perfect for low-energy and passive houses. With high-quality insulating glass, it achieves Uw values of ≥ 0.70 W/m²K, ensuring excellent energy efficiency and significant savings on heating costs.
Despite its sleek and minimalist appearance, the 4+ system is built to withstand strong wind loads. Its aluminum frames have a slim profile, ranging from 26 to 34mm, while offering exceptional strength and durability. The frames seamlessly integrate into floors, ceilings, or walls for a clean, modern look.
From mullion-free inner and outer corners to pivot units and all-glass corners, the minimal windows® 4+ offers a range of design options. Architects and contractors can create custom solutions tailored to their vision, making every project unique.
For an even more fluid transition between interior and exterior spaces, our sliding units can disappear into specially designed wall pockets. This feature provides unobstructed views and enhances the overall aesthetic, creating a truly seamless experience.

minimal windows® NGS

minimal windows® NGS delivers barrier-free, floor-to-ceiling openings up to 6 m high and unlimited in length—creating seamless transitions between indoors and outdoors with maximum design flexibility.

The NGS system brings together minimalist aesthetics and natural light, creating a harmonious atmosphere for modern living. With up to 99.3% transparency, it transforms any space into a light-filled, airy environment.
Side profiles can be fully recessed into walls, floors, and ceilings, making them virtually invisible. This allows uninterrupted views and clean architectural lines that complement contemporary spaces.
NGS accommodates glass thicknesses from 34 mm to 74 mm, giving designers and builders the freedom to tailor each installation to performance needs and visual preferences.
Effortless operation is built in. Our motorized system smoothly moves sliding elements weighing up to 1,500 kg, guided by a precision-engineered stainless steel track.
The NGS system is designed with architectural freedom in mind. Whether your project demands technical complexity or custom aesthetics, we work closely with you to realize your unique vision.