Our project is a 26-storey building located in Mexico City with more than 20 tenants. The HVAC consists of AHUs and VAV-boxes with recirculation at the AHU. I have several questions regarding the documentation required by this prerequisite and the requirements. We would appreciate some help:
1.Can we perform the VRP calculation including only the critical zone (meeting rooms) and disregarding other non-critical spaces?
2.Some floors do not comply with ASHRAE 62.1-2010 because small VAV-boxes were installed and do not provide the OA rates required by the calculator. Does the project fall under the Case 2? Can we comply with the prerequisite just measuring the outdoor air provided by the UMA and providing 10 cfm/person?
3.Is tenant ductwork a required documentation for certification? Many false ceilings are inaccesible and the plans cannot be drawn up.
4.Natural ventilation is no longer accepted as the only means of ventilation. Does it also apply to bathrooms? Does a naturally ventilated bathroom need an exhaust fan?
Thank you!
Ben Stanley
Senior Sustainability ManagerWSP - Built Ecology
LEEDuser Expert
250 thumbs up
August 31, 2017 - 7:58 pm
Hi Gustavo,
Some thoughts on your questions.
1. You don't have to enter all zones for any given system so you could just enter in the critical zone. But, the calculations have to address the total floor area and total occupants served by the system.
2. You'd have to demonstrate that your system can't be adjusted to meet the ASHRAE required flows. If the limiting factor is the VAV box, then you'd have to show that it's not technically possible to adjust it to comply. Then you could show compliance by measuring at least 10 cfm per person at the AHU.
3. Tenant ductwork is not a required submission for existing buildings projects.
4. Unless the openings are permanently open, I'd assume you'd need to meet the minimum exhaust rates from Table 6-4 of the standard. If they are permanently open you could show compliance via the natural ventilation procedure.