The Materials Book

228 occupants. Before the expansive use of active building systems for heating, cooling, and ventilation, buildings were constructed in ways that would regulate the interior climate or temperature based on their overall form, the size of openings (windows, doors), and type of building envelope. However, in past decades the global trend has shifted. By the late 1960s, most new homes in the United States had central air conditioning, and window air-conditioners were more affordable than ever. Currently in middle- income countries, such as China, passive building systems are becoming obsolete, and a “new vernacular” is quickly spreading that heavily relies on active building systems. In 2013, more than eight times as many air-conditioning units were sold in China than in the United States. 1 Designing for Natural Ventilation: Climate–Architecture–System Alpha Yacob Arsano With the advancement of technology in the building industry, temperature regulation that was scarcely imaginable a few decades ago not only has become a reality in cities around the world, it has also led to an increase in energy and material consumption. Buildings in cities with hot climates now share similar technologies with ones located in cold or temperate climates. Climate-responsive building design that relies primarily on passive strategies to regulate interior temperature is being replaced by a new trend of active systems that require large amounts of energy and material. Vernacular buildings are historical examples of passive systems: they respond to the climatic context using the available natural resources to create healthy and comfortable spaces for