Chapter 1: Introduction 1 SIMULATION OF HISTORIC BUILDINGS for enhancement of preservation and energy performance – issues and methods Torun Widström This image cannot currently be displayed. KTH Architecture and the Built Environment Doctoral Thesis KTH Stockholm, Sweden, 2019 2 Chapter 1: Introduction KTH, Royal Institute of Technology School of Architecture and Built Environment Dept. of Civil and Architectural Engineering Div. of Sustainable Buildings SE-100 44 Stockholm Sweden Copyright for all illustrations with named sources belongs to those authors/creators Copyright for the rest of the material in the thesis © 2019 Torun Widström Cover illustration and photos without specified source: Torun Widström. All rights reserved. Printed in Sweden by Universitetsservice AB TRITA-ABE-DLT-1918 ISBN 978-91-7873-217-3 Doctoral thesis which with the permission of KTH in Stockholm will be defended at a dissertation on Tuesday June 4th 2019 at 01:00 PM in lecture hall B2 at KTH, Brinellvägen 23, Stockholm. Chapter 1: Introduction 3 SIMULATION OF HISTORIC BUILDINGS for enhancement of preservation and energy performance – issues and methods “Science is not only a disciple of reason but also one of romance and passion.” – Stephen Hawking 4 Chapter 1: Introduction Chapter Preface1: Introduction 5 Preface History History is not dates. It is not the years of succession of Egyptian pharaohs, not the date of the Battle of Hastings and not a timeline recording the names of victorious kings and warlords. History is not words. It is not the text on the Rosetta stone, not Sumerian cuneiform or ancient runes. It is not letters and books from the past, not old orally transferred myths and legends, nor the written testimonies from people who lived centuries ago – or even decades ago. It is not even the books written about what happened in the past. History is not things. It is not the Chinese terracotta soldiers, the Gokstad ship, Cretan bull head statues or the frescos of Pompeii, nor coins and ceramics from any archeological dig, testifying about long-gone everyday life. It is not valued baroque furniture, impressive paintings of kings and nobility, or jewelry and robes once borne to show wealth and status. History is also not buildings. Not the Mayan pyramids or the Angkor Wat, not the gothic cathedrals of Europe, not Greek or Japanese temples or the rich reminiscences of ancient Rome. It is not Göbekli Tepe, the Bamyan Buddahs, Stonehenge or any of countless impressive fortresses and castles. It is not even the more humble buildings, like ornamented 15th- – 16th- century timber frame houses, countryside churches or sturdy log houses. History is none of these. But it is the stories that they tell. History is the knowledge that we need in order to understand of how the people before us perceived their world and their lives, and how those perceptions have shaped their actions and choices. It is the understanding of how those perceptions have varied under different circumstances, and evolved over time. It is what makes us able to analyze our present perception of our choices in life and make as informed decisions about our future as possible. On an individual level, when a person loses his memory, he loses his orientation in time. People who do not have anything to navigate after tend to move in circles, repeating the past, not by choice but because they cannot see that it is happening. We need our roadmaps in order to be able to move forward, to be able to set a course for a specific destination and not drift aimlessly through time. The same mechanism can be seen in groups of people as well, and as a species we also need access to our past in order to be able to consciously choose our future actions. Today we live in a time of urgency. But our realization of that urgency has taken time. In 1824 Joseph Fourier noted that the atmosphere had a property that made it retain heat at the surface of the earth, in 1859 John Tyndall discovered that CO2 had an important role in that property. Interesting science but not yet alarming. In 1896, however, Svante Arrhenius made some calculations and came to the conclusion that the CO2 that humans set free in the atmosphere through activities like burning fossil fuel could indeed create a rise in the global temperature, the first time a man-made impact on global climate had been shown to be possible. Still there was no sense of urgency, though, the idea that it was actually going to take place in real life remained hypothetical. In the 1950s global warming and resulting climate change passed from being a hypothetical threat to a very real one, as it started to be possible to measure the effect in reality. However, given the lack of any directly alarming consequences, and the fact that the benefits of the use of fossil fuels were too great to voluntarily desist from, the concept went from something to theorize over to something to monitor, but not to something to do anything radical about. 6 Chapter Preface1: Introduction Consciousness about a need to reduce energy usage rose and methods to do so were introduced, but there was still no urgency. Yet. Then the consequences started to show up, with coral bleaching, melting glaciers, species starting to lose their habitats and disappearing or migrating, diseases spreading to new areas, crops failing due to more frequent and more severe droughts or flooding and more volatile weather starting to cause damage on a scale that had not been seen before. And we have had to realize that more than ever we do need to make informed decisions and take action. We do need as clear a perception of our situation as possible, in order to be able to make conscious choices. We need to be innovative and efficient in dealing with it, and we need ingenuity, knowledge and cooperation. However, as humans, we base our actual choices of action on how we perceive the world, and in that context we also need history. So history is not the dates, the words, the artefacts or the buildings or anything else belonging to cultural heritage. But those facts and things are what give us access to history, to that understanding of the human perception of life. Preservation of the items and buildings of the past and making them accessible to people, though, has a tendency to require energy. This constitutes a conflict of interests, since we still have not found ways to reduce our energy usage or replace the energy that we use with CO2-neutral alternatives at a pace that will improve the situation – and we might never succeed with that in time. In 2018 80,5 percent of the energy that we used globally came from CO2-emitting heat sources like coal, oil and gas, and the usage of those fuels increased by 6,6 percent compared to the use of them the previous year (IEA). Total CO2 emissions increased by 1,7 percent and reached a record high. The increase of CO2 concentration in the atmosphere from 2017 to 2018 was 2,4 ppm, or 0,6 percent, a mindboggling increase in one year considering the size of the volume. Despite the efforts being made, despite China increasing its use of renewable energy by 10,9 percent and Europe actually reducing its CO2-emissions by 1,3 percent in that one year, in net terms we are still emitting more and more CO2 and still speeding up global warming, not slowing it down. Therefore, while we need to preserve our cultural heritage, using more energy to keep it accessible will risk making the situation worse. Also, climate change itself may constitute a threat to the built cultural heritage. The older the buildings that remain are, the more likely it is that they can be characterized by two things. Firstly, they are likely to have been of importance from the time of their construction, and therefore built to be able to withstand time, using the best materials and skills that their builders could muster. Secondly, they are likely to have been built in ways that were well adapted to the local climate, making them survive for a long time without such damage or loss of function that would have led people to abandon or demolish them. This is the reason why climate change becomes a serious threat – buildings that have proved suitable for one climate may be less suited for another. In addition to that, the traditional ways of maintaining them that worked in the historical ambient climate might not be as functional in a new one. Now the situation is urgent. We need to reduce CO2-emissions, and buildings accounted for 28,8 percent of the world’s total emissions in 2018. Therefore, if the CO2 levels are going to level out or be reduced at some time in the near future, the building sector has a lot of work to do. But we need to do that while maintaining suitable indoor climates that are not only comfortable enough for people but also ensure the preservation of our cultural heritage. So how do we find ways to do that? This thesis deals with building simulation as a tool for understanding the mechanisms of historic buildings, using that knowledge to identify issues necessary to address and to be able to design strategies to ensure preservation as well as minimized energy usage. Such a tool can Chapter Preface1: Introduction 7 also enable assessment of potential strategies so that possible consequences can be evaluated in advance instead of afterwards, when damages have already been done.