Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Metrics and Tools for Sustainable Buildings


Building stakeholders need practical information, data, metrics, and tools that can be incorporated into investment choices and policymaking related to sustainable, high performing building designs, technologies, standards, and codes. EL is addressing this high priority national need through the development of data that measure sustainability performance through science-based metrics for building products and whole buildings. In this project, sustainability encompasses both the economics of building construction and operation as well as the environmental impacts. Evaluations are completed using a life-cycle approach and include economic performance using Life-Cycle Costing (LCC) and environmental performance using Life-Cycle Assessment (LCA). These two methods are combined with whole building energy modeling to account for the integrated nature of building systems and impacts on occupants. The data is made available through user-friendly interfaces designed to provide the form and function needed for stakeholders to include the information into their decision-making process.


The Metrics & Tools project assesses whole building sustainability for buildings located in 228 U.S. cities.
The Metrics & Tools project assesses whole building sustainability for buildings located in 228 U.S. cities.

Objective:  Develop, integrate, apply, and deploy measurement science assessing the sustainability performance of energy technologies and systems in an integrated building design and operation context, and provide the necessary information to stakeholders to make more sustainable choices in commercial and residential buildings in a cost-effective manner.

What is the new technical idea?  
The new idea is to complete research and develop a suite of support tools focused on the needs from a range of stakeholders that are making sustainability-related decisions in the built environment, both at the building product and whole building level. The completion and dissemination of building sustainability research is needed to identify and develop key science-based evaluation metrics that can be used in analyzing approaches to increasing sustainability in the built environment. Architects, designers, and contractors are increasingly interested in incorporating more sustainable building products in construction products. A tool (BEES) has been developed that allows sustainability (economic and environmental) performance comparisons across building products without the need for expertise in measuring sustainability. Additionally, there is a push within the industry to expand the scope of sustainability-related decisions at the whole building level. The suite of tools and associated research allows for decisions at both levels of analysis. The whole building tools developed under this project (BIRDS and BIRDS NEST) address building sustainability measurement in a holistic, integrated manner that considers complex interactions among building energy technologies and systems across dimensions of performance, scale, and time. NIST has developed extensive databases of energy, environmental, and cost measurements for prototypical buildings based on a novel framework that combines detailed whole building simulations, innovative environmental life-cycle material inventories, and life-cycle costing (LCC). These measurements will be used to assess and compare sustainability performance for whole buildings meeting a range of energy efficiency performance criteria. The comprehensive sustainability performance metrics and databases are embodied in a decision framework within an assessment and reporting tool (BIRDS) to help building industry stakeholders develop business cases and policies for sustainable investment choices. To leverage existing software tools used for evaluating custom building designs, NIST is developing a tool (BIRDS NEST) that generalizes this approach and data sources to allow for evaluation of the environmental performance of custom whole building designs. BIRDS NEST is being designed to be interoperable with an array of existing and future tools, including whole building simulation and building energy rating software. Similarly, a tool for custom economic analysis is being developed: Economic Evaluation Engine (E3). E3 is an API that will provide an array of economic analysis capabilities in a consistent format using industry consensus standards that can be leveraged internally by NIST as well as by external stakeholders.

What is the research plan?  
Research to date has led to 4 industry support tools (and associated publications) that are at different stages of development: BEES, BIRDS, BIRDS NEST, and E3. For comparative analysis of individual products, Building for Environmental and Economic Sustainability (BEES) Online was released in 2011 to shift the original BEES tool from an executable to a web interface. To keep BEES Online on the cutting-edge of environmental science and continue to assist industry in sustainability evaluation of products, a new version has been developed (BEES Online 2) that incorporates new interface capabilities along with updating of the LCA data, approaches, and methods implemented in database development. In FY18, BEES Online 2.0 was released to the public, including 6 product categories. In FY19 and FY20, BEES Online 2.1 expanded BEES Online 2.0 to include all major product categories in the original BEES Online.

In FY 21, BEES Online 2.1 will undergo a 3rd party critical review of both the underlying LCA data and the software calculations to align BEES validation with requirements in green building certification programs.

