LEED BD+C Healthcare ventilation calculations per ASHRAE Standards 170 and 62.1

Hello Ramana and everyone - Literally asked this recently (for a non-24/7 ambulatory surgical center) that is using LEED NC (and the 62.1 standard), but has healthcare spaces that are being design to 170 (so perhaps the opposite situation you have). Regardless, this response from LEEDcoach might help: With regards to the ventilation standard question, you may use ASHRAE 170 for all spaces covered by that standard. If any spaces are not covered by that standard, ASHRAE 62.1 would be used. For the spaces that are regulated by ASHRAE 170, you can submit an air balance summary (or room by room airflow summary) table to demonstrate that the minimum OA changes, min total air changes, and space pressurization relationships provided are consistent with that of Table 7-1 of the ASHRAE Standard 170-2008. There isn't a specific calculator or format for which this must be presented, and it can be the same calculations that are required by local code. If you have a copy of ASHRAE's HVAC Design Manual for Hospitals and Clinics, Table 3-1 provides an example of this calculation that would be acceptable for the purposes of LEEDv4. This is expected to be the typical approach followed by most teams that require identical/very similar calculations for local code requirements. For cases where an ventilation system serves both ASHRAE 62.1 and ASHRAE 170 regulated space types, there are several hybrid approaches that can be used, which would be a little complicated to address in detail via email. We'd be happy to evaluate any proposed approaches and/or have a conference call to discuss this topic further if you would find that beneficial. Our MEP essentially produced their own table of all spaces, which standard governs, and what the required and provided OA was.

Warning - mechanical-speak used heavily in the following. For air handling systems that serve both 62.1 and 170 spaces, we use a single spreadsheet that calculates the 62.1 and 170 requirements for each space, and then selects the maximum supply and outside air requirements between the two standards - on a space-by-space basis.  Then we sum up all the spaces on a given air handler system to determine the max supply and outside air required at the air handler.  And then compare that against the exhaust requirements to maintain building pressurization.  The key is maintaining those space minimum air change rates and pressure relationships (like keeping clean utility positive) at VAV turndown. If you have an air handling system that serves JUST 62.1 spaces, then you fall back to the 62.1 multi-zone calculation.

Hi Ramana, In the past, we’ve provided our own spreadsheet that we’ve generated to demonstrate LEED compliance. It’s not a LEED-provided spreadsheet – it’s the one we use when we’re initially calculating required OA, but we’ve tailored it to address any additional LEED requirements. The MzCalc spreadsheet that LEED provides isn’t compatible with ASHRAE 170 calcs. I hope this helps. Kristy Kristy M. Walson, PE, LEED Fellow, BEMP Principal kristy.walson@tlc-eng.com TLC ENGINEERING SOLUTIONS® 255 South Orange Ave., Ste 1600 Orlando, FL 32801 Direct: 407.487.1118 Cell: 352.514.5920 Main: 407.841.9050 www.tlc-engineers.com [cid:BFTWF_2021-01_913daf49-aa7b-436b-924f-97e57e8ee685.png] [cid:TLCtriangle_48_313b72bc-6d34-449c-a3ce-927c30916866.png] [cid:LinkedIn_e894ae63-eb4a-4f56-8672-a2becf4e6ea0.png] [cid:Facebook_da51a450-a837-4067-a520-fb36d1102427.png] [cid:Twitter_1821bca2-a572-47a2-9271-ec19899304eb.png] [cid:Instagram_9d1c8959-77b8-4940-b946-520fe0788242.png] From: Ramana Kot

Your very welcome, Ramana. 😊 Kristy M. Walson, PE, LEED Fellow, BEMP Principal kristy.walson@tlc-eng.com TLC ENGINEERING SOLUTIONS® 255 South Orange Ave., Ste 1600 Orlando, FL 32801 Direct: 407.487.1118 Cell: 352.514.5920 Main: 407.841.9050 www.tlc-engineers.com [cid:BFTWF_2021-01_913daf49-aa7b-436b-924f-97e57e8ee685.png] [cid:TLCtriangle_48_313b72bc-6d34-449c-a3ce-927c30916866.png] [cid:LinkedIn_e894ae63-eb4a-4f56-8672-a2becf4e6ea0.png] [cid:Facebook_da51a450-a837-4067-a520-fb36d1102427.png] [cid:Twitter_1821bca2-a572-47a2-9271-ec19899304eb.png] [cid:Instagram_9d1c8959-77b8-4940-b946-520fe0788242.png]