Our project is a 700,000 square foot hospital in North Bay, Ontario. We understand that the intent of this credit is to eliminate light trespass form the building and site, improve night sky access and reduce development impact on nocturnal environments. From our understanding of the LEED Reference Guide we will discuss the lighting requirements under the following categories: 1. up-lighting 2. maximum illuminance 3. light trespass According to the Reference Guide, where it is not possible to meet the recommendations cited in Table 1, "These situations should be clearly explained and documented." Our approach to this credit is described below. 1. Up Lighting Our site has no unshielded fixtures, with the exception of the lighting at a Helipad. We feel that the helipad can reasonably be excluded from the uplighting requirements. Helipad lighting will meet the local authority\'s (Transport Canada) requirements. 2. Maximum Illuminance We do not feel that the maximum of 0.6 fc cited by IESNA RP-33-99 and the 20:1 uniformity recommended by IESNA are appropriate for the health care environment and we exceed both. The Health Centre is fully operational 24 hours a day, with shiftworkers, patients and supplies arriving at all times. This traffic includes automobiles, public transit, bicycles, pedestrians, ambulances, wheelchair transit and delivery trucks. Because of these operational characteristics, we have designed all parking, roadway and pedestrian areas with a minimum of 0.5 fc and a uniformity of 10:1 to 12:1. This is consistent with the IESNA Lighting Handbook Reference and Application Guide, 2000, 9th Edition, which states that the "Minimum Horizontal Illuminance should be 0.5 fc with a uniformity of 15:1." 3. Light Trespass The site is situated so that one side of the property back on to the Hydro right of way and a rock cliff formation. On the other sides are open space beyond our Light Standards (poles). There are no residential areas adjacent to the site. The only time where concern of Light Trespass may be in question is at the entrances to the hospital from the Highway. Our lighting will spill onto the roadway at that point, which will highlight the entrance of the hospital. Additionally, parking and roadway luminaires are full cut-off. We feel that we are meeting the credit requirements as per the LEED Reference Guide\'s strategy that we should "Interpret between existing standards and design for the lowest possible light levels while addressing safety security, access, way finding, identification and aesthetics." Please advise whether our interpretation is acceptable.
The special note under Table 1 on page 70 of the LEED v2.1 Reference Guide Table specifically states "where lighting is required for emergency egress purposes, it may not be possible to meet the Table 1 recommendations. These situations should be carefully explained and documented." In the case of your hospital project it is understood that emergency services lighting will encompass most if not all the site lighting.
1) The helipad can be excluded from the uplighting requirements.
2) It is reasonable to design the parking, roadway and pedestrian areas to the appropriate IESNA Lighting Handbook Reference and Application Guide recommendations for minimum foot-candle values and uniformity.
3) Light trespass at the entrance to the hospital is a reasonable situation in which the requirements of Table 1 are not met. The team should make certain that all other light trespass to adjacent properties, whether it is open space, residential, et cetera would fall within the recommended limits of Table 1. In all three situations the team will need to make a clear and detailed case for why the recommendations of Table 1 cannot be met. Closely follow the calculation requirements listed on pages 73-76 of the LEED v2.1 Reference Guide.