The Materials Book

225 Building Climate: From Mechanical to Material Arno Schlueter The growing awareness of buildings as significant consumers of resources, emitters of greenhouse gases, and contributors to phenomena such as urban heat islands has moved them to the center of global endeavors to mitigate climate change, transition toward renewable energy, and improve the well-being of populations in cities. Energy for a building is consumed in two principal ways: first, through the materials, from the harvesting of raw materials to the actual construction process, and second, through the operation of the building. Depending on the construction, climatic context, and building systems, the consumption of the latter could be a multiple of the former. The energy used to operate a building serves a simple purpose: to keep the interior environment in a state that is healthy and comfortable for its occupants. In most locations around the world, the effects of outside conditions and our own contributions to the indoor environment, such as carbon dioxide, humidity, and heat, require flows of energy and mass in the building to maintain such a state. Heat needs to be moved, fresh air supplied, and contaminated air removed. Humidity, though not as critical as heat, cold, and light, should stay within certain thresholds. The increasing demand for comfort has led to electromechanical systems for heating, cooling, air-conditioning, and lighting. Air-conditioning—the ability to design the indoor environment independent of the outdoors—is a transformative technology since it