What Keller minimal windows does

Keller minimal windows designs and manufactures bespoke nearly frameless aluminum window and door systems for the luxury residential and high-end commercial architectural market. The product portfolio comprises six interconnected lines — minimal windows® (standard double glazing with a 21mm wing profile), minimal windows® 4+ (triple glazing, Uw ≥ 0.70 W/m²K), minimal windows® NGS (Next Generation Slider, 26mm profile, up to 6m height, 99.3% light transmission, motorized operation up to 2,400 kg), minimal windows® highline (large fixed facades), minimal windows® pivot (rotating pivot doors), and minimal windows® curve (curved glass facades) — together with accessories including a freeway barrier-free threshold, guardline glass railings, and an integrated insect screen system. All systems are custom-manufactured to project dimensions in Troisvierges, Luxembourg, share compatible frame profiles and hardware, and carry extensive third-party certifications (EN 12207/12208/12210, ISO 717-1, RC2/RC3, DIN 18040).

The firm operates a B2B go-to-market combining an approved global distributor network (distributors in 10+ countries including South Korea via Chang Jin Korea, Turkey & Central Asia via Aluwest Yapi Sistemleri A.S., plus Canada, South Africa, Slovenia, UK, Austria, Switzerland, Italy, Germany, Norway, the Netherlands and Belgium) with direct enterprise engagement via dedicated inquiry channels for architects and private homeowners. Pricing is fully project-based, quoted ex works in Euro, with products non-returnable due to bespoke manufacture; revenue is generated from one-time hardware sales plus accessory upsells and adjacent professional services (training, assembly guidance, site surveys, crane work, technical support). Distribution is supported by the Minimal Hub customer portal (BIM/CAD data, livestreams), the BIMobject marketplace, the Luxembourg-based Keller Academy (face-to-face and webinar training), and active participation in industry events such as BAU 2025 and ARCHITECT@WORK.

Since October 2022, Keller minimal windows has operated as a subsidiary of AluK Group, a global aluminum windows, doors, and facades distributor founded over 70 years ago and now part of the Valfidus family-owned business platform. AluK contributed R&D and distribution scale (800 employees, 2,600 customers across 10 countries) to accelerate the minimal windows® brand's expansion in the luxury residential segment. The company is a relatively small standalone operation (11–50 employees per firmographics) and reports no disclosed revenue figures. Strategic positioning is anchored on proprietary minimalist frame technology, exclusive rail systems, and a project-bespoke manufacturing model that has secured reference projects including commissions by Zaha Hadid Architects, plus recognition through the Architect's Darling Award 2023 (Silver, Best Product Innovation).

Name

Keller minimal windows

Legal name

Keller Minimal Windows S.A.

Website

https://minimal-windows.com

Company type

Private

Founded year

2007

Operating status

Operating

Headcount range

11–50 employees

Short description

Keller minimal windows designs and manufactures bespoke nearly frameless aluminum window and door systems for the luxury residential and architectural market, distributing through an approved global partner network across 10+ countries. The company has been a subsidiary of AluK Group since October 2022.

Ownership category

akta.pro rank

Product category

Luxury aluminum window and door systems

NAICS

Metal Window and Door Manufacturing (332321), Architectural and Structural Metals Manufacturing (3323), Ornamental and Architectural Metal Products Manufacturing (33232)

SIC

Metal Doors, Sash, Frames, Moldings & Trim (3442), Miscellaneous Fabricated Metal Products (3490)

akta.pro primary industry

Windows (IMADAIAC)

akta.pro secondary industries

Interior Doors (IMADAIAB), Storefronts, Curtain Wall & Window Wall Systems (IMADAIAG), Frames, Sashes, Mullions & Subframes (IMADAIAH)

Keywords

• Frameless aluminum windows
• Sliding door systems
• Minimalist architectural glazing
• Aluminum facade systems
• Custom window manufacturing

Headquarters

HQ city

Troisvierges

HQ country

Luxembourg

HQ region

Europe

Offices2 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Supply Chain, Operations, Personnel, Marketing or Sales, Technology or R&D, Infrastructure

Revenue model

1. Custom aluminum window and door systems: Bespoke manufacturing of nearly frameless aluminum window and door systems (minimal windows, minimal windows 4+, minimal windows NGS, pivot, highline, curve) sold directly to or through distributors to architects, contractors, and private homeowners. Products are manufactured to specific project dimensions and cannot be returned.
2. Professional services (assembly, installation, training): Training, assembly guidance, site surveys, crane work, and technical support provided as professional services, payable immediately without deduction per general conditions.
3. Accessories and optional extras: Color customization (RAL, IGP, DB, NCS powder coating; anodized; Granodal), electric motorization, insect screens, glass balustrades, and other optional accessories sold alongside core systems.

Go-to-market motion2 records

Distribution channels4 records

Marketing channels8 records

Core offering

Keller minimal windows designs, manufactures, and distributes nearly frameless aluminum window and door systems custom-built to project specifications. The portfolio spans six core product lines (minimal windows, 4+, NGS, highline, pivot, and curve) that deliver ultra-slim profiles, oversized glass surfaces, motorized sliding, pivot, fixed facade, and curved glazing solutions for luxury residential and high-end architectural projects globally.

Product overview

Keller minimal windows is a specialist manufacturer of nearly frameless aluminum window and door systems, producing a portfolio of six interconnected product lines. The core minimal windows® system with double glazing serves as the foundation, while the premium 4+ variant offers enhanced triple-glazing for superior thermal performance in low-energy and passive houses. The NGS (Next Generation Slider) represents the latest sliding technology with maximum heights of 6 meters and motorized operation up to 2400kg. The highline system addresses fixed glass facade applications, and the pivot system provides oversized pivot door solutions. The curve series enables custom curved glass facades. All products share compatible frame profiles, hardware systems, and accessories including the freeway track system, guardline glass railings, and integrated insect screens. The company joined the AluK Group in October 2022 and operates production facilities in Luxembourg.

