Thermal bridges - avoiding momentous planning errors
With component solutions from B.T. innovation
Thermal bridges in the outer shell can significantly affect the energy efficiency of a building. To minimise energy losses and reduce the thermal conductivity of components, new and innovative solutions are on the market. In precast concrete construction, B.T. innovation comes up with intelligent and effective system solutions for thermal insulation.
Use of DowaTherm and ThermoPin for energy-efficient construction
Concrete is an ideal building material for monolithic use on construction sites as well as for precast production, but due to its high thermal conductivity and building physics parameters, it places high demands on building material connections in the constructive solution of thermal bridge-free wall and precast systems.
For the thermal decoupling of these wall systems, especially for double and thermal walls as well as sandwich elements, B.T. innovation has brought simple and highly effective solutions to the market to avoid thermal bridges.
Thus, for manufacturers of double and thermal walls, a product was made available in the form of the DowaTherm system that combines several advantages.
Advantages at a glance – BT DowaTherm:
- Corrosion resistant
- No problems with concrete cover
- Light processing
- Time saving during processing
- No thermal bridges
- Specially suitable for thermal wall production
- Rational operational use due to clear and space-saving storage
- Adaptability for any wall thickness with minimum effort
- Price stability through independence from the price of steel
- No influence by magnetic fields
The flexible spacers, which consist of a plastic-coated fibre composite, ensure exact compliance with the specified element thicknesses and can be used safely and stably in the production process thanks to simple connections with the lower reinforcement layer. Expanded by the terminal system, DowaTherm elements are very rational as individual components and, moreover, effective and clear to use with the smallest space requirement.
The ThermoPin system from B.T. innovation has been developed for the construction and manufacture of reinforced concrete walls with self-supporting facing shells, for sandwich walls or monolithic multi-layer walls.
Advantages at a glance – BT ThermoPin:
- Price stability vis-à-vis steel
- Thermal decoupling of wall systems
- Corrosion resistant
- Not thermally conductive
- Non-magnetically conductive
- Does not form electric fields
- Eliminates steel connections in multi-layer reinforced concrete elements
Due to the geometric shape of the GRP anchors and the specified installation position, they guarantee the statically required bond of the shells for all occurring load cases from temperature influence, wind, earth and concreting pressure and at the same time, through the combination of tension and compression rods, take over the dead load of the facing shells. The rod-shaped GRP anchor is conically shaped at the ends by a special process and thus contains the prerequisites for absorbing high pull-out forces. In addition to the special shaping at the rod ends, the ThermoPin has a plastic ring firmly connected to the GRP body, which serves to fix the insulation layer and as a spacer and water barrier.
With DowaTherm and ThermoPin – for the efficient production of reinforced concrete components
Due to the metal-free fibre composite, the DowaTherm and ThermoPin elements are not susceptible to corrosion, do not conduct heat and, with the possible low concrete coverings, provide the prerequisites and advantages for lean and efficient production of reinforced concrete components and their use in demanding construction projects.
The largest proportion of thermal leaks in the building envelope are the so-called linear thermal bridges. These can in turn be divided into three groups:
- Material-related thermal bridges occur when the thermal conductivity changes within a building component. Typical examples of this form of thermal bridges are reinforced concrete columns, ring beams, window lintels (seal windows) or projecting reinforced concrete parts.
- Geometric thermal bridges appear where there are large differences in size between the inner surface (heat-absorbing) and the outer surface (heat-dissipating) in relation to the surface area. Typical examples are building corners and edges.
- Finally, the constructive thermal bridge is closely linked to the material-related thermal bridge and can often hardly be avoided. Roller shutters or rainwater downpipes located in the ETICS belong to this category. Constructive thermal bridges also frequently occur on balconies.
In addition to the main categories mentioned, there are also point thermal bridges that can be caused by fasteners or single cantilevers. Three-dimensional thermal bridges can occur in the corners of the room. This is where the risk of mould is greatest, as a very low temperature field can develop. So-called convective thermal bridges are created by leaks in the building components enclosing the room, component joints or installation guides.
Thermal bridges due to faulty execution
If individual building details are executed improperly, gaps in the thermal insulation and thus heat losses occur. Typical construction defects in this area are, for example, incomplete compartment insulation, masonry gaps with mortar filling (join concrete) in monolithic exterior walls, insulation boards not laid without joints in the thermal insulation composite façade or mortar residues in contact with the material in the core insulation level of double-shell exterior walls (concrete renovation).
Thermal bridges are usually associated with increased energy consumption by the consumer. In addition to this effect, which increases the required heating power and thus also energy costs and environmental pollution, there are other unpleasant effects:
- Due to the increased outflow of heat to the outside in the area of the thermal bridge, the surface temperature of the wall decreases. This reduces the comfort in the room, a “draught” can be felt.
- Where the surface temperature of the interior wall cools down, the warm room air condenses and condensation forms on the wall surface. In the long term, a climate is created at this point that favours mould growth. Room corners, radiator niches, but also window reveals are at risk.
- If there is persistent moisture penetration of the building components, the building fabric suffers. Due to the permanently high moisture content in the building component, the surface temperature drops more and more, which means that even more moisture can condense (sealing concrete).
Thermal bridges in buildings can cause great damage. Therefore, the primary goal in planning and execution is an exterior wall with as few thermal bridges as possible. By using optimised product solutions such as the systems from B.T. innovation, the prerequisites for energy-efficient lean construction are given.