Landscape for Deemed Lighting Workpapers

• Building Code and Voluntary Program Relationship• Building Code Changes Driven by Big Vision• Voluntary Program Driven by Least Common Denominator

• Most Conservative Assumption = Low savings• Low Savings = Low Rebate• Low Rebate = Lost Opportunity to influence purchasing

• There is a technical challenge in identifying the energy savings that can justify an effective rebate for the market while accounting for the real implications of energy codes.

Downstream Incentive MechanismThese deemed incentives are intended to be simple and broadly applicable:• The measure case is driven by a minimum equipment specification. Customer

completes application after purchasing qualifying equipment: Verification of equipment qualification should be as simple as possible

• Only required documentation is customer-provided invoice:Incentive should depend on the manufacturer, model & quantity

• Customer location, market segment, and other details can be determined by processing center:• Invoice review verifies the equipment specification of the installed equipment

via applicable industry resources.• Account information is used to determine market segment and climate zone.

• The base case technology, specific application and wattage are unknown. The program has no way to determine specific application:• A 2x4 troffer at an office location may be installed in a hallway, private office, or

stairwell. • A 2x4 troffer at a retail location is located in the office, retail floor, or breakroom.Incentive savings should represent overall characteristics for the location type

Other Assumptions beyond today’s scope

• Generally downstream measures assume ROB (Replace on Burnout—i.e. the fixture could not be relamped/reballasted), claiming only the energy savings from code to proposed.

• Code baseline calculations assume every project would trigger code and 100% of the projects would be code compliant.• 40 fixtures is generally the trigger point T24 code

Key Challenge for Interior Lighting

• Recessed lighting is a key area of product growth• LED technology is making significant retrofit savings available: DLC-

listed recessed products average 93 fixture lumens / WattBut what is the code baseline assumption for a new recessed fixture?• Title 24 provides only lighting power densities:

• We looked at the CASE Reports (Codes and Standards Enhancement) written to justify savings and feasibility of Title 24 updates

• Goal is to provide fluorescent fixture performance against which any LED recessed fixture performance can be measured

Choice of Comparison Metric

Coefficient of Utilization Fixture Efficacy (lm/W)

Availability for baseline products

CU is often not present on fluorescent fixtures; industry moving towards modeling

Calculable from spec sheets (lamp lumens x lamp qty x BF x fixture efficiency)

Availability for LED products

Not available Readily available, 3rd-party verified and listed by DLC

Variability by room geometry for a given fixture

Can vary from 30% - 80% based on room geometry & reflectances

Does not vary by room geometry

Correlation with actual task illuminance

Excellent Less strong; best for large open spaces and high reflectances

Potential Variations

DLC also lists lumen output in the 0 - 60⁰ zone, even more highly correlated with horizontal illuminance

Base case vs. measure fixture comparison via either Fixture Efficacy or Coefficient of Utilization (CU = ratio of lumens hitting task plane to lumens existing lamp):

T24-2013-compliant Basecase Fixture Wattages

• Indoor Lighting CASE Reports for T24 2013 were based on an office lighting layout from an actual building:– “fixtures are ‘high performance T8’ fixtures, i.e. they are compliant

with the…new Federal lamp standard”• We suggest using this fixture type to define a energy savings

baseline for code-compliant recessed lighting fixtures which can be compared to measure case performance of LED troffers

• There are many possible options for fixture layouts and space geometries, but the model in this case report was selected as representative of a variety of interior applications.

T24-2013-compliant Basecase Fixture Wattages

• Complete Building LPD for Offices: 0.8 W– (Area Category Method blend for offices: 0.86 W)

• The modeled fixtures contain HPT8 lamp & ballast:– 3T8 Parabolic Troffer with 3100-lm lamps– 72 Watts– 8’ x 10’ spacing– 43.9 maintained footcandles on workplane– 0.59 Coefficient of Utilization

• There are many possible options for fixture layouts and space geometries, but we can compare these fixtures to modern LED troffers on the basis of efficacy in lumens per Watt.

T24-2013-compliant Basecase Fixture Wattages

• The 2x4 troffer in the CASE model most closely resembles the Cooper 2P2GAX-332S36I: – http://www.cooperindustries.com/content/dam/public/lighting

/products/documents/metalux/spec_sheets/090386_2P2GAX332_3L_T8_18C.pdf

– http://www.cooperindustries.com/content/public/en/lighting/products/recessed_linear_lighting/parabolics/_135260.ssd.html

– Also closely resembles Fixture #24 in the IES 9th Edition Handbook, p. 414

• Using either of the above as models, the fixture efficacy would be 74.7% (ratio of lamp lumens to fixture lumen output)– This yield a 68.5 lm/W fixture efficacy at initial conditions

Base case efficacy & Energy Savings

• 68.5 lu/W for 2x4 fixtures suggests 16.5 lu/W improvement from T24-compliant baseline to DLC-minimum of 85 lu/W– Average DLC-listed fixture has measured efficacy of 92.3 lu/W– 1x4 and 2x2 fixture efficacies in the 2P2GAX parabolic line are similar

and lower, so using the 2x4 for the baseline will yield a conservative estimate• 66.5% for 1x4 232S113I; 72.2% for 2x2 2U1-5/8S33I• Both fixtures provide 40 fc illuminance with 80/50/20 reflectances at 0.72

W/sq.ft.

• N.B.: Using a fixture efficacy comparison would not work well for fixtures with highly specific distribution requirements or vertical illuminance requirements such as warehouse aisles: this analysis is for horizontal average illuminance only