Rules for Protecting the Night Environment
- a necessary and sufficient set

(The numbering is the same as in the Proposal for Changes of the Czech Clean Air Act from Sep 13, 2003, see www.astro.cz/darksky/cz_law for its plain basic text and other info regarding it. This version of the rules contains very short comments meant for getting a better overview. The rules are meant as a template for legal protection of the night anywhere, esp. in the the European Union, including it into the standard protection of the atmosphere)

PROTECTION OF THE NIGHT ATMOSPHERE

§ 35a
Artificial sources of light (as sources of air pollution)

Artificial sources of light and luminaires containing them with, exception of light equipment of vehicles, are considered to be small stationary sources of pollution of the air.

§ 35b
Measures to lower light pollution

(1) (enabling lumens instead of kilograms per second for expressing this kind of pollution)
           Because of the nature of light as a polluting substance, instead or in addition to the quantities given in § 2, analogous photometric quantities are used: pollution, emission limits and ceilings are expressed rather in units of luminous flux instead of units of mass flux (units of mass per unit of time), as it is in § 2 art. 1 lett. c), e) and f), level of the pollution, imissions and imission limits in units of luminous flux density instead of mass concentration (units of mass per unit of volume), as it is in § 2 art. 1 lett. g), i) and j).

(2) (setting the demands for all future changes of lighting)
           All luminaires and systems of them, which are from January 1, 2005 being installed in the territory of the Czech Republic, have to obey the rules according to articles 3 to 6 of this §

(3) Luminaires and outdoor lighting systems shall:

a)      (shine down! - defined by a standard technical definition demanding 0 cd/klm upwards)
shine exclusively down, with exception of the case given in article 6; as a luminaire, which shines just down even each such is considered, whose specific luminous intensity horizontally and upwards is zero candela per thousand lumens of the luminous flux produced inside it;

b)      (limit on amount of light)
be used in such a way that the illuminance of the target surfaces does not exceed the value demanded by safety standards, if they exist, or in the absence of such standards, the illuminance of the target surface does not exceed 10 lux or at least the luminance of the target surface does not exceed 1 cd/m², with exception of the surfaces given in article 5;

c)      (dimming or switching-off late at night)
be equipped with devices capable of reducing the amount of emitted light by at least thirty per cent compared to the full output; such reduction of the amount of light is applied when the conditions of the use of the illuminated surface are such that safety is not endangered.

(4) (general exceptions)
           The properties given in article 3 are not obligatory for luminaires which fulfil at least one of the following three conditions:

a)      (faint sources)
contain just light sources whose luminous flux does not exceed 1500 lumens, if the cumulative luminous upward flux from the luminaires placed in any region with a radius of two metres does not exceed 2250 lumens;

b)      (temporary sources)
are in use at most for three weeks in a single year and are not used in the period from 23:00 to 5:00;

c)      (traffic lights)
are used as light signals for the purposes of ensuring transport safety, defence and security of the Republic.

(5) (higher limits for shop signs etc.)
           To illuminate surfaces which convey text information or image instructions, more light than given in art. 3 lett. b) can be used, provided the luminous intensity of such surfaces does not exceed two hundred candelas, or three hundred candelas for surfaces sized 5 m²  and more, or five hundred candelas for surfaces sized 30 m²  and more.

(6) (architectural lighting additional rules and an exception not easy to misuse)
           Illumination of buildings and pieces of art is to be, for the whole period from 23:00 to 5:00, switched off or reduced by at least one half. Even luminaires shining upwards can be exceptionally used for illumination of these structures, provided that the municipal corporation decides that such a way of lighting a specified surface is needed; in case of such illumination there is an obligation that the margin of the beam does not exceed the outline of the illuminated object.

(7) (labeling the luminaires)
           Manufacturers and importers are obliged since January 1, 2005 to declare the coherence of the luminaires with the demands of this law in such a way, that the product will carry a label “optics shining only downwards”, and in the enclosed service manual they have to include instructions on how to use the luminaires in accordance with the law.

(8) (banning skybeamers)
           Using upward, only into the air aimed movable or fixed beams of any type from a light source producing more than 1500 lumens is considered as an especially serious light pollution. Such beams are prohibited, if a special law does not say otherwise.[1]

 

§ 35c
Protection of particularly sensitive sites

(1) (nature reserves and observatories)
           Light pollution is lowered by this law in the small-sized particularly protected areas defined in a special law[2] (namely national nature reserves, nature reserves, national nature monuments and nature monuments) and further around buildings, which are approved as astronomical observatories.

(2) (reducing direct light to them soon)
          The luminaires which are located within the areas given in article 1 or in their surroundings or in surroundings of buildings given in article 1, if they are nearer than 1 km from such sites, shall be shielded before July 1, 2005 in such a way, that they will not be visible at night from there, or at least so that the luminous flux density from any of them does not exceed one millilumen per square metre when viewed from the given site. Luminaires more distant than 1 km but nearer than 5 km have to obey this condition before January 1, 2008.

(3) (switching-off unessential lights late at night)
           Luminaires placed nearer than 1 km to a given site shall be extinguished during the period from 23:00 to 5:00, if their use is not necessary because of safety reasons.

(4) (empowering communes to demand sooner and larger improvements)
          The local government may issue a generally obligatory edict, in which it sets further measures to lower light pollution, in addition to those which are given in § 35b. The reason for accepting such measures may be protection of pedestrians and drivers against glare, protection of citizens in their homes against light trespass, nature protection. The commune may declare some localities in the edict, where the direct glare and the night hours for using the luminaires are restricted.

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Additional rules for a local level (not to be a part of  the national law)

On the national level, the rules should be simple and stable. On a local level, some additional ones are recommended:

·        limiting the proportion of light flux missing the terrain to be illuminated (for the beginning, say to 15 % for broad roads and 35 % for narrow paths),

·        prohibiting light sources which emit light with a non-negligible blue component after curfew,

·        controlling the yearly change of installed light flux on a commune territory or its specified parts – allowing a positive number like 2 % for the beginning but demanding a negative number some years later,

·        demanding barriers for light escaping from windows of houses to be build.