We are undergoing energy model calculation in e+ to meet LEED's mandatory requirement. Our new construction will be a medical office and lab conditioned with VRF system complemented by independent Outdoor Air Units (OAU) to meet IAQ requirement. This OAU consists of supply and exhaust fans only (no coils, mixers, or exchangers). The result of this combination is a huge amount of unmet hours (up to 3700 hours a year). Therefore in e+, it is also possible to introduce OA without adding independent OAU by using mixer embedded inside VRF's Terminal Units. When I implemented this (both cooling and OA provision only through VRF Terminal Units), with the exact technical specifications and the same amount of outdoor air provisions, there was no unmet hours problem occurred (only around 30 hours a year). How this could be happened? Logically, it would behave similar with the OAU equipped. Or maybe I missed something?
For additional information, our project location is in tropical humid climate, Surabaya-Indonesia
Regards,
