Building stakeholders need practical metrics, data, and tools to support decisions related to sustainable building designs, technologies, standards, and codes. The Engineering Laboratory of the National Institute of Standards and Technology (NIST) has addressed this high priority national need by extending its metrics and tools for sustainable building products, known as Building for Environmental and Economic Sustainability (BEES), to whole-buildings. A sustainability measurement system has been developed consisting of whole-building sustainability metrics that are based on innovative extensions to life-cycle assessment (LCA) and life-cycle costing (LCC) approaches involving whole-building energy simulations. The measurement system evaluates the sustainability of both the materials and the energy used by a building over time. It assesses the "carbon footprint" of buildings as well as 11 other environmental performance metrics, and integrates economic performance metrics to yield science-based measures of the business case for investment choices in high-performance green buildings. Building Industry Reporting and Design for Sustainability (BIRDS) applies the sustainability measurement system to an extensive whole-building performance database NIST has compiled for this purpose. Based on the NIST Net-Zero Energy Residential Test Facility (NZERTF), the BIRDS Low-Energy Residential Incremental Energy Efficiency Improvements Database includes energy, environmental, and cost measurements for 960 000 design variations of the NZERTF for Gaithersburg, MD for study periods up to 30 years. Focusing on a single location allows for the consideration of incremental building energy efficiency measures, both those specified in the most recent International Energy Conservation Code (IECC) and those implemented in the NZERTF. Buildings designed to meet current energy codes can be compared to alternative building designs to determine the impacts of improving building energy efficiency on overall sustainability performance. This report describes the latest version of BIRDS (v4.1) including new options, namely natural gas-fired space and water heater equipment.