Rating System

LEED BD+C: New Construction, LEED BD+C: New Construction, LEED BD+C: Schools, LEED BD+C: Schools, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell

Rating System Version

v2 - LEED 2.2, v3 - LEED 2009, v2 - Schools 2007, v3 - LEED 2009, v3 - LEED 2009, v3 - LEED 2009

Inquiry

Our project includes a 120,000SF addition/renovation to a 140,000SF office building. Lighting control systems were installed to provide increasing levels of energy performance savings by adjusting the initial foot-candle levels down to IESNA acceptable maintained foot-candle levels. The project includes expansion of the existing Eaton\'s POW-R-Command lighting control system. Our approach is not proprietary to the Eaton system and could be applied to any automatic lighting control system. Use of our lighting control approach results in energy savings beyond the default 10% energy savings limit identified in Table G2.3 within ASHRAE 90.1-2004, Appendix G. We are requesting the USGBC allow us to use the alternative method to modify the lighting schedules beyond the 10% limit in accordance with the standard as outlined below. Standard lighting foot-candle design is based on maintained foot-candle levels understanding that initial levels will be higher and will degrade over time. For this project, the light loss factor is 85% of initial fixture performance. This standard design approach typically results in initial lighting designs that are over-lit and a higher w/sf value. For this project, the lighting foot-candle design and layout provides roughly 20%+ more initial illuminance than IESNA Recommended Guidelines, however upon installation, the lighting levels are dimmed through the lighting control system to those foot-candle levels which meet the IESNA Guidelines for maintained lighting illuminance. Over time, as lamp depreciation occurs, the illumination performance is automatically increased to consistently maintain the IESNA Guidelines level. This control approach has been in use within the existing facility for the past ten years. Dimming control of the system is programmed and performed by facilities staff only and the individual occupants do not have control capabilities. This feature can not be overridden by the occupants. Controlling and operating the lamps in this manner in the existing building have resulted in a 33% reduction in electrical energy use plus additional cooling capacity savings when compared to an un-controlled lighting approach and have resulted in approximately 40% lighting energy savings within the new addition. ASHRAE 90.1 - 2004 Appendix G, Paragraph G.25 - Exceptional Calculation Methods, states "When no simulation program is available that adequately models a design, material, or device, the rating authority may approve an exceptional calculation method to demonstrate above-standard performance using this method". However, in Table G3.1, paragraph 6(g), the standards states "For automatic lighting controls in addition to those required for minimum code compliance under 9.2, credit may be taken for automatically controlled systems by reducing the connected lighting by the applicable percentages listed in Table G2.3. Alternatively, credit may be taken for these devices by modifying the lighting schedules used for the proposed design, provided that credible technical documentation for the modifications are provided to the rating authority. We believe our project approach meets the intent of the alternative modified schedule approach. The system, as installed:  Exceeds the energy savings allowed using standard building modeling protocol  Meets the intent of the credit  Provides a creative method to produce additional measurable energy performance savings  Reduces environmental impact