Commercial Building Design and Performance
The U.S. Department of Energy's (DOE) Building Technologies Program is committed to the advancement of highly energy-efficient commercial buildings through innovations in design and technologies. NREL supports that goal through many research efforts:
- Defining Highly Energy-Efficient Buildings
- National Energy Use Assessment
- Performance Metrics
- Reference Buildings
- Case Studies
Defining Highly Energy-Efficient Buildings
A highly efficient building uses roughly 60% to 70% less energy than an average building. Through continual improvement in building envelope design, efficient materials, and the incorporation of smart technologies, buildings can meet this target. A recent example of ultra-efficient design is DOE's Research Support Facility (RSF), which was built on the NREL campus and involves hundreds of advancements in commercial building efficiency. In addition to reduced energy requirements, the RSF will generate energy through renewable sources. Buildings such as the RSF have the potential to offset all energy consumption. NREL has worked to define these net-zero energy buildings— see "Zero Energy Buildings: A Critical Look at the Definition."
Assessment Report
NREL conducted an assessment of the entire commercial buildings sector to evaluate the technical potential for net-zero energy buildings with technology available in 2005 and projected forward to possible technology improvements for 2025. The analysis looked at the technical feasibility of these highly efficient buildings, limitations in market penetration and utility grid structures, notwithstanding. A research report was published internally by NREL, but a conference paper summarizing that report is available.
Performance Metrics
The Performance Metrics Research Project is a research activity to standardize the measurement and characterization of building energy performance. Obtaining reliable metrics for determining a building's performance was identified by the commercial building industry as one of the core challenges to achieving widespread adoption of high performance buildings. The first objective of this project is to determine which performance metrics are of greatest value for energy consumption and on-site energy production. The second objective is to develop standard methods of measuring and reporting the performance metrics. For more information, visit DOE's Performance Metrics Research.
Reference Buildings
Many national laboratories, universities, and private companies conduct buildings research. However, differences in models and simulation tools used by these various research groups make it difficult to compare results among studies. NREL developed energy models for three sets of 16 reference buildings for 16 locations across the country, for a total of 768 energy models. Each set of models represents a different vintage of construction:
- New2004-Represents new construction following ANSI/ASHRAE/IESNA 90.1-2004
- Post1980-Represents existing buildings following ANSI/ASHRAE/IESNA Standard 90.1-1989
- Pre1980-Represents existing buildings built before 1980.
The reference building definitions are complete descriptions suitable for whole-building energy simulations and are implemented in EnergyPlus input files. The reference building definitions are shown in spreadsheet format in the "scorecard" files for each vintage on DOE's Commercial Building Initiative Web site. They are also provided in a technical report to be released shortly titled "U.S. Department of Energy Commercial Reference Building Models of the National Building Stock."
These buildings will form the basis of NREL's research on specific building technologies, energy code development, appliance standards, and measurement of progress toward DOE's energy goals. Having a common starting point allows us to better share and to compare research results and advance energy-efficient buildings. A subset of the reference building models is included with the example files in each release of EnergyPlus.
To learn more about the references buildings, read "Using DOE Commercial Reference Buildings for Simulation Studies" and see a presentation about DOE Commercial Building Benchmark Model Development. Also, access the full set of reference building models at DOE's Commercial Building Initiative Web site.
Case Studies
NREL studied six commercial buildings in detail over a four-year period to understand the issues related to the design, construction, operation, and evaluation of the current generation of low-energy commercial buildings. These buildings and the lessons learned from them helped inform a set of best practices—beneficial design elements, technologies, and techniques that should be encouraged in future buildings, as well as pitfalls to be avoided. The lessons learned from these six buildings are also used to guide future research on commercial buildings to meet DOE's goals for the development of highly energy-efficient buildings. For more information, read "Lessons Learned from Case Studies of Six High-Performance Buildings." Detailed research reports are available on the High Performance Buildings Database for the case study project buildings.
