Khi năng lượng giá rẻ, hấp dẫn để loại bỏ các biến thể vốn có trong ánh sáng ban ngày và cung cấp tất cả các ánh sáng nội thất với ánh sáng điện được bổ sung bởi một vài cửa sổ. Mặc dù daylighting cung cấp cơ hội đáng kể cho việc bảo tồn năng lượng, ngân sách cho hoạt động chiếu sáng và bảo trì chỉ chiếm một phần rất nhỏ trong tổng số chi phí xây dựng | Fire Suppression In high-rise buildings and buildings with large areas there are places that can t be reached by firefighters ladders and hoses. While most fire deaths occur in smaller often residential buildings larger commercial industrial and institutional buildings create a potential for many deaths and injuries from a single fire. High-rise buildings require an inordinate length of time to evacuate. Stack effects can be created in high-rise buildings over 23 meters 75 ft tall. Such buildings must have their own firefighting system. This is usually an automatic sprinkler system. Everybody knows that water will put out a fire. Water cools smothers emulsifies and dilutes the fire. But it also damages building contents and can conduct electricity when used as a stream less so as a spray . Water will not put out burning oil the flammable oils will float and burn on the surface. When water hits a hot fire the steam can harm firefighters. Despite these disadvantages water remains one of the main ways to suppress a fire. The earliest sprinkler system consisted of a bucket of water suspended over the likely location of a fire by a black powder fuse. When a fire lighted the fuse it blew up a powder keg and dispersed water theoretically in the direction of the fire. Automatic sprinkler systems extinguish incipient fires before they have a chance to get out of control. The sprinkler system Fig. 45-1 consists of a network of pipes in or below the ceiling. The pipes are connected to a water supply and have valves or sprinkler heads that are made to open automatically at a certain temperature. Each sprinkler head is controlled by a plug or link of fusible metal that melts at a temperature of around 66 C 150 F . Sprinkler heads are so efficient that one to two heads can usually put out a fire. Building codes commonly allow sprinklered buildings to have greater distances between exits eliminating one or more stairways in a large building. By allowing larger floor areas between
