NC-2009 MRc1.1: Building Reuse—Maintain Existing Walls, Floors and Roof

Ilana, I am checking around but I could see this going either way. On the one hand the foundation is definitely structural and is an extension of the wall. On the other hand, I have the feeling that if it was intended to be included it would be specifically named in the credit language.

Hi Emily,

Apologies for the delay in my response, hopefully it's still in time to be helpful on your project.
1. The credit language specifically refers to the retention of both the exterior structure, and envelope materials. Thus, the only "guaranteed" areas for inclusion are those which have the reused siding. There is not yet clear guidance from the USGBC on acceptable methods for calculating the portion of the wall that should be counted towards the credit when the structure but not the skin is reused. Cost and weight are never used in this credit, and a section area calculation would undercount the skin. I'd suggest either submitting for an official request for interpretation, or else submitting the credit with a proposed alternate calculation method that counts those areas with structural but not skin reuse as 50% compliant.
2. Hazardous materials should always be remediated, and removed from the calculations. Make sure that there is testing or confirmation that the materials are hazardous, and then yes, you simply leave the hazardous materials out of the baseline area.

You're referring to the calculation instructions on page 349 of the Reference Guide. It sounds to me like this situation is not what is envisioned by those instructions, and that it would be reasonable to count the area of the columns.

However, since this goes against the instructions given, it may be worth confirming before you count on earning the credit.

Brian, this is not straightforward, as you might have guessed.  Is the old building going to be in the LEED boundary? It would surely have to be to be considered for this credit. However, once you have it in the LEED boundary, questions are raised about how you count it for other credits. Does it have FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. occupants? If yes, then it should probably be certified separately. If no, then it could probably (in my opinion) count here, but you'd have to include it in other relevant credits as well. (Will it have HVAC?)

The LEED MPR supplemental guidance would be a good reference here.

I am not sure how often the existing building is going to be occupied since right now it is used for flight medical simulation, as wil the new building. Once the new building is complete, the equipment in the existing building is going to be moved to the new building, possibly leaving the existing building open for storage or undetermined use. Yes, the new building will have HVAC.
I believe the existing building will fall into the LEED Boundary since the utilities for the new building will tap into those serving the existing building and be routed around the existing building.

Hi Dave,

For this credit, you will have to include both buildings in the baseline. If that throws your calculations off and eliminates MRc1 as a possibility, you can apply the material from the retained building towards the MRc3, reused materials calculation.

Before I can give you solid answers, I have a couple questions back.

What is the square footage of the resulting construction?

What CSI section woudl the fill fall under?

We are reusing 100% of the existing foundation and rebuilding the building from the existing steel structure, which is just under 100,000 sq.ft. We have not yet calculated the square footage of the panels and roof that have been removed.

The fill will fall under either 2004 CSI 31 or 32 and will qualify to be included in calculations.

Hi Sara,

If I'm reading your question right, there are three primary questions:
1. Removing the existing roof and wall panels- which credit does that apply to?
a. MRc2- CWM – Yes, this is definitely the right credit to apply these materials to.
2. Reusing the existing structural & foundation- what can that be used as?
a. MRc1 – Building Reuse
Yes, you could definitely include these elements in the MRc1 calculations. However, the calculations might not work in your favor as the credit rewards projects that retain the structural floor, roof decking and exterior cladding. Even if the building is only a single story with an existing slab, it is unlikely that the first floor (which will include the structure) square footage will be 55% of the total.
b. MRc2 - CWM – If you do not count the materials towards MRc1, MRc4 or MRc5, then you can include them in the MRc2 calculations. There’s no clear info available on this, but logic would suggest that you either get credit for getting rid of the material (MRc2) or for keeping the material (MRc3-7).
c. MRc3- Material Reuse- Unfortunately, fixed elements that are still able to be used in their original function are not eligible for inclusion in the MRc3 calculations.
d. MRc4- Recycled Content – It could be a bit of stretch, but I think an argument could be made for including these components in the MRc4 calculations. By estimating the replacement cost of the steel, and applying the default recycled content allowance of 25% - it could add up. The reused foundation will not be able to register any recycled content unless you can verify the concrete mix that was originally used, or effectively estimate any rebar content. Both elements would become part of your baseline materials cost, but could benefit the MRc5 calculations as well.
e. MRc5- Local/Regional Content- I don’t see any reason why you shouldn’t be able to include the structural steel and foundation in the MRc5 calculations, using the estimated cost of replacement.
3. Crushing existing parking lot for usable fill – what can that be used as?
a. MRc2-CWM – yes- this is definitely an acceptable compliance path as long as you do not add this content to MRc4 or MRc5.
b. MRc4 & 5– This could be the same argument as for the foundation/steel, but it’s a bit less likely to pass muster. Although the logic is the same, there is an existing CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide history (1/30/2009) that calls for crushed asphalt to apply to MRc2, thus it might be a bit tough to make this argument.

