District Energy Systems

Otto Van Geet, National Renewable Energy Laboratory

This Presentation will cover district energy systems and the advantages of approaching energy at the district scale and how model district energy system. EcoDistricts argues that "the district is the optimal scale to accelerate sustainability--small enough to innovate quickly and big enough to have a meaningful impact."

To achieve the large energy and carbon reductions that are needed, campuses must move to net zero districts over time. There are several potential advantages to approaching net zero at larger scales. In some cases, especially for buildings such as labs with high-intensity process loads, it may be very difficult to achieve zero energy within the building footprint or site. Aggregating such buildings with other buildings and community renewable energy sources may make it possible to reach net zero. Also, approaching energy at a larger scale can bring into play district energy systems that take advantage of load diversity between buildings and access renewable energy sources in ways that may not be practical for individual buildings. Finally, economies-of-scale may be achieved through the design and acquisition of energy systems across many buildings.

NREL has identified four core net zero district design principles: 1) maximize building efficiency, 2) maximize solar potential, 3) maximize renewable district thermal energy, and 4) maximize load control.

Traditionally district energy modeling has been done in a top-down fashion. High-level models are used to develop overall goals as well as performance goals for individual buildings. Building engineers then use these performance goals to develop designs for individual buildings, potentially using detailed energy modeling software to guide their decisions. This approach meets some of the key design principles identified above. The high-level spreadsheets are able to establish and track net zero energy goals for the district master plan. Detailed energy modeling for individual buildings allows for maximizing building efficiency. However, the traditional approach misses some of the other key design principles. Modeling buildings in isolation does not allow maximizing renewable district thermal energy by examining simultaneous heating and cooling between buildings. To better support the effective design of net zero districts NREL is developing an open source district energy modeling platform called URBANopt and will present on the current status of district energy modeling.

Learning Objectives

  • understand the concept of district energy systems
  • understand the advantages of district energy systems
  • identify the four core net zero district design principles
  • understand the approach to modeling district energy systems


Otto is a Principal Engineer at NREL. Otto has been involved in the design, and operation of energy efficient research facilities such as labs and data centers, general use facilities, and low energy use campus and community design. Otto was one of the founding members of the Labs21 program and provides technical guidance for the program. He and his family live in an off grid passive solar house with a 2 kW PV/hybrid power system and solar water heating that he designed and built 19 years ago.


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