Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Get Illuminance at Reference Point (Daylight + Lamp)

asked 2020-12-27 17:51:10 -0600

Chelydrae's avatar

updated 2020-12-29 10:12:09 -0600

Dear all,

I want to get the illuminance [lux] of a zone which depend on daylighting and on the lamp intensity. Unfortunatelly, there is no "illuminance at reference point" output. There is just a "daylighting at reference point" ignoring the light from the lamps. Do you have an idea how to calculate the sum of both light sources? In concrete I am looking for the value a real light sensor would measure at a reference point.

Thank you in advance! P

EDIT: I am using EnergyPlus

edit retag flag offensive close merge delete


@Chelydrae based on your solution, it looks like you're using EnergyPlus, but could you confirm so that others can provide better help?

Aaron Boranian's avatar Aaron Boranian  ( 2020-12-28 11:40:39 -0600 )edit

I am using EnergyPlus. I will try to add this to my post.

Chelydrae's avatar Chelydrae  ( 2020-12-28 18:01:09 -0600 )edit

@Chelydrae great, in the future you should also include the energyplus tag to let others know the tool that you're using and so that others who follow that tag can get notifications or emails and provide help.

Aaron Boranian's avatar Aaron Boranian  ( 2020-12-29 10:10:58 -0600 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2020-12-28 10:32:01 -0600

Chelydrae's avatar

Dear all,

I have implemented a workaround but still look for a better solution. For anyone having the same problem, here is what I did:

  1. Daylighting Reference Point 1 Illuminance [lux]
  2. Zone Lights Visible Radiation Heating Rate [W]
  3. Divide Zone Lights Visible Radiation Heating Rate by Zone Floor Area [W/m2]
  4. Transform [W/m2] into lux (1 W/m2 = 684 lux)
  5. Sum up daylight and artificial light

This is working. I need to check whether the results are realistic though. If you have a better solution please let me know!

Have a nice day!

Best Regards, P

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2020-12-27 17:51:10 -0600

Seen: 123 times

Last updated: Dec 28 '20