Why has my VE-SBEM results changed so much by going from VE 2016 to VE 2017?
Question: My lighting results have increased drastically between the two versions of the VE and i have not changed anything. Why is this?
Answer: This is not an issue in the software, instead it is the result of a change we made for the VE 2017 release, which is also covered in the published release notes (Please take some time to read these as soon as you get a chance!).
Previously if the user had selected \"Lighting chosen but not calculated\" or \"Only lamp type known\" we did not write out the LIGHT-LUX-DESIGN value to the SBEM input file that the VE supplies to the SBEM Calculation Engine. This forced the SBEM engine to use the default illuminance level for the rooms NCM Activity. For VE 2017 we are now writing out this value which is entered by the user via the Building Regs tab > NCM Lighting Data.
Fig.1 Where the LIGHT-LUX-DESIGN value is entered.
So if it is wildly different from the NCM Activity Database value, you will see a change in the results between the two versions.
Fig.2 Comparison between VE 2016 and VE 2017 inputs. VE 2017 now writes out LIGHT-LUX-DESIGN
If you have a licence for DSM then using Tabular Room Data you can quickly check the NCM Activity Database illuminance value for all rooms. You can then copy these values and update lux values used by SBEM method by selecting SBEM method > Tabular Room Data and NCM Lighting Data, change the lighting design status to \"Full Design Completed\", paste the lux values in and then change the Lighting Design Status back to your previous seelction (Lighting Chosen but not calculated or Only Lamp Type Known)
Fig.3 You can view the NCM Database value through DSM > Tabular Room Data > Internal Gains
If you enter the NCM Database value for the lux level in SBEM method, then the lighting energy consumption in VE 2017 should be the same as in VE 2016.
Fig.4 Updating the lux to reflect the NCM Database value.
As shown in our test case below. 400 lux, the default NCM Database illuminance value for the office spaces selected in my test (other activities will be different), was entered in VE 2017 and it produced the same lighting energy result as in VE 2016.
Fig.5 Comparison of lighting energy between VE 2016, VE 2017 with default of 500 lux and VE 2017 using the NCM Database value.
Instructions to pull the NCM Database lux levels from DSM into the Design illuminance tab in NCM Lighting Data
1. With SBEM method selected select all rooms in the model.
2. Select Tabular Space Data > SBEM Lighting Only (NCM)
3. Tick on all rooms & sort the rooms by Space Name.
4. Change the Lighting Design Status from \"Lighting Chosen but...\" or \"Only Lamp...\" to \"Full Design...\"
5. Select Copy data from Current tab
6. Paste into Sheet 1 in a new spreadsheet
7. Switch from SBEM to ApacheSim method
8. With all rooms selected, select Tabular Space Data > Internal Gains
9. Sort the rooms by Space Name and then select Copy data from current tab
10. Paste this into a different sheet (Sheet 2) on your spreadsheet.
11. Using Text to Columns, delimit Column H (Gain 1 Design Illuminance (lux) (Actual)) in this sheet so only the lux value remains.
12. Copy the lux level from Column H in Sheet 2 and paste into Column F (Design Illuminance (lux) (Actual)) in Sheet 1.
13. Copy Sheet 1
14. Back in VE Compliance, select SBEM method, select all rooms and open Tabular Space Data.
15. If not already, sort the rooms by Space Name and then select Paste from Clipboard
16. The Design illuminance should now have the NCM Database values for each space.
17. Finally, change the Lighting Design Status back from either \"Lighting Chosen but not calculated\" or \"Only Lamp Type Known\"
