Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The OpenStudio Space Infiltration Design Flow rate input is assumed to be at natural pressure. So you need to convert the infiltration rate at 50 Pa to the rate at natural pressure (~4 Pa).
See the answer to "how to set air infiltration under 50 pa pressure" on the forum. There is a table for residential projects to convert ACH50 to ACHnat.
Otherwise, you can calculate it from Q_delta_P = C*(delta_P)^n, where Q is the infiltration rate at pressure differential delta_P, n = 0.65, and C is the flow coefficient. Given your known infiltration Q at 50 Pa, calculate C. Then change delta_P to natural pressure (~4 Pa) and calculate Q.
