LPD for space types not listed on ASHRAE Table

I am not aware of an expanded space-by-space table. Typically you pick the closest space type. For example your aerobic/fitness room would be an exercise area and the LPD is 0.9 W/sf. A natatorium is not as clear. Most times I have seen projects use the gym criteria. If you do you should provided a justification based on the activities in the space. Competitive swimming vs lap/recreation swimming could be the difference between the playing area and exercise area values. My opinion is that there are big differences between a gym and a natatorium and the comparison is not valid. You could also look to the IESNA Lighting Handbook and see how natatorium lighting requirements compare to other spaces on the list and perhaps justify extrapolating a LPD value from there. The most conservative approach would be to model the baseline identical to the proposed design since this space type is not listed and therefore not really regulated by 90.1. The more you deviate from a conservative approach the greater the level of scrutiny given to an issue in the review process. In other words the higher the LPD in the baseline vs the actual design the more justification you should provide to defend your baseline choice.