I have experience with 3ds max and Vray renderer... I need to simulate a spefic real world building/lighting issue-question-problem in some software (light simulation software) and get REALISTIC, TRUSTWORTHY, physically accurate results that i can use/count on in real life when (eventually) i will be moving with this project forward and building it in real life...(?)

The problem, issue is:
I need some "light simulation software" (or as i hope - i might be able to use directly 3ds max (or Vray) for this INSTEAD of some specialized separate software) for rather easy task:
I want to simulate light (only sky + direct sun, nothing else, no artifical lights needed) comming to a "room" with no roof (and no windows) at a specific altitude during each season/month and during different times of the day. Easy so far i think? I believe any light simulation software can do this task right?
But i need to apply special light reflecting material to all the 4 walls completely . That (material) would reflect 95% of the light... This is to simulate the use of special grow foil in real life that reflects like 95% of light (mylar reflective foil)
(something like this: https://www.amazon.com/VIVOSUN-Mylar.../dp/B01MZ72PAH)

Purpose? I would like to simulate how much light can i get into an "underground" greenhouse (in real life; i want to build it in real life eventually) that is 3 meters (10 feet) below the ground level, and which only light source is the light comming from (glass) roof (that is - there is "no" roof at all - "just glass") - that means that the only light source would be the sun + sky. All 4 walls of the underground greenhouse ("cellar") would be completely covered with this 95% light reflective material... (mylar diamond shape foil which is supposed to have 95% light reflactance)

Can i do this directly somehow with/in 3ds max (+Vray)...? And most importantly- will the results be "real" ? Real world, trustworthy, physically accurate, that i can replicate later on when building the underground greenhouse in real life? I need to "proof concept it", that is i need to know if i can get enough (real life) light (sun+sky) in the greenhouse for the plants to grow... I need to "simulate it" before i go forward and start building it. I need currently to "just" simulate the lighting, i dont care (currently) about designing the underground greenhouse itself (for the building of the greenhouse itself), - no architecture, no "archicadding").... I just need to sort out the light issue only now. So see if the concept of underground greenhouse is even possible, if i can get enough light there (with the reflective foil on the walls)...

So can such light simulation be done and trusted in 3ds max + Vray? (if not what other -easy to handle/learn software would you propose)?

If its possible to simulate it straight in 3ds max with Vray, shat should i do/use in 3ds max and Vray ?

1) What Light source exactly? Is it the Vray sun from the "Lights" category? Is it some other type of Light from the "Lights" category/"tab"? Or is it the "Sunlight" or "Daylight" from the "Systems" "category/tab/tray")...? (where "bones" and "biped" are located)...? Or something else...?

2) What material should i apply to the walls (to simulate the mylar foil 95% light reflectance in real life?) Vray material ("VrayMtl") with some gray diffuse color shade (128,128,128), with "95% white color" (242,242,242) in the "reflection color" (to simulate mylar foil with 95% light reflectance) and with Reflection Glossines set to 0,95 (again... to simulate that mylar foil material)...? And apply this to the walls? OR do it somehow differently? Different material? Different settings?
3) What "tool" should i use for measuring the light intensity/illuminance (i guess it will be in the "lux" unit type?)? Should i use:
A) "Vray Light Meter" (under "Create" (tab/category) and then under "Helpers" (tab/category), then "Vray" (from drop down menu) and "Vray Light Meter")?
B) Or 3ds max default "Light meter"? (under "Create" (tab/category) and then under "Helpers" (tab/category), then "Standard" (from drop down menu) and ""LightMeter")?
C) Or should i use some specialized Vray Render Pass that is meant for light measurents... for this?
D) OR should i measure it somehow completelly different...?
4) What rendering settings (if i need to render) should i use (especially for the "Global Illumination Tab" for render settings)?

And with all these "pipelines"/"workflows", "settings"), will i get a realible, physically accurate numbers (in LUX units or some other "light/illuminance" intensity units (like Lumens etc.)), that will reflect the REAL world situation in REAL LIFE...?

Thank you