Differentiator

Problem solved

Functional benefit

Brands

• minimal windows®: The company's core product brand for nearly frameless aluminum window and door systems, including variants such as minimal windows® 4+, minimal windows® NGS, minimal windows® highline, minimal windows® pivot, and minimal windows® curve.
• minimal windows® NGS
• minimal windows® 4+
• minimal windows® highline
• minimal windows® pivot
• minimal windows® curve

Products and services

• minimal windows® Flagship double-glazed nearly frameless aluminum window and door system featuring a 21mm wing profile that delivers virtually invisible frames for contemporary luxury residential and architectural projects.
• minimal windows® 4+ Premium triple-glazed version providing high-performance thermal insulation (Uw ≥0.70 W/m²K) for low-energy and passive houses, supporting oversized glass surfaces up to 6 meters high and 1000kg per leaf.
• minimal windows® NGS Next Generation Slider ultra-narrow sliding system achieving 99.3% light transmission with heights up to 6 meters, supporting sliding leaves up to 1500kg and motorized operation up to 2400kg total weight.
• minimal windows® highline Large continuous fixed glass facade system combining slim aluminum profiles with fixed glazing for expansive panoramic views, available in frameless, semi-hidden frame, and cover cap constructions.
• minimal windows® pivot Modern pivot door system rotating around a vertical axis for unique architectural expression, featuring oversized custom doors up to 1800mm width and 3000mm height with 250kg maximum weight capacity.
• minimal windows® curve Curved glass facade system enabling elegant curved elements with flowing, futuristic aesthetics, custom-manufactured for each project with curved doors up to 4.5m height and minimum radius of 4 meters.
• minimal windows® freeway Floor-embedded track system enabling barrier-free access to outdoor areas with frame completely integrated into the floor, tested, certified, and maintenance-free.
• minimal windows® guardline Glass railing system combining quality, safety, and elegant design for floor-to-ceiling window openings requiring fall protection, with seamless installation techniques.

Quantifiable outcome

• Up to 99.3% light transmission with NGS system
• +7 more outcomes

Named customers2 records

Segments4 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Integration1 record

Feature11 records

Partnerships

Two partnerships are on record, tiered core and minor.

• Aluwest Yapi Sistemleri A.S.coreChannel Partner/ Reseller/ Distributor · 22 January 2025New partnership announced January 2025 for the Turkey and Central Asia markets. Aluwest Yapi Sistemleri A.S. brings over 22 years of experience in the facade and architectural systems industry. Led by Cagdas Taylan, a seasoned industry expert who has held leading roles within the industry, the company is well-positioned to drive Keller minimal windows' growth in these strategically important regions.
• Miysis 3D StudiominorStrategic or Co-development Partner · 1 December 2022Miysis 3D Studio is identified as a joint venture partner of Keller minimal windows, providing 3D rendering services for project visualizations. Credits appear on product page imagery.

Scale indicators5 records

Recent moves6 records

Expansion highlights7 records

Emerging players

• Solarlux: German maker of aluminum/glass sliding and folding systems and winter garden solutions; overlapping with Keller on large minimal glazing for high-end residential, though with a different system type focus.
• Finstral: Italian/European aluminum-PVC window and door manufacturer with a premium range of large glazed sliding doors; comparable customer overlap in private homeowner and architectural projects.

Broad incumbents

• Aluprof: Polish aluminum systems manufacturer with a wide range of window, door, and facade solutions including slim-profile lines; competes in similar European architectural channels and on price/spec in select segments.
• Schüco: Large German aluminum and steel systems manufacturer offering window, door, and facade solutions including minimal-frame variants; competes on premium architectural projects but across a much broader portfolio than Keller.
• Reynaers Aluminium: Belgian aluminum systems supplier for windows, doors, sliding and curtain wall solutions serving residential and commercial projects across Europe; overlaps with Keller in the high-end architectural segment.
• Technal: French aluminum window, door, and facade systems brand owned by Norsk Hydro; competes with Keller's minimal-frame and curtain-wall offerings through a broader architectural systems catalog.

Direct peers

• PanoramAH!: Italian maker of minimal-frame aluminum sliding windows targeting luxury and architectural projects across Europe; directly comparable product line, customer profile, and distribution model.
• Sky-Frame: Swiss specialist in frameless floor-to-ceiling sliding window walls; the closest direct competitor on panoramic minimal glazing for high-end residential and architectural projects.
• Vitrocsa: Swiss manufacturer of minimal-frame sliding window systems with ultra-slim profiles; competes head-to-head with Keller in the luxury residential frameless windows segment and serves a similar architect-led customer base.

Others

• AluK Group: Keller's parent company and a global aluminum systems distributor; not a competitor but a strategic reference point on group scale, channel reach, and capital backing that influences Keller's go-to-market.

Market position

Strengths5 records

Weaknesses3 records

Competitive moat5 records

Key risks6 records

Key highlights6 records

Customer concentration

• YouTubeyoutube.com/channel/UCvz2F3DyQ2GL8Km_ph2Ggrg
• Facebookfacebook.com/kellerminimalwindows
• LinkedInlinkedin.com/company/kellerminimalwindows
• Instagraminstagram.com/kellerminimalwindows
• Pinterestpinterest.de/kelleragluxembourg

Compliance9 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Keller minimal windows