Objective: To develop tools to define and verify high-performance indoor air quality in low-energy buildings and data needed to improve the effectiveness of high-performance building standards and programs.
What is the new technical idea? Emmerich and Schoen (2013) discussed the tools that are available and those that are needed for supporting occupant health, comfort, and productivity in low energy buildings and concluded that a critical need exists in the area of tool development and application for the measurement and verification of IAQ in low-energy (including net zero energy) buildings. Recent analysis of the treatment of IAQ in high-performance building case studies, and in standards and guidance documents, revealed that IAQ was not covered in a comprehensive manner and when it was, it was not consistent with high-performance goals (Emmerich, Teichman et al. 2017). In response to these needs, metrics associated with high performance IAQ are being developed as well as details on how to document high performance IAQ in design, construction, commissioning, and operation. These metrics and documentation approaches need to be applied to actual buildings and evaluated by stakeholders, e.g. designers, manufacturers, and building owners, before they are used in standards and other high performance building programs. Additionally, coupled building energy and multizone airflow and IAQ modeling tools have been developed to enable designers to simultaneously consider both the energy and IAQ impacts of building design features. However, widespread use of these tools in design practice will require improvements to the user interfaces, availability of required input data and reference models, and validation studies.
What is the research plan? The planned products of this project are tools, data, standards, and guidance on verifying the achievement of high performance IAQ and ventilation. During a previous project, we analyzed the treatment of IAQ in high-performance building case studies, standards, and guidance documents and developed details on how to document the implementation of high performance IAQ. Additionally, a literature review was performed on field studies of ventilation and IAQ performance verification in high performance buildings. A workshop on whole-building performance metrics was held during the 2016 ASHRAE IAQ Conference aimed at identifying areas of focus for future development of non-energy related building performance metrics, e.g., IAQ-related metrics. This conference/workshop revealed the need to “translate science into practice” by identifying, developing, and demonstrating reliable and effective IAQ metrics as ultimately related to occupant health and productivity. NIST building energy, airflow and IAQ analysis tools will be utilized to evaluate the applicability of such metrics and to identify modeling requirements and improved simulation tools necessary to enable users to readily perform building IAQ modeling studies with the long-term goal of developing a framework for evaluating whole-building performance, e.g., occupant health and productivity, IEQ, energy and water use, and life-cycle economic analysis.
In the previous project, a method was developed to provide improved infiltration modeling in an easy to use format. This method, using correlations based on multizone analysis, has been expanded upon to include a larger set of non-low-rise residential building models and climate zones for incorporation into EnergyPlus models via OpenStudio measures. Additionally, CONTAM simulations were performed for three of the DOE commercial prototype buildings at four airtightness levels in 55 climates in collaboration with Oak Ridge National Laboratory, the Air Barrier Association of America, and the US-China Clean Energy Research Center for Building Energy Efficiency Consortium. These simulations were used to develop the initial version of the Oak Ridge National Laboratory Infiltration Calculator, which is an online tool that provides estimates of the potential energy and cost savings due to improvements in building envelope airtightness. NIST has proposed that this tool be improved by expanding it to include more buildings and climate zones.
Another focus of the previous project was the integration of multizone airflow and IAQ modeling with building thermal simulation to improve the evaluation of the energy impacts of ventilation and infiltration and of the IAQ impacts of low-energy building (LEB) designs. Previously, a new version of the TRNSYS/CONTAM coupled tool was published, and NIST subsequently developed and demonstrated co-simulation coupling of CONTAM and EnergyPlus. Enabling widespread use of these tools will require improvements to their user interfaces, the availability of required input data and reference models, and validation studies. NIST conducted a model validation study of the new coupled thermal/airflow/IAQ analysis capabilities including an analytical case study, identification of empirical validation dataset(s), simulations to generate predictions for comparison to the measured data, and inter-model prediction comparisons. A comparison will be made between the various methods of accounting for infiltration in building energy modeling, including correlations and fully coupled models, with consideration given to improving existing methods of accounting for building airflow in these models.
In recent years, work was performed, via a grant to Concordia University, to conduct verification testing of ContamHT, which is a research version of CONTAM, i.e., a fully coupled, multizone energy, airflow, and IAQ program. Also, the NIST commercial building air-tightening retrofit analysis is being extended to develop a national estimate by including a broader range of building models. In coming years, improvements to model usability will be completed, including better synchronization of airflow/IAQ and energy models as changes are made during design development, better integration with Open Studio, enabling CONTAM users to utilize existing building plans when creating building models, and developing a web-based set of verification, validation, and demonstration cases that will enable users to utilize the NIST-developed toolset.
Emmerich, S. J. and L. Schoen (2013). IAQ 2013 Tools Topic Overview. ASHRAE IAQ 2013. Vancouver, BC, Canada, ASHRAE.
Emmerich, S. J., K. Y. Teichman and A. K. Persily (2017). "Literature review on field study of ventilation and indoor air quality performance verification in high-performance commercial buildings in North America." Science and Technology for the Built Environment: 1-8.