Questions and answers
about modular construction methods
Thanks to the seamless organisation of the planning process, tried and tested technical details and standardised manufacturing processes, clear savings can be made in terms of planning costs.
The costs of constructing a modular building are on a par with the costs for a conventionally built one, or can sometimes be lower. However, because production in the "room factory" does not depend on weather conditions, LG can build all year round and thus complete the building as much as 70% faster. Firstly, this shortens the financing period, and shorter financing periods have a positive effect on the interest payable. Secondly, the property can be handed over and rented more quickly, and so revenues start to flow in sooner. In addition, with its certified processes and constant monitoring, modular construction is synonymous with quality. If we bear in mind that the "number one factor" in driving up costs on site is the repair of defects, modular construction simply offers investors security – in terms of technology, time and money.
The economic viability of modular construction lies in the series manufacture of constantly recurring, consistent units. Engineering costs are incurred for "setting up" a series of this type, and these may vary slightly depending on the complexity of the project. The consequence of this is that constructing a building using modular construction only becomes financially viable if a certain number of units and corresponding gross floor area are required. As a rule of thumb, the minimum size can be quoted as being around 500 m2 gross floor area.
Modular buildings have intrinsic advantages over conventional structures when it comes to sustainability and life cycle costs. LCC analyses are carried out to determine the overall costs that a building causes during its entire life cycle. Seen overall, over the entire life cycle of structures built using LG modular construction methods, the building's lifecycle costs are 12% lower than with conventional building methods. This has been proved by studies carried out by a recognised certification office using a number of completed projects.
If properly repaired and maintained, there is no difference from a conventionally constructed building.
The Liberty Group construction system with its self-supporting steel structural frame and non-loadbearing walls means that it is possible to adapt modular buildings very flexibly to changing requirements. Walls can be moved or opened up, and extra storeys added or extensions built in a very short time. The modular construction system is therefore extremely flexible and ideal for subsequent alterations and changes of use.
One of the greatest advantages of Liberty Group modular construction methods lies in the three-dimensional structure of the individual modules and the ability to link these to each other mechanically – and also to separate them again. These factors mean that the building can be removed, dismantled and reassembled easily ("mobile real estate"). Furthermore, the structural elements of each module can be 100% recycled, thus making a positive contribution to the reuse and recycling of building materials.
The storage capacity of the drywalls is not particularly important. With summer thermal insulation, the focus is on reducing inner thermal loads, caused by people and technology.
Like all other permanent structures, modular buildings are required to comply with the valid energy saving regulations and therefore meet the standards laid down in the EnEV (Energy-Saving Decree). The use of renewable energies required under the law combined with building component insulation, system technology and summer thermal insulation are easy to achieve using LG modular construction methods. In addition, it is also possible to construct low-energy modular buildings. A hospital has been built to "passive house"standards, for example, and a children's day care centre has been constructed as an EnergyPlus building. The ESH modular method of construction is therefore extremely suitable for energy-saving building.
A thermal bridge catalogue was created on the basis of a detailed calculation of the thermal bridge heat loss coefficients (and graphic illustration of the heat loss in the form of isothermal graphs); this then forms the basis of a precise calculation of the insulating properties of the parts of the building as part of the certification according to the energy saving regulations (not a flat-rate supplement).
A module for office use, for example, weighs about 290 kg/m² gross floor area, excluding the facade and final roof covering.
The steel structure of the modules is given a corrosion-proof coating. The external thermal skin (roof, gradient insulation and insulated facade) protects the module construction against harmful environmental and weather factors and stops it corroding.
With modular buildings, the load is transferred as concentrated loads, not distributed loads. Consequently, pad or strip footings at the module axes are sufficient. Special foundations are possible if the subsoil requires them.
In our modular buildings, we only use quality-tested materials and branded products made by German manufacturers, such as Knauf, Isover, Schüco, Sto, Herholz or Keramag.
With the double-shell Liberty Group ceiling system, the system ceiling depth is approx. 40 to 45 cm depending on the fire prevention requirements.