The project is a major renovation for a data center in an existing industrial park. The existing front parking area has an abundance of tree growth that effectively provides a cutoff of illumination generated from the pole mounted 250W HPS fixtures. The fixture is a cutoff type as required by the credit. Will it be acceptable to observe/record lighting levels at the property line in lieu of calculations? Any illumination calculations will not model tree growth and will show lighting to be non-conforming to the credit. But if we can submit recorded/observed lighting levels it is likely we will comply with the .2fc max.
The project team has asked if field measurements can be used instead of a computer simulation given that they cannot simulate the landscaping and the landscaping provides shielding.. No, field measurements are not acceptable because landscape and trees will grow or may be cut down, trimmed or changed in the future. Deciduous trees will lose their leaves for part of the year and provide a much lower shielding effect. Furthermore, the health of some species of trees may be negatively impacted by nighttime lighting. A lighting solution, based on a computer simulation without trees, that better controls the light to limit it at the tree line represents a strategy more in line with the intent of the light pollution credit. This may be accomplished with luminaire optics with a shorter "forward throw" or a lower wattage lamp. Applicable Internationally.