Lennart Karlén's selected projects

Current projects

Improving the acoustics in Kista Church
We are contributing to the improvement of the choir's conditions in the church hall. The choir hear themselves poorly and crosstalk within the choir is poor. The church hall...

Sound-damping air intakes
We are developing new outdoor air intakes with a high degree of sound damping for Casamja AB. The sound dampers are installed in the walls or at the top of windows. They are combi...

The "Östra Brovakten" Building
The eastern building of the “Brovakten” city block in the north-western part of the Stockholm district of Kungsholmen is situated above the underground railroad tunnel...

The “Loen” city block
The Swedish National Property Board, SFV, is rebuilding the “Loen” city block in central Stockholm as buildings for government departments. The “Loen” city...

Kulturhuset, Stockholm
ACAD is involved as acousticians in redesigning the entrance level at the building Kulturhuset in Stockholm. Kulturhuset is offering culture in many shapes to their thre...

The Church of Sollentuna
The parish of Sollentuna is planning for a new church in the centre of Sollentuna, next to the parish home. The church will be constructed out of concrete with a special shap...

The Solliden Stage at Skansen
We are involved in the redesign of the historical outdoor stage at Solliden, Skansen. Architects are Tengbom architects in Stockholm. The stage are one of Swedens most recognised ...

Stockholm Concert Hall
The Stockholm Concert Hall is undergoing extensive remodelling. ACAD-International AB has received the prestigious assignment of creating the right acoustic quality. The purpose ...

Blåmannen block, government offices
The Post Office’s old head office in Vasagatan in Stockholm and buildings behind it in the same block are being reconstructed as a new government office complex, to be occup...

Reference projects

Restaurant Imperiet
Imperiet is a newly-built restaurant in the Gamen block in Götgatan. It is located in a newly-built building with homes and student housing next to the Studentskrapan buildin...

The Studentskrapan building, Gamen 8 block
The high-rise building has been converted into student rooms and offices. A very stingy dimension chain dictated by the existing framework resulted in very precise work by all inv...

Animal house, SMI
The laboratory animals are kept in sterile cages with only hard materials such as concrete, tile, steel and glass. In spite of this, we have designed a room for the animals where e...

Näckström Block, SEB
We have done several different rooms for SEB in the Näckström block. We have, for example, made a possible damped room of the old bank room in Kolmården marble. The...

Globe Arena Practice Rink
Sports arenas with special characteristics to give the active participants and spectators pleasant audible experiences using simple means. In the Globe Arena, we have participated...

Eriksdalshallen Arena
The remodelling of the Eriksdalshallen arena resulted in acoustics that at field level is rather similar to outdoors, but the spectators sit in an acoustic room that strongly suppo...

Restaurant Stockholm
Restaurant Stockholm is located at the Stockholm Central Station. It is built exclusively of glass. Here, we have made glass, which is a hard acoustic material, soft and sound-abs...

Security Laboratory, SMI
A sterile environment often makes for difficult workplaces with many sources of noise such as fans, fume cupboards and others. We have as far as possible created a working environm...

NCC Komplett
NCC’s revolutionary system of prefabricated residential buildings in flat packages. ACAD-International AB handled the acoustic development of the construction system with ver...

Lennart Karlén's articles

Acoustics in Rooms and Buildings
Acoustics are important in the entire building process. The acoustic environment in a building is not only dependent on the properties of the room-forming materials, but it is als...

The walls around the orchestra at Stockholm Concert Hall
A concert hall is designed for its functions in many aspects and for many different activities. The Great Hall at Stockholm Concert Hall has an advantage in that it is the place o...

Heat recycling
Energy prices are driving developments that in the long run may provide us with interesting technical solutions, where the transformation of energy is integrated in the normal par...

Acoustics in Restaurants
It is common knowledge that you to be able to eat and digest your meal properly you need calm and harmonic surroundings. And if you are in the company of family and friends that a...

Multi-dimensional Acoustic Project Planning of Rooms
For a room to sound right, you have to plan the room with regard to all of its acoustic characteristics. These include, in addition to length, width and height, time in the form o...

Ventilation - Acoustics: When CAD Programs Are Not Enough
It has gotten better. Although noise from ventilation is one of the most common complaints about interior environments both in homes and workplaces, things have gotten better. We ...

Energy Utilisation in Commercial Buildings – Comparison between Buildings of Different Ages
For some years, we have studied the utilisation of energy in commercial buildings for one of Sweden's major real estate companies. The purpose of this job was to formulate evaluat...

Open Offices – New Trend?
For some time, building open offices has enjoyed renewed popularity. It seems to have been a trend since the mid-90’s. Many large open offices were built during the 197...

Pre-fabricated Framework and Acoustics
We have for many years worked in the field of the control of sound-proofing and step sound levels in buildings with prefabricated frameworks. This has been a question of concrete ...

Comfort Is Equal to the Qualitative Perception of the Indoor Climate
The indoor climate is comprised of all of the conditions that affect us in a room and in a building. We interpret effect, among other ways, through our senses, to form a perceptio...

Indoors climate and comfort
Indoor Climate and Comfort Often Receive Low HCI (Happy Customer Index) ValuesIn recent years, we have had contact with building owners who work with some type of quality developm...

Ventilation Noise – the Most Common Complaint about the Indoor Environment
Why are ventilation plants always noisy? They make noise both indoors and outdoors in spite of the fact that most people want buildings to be quiet. In this article, we offer a fe...

Energy and Windows
Windows are the main source of heat leakage in a normal building. Older 2-glass windows with a U-value (W/m2 °C) of around 3 mean that they release 10 times more heat energy t...

Condensation in Intake Ducts – A Technical or a Hygienic Problem?
Outdoor air intakes and the portion of the duct between the exterior wall grate and the fan unit are cooled to temperatures below the dew point. Water vapour then condenses on the...

Longed-for Freedom from Disturbance in Residential Buildings Is Being Developed
In all surveys on the wishes and expectations of people with regard to their homes, two characteristics top the list. These are security and freedom from disturbance. At the same ...