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Ventilation and Indoor Air Quality in Low-Energy Buildings Project

Summary:

NIST is developing tools and metrics to both reduce the building heating and cooling loads associated with ventilation and infiltration and to evaluate the indoor air quality (IAQ) impacts of designs and technologies used in low-energy buildings. This work is intended to support the application of approaches that can simultaneously reduce energy use and improve IAQ, and to reduce the likelihood that efforts to reduce building energy use will negatively impact IAQ. Simulation capabilities and analysis tools are being developed to enable airflow and IAQ analysis in conjunction with energy design and analysis tools. In addition, reference cases and data are being developed to support ventilation, infiltration, and IAQ analyses of low-energy building designs and retrofits.

Description:

Objective: To develop the tools and data required to determine the ventilation and IAQ impacts of strategies to achieve low-energy buildings, as well as to achieve heating and cooling load reductions through the application of technologies and designs based on ventilation, infiltration, and IAQ control by 2015.

What is the new technical idea? To develop the capabilities needed to assess the IAQ impacts of low-energy building designs and technologies, as well as to support the implementation of strategies that can both save energy and improve IAQ, current energy design and analysis software tools need to have the capability to better quantify airflow, ventilation, and indoor contaminant concentrations. Achieving this goal will require coordination with the developers and users of energy design and analysis tools to incorporate enhanced capabilities into their tools. To this end, the project will also address the need to improve the measurement science embodied in multizone airflow and IAQ modeling, building thermal simulation, and computational fluid dynamics (CFD), including the integration of these simulation capabilities to support the analysis of the complex building and ventilation system designs and retrofits being applied in high performance, sustainable buildings. These advanced tools will be applied to study the potential energy and IAQ performance of important but challenging building and ventilation design approaches, including natural and hybrid ventilation. To advance the consideration of airflow and IAQ impacts in current efforts to investigate energy savings opportunities in existing and new buildings, supporting models, data and metrics will also be developed. In addition to the need for software tools to support good IAQ in low-energy buildings, industry consensus standards that define design and construction requirements in high-performance, sustainable buildings are needed to integrate energy efficiency, IAQ, and others aspects of building performance.

What is the research plan? A key focus of this project is 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. In FY12, a new version of the TRNSYS/CONTAM coupled tool was published, and NIST initiated work to improve airflow modeling in EnergyPlus. In FY13, NIST conducted simulation studies using the TRNSYS/CONTAM tool, and created a graphic interface for creating coupled models for TRNSYS and EnergyPlus. In FY13, NIST worked with LBNL to develop a plan to incorporate CONTAM’s full airflow and IAQ modeling capabilities into EnergyPlus. In FY14 NIST will develop and demonstrate co-simulation coupling of CONTAM and EnergyPlus, add a capability to CONTAM to output infiltration rates for EnergyPlus and provide CONTAM development in support of the Energy Efficient Buildings Hub Retrofit Modeling Tool. In FY12 and 13, NIST developed correlations of infiltration rates with weather for use in DOE EnergyPlus and published a journal article. In FY13, NIST conducted a simulation study with NREL to examine energy and IAQ impacts of efficient ventilation options, which will be published in FY14.

In FY12 and 13, NIST updated the U.S. commercial building air leakage database and published a journal article on achieving airtightness to support the design and construction of LEBs including requirements in ASHRAE Standards 90.1 and 189.1. In FY14, NIST will analyze the data to evaluate the potential improvements in airtightness and energy savings through building envelope air sealing and publish a journal article.

The goal of defining the role of IAQ in LEBs is also being pursued through Andrew Persily’s role as chair of Standard 189.1 and Steven Emmerich’s role as co-chair of ASHRAE’s IAQ 2013 conference. In FY13, an air barrier commissioning addendum for 189.1 was published, addenda updating the IAQ requirements of 189.1 were submitted for public review, and a proposal for a residential high-performance building standard (189.2) was submitted to ASHRAE. Also in FY13, the conference program of IAQ 2013 was developed to identify progress made toward achieving IAQ in LEBs. In FY14, an IAQ 2013 overview article on tools to achieve IAQ in LEBs will be published. In FY12 and 13, NIST developed and demonstrated a graphical approach to illustrating the performance of high-performing buildings with respect to four key attributes of high-performing buildings: indoor air quality, energy use, water consumption, and waste generation. In FY14, NIST will build on that work by completing a scoping study for a comprehensive building performance simulation/compliance tool.

Major Accomplishments:

Impact of Standards and Tools:

  • ASHRAE Standard 189.1: Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings chaired by NIST staff.
  • Climate Suitability Tool developed to identify opportunities for building designers to use natural or hybrid ventilation to reduce energy consumption in buildings.
  • LoopDA software developed to provide building designers a tool to size openings for natural ventilation.
  • CONTAM multizone airflow and contaminant transport analysis software used by building designers to assess ventilation effectiveness and indoor air quality.
  • ASHRAE Standard 62.2, ventilation standard for residential buildings which was chaired by NIST staff, forms the basis for ventilation requirements in model codes.