EL Improves Method for Modeling Infiltration in Commercial Building Energy Models
The Indoor Air Quality and Ventilation Group (Engineering Laboratory) has developed a new method to incorporate airflow calculations into building energy calculations, which is more accurate than current approaches and easier to apply. Infiltration is often ignored or assumed at a fixed rate in energy simulations, which does not reflect known dependencies on outdoor weather and heating, ventilating and air conditions (HVAC) system operation. These effects can be accounted for by using multizone airflow modelling, which can be complex and require additional technical skills. The group developed new strategies based on the relationships between infiltration rates calculated using multizone airflow models, weather conditions, building characteristics, and HVAC system operation. Technical Note 1829 provides a detailed description of a building-specific and a generalized strategy for applying an empirical infiltration equation in a commonly-used energy simulation tool, EnergyPlus. The strategies were developed and tested using seven of the U.S. Department of Energy (DOE) reference commercial buildings, which represent different types of occupancy and HVAC systems. The accuracy of the predicted infiltration rates using the new method are impressive given that it was developed using only seven buildings. The researchers went on to perform tests on other buildings and for two other building envelope leakage values and the results were less accurate but still encouraging. This effort also identified limitations in the infiltration models currently included in energy simulation tools and suggested how to address them with minimal modifications.
Technical Note 1829 is available for download from NIST at http://dx.doi.org/10.6028/NIST.TN.1829.
Contact: Lisa Ng (301)975-4853
EL’s HVAC-Cx Tool to Aid Commissioning Providers
The Engineering Laboratory has completed development of HVAC-Cx, an automated commissioning tool that facilitates the testing and analysis of a variety of commercial heating, ventilating and air-conditioning (HVAC) systems to verify correct system performance. The software uses embedded intelligence designed to determine whether current facility requirements are met. HVAC-Cx improves surveillance quality, enables more complete and robust testing than is typically achieved in practice and plays a vital role in addressing the shortage of qualified field technicians.
To be effective, analysis tools must become an integral part of the day-to-day practice of building operators. HVAC-Cx has a graphical user interface that enables the commissioning agent or building operator to monitor the performance of the air-handling units in a building or set of buildings. Due to the custom nature of HVAC system architecture, the software has modular capabilities to assist operators in managing the tremendous quantity of data and expert rules that form the basis of the analysis can be customized. Testing can be carried out by passive surveillance of system operation or, in the case of BACnet building automation systems (BAS), active testing by use of customizable test scripts. The test scripts command the system into its various normal modes of operation and then apply expert rules that are capable of detecting improper system operation. The tool enables users to interact with real time and historical building data from BACnet systems.
NIST researchers validated the tool using emulation data from the Virtual Cybernetic Building Testbed (VCBT) and field data from the Performing Arts Center at Montgomery College in Rockville, Maryland. The VCBT data included emulations where specific faults were implemented, as well as fault-free data. The initial prototype tool was applied successfully to the analysis of AHUs. The recently completed HVAC-Cx greatly expands its functionality by adding the capability to enter multiple datasets and multiple HVAC components. HVAC-Cx is being further expanded to test chillers, chiller loops, and terminal units to provide a suite of tools for practitioners performing commissioning services, or for building operators for the purpose of ongoing commissioning. The NIST Engineering Laboratory is engaged in public outreach to demonstrate the application of the software tool and to engage industry partners for dissemination.
Contact: Natascha Milesi Ferretti (301) 075-6420, Michael A. Galler (301) 975-6521
EL Hosts Inaugural Disaster Resilience Workshop
EL hosted the inaugural Disaster Resilience Workshop at NIST in Gaithersburg, MD, on April 7, 2014. The workshop convened a multi-disciplinary community of over 150 stakeholders to begin development of a Disaster Resilience Framework in response to the President’s Climate Action Plan. The Framework will provide local and regional authorities with guidance on codes, standards, available tools, and best practices that support community resilience and “consistently safe buildings and infrastructure”. A total of six workshops around the country are planned over 18 months.
Opening remarks were delivered by Acting Deputy Secretary of Commerce and NIST Director Pat Gallagher and Acting Director of NIST’s Engineering Laboratory, Howard Harary. Invited presentations were given by Warren Edwards, Executive Director, Community and Regional Resilience Institute (CARRI), Oak Ridge, TN, “What Is Community Resilience and Why Is It Difficult to Measure?” and by Chris Poland, co-Chairman of SPUR Disaster Planning Program’s Resilient City Initiative, “Creating Disaster-Resilient Communities”. Breakout sessions followed each presentation to obtain stakeholder input on subjects ranging from performance goals and metrics, recovery from disasters, interdependencies among infrastructure systems, lessons learned from past events, and how to achieve resilience within building and lifeline infrastructure sectors. The input from these workshops will be incorporated into the Disaster Resilience Framework with a draft for public comment released in early 2015.
More information about the NIST Disaster Resilience Framework, future workshop dates and locations, and related research can be found at http://www.nist.gov/el/building_materials/resilience/index.cfm.
* The President’s Climate Action Plan can be found at http://www.whitehouse.gov/sites/default/files/image/president27sclimateactionplan.pdf.
