At one time a traveler could learn

At one time a traveler could learn about a region by looking at the houses. For example, he could understand what building materials were available. In areas with many wood houses, the traveler would have guessed that there were forests nearby. Stone houses would have indicated that stones were easy to get. And a closer look at the houses would have told the traveler even more about the area.People used to build houses that fitted the climate of their areas. For example, in desert regions there is a big difference between daytime and nighttime temperatures. Therefore, many desert people built houses with very thick walls. These thick walls served a useful purpose in the houses. In the winter the thick walls absorbed the sun's warmth during the day and radiated the heat at night. Desert people were relatively comfortable in their homes at all times because they built them to fit the desert climate.Later, the supply of fuel for electricity became both cheap and easy to get. The effect on housing was immediate. People began to build their homes according to fashion instead of utility. During that time, building materials were moved across continents, and people did not worry about how much fuel they used to heat and cool their homes. Houses no longer reflected the availability of building materials or climate.Houses with steep roofs could be found in the warm regions of the earth, even though these pointed roofs originated (起源于) in snowy regions of the world. Heavy snow falls off a steep roof. Another example is the use of glass. Houses made almost completely of glass could be found in very cold places. Yet ordinary glass does not insulate (绝缘) well because it neither keeps out cold air nor keeps in warm air. As long as fuel was cheap and easy to get, people could build any type of house any place.