Energy efficient ventilation - retrofit is the new direction for the construction industry

Intelligent building renovation, or retrofit developments, have become an important tool in the construction industry in terms of energy efficiency and climate protection. Lindab offers forward-looking solutions worldwide.

The changed market environment requires new engineering thinking

The recent Green Engineering Forum 2025 event in Budapest provided a platform for the building services industry to share their experiences and climate-smart solutions.

At the event, the commercial manager of Lindab, Gellért Vigh, raised a rather topical question: what can we do about energy-wasting ventilation systems?

There is more than 4.5 million square metres of office space in Budapest. This market will soon be flooded by a further 400-500 thousand square metres of unused office space, after public companies move into new office buildings. What can we do about this situation?

Modernisation and change of function become key issues

Two thirds of speculative office stock is classified as „A”, while one third is classified as „B”. The latter are generally more than 10 years old, built in the outer suburbs and lack the technical content of „A” or „A+” grade offices with modern wiring, state-of-the-art air conditioning, excellent location and parking. These B-class office buildings therefore offer potential for renovation. Gellért Vigh pointed out that rental patterns have changed. Demand for office space has fallen, with leases for smaller areas and shorter periods.

Office buildings have a high vacancy rate of 13 percent, which predicts that many will need to be modernized or re-purposed for further use.
In such a dynamic environment, the flexibility and energy efficiency of building services becomes crucial.

Energy efficient ventilation is not an extra service

„We build our buildings not for the past or the present, but for the future. It's important not to think in terms of 40-50 year old technologies,” said the Lindab specialist. He added that energy efficient ventilation is no longer an extra service, but part of the basic infrastructure of buildings.
A problem that often arises in relation to the cost of operation is the lack of measurement data to help identify intervention points to improve efficiency, Gellért Vigh reminded.

Buildings of the future can be monitored by installing sensors, which will also provide strong support for preventive maintenance.

Demand controlled ventilation - when technology adapts to the building

Among the developments of the Lindab, a prominent role is played by demand-controlled ventilation (DCV – Demand Controlled Ventilation), which always adjusts the air volume to the current usage. The system's intelligent sensors – such as CO₂, temperature and presence sensors – respond in real time to changes in the environment, such as changes in the number of people in the room, ensuring optimum comfort and minimum energy consumption.
The Lindab Ultralink technology offers an additional advantage for operators: the performance and condition of the ventilation system can be continuously monitored, allowing maintenance to be planned in advance and faults to be prevented. Such systems transform mechanical engineering into an active, data-driven infrastructure, which reduces maintenance costs in the long term.

Let the numbers speak!

He illustrated the difference between the energy demand of static and demand-controlled systems. The latter can reduce the energy consumption of a fan alone by up to one eighth. Ensuring product qualification is also a priority for the Lindab. The company provides EPDs issued by an external, independent accredited organisation for many of its products. In addition, air ducts made from 75 per cent recycled steel were introduced two years ago and are now available in Hungary. This allows emissions to be reduced by almost a third at the manufacturing stage.

German and Swedish examples show the effectiveness

Gellért Vigh also presented several reference projects, where the results of the modernisation of building services engineering were quantified. The ventilation system installed at Lindab's office in Bargteheide, Germany, in the 1990s was modernised with a DCV solution. The existing network was partially retained, but the control and air volume control was completely renewed. The operation is now demand-controlled, resulting in significant energy savings of 68 percent and comfort gains, while the payback period remains short. Even as the ventilation air volume for the office building was increased to 6,000 cubic metres per hour.

The reconstruction of the office building at Jakobsbergsgatan 24, the former Royal Swedish Telegraph, in Stockholm, is a prime example of sustainable use of materials. During the work in the historic environment, Lindab installed an air duct network made of 75 percent recycled steel, which resulted in a 62 percent reduction in CO₂ emissions.

The 15,000-square-metre building, 80 percent of which is office space, has a completely new mechanical system, which has saved enough energy to charge 2.5-3 million smartphones.
The solution is clear evidence that circular economy principles can lead to measurable environmental results in the construction industry.

Domestic advantage: reduced carbon footprint, unchanged quality

Lindab now offers duct elements made from 75 percent recycled steel in Hungary, which have the same technical parameters as conventional products, but with a significantly lower carbon footprint. For a medium-sized office building in Budapest, this could mean a saving of up to 38 tonnes of CO₂ - equivalent to the emissions of more than 200,000 kilometres of car journeys.
The solution is therefore not only environmentally attractive, but also economically attractive, as energy consumption and operating costs are tangibly reduced.

Engineering of the future available today

The philosophy of the Lindab is that modern, high-quality and sustainable engineering is not a promise of the future, but a challenge of the present. The combination of demand-controlled ventilation, data-driven systems and recycled materials takes building management to a new level - both technically and environmentally.
Retrofit is not just a renovation: it is a conscious choice by the modern building industry towards energy-efficient, healthy and sustainable buildings in the long term.