Reducing the environmental footprint of church lighting: matching façade shape and lowering luminance with the EcoSky LED

Abstract

In rural areas of Europe, ornamental lighting, and particularly church lighting, is often among the most important sources of light emissions from communities. In current practice of façade lighting for churches, much of the produced light misses the target area, and façade luminance is often far larger than is necessary. This results in a dramatic waste of electrical energy and significant light pollution for the surrounding areas. This article discusses the concept of sustainability with regards to cultural heritage lighting, within the context of the façade lighting of a specific church. The lighting of the Church of the Three Kings in Logatec, Slovenia was replaced in 2014. The power of the installation was reduced 96% from 1.6 kW to 58 W, and spill light from the site was effectively eliminated. As a result, the church is no longer visible in nighttime satellite images of the area, indicating a reduction of waste light from the site of at least a factor of 30. This example demonstrates the dramatic extent to which more general application of lighting design principles could reduce energy consumption and light pollution in the rural European context.

Changes in outdoor lighting in Germany from 2012-2016

“…By the sustainability criterion of using only the minimum amount of light necessary (see discussion in [28]), many or even most areas in cities in wealthy countries are not currently sustainably lit. For example, American cities are 3-5 times brighter per capita than German cities [4].…”

Variation of Individual Location Radiance in VIIRS DNB Monthly Composite Images

“…The approximately 15-20% variation in observed DNB radiance from month-to-month places a limit on the level of change in light emission that can be positively detected by the DNB. Dramatic changes, such as the appearance or disappearance of a lamp are readily seen, as in the example of the Bakken flares above, or through an intervention to intentionally eliminate upward light emissions [9]. However, more moderate changes, such as may be expected from a conversion to LED lamps or the addition of new advertising or facade lighting in an already bright urban center, may be less obvious.…”

“…For example, night lights data have been used to monitor changes in urban footprints [2], gross domestic product [3], and infrastructure damage due to war [4][5][6]. Changes in both spatial positions and intensities of emitted visible light over time are of interest to those studying light pollution, for example to examine light encroachment into protected areas [7,8], light emission from individual bright sources [9], as well as global and national rates of change [10]. Moreover, individual night lights datasets are often fused with other geospatial datasets to provide information at subnational levels [11][12][13].…”

“…• Differences in imaging angle [14,15] • Time of night (because lights turn off as night progresses) [16,17] • Seasonal variations in vegetation and snow cover [18] • Atmospheric parameters such as aerosol content [19] • Shift in the ground footprint of pixels, and/or differing pixels used in building monthly or annual composites [20] • Changes in the sensitivity or errors in calibration of the imaging sensor [21] • Presence or absence of moonlight [21,22] • Presence or absence of temporary (e.g. seasonal) lighting [23] • Electrical blackouts or brownouts, disasters [24][25][26] • Actual changes in permanently installed lighting [9,10,27,28] For example, consider how different imaging angles affect the visibility of facade lighting (Fig 1, see also [29]). The two aerial photographs of the area near Berlin's "Zoologischen Garten" train station appear similar at first glance.…”

Variation of Individual Location Radiance in VIIRS DNB Monthly Composite Images

“…For example, night light data have been used to monitor changes in urban footprints [2], gross domestic product [3], and infrastructure damage due to war [4][5][6]. Changes in both spatial positions and intensities of emitted visible light over time are of interest to those studying light pollution, for example to examine light encroachment into protected areas [7,8], light emission from individual bright sources [9], as well as global and national rates of change [10]. Moreover, individual night light datasets are often fused with other geospatial datasets to provide information at subnational levels [11][12][13].…”