My biggest comment--if I were limited to one change--is to the overall credit category weights. I raised this back during our summits and committee presentations. The work I've done and many others on Whole Life Carbon shows that there is quantitatively--or even qualitatively--no reason to skew so many credits into EA and downplay the carbon reduction strategies needed in MR and LT! As the immediate past chair of EA TAG, I beseech you to give at least an equal number of points to MR--if not more than EA. Similarly give LT an equal or higher number of points than is presently proposed!
I cannot speak to locations outside the Lower 48, which are not covered by NREL's Cambium projections. Within the regions in Cambium's database, the lifetime sums of B6 energy use emissions, B7 water usage emissions, B1 refrigerant leakage and C1 disposal refrigerant leakage emissions of all-electric buildings built to a minimum 90.1-2019 compliance with no other on-site renewables or storage are not likely to exceed the initial A1-A5 emissions from the construction of the building. And that only includes the major structure and materials and none of the MEP systems' embodied carbon. To put that another way, doing a business as usual albeit, all-electric building and business as usual construction will have similar lifetime emissions. There is no reason to downplay the initial construction--particularly when we are still learning about MEP impacts in the MR credits from the work of CLF's MEP 2040.
If the bulk of prior LEED NC projects are really new construction and not major renovations, then more than ever we need to incentivize design teams to focus on lower carbon material choices today since there will never be a chance to reverse that decision over the life of the building. Whereas space heating, service hot water and cooking can be changed out after construction and thus are not locked in for the life of the building. Doing all-electric from Day 1 is ideal in most cases but does not have the same imperative as low embodied carbon choices from adaptive reuse, mass timber or low carbon concrete mixes and steel.
When it comes to B8 user activities' emissions, we have failed. CNT created a tool with USGBC funding back in 2008 to estimate B8 emissions from employees, visitors, tenants, and residents. There is certainly double counting of the attribution of mileage and resulting emissions in CNT's methodology to the home and the work location. That double counting is also present in LEED Zero Carbon's commuter survey form. What we do know is that average car lifetimes have been continually increasing in the US to over 12 yrs and the fleet-wide CAFE standards have boosted fuel economies. But EVs are not a panacea and won't do anything to solve traffic congestion. LEED v5 hopes to have a 5-yr shelf life until the next iteration. EV adoption rates are slowing in some early adopter regions and have slowly grown in others. That is, for LEED v5 buildings, EVs will not save them from transportation-related emissions. Greater importance needs to be placed on location and more specifically on location efficiency. We need transit-oriented, walkable locations prioritized. We need actual calculators and tools to assess site options and elements such as the proverbial LEED bike rack. Designers need to get away from these proxies with the advancement of tools which tell the designers and owners what the value of carbon reductions are from adding bike racks, EV chargers, reduced parking, being near 10 or more neighborhood amenities, etc. We moved away from similar proxies like "500 miles" for materials in LEED v2009 and earlier. We need more tools to understand LT choices made during site selection and design which are unlikely to rapidly change but could get better if growth or sprawl eventually surrounds the site. Until then LT needs more points to incentivize better choices. Take some of those from the EA category.
Jamy Bacchus
Associate PrincipalME Engineers
26 thumbs up
May 25, 2024 - 6:06 pm
...and if we want even bolder action in LEED v5 then here are a few other ideas:
We should radically alter the credit weightings to be bare bones minimum—one point max per credit—and all the additional weightings would be set by regional priorities because no international rating system can correctly address all the local issues; local USGBC chapters should set their weightings appropriately to what issues are priorities. This would give regional chapters the ability to reallocate over 50 credits to important issues relevant to those communities and if they don’t provide guidance, then the national version of current weightings would serve as the default.
It was deemed too difficult to implement by those doing the reviews. I contend a static weighting with only a 5% of the credits weighted towards local concerns is insufficient to properly push design teams toward location-appropriate designs and our current system may steer projects away from doing the right things.