10. Building and construction

Website:	Hamburg Open Online University
Kurs:	Process engineering for the bioeconomy
Buch:	10. Building and construction

Gedruckt von:	Gast
Datum:	Montag, 21. Juli 2025, 23:00

Beschreibung

Learn about alternative, environmentally friendly construction materials.

Inhaltsverzeichnis

10. Building and construction

10. Building and construction

According to a United Nations study, the construction of buildings and the production of building materials accounted for around 9% of global greenhouse gas emissions in 2021; this corresponds to a total of around 3.5 Gt CO₂ (UN 2022). A large proportion of these emissions can be attributed to construction materials that are particularly energy-intensive to produce. Examples of this are steel, aluminum and concrete, whereby the greenhouse gas emissions from concrete are largely not due to its energy-intensive production, but to the process of deacidifying the clinker and the CO₂ released in the process.

Substituting these materials with renewable raw materials therefore offers an important starting point for reducing greenhouse gas emissions in the construction sector. Wood and wood composites in particular are mentioned in this context.

10.1 Wood as a building material of the future

Building with wood is not a new invention. For example, remains of Pfahlbauten (stilt houses or lake dwellings) have been discovered in the Lake Constance region, the oldest of which date back to the Neolithic period (approx. 3900 BC). Wooden piles were driven into the shallow water on the shore to build huts made of wood, straw and clay on a jetty. The construction of these Pfahlbauten offered the inhabitants protection from raids and direct access to the lake, which served as a transportation route and food source (bodensee.eu 2023).

Reconstruction of the Pfahlbauten at Lake Constance (Pfahlbauten Unteruhldingen) by pixabay_schnitzgeli (CC 0)

Today's motivation for using wood as a building material is fundamentally different from that of our ancestors. Thanks to a variety of alternative building materials, we are no longer exclusively reliant on the use of natural building materials, but wood offers some important advantages that speak in favor of its increased use today:

In the face of climate change, the substitution of CO₂-intensive building materials with wood, which can lead to a reduction in greenhouse gas emissions, is desirable.
Furthermore, wood as a building material can represent a carbon storage option. As already explained in Chapter 2, in plants the gaseous CO₂ from the atmosphere is converted into solid molecules (e.g. carbohydrates) through the process of photosynthesis, which form the basic building blocks of the macromolecules cellulose, hemicellulose and lignin, the main components of lignocellulosic plants. By using these molecules in the form of wood as a building material, the carbon remains bound for the life of the building. In combination with sustainable forestry, a CO₂ sink can be realized.
In contrast to mineral building materials, wood is a lightweight building material. This offers ecological and economic savings, particularly with regard to transportation costs.
In addition, wood has a lower thermal conductivity than conventional building materials such as steel or concrete, which is a favorable characteristic, particularly with regard to thermal insulation and the energy required for heating and cooling.
The wide range of applications for wood as a raw material offers the opportunity to reuse disused building material wood, also known as waste wood. The further use of waste wood by means of so-called cascade use is explained in more detail in chapter 10.3.

10.2 Possible applications for wood as a building material

In principle, wood can be used as a building material for all elements of a house. From the floors to the walls to the roof, wooden elements can be used. This can be increased to such an extent that complete houses can be built almost exclusively from wood (this is possible with log houses, for example, but also with modern houses in solid construction). For further information on the individual timber construction methods and timber construction elements, we recommend the clearly structured information platform of the architecture magazine BauNetz (BauNetz).

When using wood as a building material, it is important to protect the wood from moisture. As wood is an organic material, it can be decomposed by fungi and microorganisms if exposed to moisture for long periods, which leads to the destruction of the structure and thus to a loss of load-bearing capacity. Therefore, when using wood in construction, care must be taken during the planning and construction stages to ensure that it is protected from weather and living-related moisture (e.g. in the bathroom) by means of structural measures. The use of chemical agents to protect wood from moisture and pests (e.g. Xyladecor), which was very popular in the last century, is largely avoided nowadays due to the environmentally harmful and unhealthy properties of these substances.

To see and experience a modern solid timber house up close, all you need to do in Hamburg is take the S-Bahn to Wilhelmsburg. A 5-storey solid timber residential building, the so-called WOODCUBE, was erected there in 2013 as part of the International Building Exhibition IBA Hamburg. This building demonstrates how modern construction and living can work with sustainable raw materials.

10.3 Cascade utilization of wood

A major advantage of using wood as a building material is that the usability of this timber does not necessarily have to end at the end of its useful life. Depending on the condition and quality of the waste wood, it can be reused in many different ways. The waste wood should pass through several stages of utilization. This can be clearly explained using the example of a cascading watercourse. Just as the water slowly flows down the course of the river from stage to stage, losing potential energy with each stage, the waste wood should also be used in one form of utilization after another. Analogous to the energy loss of the water in the cascading watercourse, the wood loses structure with each form of use and can only be transferred to the previous form of use with great effort or not at all. The individual forms of utilization of this so-called cascade utilization are briefly presented below.

If the waste wood is of good quality, it should first be processed into solid wood. Examples of this are furniture, flooring or wall paneling made from reclaimed wood. Visually appealing effects can be created if, for example, old beams are processed into a new beamed ceiling or tables.

If it is not possible to use the wood directly, attempts should be made to produce chip-based products (e.g. pressed chipboard for furniture construction). The wood shavings are first pressed into board form with the addition of an adhesive. The resulting boards are then used as the starting material for new products. In furniture construction, these are usually visually enhanced by covering them with veneers (very thin layers of wood) or decorative foils before processing.

After chip-based use, the next smaller wood components, the wood fibers, should be recycled. This can be done in various ways, such as further processing into paper, medium-density fiberboard (MDF) or the viscose fibers presented in Chapter 5.

The final material use of waste wood is the production of chemical products. The substances lignin, cellulose and hemicellulose (the main components of wood) can be the starting materials for a variety of products. Processing can take place in a biorefinery plant; one such biorefinery plant is operated by the Fraunhofer Center for Chemical-Biotechnological Processes (CBP) in Leuna, for example. A short presentation of this plant can be seen in the following video

The final use of wood is for energy recovery. The energy stored in the wood can be converted into heat through combustion. This can then be converted into electrical energy via a steam cycle or used directly as useful heat (Höglmeier et al. 2016).

10.4 Other building materials made from renewable raw materials

In addition to wood, there are other renewable raw materials that can be used as building materials in different ways. There are a number of renewable alternatives to conventional insulation materials of fossil or mineral origin, particularly when it comes to thermal insulation. Hemp, cork, coconut fiber, seagrass, reed, straw or even wood wool and fibers can be used as insulating materials. All of these renewable materials have specific advantages and disadvantages that need to be carefully examined before use. In general, however, such materials are always carbon carriers whose long-term use removes carbon from the atmospheric cycle and stores it.

In addition to being used as insulation material, renewable raw materials are also used in roof construction. One option that is often associated with the North Sea and Baltic Sea region in this country is the use of reed for roofing. The reeds are processed into the distinctive thatched roofs according to a centuries-old building tradition. In addition to the visual advantages of this type of roof, such roofs offer good insulation. However, the costs as well as the installation and maintenance costs are significantly higher than for conventional roof types.