Hello everyone!
If you are familiar with the calculations of this prerequisite, you'll notice that you basically calculate the average CO2 equivalent of a commute trip (one-way) based on type of transport and distance, and then get a transportation score; very straight forward. But of you look closely on the table with CO2e pounds/mile for each mode, the difference between car solo and bus is not that much, about 26%. I ran the calculations for the project, and it seems that it will not comply with the prerequisite since most people travel by bus.
So, I did some research, and it seems that the value comes from the document "Updated Comparison of Energy Use & Emissions From Different Transportation Modes Oct.2008", which shows 308 gCO2/pass-mile for a transit bus. Then, I found a new version of the document "Updated Comparison of Energy Use & CO2 Emissions From Different Transportation Modes April 2014" which shows 136 CO2/pass-mile for a transit bus; considerably lower than the value from Oct.2008.
Does someone know if there is some error on the calculation from 2008? Any suggestions on how to proceed?
Thanks!
emily reese moody
Sustainability Director, Certifications & ComplianceJacobs
LEEDuser Expert
476 thumbs up
March 13, 2019 - 9:35 pm
Hi Gaston,
I haven't gotten this far with a project yet, but it looks like even in the online version for 4.1, the references are still to the 2008 version.
You'll prob get the best answer if you contact LEED Coach or GBCI directly and ask for clarification about the updated version, citing the significant difference you pointed out here. I'm surprised this hasn't been updated yet, but maybe they have plans in upcoming addenda?
Please post back here if you do this and get a response.
Gaston Michaud
Mechanical EngineerENEX
14 thumbs up
March 19, 2019 - 4:07 pm
Hello Emily,
Thank you for your response. I did contact GBCI directly, and their response was that they are aware of the issue and that they are researching the most accurate values to represent each transit mode. Additionally: "for now, your project team should use the standard figure given of 0.68 CO2e pounds/mile" for transit bus.
I'll keep you guys updated if I get any other news.