It is doubtful that any built environment professional inadvertently wants to cause the degradation of ecosystems, climate change to continue, or for people to become ill because of their decisions about building materials. Unfortunately, this is the current norm. This book set out to discuss the principles and issues behind evaluating building materials for sustainable construction, and has explored a broad variety of issues, discussed new and established methodologies, and used case studies to illustrate how decision-making processes might change to reflect shifting requirements and ethics. The size and complexity of the book clearly indicate that this is neither a simple nor straightforward process. Rather, there is much to be considered. The most important overall message of this book is that each material should be considered according to the numerous criteria outlined here and a recommendation of whether or not it can contribute to making sustainable buildings will vary depending on many parameters. These include where in the world a particular material is to be used, where the material comes from, how it is to be used in the building, and whether or not the building users have particular health requirements that might be affected by the indoor air quality. No material is good in all aspects and the best (and for designers most unpalatable) advice for sustainability is not to build.

Where building is unavoidable the most important objective in relation to mitigating climate change, is to reduce the nonrenewable operating energy to zero, whether this is energy for heating or cooling or running the other services. When it comes to sustainable design, the materials used to achieve this goal have to be selected based on their ability not to reduce local ecosystem services, but if possible to improve and support these. The material also needs to be considered for its effects on the health of its users. However, materials are only part of a building—the design, form, and systems of the latter also have to be appropriate for its purpose. Thus, choice of materials and overall building design need to be synchronous. What this book argues is that this complex consideration of materials needs to be part of making sustainable buildings.

In the past this was all part of local vernacular traditions, where the choice of materials had been honed over many years and through many experiences. This approach has been lost with industrialization, but new ways of thinking about sustainable materials also require building professionals to think about the local context, climate, ecosystems, and health impacts. A building that lasts a long time with minimum maintenance may be a good strategy for sustainability and this again means thinking about climate. Building in earth, a low embodied energy material, may not be appropriate for all locations or climates. This is where vernacular traditions have much to teach, because they evolved in response to climate, locally available materials, and cultural context to make buildings that would have a minimum environmental impact. The big difference between such traditions and now is that expectations about the building process have also changed. It is no longer acceptable to wait a year for an earth wall to dry out before occupying a building. Rather, numerous pressures demand accelerated construction, which can conflict with sustainability considerations.

To be sustainable, the built environment has to be part of a sustainable society that operates in a sustainable way. Of great importance is employing strategies to decrease (or eliminate) nonrenewable operating energy, when possible to construct with low embodied energy materials that will be easy to maintain, and to design spaces that are flexible enough to be adapted to new uses over the life of the building. Careful consideration of the impacts that extraction and manufacture of materials have on ecosystems, and the effects of materials on the health of building users is also of paramount concern. This book asserts the importance of considering all of these parameters when choosing building materials.

This book has brought together knowledge from many fields and applied it to built environment design, asserting that such an integrated or holistic approach is essential for complete evaluation of materials. Some sustainability considerations, such as those discussed in Parts I and III, are only in the early stages of being included in architectural decision making. Others such as lifecycle energy assessment (discussed in Part II) are more common but still not universal. This book further proposes that transdisciplinary considerations of building materials are essential for a more complete understanding of their total implications and impacts, on people, ecosystems, and the climate. What is needed is powerful individual drive from building professionals to look for a greater level of detail and to find information on all relevant facets of materials. This in turn might require rethinking many aspects of traditional architectural construction, to include these broader and more complex considerations if sustainable buildings are to be the result.