I am modeling a laboratory which has a small area of office space for LEED and wanted to check a couple of approaches:
1) The engineers have informed me that the lab has to be a once through system 100% outside air and therefore the baseline should be the same. I can't see anything in 90.1 which specifies this to be true or not however i do agree that it seems to be the correct approach.
2) They are also saying he baseline should use a constant volume exhaust as this is standard with bypass air (when the 100% outside air system loads arent high enough to meet the rate) to stack velocity. The proposed will undertake wind tunnel modeling to be able to reduce the exhaust makeup which is not standard practice and therefore can be done as an exceptional calculation.
3) Based on G3.1.1 (c) The baseline systems will be split for the lab (100% OA) and office (which will be VAV with re circulation).
Thanks, Victoria