Our architecture firm is considering whether we should tackle the LCA reporting for LBC in house. We would have to self train on Tally so trying to get a handle on what those internal costs might be. Staff has strong technical background and Revit resources. We are looking at a 120,000 GSF model as a pilot project. Any anecdotal estimates would be helpful.
This is a good question to ask before jumping in.
My best answer is “it depends”.
As an architect you are looking at a WBLCA which manages up to six building systems (structure, enclosure, interiors, MEP, site, FFE). Most architectural firms start with structure, and enclosure, as these are usually well-modeled in Revit.
The numbers I am providing are based on the following assumptions:
- You and your firm have a background in reporting operating carbon emissions, and you want to use an LCA tool to calculate embodied carbon emissions only.
- Your structural consultant uses Tally and understands the BIM rigor required so that you can use their structural model.
- You will be using proxies for your Interiors, FF&E, and MEP. CLF has published excellant resources here (MEP and TI).
- You are not including Site & Landscaping in your pilot project.
The time required (assuming two staff minimum) to complete your pilot project is estimated at 40-60 hours per person.
You also need to realize that completing this pilot project will set in motion additional time requirements to continue performing WBLCAs, including training of staff, coordinating BIM with your consultants, developing internal standards, quality control, working with your consultants to develop LCAs of their systems, etc. Each WBLCA you perform will require less and less time, and it may take you as much as a year to understand what your final costs will be for each WBLCA.
These suggestions represent my opinon only and your actual time spent could be higher. Please accept this information as a starting point that will hopefully be corroborated or challenged by others in this forum.
While I echo Mr. Redwine’s estimates a more basic answer is that with 4 or so hours, possibly less, a skilled technician can learn Tally well enough to generate a report. Understanding the report and actually reducing embodied carbon impacts is a whole different set of considerations and must be addressed with long term education, but if you’ve gotten this far I assume you are committed to education already.
My comments below assume a Core and Shell analysis.
There are a number of typical modeling practices that need to be addressed in the long run. Material consistency has been our biggest impediment to being able to simply run Tally, as the program is very literal about material designations.
For instance two W12x26 beams, one with a designation of Steel-ASTM A992, and the other with a designation of Metal-Steel-ASTM A992 will result in two Tally entries for W12x26. Fortunately Tally is also an excellent tool for ensuring modeling integrity, via the 3d interface with Revit, and the issue is easily resolved. This effort may take as long as 6 to 8 hours unless you have a complicated façade, in which case add 4 hours.
Overall, the process discloses a longer term effort at better modeling practices, at least in my experience.
Adding to what has been already said - Our early studies took a single staff member ~40 hours to do LCA modeling, but this has trended lower with each new project. We’ve reached a point where we’re able to do most Tally models here from anywhere between 4 and 16 hours per model. This depends on model complexity, BIM cleanliness, naming standards, and how consistent materials are across projects. We like to argue that the Tally process is part of the QA/QC process, as it requires people to really look at model health and project specs. If it’s hard to enter data for Tally, it’s probably not clear yet.
Tally is an easy tool to pick up - I handle training at the office, and within 30 minutes, most people can get up and running on the tool and know 90% of the quirks. What’s not immediately apparent are the quirks and limitations of Tally and how to work with them. For instance, complex curtain wall families and generic models do not report well (if at all). We’ve learned over time that it’s better to exclude things that don’t report correctly and add rough volumes of material to our model that represent the excluded geometry. This requires manual take offs of materials, which is slow for the LCA process, but allows our project teams to continue working quickly on the models. There are a lot of trade offs like this. In general, some things that we do to try and speed the process up is to remind project teams to use consistent material naming, identifying things that Tally is looking for to speed up the material application process. An example is identifying stud depths in their material names and specifying which studs contain insulation in their cavity - ie “6” metal stud w/ batt insulation." It’s also helpful that the number of LCA practitioners has grown quickly, and there is a large amount of support in user groups and forums like this.
On structural models - It’s extremely helpful to have a structural consultant who works in Revit and can handle their own Tally model. They have a better understanding of reinforcement and concrete strengths, so they can better apply it to their model definitions. It also allows the Tally data to live in their model, as opposed to having someone on your end have to enter it into a split off model (we don’t work in our consultant’s models, so if we have to enter structural data, we create a new central copy).
On MEP, Interiors, and FFE - adding onto Bob’s comments - Tally is not really designed for these. Some interiors track - carpet tiles and general wall finishes - but anything that is custom, especially custom work that’s built as a 3d family and not a native revit wall or floor, will generally not Tally. When we track them, we have to develop a side process involving manual take offs and spread sheets.
Good luck with this. I think it’s a worthy rabbit hole to go down, but it is a very deep one.
Thank you so much for your reply. This has been incredibly helpful to gage the workflow and suggestions. I just completed my first test using the trial period on previously completed core and shell project and was pleasantly surprised at how easy to move through the modelling process.
Fortunately, for the LBC certification, we are able to exclude MEP, site, and FFE. We will be tasked with reducing embodied carbon for Structure (including foundation) and Enclosure by 20%. I can see our current BIM standards already addresses many of the workflow pains that Tally users might experience. But I also see where they can use improvement and more rigor from our staff.
I imagine with the need to compare and reduce embodied carbon, our research and modelling effort could easily reach your estimate. I think we will do smaller component comparisons for DD and then for our final report comparing baseline and proposed at the end of CD.
Thanks so much for your time and I’m sure I will be back with more questions.
Thank you, Justin. Your estimates helped quite a bit. I completed my first test model with the trial version on a project I took through CA several years ago that was only core and shell office with not any interior finishes. The work flow is very intuitive if you know the assemblies and specs well but it still took a good amount of time. Luckily our BIM practices generally include the information in the assemblies (or at least we did in that project). The project I tested was fairly simple with few linked families but I did notice in my brief study that linked window families could present problems. Since I was just trying to get a feel for the software, I didn’t investigate if they reported properly.
Thanks so much for your advice and feedback. We will be moving forward with our pilot project for LBC certification and that will require several iterations for reduction comparisons. I’m sure I will have many more questions as we move along.
Adding to what Mr. Redwine said, the structural firm I work for runs the Tally Model for the structural system. This is to eliminate any confusion or under/over-conservative assumptions as not all structural materials are adequately represented in Tally, namely with regards to concrete and CMU systems. The discussion of including a Tally LCA Run happens early so the appropriate fees and timelines can be discussed.