More than two-thirds of people in the U.S. live in urban areas, which are facing huge challenges related to retrofit, expansion and operational efficiency to reduce resource use and greenhouse gas emissions and to meet sustainability goals and resiliency to combat nature extreme events and emergencies. U.S. city buildings and urban infrastructure are aging. The existing tools provide limited technical strategies and fail to use open standards that are critical for energy modeling communities to embrace. Cities need dramatically improved analytics-based decision analysis tools that combine measured data, physics- and data-driven models to support their new development and retrofit planning.
The most efficient and sustainable low-GHG and -energy systems are found in campus and urban district shared energy infrastructure that enables waste-heat recovery and integrates renewables, and thermal storage to offset fluctuations in energy demand and supply. Designing and operating such systems requires dynamic simulation and optimization to account for the dynamics of energy systems, changing loads and temperature levels, uncertainty and variability of weather and user behavior, and analysis of different design and operational scenarios. When hundreds of buildings are involved, integration of these computations with geographical information system (GIS) to obtain input data and to visualize results in a form that is accessible to urban planners and designers is needed.
District Energy Systems
A bidirectional thermal network for district heating and cooling is analogous to a smart grid in that the direction of the water flow reverses depending on the heating or cooling needs of its consumers. Buildings can feed waste heat and excess renewable energy into the grid, and offer storage capabilities as well. Such networks exhibit very high efficiency if used with heat pumps, and can play a key role in increasing resilience.
As these systems can be built out modularly, they can gradually be expanded by adding new buildings and new generation and storage, allowing for incremental investments. They have been shown to be cost competitive with conventional heating systems in Switzerland, where they are a key part of the strategy to reduce building and energy demand by a factor of five. We will leverage our international partnerships built through our leadership within International Energy Agency activities and the International Building Performance Simulation Association, plus our collaboration with the Swiss Competence Center's "Future Energy Efficient Buildings and Districts." We will develop tools and conduct technology demonstrations to enable design and operation of such systems, and research how to adapt them to different geographic circumstances. The anticipated outcome is a five-fold reduction in energy demand of buildings, and a transformation of building heating and cooling systems to bidirectional systems that can transact thermal energy in a dynamic market.
We analyze how the combination of vehicle technology, land-use patterns, and driving behavior affect energy use, greenhouse gas emissions, and criteria pollutant emissions in the transportation sector.
The goals of the urban systems research are: (1) develop a data and computing platform that builds upon modeling and simulation tools, and integrated city data using open standards; (2) deploy the platform to support stakeholders and users to plan and design new communities or retrofit existing communities to reduce energy use and GHG emissions of buildings by 50%.
Ongoing Research Efforts
- A data and computing platform, City Building Energy Saver, CityBES is being developed
- 3D city models based on the international standard CityGML are being developed by integrating cities' public datasets available across multiple city departments.
- Advanced district energy systems, using a single water loop at near ambient conditions, that take advantages of thermal load diversity and density in a district, and optimize the integration of community scale renewable and storage systems.
- Case studies to retrofit city building stock to cut energy use by half, and design strategies for new community developments to achieve zero-net energy goal
Urban Heat Island Mitigation: heatisland.lbl.gov