In 1973, an energy crisis led to the development of ASHRAE Standard 90. This event served as a catalyst for the creation of building design efficiency requirements, which eventually led to the creation of what is now known as the energy code for buildings. These requirements are crucial in America because 39 percent of all energy consumption in the U.S. takes place in the residential and commercial sectors.
In the commercial sector, space heating consumes 25 percent of all consumption, with boilers being among the most popular heating equipment. For this reason, policies for energy efficiency invariably target boiler efficiency.