text: The term is also used in the field of environmental engineering, particularly to describe construction or renovation projects on previously built sites, to improve water quality in nearby streams, rivers or lakes. The concept has also been applied to changing the output mix of energy from power plants to cogeneration in urban areas with a potential for district heating.
  Sites with extensive impervious surfaces (such as parking lots and rooftops) can generate high levels of stormwater runoff during rainstorms, and this can damage nearby water bodies.  These problems can often be addressed by installing new stormwater management features on the site, a process that practitioners refer to as stormwater retrofitting. Stormwater management practices used in retrofit projects include rain gardens, permeable paving and green roofs. (See also stream restoration.)