The Lukiškės Prison is one of the oldest prisons in Lithuania and is located in the centre of Vilnius city.
As part of a refurbishment program, the old incandescent luminaires, were replaced by bi-colour LED ones. This gave an immediate 85% reduction in energy saving. The luminaires have also been designed to incorporate aspects of human centric lighting.
The prison regulations demand that the prison cells receive at least 200 lux by day and at least 15 lux by night.
The existing incandescent lighting used 4 x 40W and 2 x 40W lamps but did not fully meet the regulations.
The luminaires operated 24/7 all year (8 hr “night” and 16 hr “day”) and so maintenance was also an issue due to the number of incandescent lamp failures.
The new LED luminaires incorporate 35W of 4,000K white LEDs plus 5W of Amber LEDs. The LED luminaires were made by a local manufacturer, Lumo.
These were then fitted inside custom anti-vandal enclosures made by the prisoners themselves. Futhermore, the benefit of only low voltage DC inside the prison cell (the 230v convertor is outside) results in increased safety.
An interesting aspect is that although the ratio of day to night photopic illuminance is about 13:1 (200/15), the melanopic illuminance is approximately 65:1 due to using Amber coloured LEDs at night.
Melanopic illuminance variation during the day has a crucial influence on the human biological clock and circadian rhythms, resulting in significantly improved sleep quality at night and alertness at day time. Prisoners have welcomed this innovation and noticed the better sleep conditions after renovation.
Approximately 180 prison cells have been modified and the new luminaires have also been installed in the corridors.
Payback time for the new luminaires is expected to be less than 12 months.