The best wood for fine windows

Production of windows and doors is going through a powerful transition. As energy becomes a crucial consideration in almost everything, energy efficiency is assuming a key role. This only increases the need for quality timber.
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  • 2023, Sawn timber

Danish window and door manufacturers have always relied on Nordic timber as the backbone of their operations.

“Our members only use Nordic pine, since it is of high quality and easy to work on,” says Director Johny H. Jensen of the Association of Danish Window Manufacturers (Vinduesindustrien).

“They source mainly from Finland, Sweden, Estonia and Germany and also from Norway to smaller extent.”

The association, formerly known as VSO, was founded in 1977 to unite manufacturers and also to protect Danish facade architecture. The same year it launched the Danish Window Verification (DVV) system, which would gradually become a mark of quality recognised all over Europe.

“Back in 1977, Danish manufacturers felt that quality needed a lift and DVV was their response”, says Jensen.

Certified quality

Today, products marked with the DVV label must meet specific technical requirements, and the companies producing DVV labelled windows and exterior doors are subject to independent auditors. All Association members are certified under the DVV scheme.

“They all give a five-year warranty and are also members of a guarantee scheme that protects the consumer if some manufacturer does not live up to its warranty promises,” explains Jensen.

Barrus AS, an Estonian producer of finger-jointed and laminated timber, is a member of the Association and a proud believer in DVV. Its Sales Director Morten Glinvad says that DVV has a long tradition for guaranteeing the best possible windows and doors for the consumer.

“The DVV specifications are a result of decades of knowhow and the experience of all members of the industry. The specifications are reviewed on a quarterly basis to ensure that they represent the best practice in the industry,” says Glinvad.

Warranty for 10 years

For the wood material used for DVV products, there are numerous demands, such as specific density, the size of growth rings, the amount of heartwood and where it must be in the product.

“There are also specific rules for moisture content and permissible defects. The specifications for the raw material play a fundamental role in allowing manufacturers to provide consumers with a warranty that can be as long as 10 years,” says Glinvad.

He points out that pine of precisely defined, high quality also allows paint suppliers to develop very specific paint systems, leading to extended lifetime.

“If the raw material is not specified, no one can properly study the product’s lifecycle. Decades of experience have shown that pine of the right quality has excellent durability. We know that it will last longer than most other window materials.”

Boost for high ecological performance

Jensen from Vinduesindustien points to the uniform look and feel of Nordic pine.

“For example, consumers do not like knots in the wood. They view a window as they would any piece of home furniture. It needs to be pleasing to the eye, too.”

Wood-based products also offer energy savings. Jensen says that Denmark’s environmental requirements for such products are among the toughest in Europe.

“The focus is now on the energy balance of buildings, and windows have an important role in boosting energy efficiency.”

Glinvad from Barrus agrees that energy optimisation is a trend that is only increasing in importance. For example, most windows have changed from double glazing to triple glazing over the last 2–3 years, he notes.

“The high cost of energy, in combination with EU’s ambitious plan to reduce carbon footprint of housing, is a strong driver for several countries and for consumers to get the best energy performance.”

Jensen comments that the EU’s upcoming Energy Performance Building Directive will only boost the need for high ecological performance in windows.

“We see great potential in the market as a consequence of the directive.”

At the same time, the whole industry is moving towards a circular economy, which favours material that can be recycled into a new product at the end of its life, eliminating waste, says Glinvad.

Nordic wood is trusted

Denmark’s Inwido Group is another long-time member of DVV.

“The number one thing that our customers expect from us is quality. It is important to follow the DVV standard to provide that quality,” says Purchasing Manager Allan Eibe Staffensen.

Inwido Group develops and sells customized window and door solutions, with 32 business units and approximately 4,900 employees in 11 countries. DVV’s Rules for Wood are one of the “green tools” that supports Inwido in its drive for sustainability. The company is constantly looking for new ways to improve in this area.

“We have already worked very hard to realize our CO2 reduction ambitions. This work is ongoing,” promises Staffensen.

Nordic timber has always been a signature of Inwido.

“We have sourced sawn timber from Sweden and Finland for more than 20 years.”

Sustainable raw material

Founded in 1993, Barrus has become a leading manufacturer of glued and laminated timber components in Europe. The company’s choice of solid wood for its doors and windows has always been easy and obvious, explains Glinvad.

“Wood is more energy efficient than PVC and aluminium. It has a supreme aesthetic look and feel, which allows everyone to experience luxury while, at same time, it helps to reduce global warming.”

He believes that wood has a “huge role” to play in saving the planet.

“Wood is outstanding in comparison to any other material because it absorbs and sequesters the CO2 emissions from several other industries.”

Barrus is big fan of Nordic timber because, as Glinvad notes, Nordic forests are very well managed by their owners and protected by law.

“For decades, the Nordic countries have managed the forest as a sustainable resource. Nordic wood is the best guarantee the consumer can get for a sustainable raw material.”

This article was originally published in Timber Magazine issue 2023.