[bldg-sim] Lighting Energy

Who should I contact at IECC for interpretation of the code? In the meantime I have some questions (pardon my ignorance) regarding lighting.

IECC-2000, page 114, table 805.4.2 (also in the Chicago Building Code) shows the following lighting power densities for office building:

Entire Building: 1.3 W/ft2

Tenant Area or Portion of Building: 1.5 W/ft2

There is a Note “b” associated with office (and also classrooms/lecture halls) which states:

“Where lighting equipment is specified to be installed to meet requirements of visual display terminals as the primary viewing task, the smaller of the actual wattage of the lighting equipment or 0.35 W/ft2 times area of space that the lighting equipment is in shall be added to the interior lighting power determined in accordance with this item”

I assume that the entire building area is the gross area which includes the core (elevator & duct shaft plan sections) and underground parking. The net area is about 15% less than the gross area and this would be the tenant area. 1.3 W/ft2 * 1.15 = 1.5 W/ft2

Is the “lighting equipment” task lighting only, or does it include other equipment such as projectors?

Are computer monitors (visual display terminals) a “lighting equipment” since it also generates light?

What is “the smaller of the actual wattage of the lighting equipment or 0.35 W/ft2 times area of space that the lighting equipment is in shall be added to the interior lighting power”? Given a tenant space of 100 ft2 that has 1.0 W/ft2 general lighting and a 100 watt task light, what is the area lighting of the space for code compliance?

Is there a lighting program or Excel spreadsheet program that will calculate the W/ft2 at the ceiling given the illuminance required at the task level, the type of lighting fixture or luminaire, and the ceiling height? I think manufacturers should provide this calculator for their luminaires.

How would you show energy savings for occupancy based lighting controls? In 10CFR435 Table 514.1 “Power Adjustment Factor (PAF)”, the PAF for Occupancy Sensor is 0.3. When using energy analysis programs, can we reduce the lighting schedule fractions by 30% for the proposed design compared to the prototype or base design?

Increasing the percent glass of the envelope and increasing the ceiling height also reduces lighting usage because of increased daylighting. Daylight can now reach deeper into the interior. How would you show this energy savings using computer programs? Can the perimeter zone depth be increased to say 30 feet? The DOE2.1E program lets you locate two light sensors in the perimeter zones but the codes do not specify where in the zone. They could both be located 5 feet from the window as representing the entire perimeter zone depth.

Varkie Thomas