KfW Award "Building and Living

Timber construction can be cheaper than standard construction - At the same time significantly better CO2 balance

Current comparative calculations based on realized new buildings in timber construction show: Building with wood does not have to be more expensive than the standard construction method. This result is surprising, as it contradicts the common perception that timber construction is more expensive. At the same time, the CO2 balance of timber construction is significantly better; as a result, its CO2 avoidance costs are very favourable, in some cases even negative. An expansion of timber construction would therefore be climate protection at comparatively low cost.

The architect and developer of the Legep construction software, Holger König, has balanced the construction costs and CO2 emissions for the production of five public and private timber buildings and compared them with the results that would have been produced for the same buildings if they had been built in the conventional way. Legep can be used to calculate the manufacturing and life-cycle costs, energy requirements and environmental impact of buildings. In this case, König only looked at manufacturing. For the prices, he used current sirAdos data, which represent the market very realistically. He then went to the trouble that many architects, civil engineers and building owners shy away from: He modeled the buildings with the same area and cubature and the same energy standard, but replaced the wooden components with conventional materials - depending on the building project, solid masonry in brick, sand-lime brick or aerated concrete, or a column-beam supporting structure made of reinforced concrete. He used reinforced concrete for the floor slab, cellar, ceilings and flat roofs, mineral wool or polystyrene for the insulation, and plastic or aluminum frames for the windows. König explains the fact that four out of five buildings in timber construction cost less or the same as in standard construction with the industrial-technical development that many timber construction companies have undergone in recent years. Two of the timber buildings even achieved a negative CO2 balance in the manufacturing phase due to the large amount of renewable raw materials used, which act as carbon stores. In the other three buildings, a slightly higher proportion of non-wooden components, which every timber building also contains, caused the slightly positive CO2 balance.

If one relates the difference in CO2 savings to the difference in construction costs, one obtains the CO2 avoidance costs of timber construction. Negative abatement costs here mean that the builder has saved costs with timber construction compared to standard construction and at the same time protected the climate.

By increasing the proportion of timber construction, more climate protection can be achieved at low or even negative costs, while at the same time strengthening rural areas. The green-red state government in Baden-Württemberg has recognised this and created more favourable framework conditions for the building material in its state building code, which was amended on 1 March (information here). In contrast, some state building codes still contain legal obstacles to building with wood.

The city of Munich also wants to convince more builders to use timber construction: as part of its "Munich Energy Saving Promotion Programme", it has been granting a CO2 bonus for the use of timber and other renewable raw materials in building construction of 30 cents/kg since 2013 (information here).

A high insulation standard with insulating materials made from renewable raw materials is also a contribution to climate protection. The plant raw materials from which the insulating materials were obtained have bound CO2 from the atmosphere, which is now stored in the building material for long periods of time. And finally, heating based on renewable energies also reduces CO2 emissions.

The Agency of Renewable Resources (Fachagentur Nachwachsende Rohstoffe e.V.). (FNR) funded the determination of LCA baseline data for the Legep programme with funds from the Federal Ministry of Food and Agriculture (BMEL) between 2004 and 2006.

You can find the program here: www.legep.de

The five calculated buildings:

The foundations for the calculations were laid in the following project: https://www.dbu.de/OPAC/ab/DBU-Abschlussbericht-AZ-29239.pdf.

Source:

Keywords:
Building materials / Construction, DE-News, Wood construction, Climate protection, New books and studies, Life cycle assessment, Ecology