The initial version of the Building Industry and Reporting and Design for Sustainability (BIRDS) web interface was publicly released in 2014 followed by new versions each year, allowing for stakeholders to compare the sustainability of a range of building prototypes across different levels of energy efficiency based on industry consensus commercial and residential building energy standards and codes. The release of BIRDS v3 introduced a residential buildings database that allows for incremental analysis of energy efficiency to and beyond net-zero energy performance. In FY18, BIRDS v4.0 was released and included an updated commercial buildings database based on Department of Energy Building Energy Code Program’s Commercial Prototype Building Models. The commercial and residential databases were combined into a single interface with additional features to improve the user experience. Additionally, the residential database designed for incremental energy performance analysis was expanded to include natural gas-fired space and water heating. In FY19, the commercial buildings database was expanded to include ASHRAE 90.1-2016. In FY21, the low energy incremental residential buildings database was updated with new energy LCA and construction cost data to provide results using the best available underlying data. Based on limited time and resources, BIRDS will no longer be actively supported starting in FY21, with focus being given towards the other 3 tools developed in this project.

In FY17, NIST used the same underlying framework and data from BIRDS to develop an internal beta version of the BIRDS OpenStudio Measure API – renamed BIRDS Neutral Environment Software Tool (BIRDS NEST) – that allows an architect, designer, or other OpenStudio user to calculate the environmental performance of a custom residential building design without leaving the OpenStudio application. BIRDS NEST allows for sustainability evaluation of building designs in real time without the need for the user to have technical expertise in LCA. In FY18, the BIRDS NEST Measure (Beta) was publicly released on OpenStudio's Building Component Library (BCL), allowing for OpenStudio users to easily download the Measure and submit requests to the BIRDS NEST API. In FY 19, a formal collaboration agreement was put in place and funded to update BIRDS NEST to combine the new, more comprehensive and precise capabilities of Athena’s Impact Estimator for Buildings (IE4B) with expanded building component options in BIRDS NEST, including all common single-family home building envelope and systems, using the HPXML standard format. NIST also created input and output enumerations and example files based on HPXML to ensure interoperability across tool platforms. In FY20, each entity updated its respective aspects of the collaboration: NIST updated the OS Measure and BIRDS NEST API while Athena has developed a compatible IE4B API.

In FY 21, BIRDS NEST will be validated.

A fourth industry support tool has been identified as a potentially high-impact resource, both within and external to NIST. The Economic Evaluation Engine (E3) is an API that provides an array of economic evaluations based on ASTM standards, including Life Cycle Cost (LCC) and Benefit-Cost Analysis (BCA). By design the E3 API allows any software tool (e.g., script, executable, web interface) to call on the API and ensure the calculations are providing consistent, standards-based results. In FY19, the software requirements specification (SRS) document was written to provide software developers a guide for developing E3. In FY20, the SRS document was used to develop a beta version of E3 and a pilot web interface (Present Value of PhotoVoltaics – PV2) to show proof of concept.

In FY 21, E3 will be validated using PV2 and other test examples.

The sustainability research for this project will be closely aligned with efforts across federal agencies, non-profit research organizations, standards, codes, and certification organizations, and private sector vendors related to building energy efficiency and sustainability efforts. Interaction, participation, and collaboration efforts to date include the following:

  • Federal LCA Commons Technical Working Group (FTWG) (participation and collaboration)
  • Athena Sustainable Materials Institute (collaboration)
  • National Renewable Energy Laboratory OpenStudio Team (collaboration)
  • American Center for Life Cycle Assessment (board member)
  • USGBC LEED (Communication)
  • GSA Green Building Advisory Council (GBAC) Embodied Energy (Embodied Carbon) Task Group (participation)
  • DOE BTO Peer Review (participant)
  • Federal Highway Administration (FHWA) Pavement Vehicle Interaction (PVI) Technical Review Panel (TRP)
  • DOE FEMP (existing related building life cycle cost project and forthcoming user of E3)

Major Accomplishments


  • BIRDS v1.0 released in September 2014;
  • New technical expertise in energy simulation and top-down LCA enabling science-based sustainability assessment of whole building energy, environmental, and economic performance on a life-cycle basis.
  • New database for U.S. building sustainability assessment covering 228 locations, 12 building types, and 5 levels of energy efficiency.
  • New guidance for policymakers on benefits and costs of energy codes.


  • The environmental importance weights developed by the BEES Stakeholder Panel are used in LEED version 3 and standardized in ASTM E1765-11 for Multiattribute Decision Analysis.
  • 50,000 Unique Visitors to BEES Online in its first year.

Standards and Codes:

  • Expected impact: Adoption of more efficient and cost-effective energy and green construction codes by states currently using outdated or no codes.
  • B. Lippiatt, International Green Construction Code Committee.
Created March 9, 2009, Updated December 31, 2020