While the owner of the 2.6-million-sq-ft Empire State Building gears up for a $500-million renovation, designed to cut energy costs by 38% and be a model for other green office-building retrofits, a construction firm that recently moved into its green ESB offices is releasing hard data on the 24,000-sq-ft retrofit. Skanska USA Building, which moved into its 32nd-floor space in November, reports it has reduced its energy bill by 46% over its smaller, previous offices elsewhere. Photo: Guy Lawrence / ENR Building landlords target $4.4 million in yearly savings. This fall, Skanska expects to be awarded LEED Platinum status for
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.