Life was once intertwined with the natural environment. People’s daily lives were full of sunshine, greenery, fresh air and exercise. Today’s way of life has brought changes, as we spend most of our time indoors, isolated from nature. In modern buildings we are confronted with poor lighting, artificial materials, low air quality, sedentary lifestyles and other factors that negatively affect our well-being.

We need to move from simple harm reduction, such as noise reduction, to creating spaces that support people’s many and varied needs. People want to live and work in spaces with natural light, with views of greenery and water; we want to be surrounded by plants and natural materials; we want to breathe fresh air. People’s needs and desires are many and, accordingly, we need to take a variety of approaches and guidelines into account when designing spaces. One of the simplest ways to create buildings that are pleasant for people is to integrate wood into the built environment.

Looking and touching wood

People generally have a positive attitude towards wood. We perceive it as a natural material that brings a feeling of comfort, relaxation and warmth. Compared to other everyday materials such as steel, plastic or stone, we tend to prefer wood for various reasons, one of which is its aesthetic appeal. The appearance of wood is influenced by several factors, such as the type of wood, the presence of knots, the colour, texture and surface finish. People usually like wood that looks coherent and harmonious, with only a few evenly spaced knots. However, it is important to note that there is a wide variability in preferences for wood.  Different individuals will prefer different types of wood based on their personal preferences alone, which may also vary depending on the context in which the wood is used.

One study compared people’s preferences for rooms with different wood content – including rooms that were completely wood-free and those that were fully furnished with wood. It showed that people rated rooms with medium wood content highest in terms of aesthetics, compared to rooms that were completely wood-free or made entirely of wood (Nyrud, Bringslimark and Bysheim, 2014). In contrast, another study investigating people’s aesthetic preferences for office desks showed the opposite results: desks were generally rated higher if they were made entirely of wood or entirely without wood (white) than if they contained a medium amount of wood or wood in combination with white materials (Lipovac and Burnard, 2023).

Besides the look of the wood, the feel is also important, as people often touch wood indoors. Again, wood is generally preferred over other everyday materials, and many people like the feel of natural, lightly treated wood that has not been coated with a finish. They usually describe such wood as warm and pleasant to the touch. One study looked at how older adults from Slovenia and Norway perceive fence handles made of different materials. People generally liked wood better than steel, regardless of the participants’ country of residence, and regardless of whether the participants could only touch the materials or look at them when giving their ratings (Lipovac, Wie, Nyrud and Burnard, 2022).

Incorporating wood into interiors can make them more attractive to people. Such spaces are not only visually pleasing to people, but can also affect them in terms of well-being and stress. In one study, 61 participants were exposed to two offices, one furnished with wood furniture and the other with white furniture. Participants spent 75 minutes in each of the rooms, during which they were exposed to a stress-inducing video. Compared to the control room with white furniture, participants in the room furnished with wood had lower average levels of cortisol – a biomarker of stress (Burnard and Kutnar, 2020). Although many open questions remain in this scientific field, some research suggests that visual exposure to wood alone could improve the well-being of building occupants.

Wood and air quality

In the case of timber buildings, it is necessary to take into account the substances that come from the wood, in particular the so-called volatile organic compounds (VOCs). These are chemicals that can be released from wood and are important for the quality and odour of the air in the building. Wood is composed of various substances such as cellulose and lignin, but also contains various other chemicals. These chemicals can vary depending on the type of tree from which the wood comes and where it was grown. The way the wood is dried, including temperature, also affects the emissions of these chemicals. When wood is dried, especially if it is freshly dried, it can release a lot of volatile organic compounds into the air. Wood from certain tree species, such as pine, which is often used in construction, tends to release more VOCs than wood from other trees.

VOCs can affect indoor air quality in a variety of ways and, as a consequence, human well-being and health. Some of them can make the air smell pleasant, others unpleasant, depending on people’s specific preferences. Some of these chemicals, such as aldehydes, can be irritating to the eyes and nose, and in high concentrations can be harmful to health. One of them, called acrolein, has been linked to lung problems and asthma (Alapieti, Mikkola, Pasanen and Salonen, 2020).

The good news is that in most wooden buildings, levels of these VOCs are usually too low to cause health problems. However, some chemicals in wood, such as terpenes, which give wood its pleasant smell, can have a positive effect – they can improve mood, help relaxation and boost the immune system. However, problems can arise when terpenes react with other chemicals in the air. In this case, particles in the air may form that are not beneficial to health. Fortunately, in typical indoor environments, these reactions do not usually reach harmful levels.

Wood can thus have a soothing smell and although caution must be taken with some chemicals, these are usually at safe levels. However, it is important to remember that each room is unique and it is recommended to regularly monitor air quality and, if necessary, make changes to ventilation systems and habits.

Acoustics and wood

Acoustics plays a key role in the quality of life in buildings, as it determines how we experience sound in a space. When we talk about the acoustics of a room, we are talking primarily about how sound reflects off walls, ceilings, floors, furniture and other objects. These interactions affect how sound propagates and dissipates in a room. It is important to choose the right materials for different parts of the room, depending on how the room will be used – for talking, listening to music, working or something else.

