Did you know that buildings account for more than 40% of U.S. total energy use and 70% of the country’s electricity use? Reducing that consumption to match renewable generation is one of the key challenges of our clean energy future, according to the U.S. Department of Energy. The need to design and operate buildings to be more efficient, flexible, and responsive is essential to help meet that challenge. This is a primary focus at the FSEC Energy Research Center, which has been awarded a $1,000,000 contract for continued efforts in the Department of Energy’s flagship whole-building energy simulation software engine, EnergyPlus.
EnergyPlus is an open-source, whole-building energy simulation software that engineers, architects, and researchers use to model both energy consumption—for heating, cooling, ventilation, lighting and plug and process loads—and water use in buildings.
FSEC ERC has decades of whole-building energy simulation program development experience and has been part of the Department of Energy’s EnergyPlus core development team since 2001, when the Department of Energy changed from the DOE2.1 simulation program to EnergyPlus. Since then, FSEC ERC has been one of many central teams working with DOE’s National Renewable Energy Laboratory, to maintain, research, and develop the simulation program.
FSEC ERC is an essential part of the bi-annual updates for the program every year, not only providing software updates and fixing glitches, but also writing and creating new software within the program.
The newest award includes a contract for another four years of research and development for EnergyPlus. In the current fiscal year, FSEC ERC has been tasked with four major priorities.
The first priority resides with autosizing of airflow network ducts.
“Duct sizing is one of the remaining barriers to greater usage of the airflow network distribution feature in EnergyPlus,” Dr. Lixing Gu, research associate for buildings research at FSEC ERC, says. “It’s a complex feature that will be divided into several phases that will be completed next year.”
“For simpler and smaller models, inclusion of the pressure network may require more inputs and information than the base energy model itself. Removing duct size inputs will be especially helpful in schema-driven modeling efforts, such as the approach used in several audit-related interfaces, that may need a legitimate distribution system but lack detailed inputs to construct one,” Gu says.
“Due to complexity of the new task, the task will be divided into several phases,” Gu continued. “The present work will cover Phase 1 to establish foundation for future expansion. The remaining work will be completed in the next year.”
Adding autosizing of airflow network ducts will greatly simplify the required inputs to create a fully-featured residential Air Flow Network model with distribution.
The second task is autosizing for high latent loads. Modifying the sizing algorithms to properly handle simulation cases with high or dominant latent loads, such as indoor growing facilities, will be a huge assist for modelers.
“Users of EnergyPlus have historically sized the cooling coil based on building thermal loads,” says Richard Rastaud, program director for buildings research at FSEC ERC. “With the new latent sizing feature, we will be able to size the cooling coil to also meet the building moisture, or humidity loads. This is a feature that designers of green houses, spas and ventilation systems have requested.”
The third phase of the current award involves multiple ground surfaces.
“Currently EnergyPlus only allows one single ground surface with user-defined ground solar reflectance and ground temperature,” says Bereket Nigusse, senior research engineer for buildings research. “However, a real building usually sees multiple types of ground surfaces, which have different solar reflectance and temperature. This new feature allows building exterior surface to view multiple types of ground surfaces for exterior surfaces energy balance calculation.”
This change will ensure that users can more accurately depict realistic surroundings for their buildings when simulating, such as bare soil, grass, sidewalks, driveways, and water surface, all of which have different solar reflectance and temperature.
Finally, the award allows the EnergyPlus team to resolve software and documentation defects.
With the current award, NREL will disburse tasks to FSEC ERC each year based off research conducted and needs of the workforce within the renewable energy building industry. With so much of the Department of Energy’s focus turning to renewable energy, and a success of working with EnergyPlus for more than 20 years, FSEC ERC can expect to be a part of the program for many more years to come.