Alternative LCA Process???

Patrick - 100%, as in I agree - We are still nowhere near 100% WBLCA but think the value of it is really honing intuition, certifications and tracking, and discovering what you don’t know you don’t know (speaking of, most WBLCA ignores MEP and often interiors, which are areas I’m advocating for inclusion as possible to inform our intuition for future projects). Having that Iintuition (or access to data from industry studies) to inform project focus to areas where you can make a tangible difference (with or without a WBLCA). I call this “just in time “ LCA and try get the integration of LCA as an important criteria when making decions about key systems choices. I’d add or expand to your list: 1) with structure (which of course is biggest day one impact ) we’ve found a great synergy when different systems are being explored for cost; we (or they) can translate system quantities developed for cost to GWP. 2) everyone of our projects has wall assemblies. We’ve started with exterior systems and developed a relatively simple excel tool to mock up 2D exterior assemblies to understand the relative impact of each layer and better options - I’ve become a fan of folded metal panel cladding as a result. We’re doing this right now on interior systems. On May 9, 2024, at 2:47 PM, Patrick Donnelly wrote:  EXTERNAL ((( Reply ABOVE this LIN

Patrick, what you're describing is very similar to the approach taken in the LEED v5 draft for a proposed low-EC material credit. Basically, in the draft version, they're asking teams to focus exclusively on the four categories from the federal Buy Clean procurement rules—concrete, steel, glass, and asphalt. At a February EPA press event about the forthcoming low-EC label for building materials, I learned that these four materials represent 98% (?!) by cost of the federal government's spending on construction materials, and they all have extremely high GWP.  As Chris suggests, this approach would leave out a lot, including the envelope—not to mention the continual purchase of high-GWP MEP and interior items over the whole life cycle. But it's a place to start and would probably get you huge savings on the upfront emissions. (Speaking of hot spots and glass, I just had a random thought! I'd love to see a whole-life comparison with three to five different window-to-wall ratios, with all the materials the same, just changing their quantities based on the WWR. Has anyone ever seen a study like that?)

I was going to point to v5 too. Another source that might be good to hit hotspots is the v4.1 Procurement of Low Carbon Products PCredit -- it's a solid list of high impact products and outlines a workflow using BIM bill of materials. This can become a really simple excel model, develop a baseline and design model. We're trying to formalize this workflow on project since the full Tally/OneClick is too much time for most. The list also has established CLF baselines.  Payette's Kaleidoscope tool needs a shout out for early assembly comparison. We have a catalog for additional assemblies too. SE2050 has published bay studies that are useful in early design as well.  We've studied WWR and whole life carbon/LCA on several projects. The short verison; almost any glazing assebly (window, storefront, curtainwall, unless it's wood) is much higher embodied carbon than your average opaque wall assembly. With the lower WWR and a code minimum wall, life time energy use is significantly reduced. So lower upfront and lower lifetime impacts. This assumes a "average wall" which means, you're doing precast with sprayfoam or have the budget for fancy stone cladding. Also assumes low lighting power denisty. That pilot credit list:

• Concrete (ready mixed concrete, slurry, shotcrete)
• Masonry (CMU)
• Steel (rebar, steel wire and mesh, plate steel, structural steel, steel decking, cold formed steel, open-web steel joists)
• Aluminum (aluminum extrusions, thermally improved aluminum extrusions)
• Wood & Composites (dimensional lumber, plywood/OSB sheathing, glass mat gypsum sheathing, prefabricated wood products, composite lumber, mass timber)
• Insulation (board, blanket, foamed-in-place, blown)
• Cladding (insulated metal panel, metal panel)
• Finishes:
  • Gypsum Board
  • Acoustical Ceiling Tiles
  • Resilient Flooring
  • Carpet
• Communications (data cabling)
• Bulk Materials (flat glass)

Procurement of Low Carbon Construction Materials https://www.usgbc.org/credits/new-construction-core-and-shell-schools-new-construction-retail-new-construction-data  

Paula - Arup did a big study on different window parameters including WWR: https://www.arup.com/perspectives/publications/research/section/carbon-footprint-of-facades-significance-of-glass My CLF chapter hosted a presentation by Scott Farbman on his LCA research which tested WWR and double vs triple paned: https://youtu.be/lcSf1mw6LH8?si=vOymsnZ80N2PYSpb&t=1974 (this link should jump to the part of the video that gets into the envelope study, it's about 32:00 in)    And yes, seconding the other comments that this hot spot approach is valid, and I think especially helpful for informing future projects. I'm not typically getting the question, "how can we optimize whole building embodied carbon?" from project teams, but "what's the best option for [insulation/glazing assemblies/steel] given these project constraints?" and this kind of approach helps build your database of answers. 

These are great approaches for prioritizing embodied carbon. The only category I would add would be some types of foam insulation. The GWP of foam has improved and is improving, , but there is still a lot of foam out there with very high GWP that is used in high enough quantities to be worth paying attention to. I'm thinking of extruded polystyrene (XPS) used for under slab and below grade insulation. In a project we analyzed about ten years ago, the GWP of the foam was the highest source of emissions, higher than the steel or concrete. (It was metal building with foam insulated panels) On Fri, May 10, 2024 at 7:42 AM Emily Purcell wrote:

We have done something similar. After an initial grand idea to model every single project for embodied carbon, we have adjusted to:

• Model several typical buildings of different project types (low rise, mid rise, high rise) to establish some internal baselines.
• Use those findings to focus in on doing better for the high carbon items which are similar to what others have stated (concrete, steel, GWB, carpet, insulation)
• Further model to compare similar items to each other (e.g different types of siding) to refine material choices.
• As we are seeing some projects with more aggressive embodied carbon goals, where the cleint's project design budget actually includes embodied carbon analysis, use that more detailed whole building modeling to continue to refine lessons learned across other projects for those lesser carbon intensive materials.

Good ideas so far. I see it this way: Early in your understanding of EC, it’s great to run some models. You get to see what varies, what is unique, what is tough to understand. Once you’ve run a few models, seen some results, then it becomes about asking questions and then answering them. What is the optimum bay size from a CO2e perspective? How much does mass timber stricture reduce CO2e in my building (that’s a tough one even with EC modeling)? What is the impact of a 30% reduction in cement content of concrete on my project? What is the EC impact of polyiso v mineral wool v XPS in my assembly? What are the top 10 materials for EC in my building? How much CO2e would I save by using this salvaged material? The latter is where we are with energy modeling now – models should only be run to answer a question that can impact a building design. Asking for an energy model generically is like walking into a restaurant and asking for food: more nuance is needed to get what you want or else both you and the chef get frustrated. Once the basic understanding of EC is there, we are in the same space where we need to ask intelligent questions where the answer will impact our design. I think this stage is parallel to developing resources to get at more nuance. I like the idea of an envelope menu more specific to our practices and climates. -Kjell Kjell Anderson FAIA, LEED Fellow Principal, Director of Sustainable Design LMN Architects lmnarchitects.com M 206 812 6546 O 206 682 3460 S Linkedin | X | Instagram From: C

What a great thread. The only thing I have to offer is that you're not starting from scratch on each project. Record the studies that are being done on projects and give everyone access to them so the design teams can see what is appicable to there project and how they will add to the them.