A common aim of room acoustics control is to ensure speech intelligibility. In spaces where communication is essential, such as offices, classrooms and conference rooms, users need to be able to hear and understand each other without undue effort. More often than not, the aim of room acoustics is to reduce noise, which is annoying and distracting for people and can quickly lead to higher stress levels and poorer ability to concentrate. Appropriate acoustic design can help to reduce reverberation, thereby reducing noise and making it easier for users to communicate.

From an acoustics point of view, sound absorption – the ability of a material to absorb sound energy – is important in materials. This limits sound reflections and reduces the reverberation time of the room, which generally improves the acoustic comfort of the room. The most commonly used materials for sound absorption are various wools, foams and fabrics formed into panels, sheets or coverings that can be placed in the ceiling and wall area of a room.

Wood is not the best at absorbing sound. In fact, sound is mostly reflected from wood, similar to other rigid materials such as concrete and stone. However, wood can be treated in such a way as to create small holes in the wood into which sound can enter. In combination with other materials, this can create a sound absorber, where sound energy is converted into heat as it propagates through the porous structure. The correct arrangement and design of the holes can influence the resulting absorption properties, which are strongly dependent on the frequencies of the sound. It is quite different when we want to increase the sound reflection on wood, where many factors play a role, including the type of wood, surface treatment and design of the wood structures. Thus, it is not surprising that wood, due to its wide adaptability and usefulness, has historically been found in the most acoustically demanding spaces, such as concert halls, where massive wood structures are used to control the sound reflection (Alapieti et al., 2020).

The sound insulation properties of wood are also slightly worse, which in practice is mainly observed in the low-frequency range. High-density materials such as brick and concrete would perform better in this range.  Wood is therefore used in combination with other materials, such as plasterboard, to create multi-layered structures with high sound insulation properties. Similar to the sound insulation performance of airborne sound, wood performs less well in the case of impact noise, such as people walking, which can be disturbing in buildings with a timber structure.

These acoustic shortcomings of materials have led to many original solutions. The double construction – two separate walls with an air space in between – prevents the transmission of sound between rooms. A dropped ceiling – a second ceiling suspended below the main ceiling of a room – can also reduce noise. There are also various combinations of wood with other materials, such as concrete, which help to improve the acoustic properties of a room.

Wood is therefore not in itself the most suitable material for improving the acoustic performance of buildings, but it can be used successfully in construction if its limitations are properly understood. Conversely, sub-optimal use of wood can lead to noise and reverberation problems, which can make it difficult for building occupants to communicate, increase stress and make it harder to concentrate.

Conclusion

Wood has many advantages in designing spaces to improve the quality of living. Positive effects are usually experienced just by looking at, touching and smelling the wood. Other benefits are seen in its ability to regulate temperature and relative humidity and its antibacterial effects. In some cases, building with wood may seem questionable. Volatile organic compounds released from wood can be problematic, but these are usually present in quantities too low to be harmful. In particular, we need to pay attention to room acoustics, which requires a little more knowledge, consideration and care in timber construction.

In general, the use of wood as a material seems to be one of the most appropriate ways of improving the quality of life in buildings. For every disadvantage of wood, there are many advantages, especially in terms of comfort, which other materials find difficult to match. The science in this field still needs to develop considerably before we can know exactly how and where to use wood to create pleasant and healthy spaces. Nevertheless, we already know a lot and, given this knowledge, wood seems to be the obvious choice for building living spaces in many contexts.

References

• Alapieti, T., Mikkola, R., Pasanen, P. in Salonen, H. (2020). The influence of wooden interior materials on indoor environment: A review. European Journal of Wood and Wood Products, 78, 617–634. https://doi.org/10.1007/s00107-020-01532-x
• Burnard, M. D. in Kutnar, A. (2020). Human stress responses in office-like environments with wood furniture. Building Research & Information, 48(3), 316–330. https://doi.org/10.1080/09613218.2019.1660609
• Lipovac, D. in Burnard, M. D. (2023). Human Preferences for the Visual Appearance of Desks: Examining the Role of Wooden Materials and Desk Designs. Buildings, 13(7), 1680. https://doi.org/10.3390/buildings13071680
• Lipovac, D., Wie, S., Nyrud, A. Q. in Burnard, M. D. (2022). Perception and evaluation of (modified) wood by older adults from Slovenia and Norway. Wood and Fiber Science, 54(1), 45–59. https://doi.org/10.22382/wfs-2022-05
• Nyrud, A. Q., Bringslimark, T. in Bysheim, K. (2014). Benefits from wood interior in a hospital room: A preference study. Architectural Science Review, 57(2), 125–131. https://doi.org/10.1080/00038628.2013.816933

Authors: dr. Dean Lipovac, dr. Rok Prislan, dr. Črtomir Tavzes

Photos: Miran Kambič