In the NBI webinar conducted Thursday of this week, NBI laid out options and recommendations for electrification in building codes to achieve “zero carbon” via electrifying residential and commercial end uses.  NBI’s term “zero carbon” was used interchangeably with “net zero” and “decarbonization” in describing policy objectives, allowing no role for natural gas or propane in end uses either as an interim consumer option or with alternative policies such as carbon offsets.  Policy options ranged from outright bans in new construction and building retrofits to “feebate” mechanisms for disincentivizing gas appliance and equipment installation, all with the goal of full electrification of residential and commercial end users.  Detailed discussion of state and local amendments to the 2021 International Energy Conservation Code (IECC) to reintroduce electrification measures that were removed as a result of appeals by AGA, APGA, and other organizations and to expand on such measures. NBI suggested that it would be publishing its recommended energy code amendments but did not provide a timetable for doing so. In several draft proposals shown on the webinar, specific requirements for gas-fired equipment were described that would both disincentivize consumer choices of gas-fired options and lead to energy code scope intrusion into fuel gas code coverage.  A link to the presentation slides from the webinar will be provided in next week’s Friday Update.

 

EO 13990, signed this week by President Biden, includes among its many provisions, the following directive:

 

This directive is likely to require the Department of Energy to review recent successful actions by the Office of Energy Efficiency and Renewable Energy (EERE) including the recent “Interpretative Rule” recognizing appliance design elements as features that provide unique consumer utility and reforms to the Process Improvement Rule, both of which fit within the four year window for review.  Other actions such as the final issuance of the commercial package boiler minimum efficiency rule, issued final in late 2016 but contested up through 2020, are less clearly within the scope of the Executive Order.  Inaction on standards for non-weatherize residential gas furnace efficiency are likely to be a key target of EERE activity, with or without the Executive Order review, although we expect that the delays will receive special scrutiny.  Codes and Standards staff will track how response to the Executive Order plays out at EERE and will work with other AGA staff following federal actions to the ED possibly impacting the natural gas value chain.

 

Most recently, indoor air quality (IAQ) issues associated with  unvented gas appliance operations have focused upon combustion-related pollutant emissions with acute health effects and regulatory coverage, such as carbon monoxide (CO) and nitrogen dioxide (NO₂) and domestic cooking appliances as emissions sources.  However, a small number of recent press accounts has suggested a concern about carbon dioxide (CO₂) from unvented combustion appliances and its impact on human health.  AGA BECS staff has worked in issues associated with CO₂ and human response since the late 2000s, principally through standards activities of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and its standards on ventilation and indoor air quality in residential and commercial buildings. In the 2010s, activity on CO₂ have been picked up within the ASHRAE and the successor standards development activity to the ASHRAE “green” commercial buildings Standard 189.1, the “International Green Construction Code.”  Within the ASHRAE technical discussions of CO₂ exposures and health effects, an “ASHRAE Technical FAQ” and ASHRAE’s Position Paper, “A Summary of ASHRAE’s Position on Carbon Dioxide (CO₂) Levels and Spaces” state the Society’s Guideline for exposure to CO₂ as a steady state  maximum of 1,000 ppm.  In ASHRAE’s standards development for IAQ, measured CO₂ concentrations below 1,000 ppm demonstrate adequate ventilation and air circulation for CO₂ concentration mitigation and a range of other indoor air contaminants.  Note that the 1,000 ppm Guideline is not directly associated with specific health effects of CO₂ exposure.

 

In contrast to the ASHRAE Guideline, the national standard addressing the Permissible Exposure Limit (PEL) promulgated by the Occupational Safety and Health Administration (OSHA) for CO₂ is 5,000 parts per million (ppm) (0.5% CO₂ in air by volume) averaged over an 8-hour period (time-weighted average or TWA.). Occupational limits for CO₂ exposure are relevant to industrial setting and are the only relevant environments for regulating CO₂ exposure since feasible residential and commercial exposures are more than one order of magnitude below these exposures. 

Considering these CO₂ thresholds, residential unvented natural gas combustion from cooking appliances cannot reasonably generate hazardously high concentrations of CO₂ due to mitigating consequences of such high rates of natural gas consumption in cooking and the intermittency of cooking activities.  For example, natural gas ranges cannot produce those concentrations of CO₂ without intolerable excessive heat in a kitchen and requiring mitigation by either suspending cooking or ventilating the kitchen to the outdoors.  North American standards for air emissions from gas-fired cooking appliances have recognized this relationship and set emission standards based upon this relationship since the 1920s using a heat gain threshold of 31 degrees F to the kitchen as the upper bound for tolerability.

 

While the natural gas industry has never seen a need to analyze CO₂ concentration development in residential occupancies, a groundbreaking analysis funded by the Propane Education & Research Council in 2015, “Assessment of the Potential Impacts of Vent-Free Gas Products on Indoor Air Quality In Residential Energy Conservation Structures,” predicted CO₂ concentration development from unvented combustion heating appliances using natural gas and propane for unvented heaters with input capacities highly correlated with cooking appliance firing rates.  The study, using continuous operation at maximum input rates and simulated for 20,000 appliance installations across the five U. S. DOE regions, found that at least 95% of the occupancies (kitchens) in each region and under all occupancy configurations and air change rates stayed below the ASHRAE 1,000 ppm Guideline at steady state.  Given that unvented heating appliances were operated continuously for the steady state simulation, cooking appliances of similar capacities would produce much lower CO₂ exposures and even fewer exceedances when cooking behaviors were simulated.

 

 

 

[This is a weekly feature of the “Friday Update” covering state code calendar activities as presented by the online utility “Fiscal Note,” which is sponsored by APGA and AGA Code and Standards. AGA staff has received only positive comments on retaining this feature and will continue providing it in  future End Use Codes and Standards Updates]

 

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