I have posted this in an other area of LEED User as well but maybe I will get more responces with this one. We need to register a project for one of our clients and am not sure what the best approach is. We are adding on to an existing LEED v2.2 Silver building. The existing building is 6,000 sf and the addition is about 3,000 sf. We are moving walls, replacing ceilings, reprogramming, and refinishing the existing 6,000 sf. existing building affecting about 25% of the original. I could email you a drawing as well to make our case clearer. I see 3 possibilities but don’t know if these are acceptable ways to approach this project. Perhaps the best way is to forgo LEED altogether (for this project) and just build a regular building with many green features incorporated. This however is not what we prefer but if we don’t find a good solution soon we might have to.

Option 1:
Address the entire building as new construction under the current 2009 LEED system. We will be providing a new HVAC system for the addition that operates independent of the existing one but otherwise we would not distinguish between the two halves. This approach creates many questions:
Do I need to upgrade the existing building components to comply with all MPR’s, Prerequisites, and credit requirements for LEED NC 2009 for all the credits we are planning to go after for the new addition? For example: The existing exterior walls do not meet the ASHRAE 90.1-2007 mandatory provisions required by LEED NC 2009 EAp2 Minimum Energy Performance. Required is continuous insulation. Do I need to strip the exterior cladding, add more rigid insulation board for continuity, extend all the window and door jambs, then reclad the building? Another example is do we need to upgrade all the lighting controls or just in the areas that are new and renovated? If the new roof complies with Heat Island Effect requirements but the existing roof does not do we upgrade existing to comply or are we ok with only a compliant proposed roof?

Option 2:
The second option is that we can design this addition as totally separate from the existing demarcated by a common party wall. With this option we certify the addition as LEED NC v2009 and upgrade the existing per the LEED NC v2.2 requirements to stay in line with the credits that where submitted back in 2009. We won’t recertify the existing area but all work we intend to do in this area will comply with LEED NC v2.2 requirements.

Option 3: might be to certify the addition as LEED NC v 2009 (per option 2 above) but do all existing building improvements under LEED EBOM?

Any help in this is greatly appreciated.

Thank you,
Lee