Hi all,

I am looking for some guidance on a project that I’m working on. It is an extension to an existing pharma building, with the extension seeking LEED certification. The new extension has its own dedicated plant for the most part, however, it is receiving hot water (heating only) from a central boiler plant located in the existing building. I have the following questions if you could please provide some insight.

Do I have the option to follow either Addendum ai or the DES guidance document (Option 1 or Option 2) to model the district heating energy?

Does Addendum ai allow you to take advantage of the efficiency of the upstream boiler plant, or do you have to follow DES Guidance Option 2 (full accounting) to do this?

Addendum ai states the same heating source shall be used in the proposed and baseline building design. I assume you set the boiler efficiency the same for both the proposed and baseline models. Is it set to the minimum boiler efficiency requirements outlined in 90.1 Table 6.8.1F?

If following the DES Guidance Option 2, is it sufficient to account for the upstream equipment that is only related to the new building that is seeking LEED certification, e.g. for the project I am working on, they installed a new hot water distribution header in the central plant room (part of existing building) with a new set of dedicated pumps to serve the new extension. Thus, are these pumps and the boiler plant the only equipment I am required to include as part of DES Option 2? There are other distribution pumps serving the existing building.

There are two lab spaces within the new extension that have RH requirements. I assume I will set up a humidifier in the baseline design with the same parameters as the proposed, however, I doubt the energy consumption associated with the humidifiers will be the same between the proposed and baseline. Is it a requirement that the humidifier results are the same? Or do I simply add the proposed humidifier energy consumption to the baseline results afterwards?

The lab spaces in the proposed design have high air change rates to maintain the RH within the space. Is assigning the fan power limitation pressure drop adjustments to the baseline model, based on the added filtration in the proposed design, the only way to account for this additional proposed fan energy in the baseline?

Any help is appreciated.

Dónal