Don't cry over spilt light
The Insight
Artificial light has many advantages in the outdoor environment. It provides safe passageway for pedestrians and vehicles, improves the security around buildings and environments, enhances sporting and recreational activities, and is used for aesthetic or accent appearances. But where does that benefit become more of a hindrance?
Areas that require high lighting performance produce obtrusive light. This type of light can be difficult to contain as the intensity of obtrusive light increases relative to the surrounds. It is colloquially termed ‘spill light’.
Anyone who has tried to sleep with a floodlight outside their window can tell you, spill light is a nuisance.
Spill light comes in many forms. It can be light exposure onto nearby property or into the sky, a disabling glare, or perceived excessive light intensity from luminaries that hinders vision.
As with all design, it’s important to consider who will be affected by the product. While the benefits may speak for themselves, the negatives can be detrimental.
Light influences your body on a physiological and psychological level. Excessive light during standard ‘night’ hours can have adverse effects, particularly on one’s ability to adequately rest. Lack of sleep and depression are deeply connected and can cause a rapid downward spiral.
It’s clear that limitations are essential, but what are those limits?
The Impact
AS/NZS:4282:2019 ‘Control of the obtrusive effects of outdoor lighting' details the key technical parameters that assist in the assessment of unwanted lighting in a particular lighting installation. While the standard provides consideration of obtrusive light to a number of environmental zones, it is complicated by the fact that it cannot be 'one size fits all'.
For example, more sensitive environmental zones such as starlight reserves have harsher obtrusive lighting limits.
As the client, it’s logical to want the best quality LED fittings and it’s not always obvious what those are, especially as the market is oversaturated. While deciding, consideration must be given to how well a light can limit its spill while still sufficiently illuminating a space.
There are instances where the restrictions are overridden. The Department of Defence and aircraft authorities are able to impose additional requirements within the vicinity of their facilities. Additionally, when it comes to public lighting for safety and security purposes, surrounding residential comfort takes a back seat.
Before installation, it’s important to undertake desktop analysis of the useful and obtrusive light performance to ensure the lighting is not a nuisance to nearby properties and environments. It’s essential to also ensure that the installation is compliant with the design performance by engaging a lighting survey post-installation.