Technical Reference Request: Definition and Use Cases for Greenhouse Gas (GHG) Emissions Metrics

There is a great PNNL paper that talks about this.   See relevant sections below.   It turned on different ASHRAE standards use different data.   There will be a seminar focus on this in the ASHRAE WINTER Meeting, and I will speak to this topic.  Recommendations from PNNL: Recommendation 4: Determine equivalency of the data sources used, including overall methodology, inclusion of precombustion and combustion values, accounting for extraction, processing and transportation, and output values for GHG emissions. If wide variation exists, limit the sources of data that can be used. (different standards include precombuston and combustion only values)  Recommendation 5: Standardize the years of source data for use in carbon metric calculations.  (inconsistent use of source data for carbon calculations) Recommendation 6: Standardize the use of annual or hourly factors across standards. Standards for new construction should be put on a path to use hourly factors. Standard for existing buildings should engage to better understand transition to hourly metering infrastructure across U.S. (inconsisten use of annual or hourly factors across standards) Recommendation 7: Develop additional research on the use of forward-looking grid emissions factors including market readiness and data reliability with a goal of developing specific recommendations for the standardization or not of historic or forward-looking factors across standards. (some use backward looking, others forward looking data) I have not seen 240's work yet, but will not be surprised if it start to address above, which is already in motion among ASHRAE discussions.

Let me check if the authors have published that paper.  The title of the paper is: "ASHRAE Standards GHG Emission Calculation".  Prepared by Pacific Northwest National Laboratory on October 12, 2023 Standards included: 90.1, 90.2, 100, 105, 189.1 and 228.  It talks about use of marginal rate in the forward looking scenerios of selected standards referencing the electricity conversion factors are 2022 Cambium long-run marginal emission rates presented at the Cambium eGRID subregion level. 

Victor— I’m not an engineer, so I needed a explanation of these things in plain English. SMEPL member Karina Hershberg provided an explanation that I found really helpful in Part 2 of her six-part series on LinkedIn . After reading that, I felt like I finally understood the differences between average, long-term marginal, and short-term marginal rates. More importantly, I got a handle on why/when one might use each of them. I wish I could be there for Luke’s presentation on this!