Despite its many benefits, district energy – when a single energy source serves more than one building – has not caught on and become widespread in the US, reports HPAC Engineering.
The root causes are that it takes longer to see a payback, most building owners don’t know what their actual heating and cooling costs are to be able to make a comparison and the lack of a well-defined energy policy, says author Steve Tredinnick, vice president of energy services with Syska Hennessy Group.
A district energy system is comprised of three major components – a thermal energy generating plant, a distribution system with piping and building interconnections with valves and meters that act as transfer stations.
Among its benefits are:
- better space utilization, since interconnected buildings can use the space that would have been allotted for heating and cooling for additional rental income;
- better operations and maintenance, since district energy systems are typically staffed around the clock;
- less expensive compared to in-house heating and cooling systems in terms of initial and life-cycle costs;
- better efficiency, with a 75 percent improvement when used with combined heat and power (CHP) or cogeneration.
It’s considered a well-kept secret because most of its components are out of sight and so the public is not aware that their hometown or university campus uses it.
Tredinnick reports that typically, district energy systems are found where load densities are high, reliability is prized, and/or payback requirements are not as stringent as elsewhere.
It is used by college and university campuses, major airports, large health-care and corporate campuses, manufacturing facilities, resorts, downtown business districts, government and municipal building complexes, military installations and the like.
He says that while the oil crisis of the 1970s triggered the Heat Supply Act in Scandinavian countries, requiring all electricity-production facilities to recover useful heat for district-heating networks and that buildings connect to a district energy system generated via CHP, in the US, the reaction to the crisis was not as focused and did not result in any long-term energy-policy solutions.
But he points out that district energy is on Congress’ radar, with briefings sponsored in both the House and the Senate. District energy does receive investment and production tax credits.
This measured progress will change as awareness grows and district energy catches on, Tredinnick concludes.
In May, the State University of New York, Cortland updated its heating plant, replaced it with satellite boilers and expects to save nearly $600,000 in energy costs per year. The 60-year-old, centralized heating plant was taken offline in May and replaced with new high-efficiency boilers installed in each building across campus, according to SUNY Cortland.
Image courtesy: International District Energy Association