Your museologist is right. From the perspective of an art exhibit, the annual metrics like sDA, ASE do not work, as practically the amount of degradation to them is likely to be proportional to the amount of radiation that they receive. Unlike people or plants, paintings and sculptures do not require light to subsist.
The simplest metric you can calculate is total annual illumination (TAI). You can find more about it here: http://www.ibpsa.org/proceedings/BSO2016/p1118.pdf
TAI features in other papers of Elenora as well. So, I would suggest doing a bit of searching to locate other papers authored by her. Elenora’s advisor, John Mardaljevic, is one of the foremost exports on daylighting simulations and has done a fair bit of research on impact and quantification of daylight in museums.
I havent had a chance to go through it yet, however, this paper was recommended to me by a colleague last year: https://www.tandfonline.com/doi/pdf/10.1080/19455224.2016.1214610