Hope this rather long winded answer helps you out. Let me know if I misunderstood any of the issues.
- a

Thanks so much! If I opt to go for MRc5 - Local/Regional Content, do I use the location of the project as the extraction point for the reused steel and foundation?

Yes, that's right.

Hi Mara,

It looks to me like you should be able to exclude any mold contaminated materials for these credit calculations. The reference guide specifically calls out as hazardous "materials that pose a contamination risk to building occupants." In addition, while it is not technically on the list of the EPA's hazardous substances (Table302.4), mold is often included in ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services ESA Phase I & II. You should be in the clear as long as the extent of the contamination is well documented.

Hi Anne,

Thanks. I was uncertain, as mold was not included in our ESA (we have asbestos).

The mold is very widespread, but not literally on 100% of the surface. But a bad detail is a bad detail -- those surfaces not yet moldy would have had a very likely gone that way eventually. Any thoughts? We aren't in a position to calculate exactly what percentage of the wall was moldy.

The nature of mold spores and fungal hyphae (the "roots" of mushrooms) it can be hard to draw a clear line between material that is definitively moldy and that which is definitively not. Seems like a conservative approach in terms of casting a wide net to avoid future health and durability issues would be justified.

Hi Mara,
I've been thinking on this one for a bit, and it seems wise to go back and conduct another phase II ESA, this one with the explicit instruction to include an examination of the mold and mildew. In order to make the credit claim, the reviewing team will likely feel more comfortable if somebody has "officially" classified the hazardous material.
-a

Can you give a more specific example? My initial response is that it would be a matter of degrees, i.e. after a certain point if you alter the assembly it does not count as reuse. Can you quantify how much of the assembly is being replaced?

Perhaps the best way to approach it would be if you touch it, it is not considered reuse. For instance, if we are placing a window into a wall without openings that is metal stud assembly (exterior envelope) we would count only the untouched portions of the exterior assembly (larger that just the SF of the window opening). Thoughts?

Hi John, It's always a safe bet to go with the intent of the credit, and with this credit, the calculation is geared towards the area retained. So, I would lean towards counting only the untouched portions of the exterior assembly. That said, there is an old CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide (ruling dated 9/19/2005) that allows for calculating the percentage of a wall section retained based on weight. If it gets down to the line, you could submit a CIR based on the same logic.

This credit focuses on the building envelope and I don’t think that exterior elements would be able to count towards credit compliance. However, I’ve not actually had any experience with this so it might be best to write a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide. Let us know if you get confirmation either way.

Thanks,
Shannon

I had a question about this item also. I have a retrofitted existing masonry trash/recycling enclosure that I would like to include under MRc1.

Would I be able to include this? I'd argue that it's part of the overall building structure.

As Shannon said I don't think you could know for sure without a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide, or just submitting it and seeing if it's approved. I would recommend the latter, but it's up to you. Let us know how it goes.

My old study notes say this only applies to structural elements, but you'd have to double check me.

Hi Susan and Jean,
As the credit specifically references the exterior cladding, you definitely cannot count the walls as 100% reuse if the wood siding is being removed. You could propose an alternative compliance path, either in a formal interpretation request, or with your credit submittal, to count a portion of the walls for reuse.
Let us know how it turns out.
-a

Michael, the answer to your question depends on whether or not a major renovation is being undertaken, which would determine whether or not the project would qualify for LEED for New Construction and Renovations, or LEED for Existing Buildings: Operations & Maintenance. How much of the square footage is involved and will the occupants be displaced? If most or all of it, then LEED-NC is the best system.

As long as you are not building an addition that is more than 2X the size of the original building, you should qualify for building reuse.