Rationel Windows


Since our very first order of 31 barn windows was shipped from our factory in Sonder Fielding, Denmark in 1954, Rationel has been characterized by skilled design work and proud craftsmanship.

Today, Rationel supplies bespoke, premium quality windows and doors to families and home-builders all around the world.

Our energy-saving products combine the aesthetic beauty of natural timber with durable, high performance hardware, bringing your family the highest standards of comfort and security.

About the company

Rationel is an international company, manufacturing and selling state-of-the-art windows and doors around Europe and other parts of the world. Every year we dispatch 350,000 windows and doors from our factories in a variety of styles for both new build and refurbishment projects.

How it began

It all began in Sønder Felding, Denmark, with a hard-working carpenter and an order for 31 barn windows. As a young joinery apprentice in the 1930s, Richard R. Nielsen had craftsmanship in his soul. In 1954, he had his first order for 31 barn windows, which enabled him to invest in some modern machinery. Soon, Nielsen’s workshop became a factory and he built up a solid business based on consistently high standards of workmanship and quality.

High quality windows and doors

More than 60 years later, Rationel employs 1,050 people in Denmark, England, Ireland and Poland in the name of Richard R. Nielsen’s vision. We continue to manufacture high quality windows and doors that are durable and designed to last. They withstand the most severe wind and rain, as well as the constant wear and tear of busy family life, and the thousands of openings and closings of windows and doors year after year. Our windows and doors are even built to endure exhaustive break-in attempts and extreme instances of blunt force. But this is not just something that we talk about. Durability is something that we test again and again from every conceivable angle. See how we test our windows and doors to ensure that they are Secured by Design.

Continuous Improvement

Making an investment in new windows and doors means making an investment in the future. They must match the style and energy requirements of the house in question, while also living up to homeowners’ expectations and lifestyle aspirations. This is why we are continually working to improve and make our products even better - always looking to be more efficient and optimise our workplace.

Caring for the environment

We believe it is important to look after the climate and the environment. Our timber comes from FSC-certified forests in Sweden, which we then treat with eco friendly products. We recycle waste glass, paint and aluminium and we heat our factories with recycled wood from our production processes. In other words, we produce windows and doors with a clear conscience. Rationel is part of DOVISTA, a group comprising 10 leading window manufacturers in Europe with a common mission to bring natural daylight, fresh air and a better environment into people's everyday lives. A portion of our profits goes to the Villum Foundation, the main shareholder of VKR Holding, which owns the DOVISTA group. Arguably one of Denmark’s most discreet and wealthy environmentalists, the Foundation donates 15 million pounds to environmental and climate projects every year. Together with several other foundations associated with the VKR Group, it funds nonprofit scientific, cultural, artistic and social initiatives.

High quality windows and doors

At Rationel, we supply a wide range of windows and doors with beautiful Scandinavian designs. Our bespoke products come in both timber and timber clad with aluminium. Whether you are wanting a natural look from a sustainable source, or a low-maintenance option that is purpose-built to protect your home against the elements - not to mention the wear and tear that comes with frantic family life – Rationel have the right solution for you.

Shaped windows

We also manufacture and supply bespoke shaped units which are capable of fitting a broad range of unique openings, including curved, circular and slanting spaces. No matter how complex your stylistic ambition, we'll makei t a reality for your home. Contact us today to discuss your next project