Heat trading networks are district energy systems that exchange heat between energy efficient district heating and cooling infrastructure. Usually, they connect low temperature hot water systems (LTHW) and chilled water district cooling systems.
Low-temperature Hot Water (LTHW) and chilled water systems utilize water at temperatures closer to ambient ground source temperatures than traditional steam based systems. Bringing the water to those temperatures requires less energy than traditional steam-based systems. These newer systems also waste less heat and energy, respond more quickly to controls, and result in improved comfort for building occupants. Additionally, they are compatible with high-efficiency equipment and renewable heat sources such as heat pumps, heat recovery chillers, solar-thermal arrays, and ground source heating. Heat trading entails utilizing this equipment in an interconnected system so that waste heat from one building can be reused elsewhere. Moving and reusing waste heat saves energy, making these systems more efficient and cost-effective.
Benefits of Heat Trading
- Unlocks numerous renewable technologies including ground-source heating, heat recovery, and thermal energy storage.
- Heat-trading networks use less water and have lower operational, maintenance, and fuel costs than traditional district energy systems
- Provides a path to campus-wide electrification
- Retrofitting existing district energy systems and/or connecting stand-alone buildings may require significant capital investments.
- Where distribution piping is required, there can be significant physical disruptions to the campus during installation.
- While total input energy will be dramatically lower, Heat-trading Networks will increase campus reliance on electricity.
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Campus Energy & Sustainability Podcast: Losing Steam - Carleton College’s Energy Transition
In this episode of the Campus Energy & Sustainability Podcast, learn about how Carleton College replaced their 20th century steam system with a geothermal-based district energy system. Martha Larson, Carleton’s former manager of campus energy and sustainability, describes how the new geothermal system utilizes the consistent temperature of the earth to regulate campus heating and cooling. She explains the physics of the geothermal system, the project’s planning and approval process, and its impact on Carleton’s decarbonization goals.