The controlling factor in garden lighting is direction, not brightness. A modest fitting aimed sideways or upwards spills light into neighbouring gardens and the sky, while a brighter fitting aimed downwards and shielded can illuminate a path without leaving the boundary. Almost every complaint about domestic garden lighting, and almost every ecological objection to it, comes back to light that has been allowed to travel where it was not needed.<\/p>\n
There is also a legal dimension that many households are unaware of. Artificial light emitted from premises can constitute a statutory nuisance under the Environmental Protection Act 1990, following amendments made by the Clean Neighbourhoods and Environment Act 2005, and local authorities in England have powers to act on it. Garden lighting is therefore a neighbour matter as well as a wildlife one.<\/p>\n
Street lighting and commercial floodlighting dominate discussion of light pollution, but domestic exterior lighting is widely distributed and largely unregulated. Householders choose fittings, aim them and set their operating hours with no design input, and the cumulative effect across suburban streets is substantial. CPRE’s night blight mapping of England makes the scale of night time light across the country visible.<\/p>\n
The ecological concern is specific rather than general. Bats are the most commonly cited example in UK guidance because several species avoid lit areas, which can sever commuting routes between roosts and feeding grounds. The Bat Conservation Trust’s published guidance on artificial lighting addresses exactly this, and the protected status of all UK bat species means lighting near known roosts is a legal as well as an ethical consideration. Nocturnal insects are affected too, drawn to light sources and away from the behaviours they would otherwise perform, which has consequences further up the food chain.<\/p>\n
Hedgehogs, which use gardens as connected territory, are affected differently: bright lighting alters where they will forage and how they move between gardens. The practical implication for a garden owner is that the dark corners and boundary hedges are ecologically the most valuable parts of the plot, and they are precisely the parts that decorative lighting tends to target.<\/p>\n
Three specification decisions determine whether garden lighting is well behaved. The first is aiming. Downward facing fittings that direct light onto a surface, and away from boundaries, do the job that a garden actually needs. Uplighting a tree or a wall sends a proportion of the output straight past the object and into the sky.<\/p>\n
The second is shielding. A full cut off fitting emits no light above the horizontal plane, which means the source is not visible from a neighbouring window or from across the garden. Recessed ground lights, bollards with solid tops, and wall lights with closed upper housings all achieve this. An exposed lamp in a clear glass lantern does not, regardless of its wattage.<\/p>\n
The third is colour temperature. Warmer light, commonly specified at or below 2700K, is the standard recommendation in wildlife sensitive lighting guidance, because shorter wavelength blue rich light scatters more in the atmosphere and has greater effect on nocturnal species. Cooler white light may look crisper in a product photograph, but in a garden at night it reads as harsh and travels further than intended.<\/p>\n