# How to do a simulate lux/hour exposition per year? (Daylighting for a museum)

Hi everybody,
First of all, I would like to apologise for my poor English and thank all the community because I have learnt a lot by reading the different topics of this forum.
Currently I am working on a lighting project of a museum. I have done several daylight simulations with metrics like SDA, DLA and ASE, but now the museologist have said me that the art pieces cannot receive more than 100000 lux/hour exposition per year. I have been trying different ways to achieve a simulation with these metrics, but I have not get it. Does any of you know how to make a simulation with this metric?

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

Thank you Sarith for your answere. I will research about it following the path you suggest, that is seem to me very interesting.
Curiously the case I have to solve is quite similar that the one that appear on the last paper you sent. Thank you very much!

this calculation method is require in order to avoid the material/color degradation due to the light (natural and/or artificial). 10000lux hours per year are the sum of the lux level per hour. Example: if the museum is open 5 hours per day weekly. the total hours per year are 52x7x5 = 1820 hours. So if the requirement are 10000 lux hours per year the max lux per hours is 10000/1820= 5,49 lux
I think you can use the 1st step of 3phase method (that includes both 8760 direct and indirect illuminance per hour) and than you must sum every lux level included in the time of use of the museum hall.

The better choice is to use daylight coefficient recipe (2-phase) method which has a more accurate calculation for direct daylight contribution.

Thank you for all of your comments, they have been really useful for me to understand the Total Annual Illuminance concept.

I have made the grasshopper definition I attach to this reply. It takes all the lux of all the hour of the year, and it made a mass addition. It is very basic (materials and windows are not defined yet) and the way of defining occupancy is a little bit “rudimentary”, but I have not been able to get another way (I still learning to use and understand all the components). I would be very grateful if you could give me your opinion, especially in the aspect of the correctness of the calculations. Do you think this grasshopper definition is correct for calculating TAI? Do you know any other way better to do it?

Thank you very much, I really appreciate your help.