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Dark Sky Range
Artificial Lighting / Bats and the Built Environment
Hunza and LuxR outdoor lighting has a range of light fixtures that have previously been supplied on various projects that need to comply with Artificial Lighting / Bats and the Built Environment. In particular, a large commercial project in Bath where Martin Thomas Associates of Hampshire were brought in to advise and provide recommendations for what type of fixtures can or can’t be used.
For the purpose of conservation, we have highlighted some of the key recommendations as follows:
- LED luminaires should be used where possible due to their sharp cut-off, lower intensity, high colour rendition and dimming capability. A warm white spectrum (ideally 2700K or warmer and without the design and implementation of appropriate low lux artificial lighting).
- Lighting should be avoided where there is a likely risk of commuting routes and foraging bats within the surrounding areas near the property.
- ILP Guidance for the Reduction of Obtrusive Light. Accessories such as baffles, glare guards, hoods or honeycomb louvres should be used to reduce light spill and direct the light only to where it is needed, if there is any evidence of a bat roost regardless of age, no light will be permitted for that confined area.
Peak wavelength
LED lighting typically does not feature any UV components and research indicates that while lower UV components attract fewer invertebrates, warmer colour temperatures with peak wavelengths greater than 550nm cause less impact on bats, therefore; 2700k meets the criteria. (Stone, 2012, 2015a, 2015b). All Hunza and LuxR LED fixtures feature Cree LED boards.
According to f.luxometer, Cree 2700K has a Peak wavelength: 618nm at 0.261 µW/cm2. Note that 3000k does not meet this criteria.
In order to demonstrate compliance with the guidance notifications, lighting requirements for bat sensitive areas will predominantly need to be ‘down-lighting’ or low level lighting.
In the case of feature lighting, a degree of up-lighting may be allowed in certain areas as long as there is proof that suitable glare control is applied, for instance; when using a Spike Spot, the fixture would now require to be fitted with following:
- Hex cell louvre extension kit combined with a glare guard to offer a duel level of glare control ✔
- The LED’s must be 2700K (warm white) or warmer in order to reduce blue light ✔
- No UV elements ✔
- Controlled beam angle ✔
- Colour rendition: 90+ CRI ✔
- Dimmable ✔
Further considerations
It should be noted that any form of permitted up-lighting will always be left to the discretion of the consultant.
For most projects, low wattage fixtures will be the preferred option based on 1 watt (80 lumens from source) / 2 watts (170 lumens from source) and 4 watt (420 lumens maximum). This will allow certain fixtures to be used for controlled up lighting and ensure a controlled beam angle makes the light ‘focal-point-specific!’.
Be aware that all light fixtures would need to be positioned as to not allow any stray light spill onto any boundary trees which may likely be utilised for possible foraging and commuting bats within the area, as covered earlier.
If any areas of the landscape prove to be particularly sensitive where up-lighting is not permitted, then the lighting will need to be controlled to ‘down’ or wayfinding lighting which does not permit any light spread above the horizontal plane.
Dark Sky Range
The Hunza compliance team are working on preparing files for dark sky certification and are aiming to create a Dark Sky Range across both the Hunza and LuxR brand, however; the process of modifying existing fixtures in order to meet these demands is still work in progress and may take some time for completion, in the meantime; we have included a list of Hunza and LuxR fixtures that currently comply with ‘Dark Skies’ recommendations as shown below.
Spike & pole mounted luminaires
Wall mounted luminaires
Luminaires featuring a TIR lens
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