and Lighting Codes
An Analysis of theControl Effectiveness of the IDA-IES Model Lighting Ordinance and the IDA Pattern Outdoor Lighting Code
From the Executive Summary:
The POLC is found to provide substantial improvements over unregulated outdoor lighting practice in all evaluatedimpacts. In the “brightest” POLC LZ 3, the total lighting amount for commercial sites is reduced on average to about one-half or less of the amount used on unregulated sites; in POLC LZ2 they are reduced to one-quarter and less. The amount of expected is reduced nearly a factor of 100 compared to average unregulated outdoor lighting practice.
Under MLO standards, outside of MLO LZ 0 and 1, the total lumen allowances, direct uplight allowances, and amount ofare notably greater than expected under POLC standards; in MLO LZ 3 and 4 they are dramatically greater. In LZ 2 and above impacts are greater than what can be expected even when lighting is unregulated.
The MLO approach to fixture shielding and “limits to off site impacts” is ineffective in limiting, and . The MLO allows any (including no) fixture shielding, permitting the installation of the most egregious types of lighting fixtures. Compared to POLC lighting codes with “ ” standards, even the (optional) MLO Luminaire Classification System “BUG” shielding standards and “off-site impact” limits offer weaker control of and uplight than the POLC.
The POLC requires the use of yellow (, , amber ) or warm-white ( <3500K) for general area lighting, which accounts for 80% to 90% of outdoor lighting, thus reducing many aspects of such as visible , , human impacts, and impacts on many biological systems. MLO does not address lamp spectrum, and thus leaves this crucial aspect of unaddressed.
In general, the POLC is shown to be far more effective than the MLO in curbing the detrimental aspects of outdoor lighting. The analysis of the various MLO regulatory options shows that the Performance Method Option B provides notably poor control of both direct uplight (and therefore skyglow), and .
We conclude that a substantial reduction inis attainable to communities that adopt lighting codes following POLC standards. Adoption of a code based on the IDA-IES MLO cannot realistically be expected to produce improvement. Certainly for the medium-sized and small communities and rural areas that most frequently seek to reduce and protect the natural night environment, the MLO represents a significant step backward in limitation and control compared to the older IDA POLC model.
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