34' X 36' ROOM DAYLIGHT HARVESTING DESIGN

Fixture: P4 Series Columbia Lighting 2-lamp Parabolic, 2X6 Cell, Axis 277V Ballast.

Quantity 16, Mounted on 8' X 8' Grid Spacing.

GE Lighting HL Series “Super T8" Lamp, 2915 Maintained Lumens.

Room Light Level: 51.08 FC Average Maintained.
Room Load: 1056 Watts, 0.86 Watts per Square Foot Maintained .

Daylight Harvesting (16' Room Daylight Depth Penetration) Load Reduction: 21%
Revised Room Load: 0.86 X .79 = 0.68 Watts per Square Foot Maintained .

Total Building Added Daylight Harvesting Savings :

Annual Total Building Electricity Reduction: 8%
Annual Lighting KW Load Reduction: 26% (5% Peak)
Annual Cooling KW Reduction: 3% (1% Peak)
Annual Heating Therms Increase : + 5%
Annual Source Energy Reduction (Mbtu): 6%

Here's a look at integrating the dip-switch tuning into the design. We'll run the same room to a 30 footcandle average to incorporate a scotopic / photopic adjustment or to integrate task lighting with a reduced general light level. Using the same 8' X 8' ceiling grid placement to maintain uniformity, and by tuning the ballast to a 40% dimmed output level, we get:

Room Light Level: 32.50 FC Average Maintained.
Room Load: 772 Watts, 0.63 Watts per Square Foot Maintained .
Daylight Harvesting Load Reduction: 21%
Revised Room Load: 0.63 X .79 = 0.50 Watts per Square Foot Maintained .

These above calculations are based on the following design factors:

• Suspended T-Bar Grid 9' Ceiling, 80 / 50 / 20 Reflectance.
• Dual Pane Tinted Windows, Single Side, 47% Window to Wall Area.
• LDD = .89 Axis Ballast BF = .99, Input Watts = 66
• Point by Point Task Height 30", Points Spaced 2' Apart. (Calculations from AGI 32 Software.)
• DOE-2 base and daylighting energy analysis simulation for a 2-story Office Building, 25,000 square foot total size, located in Lincoln, Nebraska.