I am modeling a space which has some spaces which have area greater than 250 ft2, now this is an office space and using building area method LPD comes out to be 0.9 W/ft2, and these spaces are sidelight area, as per ASHRAE 90.1-2010 9.4.1.4 Automatic daylighting controls for sidelighted areas states that lamps should be controlled by atleast one multilevel photocontrol . Based on this how should I model the baseline lighting, should I add more lighting to the space and use a dimming sensor control by photocell? Right now the software that I am usingn is automatically creating and adding an extra lighting gain which in turn is consuming more lighting in that space when compared to baseline value of 0.9 W/ft2 and beacuse of that MEP calculator is giving an error stating the demand is different in performance output tab as compared to lighting tab.And this is true becuase in the lighting tab I am only mentioning 0.9 W/ft2 of lighting but the simulation is taking extra lighting gain because of 9.4.1.4.
Can I write a comment in the error stating that spaces with 250ft2 or extra have an extra lighting gain confirming to the requirement of 9.4.1.4?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5906 thumbs up
April 10, 2023 - 4:35 pm
The baseline lighting is modeled with the baseline allowance and the mandatory lighting controls in section 9.4. You don't add more lighting to those spaces. The proposed is modeled as designed.