Contact: Steve Cauffman (301) 975-6051
NIST/ASHRAE to Cosponsor Building Commissioning Research Roadmapping Webinar
EL partnered with ASHRAE’s Technical Committee on Building Commissioning to host a research roadmapping webinar on April 29, 2014. Building Commissioning is a quality control process that can be applied to new buildings to achieve the owner’s project requirements or applied to existing buildings to ensure that the current facility requirements are met. The webinar was a facilitated discussion with a free exchange of ideas. The goal was to capture a snapshot of the state of the building commissioning industry, identify research gaps and priorities and to ensure that the existing measurement science (measurement methods, methods of test, tools, performance metrics, etc.) meets industry needs
Building Commissioning has a significant potential for reducing energy consumption in existing and new buildings and the last decade has seen an increase in market adoption, yet significant barriers remain to widespread implementation. There has not been a recent assessment of research needs in the commissioning industry to provide the information necessary for making informed research investment decisions. This webinar sought input from a diverse set of stakeholder experts from the building industry, research organizations, and public sector entities, leading universities, ASHRAE and consultants to guide future building commissioning research activities. Post-webinar, ASHRAE intends to conduct a survey of participants to help set priorities for the specific technical areas identified by the stakeholder experts. The US Department of Energy (DOE), Natural Resources Canada (NRCan) and the National Institute for Building Sciences’ Commissioning Leaders Council have already indicated interest in the results, a Building Commissioning Research Roadmap, which will be publically available in late spring.
Contact: Natascha Milesi Ferretti (301)975-6420
EL’s Domanski Gives Keynote at the Annual Meeting of the Air Conditioning and Refrigeration Center
EL’s Piotr Domanski was invited by the Air Conditioning and Refrigeration Center (ACRC) at the University of Illinois, Champaign-Urbana, to give a keynote lecture at the annual meeting of the ACRC Industrial Advisory Board Meeting on April 2, 2014. The audience included graduate students, faculty, visiting scholars, and representatives of about 30 ACRC member companies.
Domanski’s presentation, entitled “Transition to Low-GWP Refrigerants: Opportunities, Challenges and Tradeoffs”, discussed recent results of an ongoing research undertaken jointly EL (Piotr Domanski) and MML (M. McLinden and A. Kazakov). The goal of the project is to identify molecules having a low global warming potential (GWP) to replace the currently used high-GWP refrigerants without negatively impacting the efficiency of vapor compression equipment such as heat pumps, air-conditioners and refrigerators. The study started with a comprehensive database (100 000 000 compounds). By applying screens for desirable attributes and the knowledge of optimum refrigerant thermodynamic parameters, the number of candidate fluids is being pared down to about 100 for a detailed performance analysis. The results obtained so far indicate that low-GWP refrigerant options are limited.
Contact: Piotr Domanski (301)975-5877
EL’s Lipman Receives PDES, Inc. 2014 Bryan K. Martin Technical Excellence Award
On March 13, 2014, Robert Lipman was awarded the Bryan K. Martin Technical Excellence Award by PDES, Inc. . Mr. Lipman made significant technical contributions to both LOTAR and the CAx-IF, consortia comprised of international automotive, aerospace, and defense manufacturers and supporting software vendors. Development of the NIST STEP File Analyzer (SFA) - The SFA, was the first means of performing automated semantic analysis of ISO 10303 files for compliance with prospective commercial implementations of the standard. ISO 10303, most commonly known as the Standard for Exchange of Product model data (STEP) is the most popularly used international standard for exchanging product data among US and global manufacturers.
The PDES, Inc. Executive Board established the Bryan K. Martin Technical Excellence Award in memory of Bryan K. Martin, whose exceptional record of strong leadership and tireless work helped to achieve PDES, Inc. goals. The Board presents this award annually to a PDES, Inc. member who has demonstrated superior technical contributions to the program.
Contact: KC Morris (301)975-8286
EL’s Lipman Most Cited Automation in Construction Article
The Automation in Construction journal recently published a list of those articles published since 2009 that are the most highly cited. The Engineering Laboratory’s Robert Lipman coauthored the number one most-cited article, Tang, P., Huber, D., Akinci, B., Lipman, R. , Lytle, A., “Automatic reconstruction of as-built building information models from laser-scanned point clouds: A review of related techniques,” Volume 19, Issue 7, November 2010, Pages 829-843.
Article Abstract: The paper addresses building information models (BIMs) as a maturing new paradigm for storing and exchanging knowledge about a facility. BIMs constructed from a CAD model do not generally capture details of a facility as it was actually built. Laser scanners can be used to capture dense 3D measurements of a facility's as-built condition and the resulting point cloud can be manually processed to create an as-built BIM-a time-consuming, subjective, and error-prone process that could benefit significantly from automation. This article surveys techniques developed in civil engineering and computer science that can be utilized to automate the process of creating as-built BIMs. We sub-divide the overall process into three core operations: geometric modeling, object recognition, and object relationship modeling. We survey the state-of-the-art methods for each operation and discuss their potential application to automated as-built BIM creation. We also outline the main methods used by these algorithms for representing knowledge about shape, identity, and relationships. In addition, we formalize the possible variations of the overall as-built BIM creation problem and outline performance evaluation measures for comparing as-built BIM creation algorithms and tracking progress of the field. Finally, we identify and discuss technology gaps that need to be addressed in future research. © 2010 Elsevier B.V.
Contact: Robert Lipman (301)975-3829