The U.S. Department of Energy (DOE) has released a new version of its building energy modeling (BEM) software for architects, engineers, researchers, and policymakers. DOE estimated that EnergyPlus v7.0 -- which can calculate the energy required to heat, cool, ventilate, and light a building -- is up to 40 percent faster than the previous version of the software. The software can model various types of residential and commercial buildings and HVAC system types, including passive building designs and low-energy systems.
Among the enhancements in EnergyPlus v7.0 over the previous version are the following:
- 25-40 percent faster execution speeds on various models. Up to 500 percent improvements are possible on models using airflow networks.
- Improved modeling of ventilation rate procedures based on American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62.1.
- A new thermal comfort report based on ASHRAE Standard 55.1.
- New equipment performance data sets for packaged rooftop air-conditioners and heat pumps.
- New model for variable refrigerant flow heat pump air-conditioners.
- Extensions to the energy management system and runtime language.
- Updated utilities.
EnergyPlus v7.0 is available free of charge for Windows, Mac OS, and Linux.
For the past several years, DOE has emphasized EnergyPlus execution speed in an effort to reduce analysis time for architects and engineers and allow them to perform additional design iterations. EnergyPlus v7.0 is 25-40 percent faster than EnergyPlus v6.0 and twice as fast as EnergyPlus v4.0, and it has significantly more capabilities, according to DOE’s Office of Energy Efficiency and Renewable Energy.
This latest speed increase was made possible in part by a code donation from Autodesk Inc. By focusing on the simulation speed of large models that can take hours to run, Autodesk identified ways of speeding up certain computations within EnergyPlus related to temperature and humidity calculations, schedule tracking, and output reporting, and shared these improvements with DOE and the EnergyPlus development team.
“[BEM] is a key technology that helps achieve our mission of significantly reducing energy consumption in new buildings and retrofits,” DOE stated. “In addition to helping architects and engineers find low-energy building designs, BEM is used in the development of building energy efficiency codes and standards, in the creation of energy design guides, in certification of building energy performance, and more. In addition to supporting EnergyPlus, DOE supports basic building science research, BEM training and education, and a number of initiatives related to BEM standards, productivity, and fidelity. We are committed to making our BEM projects, including EnergyPlus, more market-facing and productive as well as to addressing other technical, procedural, and educational BEM barriers.”
DOE Provides Additional Details to Green Building Insider
In response to Green Building Insider's questions about the software, DOE spokesperson Lindsey Geisler said, “Building Energy Modeling (BEM) tools, like EnergyPlus, help industry and building owners calculate the energy required to heat, cool, ventilate, and light a building. Having this information can help them drastically reduce building energy consumption. DOE has been the prime mover of BEM research and development. Going forward, DOE is committed to making BEM more accurate, reliable, usable, effective, and pervasive and to working with stakeholders to advance this vision.”
DOE provided the following additional information: "The only statistic we track is number of downloads, though downloads do not correspond directly to 'number of projects' or even 'when in the project life-cycle' simulation was used. We do not have EnergyPlus v6.0 download statistics yet. EnergyPlus v5.0 was downloaded slightly more than 10,000 times. We estimate that there are about 1,000 regular users of EnergyPlus in the U.S. and about 2,000 worldwide. EnergyPlus is used by ASHRAE to develop the 90.1 building energy-efficiency standard (which is referenced by state and local building energy efficiency codes throughout the country, as well as by USGBC for the LEED atmosphere and energy credit) and the 30 percent and 50 percent Advanced Energy Design Guides. ASHRAE or USGBC may have some statistics about the energy savings enabled by these efforts. DOE spent about $3.500 million to develop EnergyPlus v7.0. It spent about $60 million to develop EnergyPlus v1.0 through v6.0 starting in 1996. This money has supported a considerable amount of building science and building energy modeling research, much of which is embodied and codified within EnergyPlus. Commercial interfaces from DesignBuilder and Bentley Systems has been available for several months. A free interface will be available in the spring or early summer.
"DOE is also investing in interoperability to allow existing architectural and engineering design packages to link with EnergyPlus.Generally speaking, EnergyPlus has three distinguishing features. First, it has a fully integrated solver for building energy demand (i.e., heating, cooling, ventilation, and use-specific loads) and supply (i.e., air and water systems that meet those loads).
Second, EnergyPlus models building geometry precisely and models the physical effects that relate to building surfaces separately.
"Finally, EnergyPlus models HVAC at the component level. The upshot of these differences is that EnergyPlus is capable of modeling advanced low-energy building designs and HVAC systems, including radiant cooling and natural ventilation.
For the past several years, the EnergyPlus team has released major updates on an annual basis, usually in October. We are expecting EnergyPlus v8.0 to be released in October 2012. Some of the planned enhancements for EnergyPlus v8.0 include upgrades to the automatic component sizing features, new models for advanced fenestration systems and solar shading, further improvements in execution speed via parallelization, support for co-simulation with other engines via a standard model-exchange interface, and multi-language support, among others.
"At the large scale, demand side, BEM is already making a strong contribution to the development of energy-efficiency codes and standards like ASHRAE 90.1 and 189.1, certification and rating labels like LEED, and utility energy-efficiency programs. Most of the untapped potential of BEM is on the individual building, supply side. A recent analysis by RMI estimates that buildings designed using an integrated BEM-driven approach can consume 8-16 percent less energy than buildings designed using conventional processes where energy-optimization is one of the final steps, one that is often less effective than it could be because many decisions that impact energy consumption are already fixed by that time. BEM can be used to diagnose and pinpoint faults in building systems, keeping building systems healthy and their energy performance high. BEM can enhance the development of building control systems and even actively drive those control systems during building operation, optimizing building performance based on current usage and weather information."