Changes

By the late 4th millennium BC or at least early 3rd millennium BC, it was evident that if people were going to live in cities then they had to figure out a way to keep cool. In Mesopotamia, modern Iraq and Syria, and Egypt the earliest cities already show evidence for cooling methods. Already by 7000 BC, homes were made of mud in the Middle East, which allowed them to stay relatively cool in the summer months. Mud insulates a home from heat seeping in during the summer, while it also acts to seal in heat during the winter. However, to live in larger cities, home also had to be designed differently. One form of design that helped things stay cool was to keep houses near each other. Cities were very compact, which helped to create more shade. This allowed many homes not to receive direct sunlight at all hours and created shade for people to move around their homes, courtyards, and neighboring streets. The use of mud for construction material also enabled homes to stay relatively cool by insulating homes from outside temperatures. Courtyards and alleyways between homes were used as a way for air to circulate and create a breeze, and to create cross drafts, helping to keep air flowing and create cooler conditions. Homes could also be oriented towards the direction of prevailing windows, helping air flow through the house. Ventilation were also sometimes built that encouraged trapped air to flow through the house. Two outer walls, with a small gap between the two, or a vent would be built that would capture air and that air would be circulated around the house. Another early device known to capture wind and circulate air in houses in Iran, Egypt, and elsewhere in the ancient Near East were wind catchers. These were tower-like structures built to capture airflow and then that air would be brought downwards to the home. Clothing itself was also effective for staying cool. What may seem counter-intuitive, but wearing wool or thick clothing in summer could help cool someone in a hot place. As the person quickly sweats, air hitting that moisture, as well as possibly water added, would then make the person's skin feel cool. Encouraging sweating or using water in cloth which did not evaporate quickly could act as a coolant. Planting vegetation also helped to keep houses cool. By planting along the walls and courtyards, this helped to produce cooler temperatures by preventing the walls from absorbing heat. Other strategies to stay cool was to dig houses slightly underground so that natural soil would help insulate the house from outside temperatures. This kept houses cool in the summer and warm in the winter. Already in the Bronze Age, by around 1800 BC, ice houses or ice storage areas were created so that ice could be brought in and kept in these presumably underground shelters, where the ice would be used to create either cool drinks (or even a form of ice cream) or be used to cool someone. The Roman period gives us some of the terminology we use for summer. For instance, the expression "dog days of summer" comes from the ancient Latin phrase that referred to the star Sirius, which is the brightest star in the night sky and is part of the Canis Major (Greater Dog) constellation. This star would rise high during mid-July to late August, which is the period referred to as the dog days of summer, where the rising of the dog star was considered responsible for bringing stifling heat in the summer. Many people simply went to the frigidarium, or a cold or cool pool in bath houses found in most Roman cities. These pools would sometimes be cooled using ice brought in from the mountains and stored in underground shelters that kept ice from melting in the summer months. Some Roman houses have been found to have a system of pipes taht would circulate cold water around the walls, with the pipes inside the outer wall, to help keep the walls cool and the entire house feeling colder. The opposite, which was circulating warm water, would be done in winter.