Sustainable thermal break solution protects worldwide art from the top

Schöck Isokorb KST installation in the Indianapolis Museum of Art

During steel erection. The Isokorb provides a thermal break between the components, thereby reducing the risk of construction damage, and slows down the heat flow as well as the wastage of energy that this causes. (Source: Marlon Blackwell Architect)

Detail of load bearing thermal break connection: Up to five modules per beam were necessary to bear the forces of the roof construction. (Source: Marlon Blackwell Architect)

The Isokorb type KST offers complete freedom of design for the canopy in steel constructions, and its characteristics make sure that the unit is completely protected from corrosion. (Source: Marlon Blackwell Architect)

The Indianapolis Museum of Art (IMA) is one of the oldest and largest general art museums in the United States, with a permanent collection of more than 50,000 works of art. Situated on 152 acres that incorporate Oldfields-Lilly House & Gardens and the Virginia B. Fairbanks Art & Nature Park, the IMA features significant collections of African, American, Asian, European, contemporary and decorative art, including paintings, sculptures, prints, drawings and photographs as well as textiles and costumes. At the heart of the museum is the visitor pavilion. The interpretive 3,000-square-foot pavilion contains educational facilities. Designed to be seamlessly woven into the natural environment, both centres will be constructed with recycled materials in order to achieve LEED (Leadership in Energy and Environmental Design) certification from the U.S. Green Building Council.

Steel beams: a point of weakness

To meet the criteria of LEED, the architect Marlon Blackwell also has to take steps to ensure the avoidance of thermal bridges in the building, for instance the detail of the roof construction with large steel beams. It is a potential point of weakness that could cause thermal outflow from the museum. Inside the building it is warm, outside it is cold. The steel beams, which were installed as the load-bearing elements for the roof construction, run from inside to outside, a typical thermal bridge situation. During the winter, in the area around thermal bridges, the surface temperature on the indoor side of the components falls. When this temperature falls below the dew point, condensation occurs. Mould formation, however, occurs considerably earlier than this. Thermal bridges also result in higher heating energy requirements and thus higher heating costs.

Low energy loss, high freedom in design

In order to reduce the thermal flow and minimise the thermal bridge problem, use has been made of the Schöck Isokorb KST. The Isokorb range, invented by Schöck in Germany, is the effective solution for combating this weak spot on a building’s façade. It provides a thermal break between the components, thereby reducing the risk of construction damage and it also slows down the heat flow and the wastage of energy that this causes. But at the same time, the Schöck Isokorb is a structural design component. The Isokorb type KST in particular offers complete freedom of design when it comes to steel construction. The unit is able to withstand extremely high loads and is effective against bending moment and shear force. Its stainless steel components mean that the unit is completely protected from corrosion.

Design support included

With the aid of a calculation programme and technical support from design engineer Hanaa Sadallah, the project designer from Guy Nordensen was able to dimension the required types. It was no problem relating European standards to those required by the US market. Only the length of the steel beams and the thickness of the sheet had to be adjusted and recalculated. The Schöck design department created CAD drawings with US standards and US profiles. It was a matter of teamwork between architect, designer, steel contractor and the Schöck engineers all through the planning process. Schöck also accompanied the installation of the KST modules on the building site. The US Area Manager Alexander Krenczik was on site to support the installation with his experience and a specially designed installation manual for the modules. Up to five modules per beam were necessary to bear the forces of the roof construction.

Modular layout for high internal static forces

Structurally, the Isokorb type KST reliably transfers internal static forces across the insulation joint – there is a choice of module variations offering different options depending on the profile and cross-section size. This allows for conventional front plate connection techniques typical in steel construction.

For large steel members, several individual modules can be combined in order to transmit the respective internal static forces. This modular concept not only allows flexibility in application, it also ensures ease of installation and simple handling logistics.

The following modules are available, each of them with two different load capacities:

•    KST-ZST module for the transfer of tensile forces
•    KST-QST module for the transfer of compression and shear forces
•    KST-ZQST module for the transfer of tensile, compression and shear forces

The machining principle is the same for all module types. The steel construction company produces the steel members and the on-site front plates with complete positions and dimensions as specified. On site, the Isokorb is then installed between the two members in the insulating and façade layer of the building, with the elements joined by simple screw connections.

Reduction of the thermal bridges to a minimum

The Isokorb KST thermal break module, developed by Schöck, one of Europe’s leading companies in the provision of thermal energy insulation and noise suppression systems, has been specifically developed for use in steel construction. The KST module has an 80 mm rigid polystyrene foam insulation joint working in tandem with stainless steel connective rods, resulting in particularly low thermal conductivity and corrosion-free performance and guaranteeing excellent thermal insulation. The module ensures that no condensation can occur at normal indoor humidity levels and, thanks to the optimisation of the thermally-conducting cross-section area, thermal bridges are reduced to an absolute minimum. The component is additionally able to absorb the temperature variations on the outer steel structure without any effect of fatigue as long as the Schöck guidelines concerning fatigue are taken into account.

Details

Project: Indianapolis Museum of Art
Architect: Marlon Blackwell Architect
Structural Engineer: Guy Nordenson and Associates
Construction company: The Hagerman Group, Fishers, Indiana
Products: Schöck Isokorb type KST
Start of construction: 2009
End of construction: May 2010