Dr Anna Sandak, research group leader of the Wood Modification group at the InnoRenew CoE, has recently published Bio-based Building Skin, a book she wrote with Dr Andreja Kutnar, director of the InnoRenew CoE, Dr Jakub Sandak, researcher at the InnoRenew CoE, and Dr Marcin Brzezicki, Wroclaw University of Science and Technology.

Biomaterials are sustainable and versatile, but their use in façade suffers from a lack of training in proper use. This book aims to change that by addressing a wide audience of architects, engineers, designers, and contractors so that they may gain technical knowledge and environmental awareness about the design, use, and performance of biomaterials as building skins.

Façades are integral to buildings. As the “skin”, they are the interface between outside and inside, and they can be designed and engineered to make structures more attractive, energy efficient, responsive to the environment, and restorative to occupants. Biomaterials make bio-based façades a promising alternative for new construction as well as renovation and retrofitting of existing building stock to help the built environment become healthier and more sustainable.

We talked with Dr Sandak about her book, her thoughts on biomaterials, and how she envisions the InnoRenew CoE’s role in this renewable materials technology.

In the book, you talk about history and how bio-based façades were used in the past but fell out of favour. Are scientists and architects beginning to understand bio-based façades were useful and should now be seriously considered for the built environment?

Wood and other bio-based materials are one of the earliest building materials, but, luckily, due to recent developments, are now being considered as one of the most innovative. Unfortunately, not all architects are aware of bio-based materials, and education about timber architecture is rather ignored. By using bio-based building materials, we can move the traditional building concept towards green architecture.

Different natural materials usually look good together, even if they have different forms or patterns; therefore, biomaterials give an impression of being suitable for any context.

And, in fact, they are! Bio-based building materials fit very well with the general concept of minimizing the amount of waste based on the “reduce-reuse-recycle” paradigm. They allow architects to create an iconic structure, while also providing comfort for occupants, good performance, and aesthetic pleasure.

The InnoRenew CoE’s activities are centred on two key technologies: wood modification and restorative environmental and ergonomic design (REED). As an expert in wood modification, what makes you enthusiastic about the use of bio-based materials?

No two pieces of wood are the same, and no other building material is so honest and genuine. The properties of wood are changing as a response to variations in the surrounding environment. Such changes are autonomous and do not require any control mechanisms. The most exciting prospect is to take advantage of these mechanisms and use them according to our aspirations.

In the context of modification, wood can be enhanced by several processes that improve their surface, bulk, or both. Several modification methods are already established and commercialized, but there are still a lot of things to discover. The most fascinating for me is using biomimicry and bio-inspiration while searching for new wood modification solutions. The other aspects, which we try to investigate in our team, are understanding the hierarchical structure of wood (and other biomaterials) and using computational modelling for designing new functional biomaterials.

In terms of REED, what architectural and human health problems are solved by using bio-based materials?

Biomaterials enable prefabrication and fast installation. Due to a favourable weight to load-bearing ratio, they enable erection of multi-storey structures while providing great design freedom. Moreover, they possess low environmental impact due to their renewability and cascade use. The production of wood as a building material involves only about 10 percent of the energy consumption required to produce an equivalent amount of steel!

Another important advantage is their naturalness and ability to reconnect people with the natural environment according to biophilic design.

What is the most interesting thing about bio-based façades for materials and building scientists?

None of the other materials can be utilized in such numerous ways as wood. It is remarkably versatile, aesthetically charming, and, at the same time, entirely recyclable. There are still a lot of things to discover and improve, which I believe will provide an interesting scientific challenge to solve in the future.

Can you give some examples of bio-based façades already being used and explain how they are successful (or not)?

In our book, especially in chapter 4, we collected examples that we hope will inspire the next generation of architects. We wanted to show how buildings interact with occupants and explore what motivated architects along the design process.

It is important that the built environment is sustainable, safe, comfortable, and also beautiful since a majority of people spend most of their time in offices, factories, or homes. In particular, I appreciate the projects of Renzo Piano for his innovative approach to rediscover wood as a building material.

Is there controversy or concern about using bio-based façades? Why aren’t they used more often?

There is an overall opinion that wood and other bio-based materials used for façade require particular and frequent maintenance. In fact, any façade material should be regularly cleaned, renovated, and replaced, if needed. If you look at tall glass buildings, you will realize that they are cleaned most of the time.

I agree that implementation of bio-based materials requires knowledge about how to do it correctly, but there are so many new materials, including modified wood, that perform well even in demanding environments. Therefore, the most critical consideration the selection of correct material for particular application.

What role do you see bio-based façades fulfilling in the years to come? What do the next five years look like for this technology and how will the InnoRenew CoE, especially the Wood Modification group, assist in bio-based façade design, development, and use?

I wish bio-based materials will follow the trend of active and adaptive façades. This means that they will provide additional functions other than just being the static barrier between the interior and the environment.

In buildings, adaptive façade systems may assure controllable insulation, radiant heat exchange, daylighting, solar shading, humidity control, ventilation, and energy harvesting. This can be achieved by designing new materials, and I believe that the source of inspiration may be found in nature. In fact, the message for architecture that emerges from observing nature is “less materials, more design”.

I hope that at the InnoRenew CoE, we will be able to create new bio-based materials, successfully implement them as building elements, and finally provide comfort and wellbeing for future users.

Bio-based Building Skin is an open access book published by Springer as part of their Environmental Footprints and Eco-design of Products and Processes book series. It is available for download and order.