Hello everyone,
I have a proposed building in which there are no daylight control systems for lighting. I implemented lighting using occupancy controls (schedules) in both baseline and proposed (as stated on section 9.4.1.1 and 9.4.1.2).
My question is, do I have to include daylighting controls in perimeter areas in the baseline model? Even if the proposed design does not consider this feature. And if so, do I still model the schedule-based occupancy controls in the baseline? I also have a skylight with 67 m2 (721 ft2), which is less than 900 ft2. Do I need to implement daylight controls in the zones below, or it can be excluded because of its small area?
I also would like to ask how do you usually model occupancy and lighting in zones with very low and uncertain occupation, as for instance, electrical/mechanical zones. I usually create an occupancy schedule with one hour of occupation per day, in which, lighting is also on. This results in approximately 260h per year for maintenance and related work. Is this a valid approach?
Thank you in advance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 20, 2018 - 3:21 pm
Yes you must model the daylighting controls in the baseline if none of the exceptions apply. Yes you also still must model occupancy sensors in the baseline where required. If the skylit area is under 900 sf then you do not have to include daylighting controls in the baseline.
The lighting schedule for those space types you suggest seems reasonable to me.
Greenlab
Green Lab6 thumbs up
April 23, 2018 - 4:21 am
Thank you for the reply Marcus. I have one last question.
I am using design builder to model this building. In order to implement Automatic daylight controls I have to input the control type which I have defined as “stepped” with 3 steps. Additionally, it requires a “working plane height”, a “maximum allowable glare index” and the “view angle relative to the y-axis”.
Are we free to decide which values to input on these fields? In other words, if I have a zone with windows facing both south and west, am I free to decide the light sensor’s orientation? And what about the distance from the windows at which the sensor is placed?
Thank you.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 23, 2018 - 11:40 am
Those values should make sense from a lighting and daylighting design perspective. So no you are not free to input whatever you like, they should make sense for the space types in your project. The definitions in 90.1 can help a bit.
You do get to decide the location of the sensor in the space. The sensor would need to be in the daylit zone which 90.1 defines as one window head height for side lighting scenarios.