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Hot Water District Heating

Category: HVAC

Many universities heat buildings using steam generated at a central plant. Steam powered systems are often old, inefficient, and expensive to maintain; sometimes, their age and increasing precarity make them hazardous. Replacing legacy steam systems with hot water district heating reduces energy and water use, improves indoor comfort and temperature control, and allows for integration with renewable energy sources. 

Converting steam systems to more efficient hot water heating systems offers the opportunity for reduced energy usage and carbon emissions. Hot water systems operate at a lower temperature than steam, retain more energy in transmission, and reduce water lost to evaporation. Water use and waste heat loss can be reduced by up to 70%. Hot water systems eliminate junctions that leak heat, such as steam traps, valve stems, and packing glands. In addition to being more efficient, they improve indoor thermal comfort and boast faster response times. Steam often heats unevenly, making some rooms too hot and some too cold for their thermostat settings.

Finally, hot water heating systems offer the advantage of compatibility with many potential sustainable technologies. For example, heat storage can be implemented by storing reservoirs of hot water to deploy during peak demand periods. Waste heat recovery technologies can either heat or improve the system. The systems can source renewable heat energy from geothermal or solar thermal. 

You can replace steam systems with hot water in two ways. One option is to adapt the steam heating system to utilize hot water instead. Although this saves money, it loses efficiency. Alternatively, you can replace the entire system with equipment specifically designed for hot water. This option costs much more up-front, and is best to complete during major retrofits or renovations.

Benefits of Hot Water District Heating

  • Significantly reduce energy use and emissions
  • Significantly reduce water use 
  • Systems are simpler and easier to maintain
  • Heat can be supplemented with solar hot water heating
  • Requires less space and equipment
  • Lower temperature heating creates opportunities for integration with alternative forms of energy

Challenges

  • Conversions of legacy steam system can be expensive
  • Some buildings may require higher temperature steam.
  • Converting a campus will require careful sequencing and multiple phases.

Sources: UHN, NY Engineers

 

Impacts

  • GHG Impact

    Large

    University of British Columbia reduced greenhouse gas emissions by 22%.

     

  • Economic Impact

    Small Net Cost

    Although the conversion is a large upfront cost, the energy savings and reduced maintenance needs will pay off over the long life of the heating system. Additionally, steam systems of a certain age are too expensive and dangerous to continue maintaining, and will need to be replaced anyways.

  • Feasibility

    Difficult

    District steam to hot water conversion can be a multi-year, capital-intensive project.  

  • Timeline

    2-5 years

    Implementation for an entire campus can be a multi-year, multi-phase project.

  • Maintenance

    Moderate

    Maintenance costs can be 30% less than maintaining steam systems.

     

  • Publicity

    That's really cool

    A campus wide conversion to hot water heat shows a commitment to the long term environmental and financial sustainability of an institution.

     

Hot Water District Heating Providers

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