Artificial light at night 2: Six design solutions to responsibly light our gardens

Why? In short, because of the adverse effects of artificial light at night on wildlife (and us). Given that light pollution is one of the drivers of the decline in biodiversity and we need to share our gardens with wildlife to help reverse this decline, the least we can do is not light our gardens (or the outside of our houses and driveways) unnecessarily at night. See Artificial light at night: its effects on wildlife post for more information on this.

Moodlighting: well-directed mini-spot lights (75 lumens) gently lighting a sculpture at night. Photo credit: John O’Connor Sculpture -Chelsea 2018; Landscapeplus.com

Warm white strip lighting under the seats offers a way finder to the benches and a gentle mood and vibe for hanging out in this public space. Photo credit: Rachel Bailey

1. Consider whether you need lights and if so where

   First question to ask yourself - do you really need outside lights? For paths and access to the house the answer is probably yes. And perhaps where you sit, entertain or hang out in the garden at night. However, ask your self, do I need my garden lit up like Blackpool illuminations or do I need lights on the outside of my house and driveway on all night - probably not. In a garden, less is more when it comes to creating a mood.

2. How the lights are controlled

   Next to consider is how the lights are controlled. Likely you will have lights that serve different functions. Lighting of the driveway, lighting the entrance to the house and front garden paths. Perhaps you use or would like to use the back garden path after dark and you like to spend evenings in your garden entertaining sitting on a terrace. With this in mind, none of the lights need to be on an automatic light sensor (dusk to dawn) or on a timer to be on all evening or night. Instead, the lights can be connected through a remote control system with the lights that serve different functions on different channels (obviously this along with the light installation will be done by an electrician). 

   The advantages of the remote control system: 
   - you can switch the lights on when in use and then back off when they are no longer needed, so minimising the amount of light pollution created.

   - You can switch the lights on on approach to your house using a key fob or whilst sitting in the garden and the natural light fades, without needing to get up and go into the house. If you have mood lights in the garden, you could also switch them on and off as the evening progresses too.

3. Light intensity

   Next is to consider how bright the lamp [ie. the bulb] needs to be (look at the lumen output of the lamp). Avoid the temptation to over-light because LEDs are cheap to run and the luminous efficiency of LEDs. Plus in a garden, less is always more.
   
   For a single entranceway-come-driveway lighting, a brighter light might be required, but the time that this light is on could be limited (see point 2 above). For most applications, you don’t want or need to light up the whole neighbourhood or a big area, so a 75 to 95 lumen lamp would be more than sufficient for gently highlighting a feature in the garden. For lighting a path, you could include several pathway lights along the length of the path and depending on the width of the path they could be at 2 or 4 lumens.

4. Lamp design and arrangement

   Ensure you choose lights that are fully shielded and point downwards up to the horizontal plane to minimise glare and light trespass. It is important to only light what you need to see so consider the angle of the beam and its direction and then correctly place the light. For lights such as pathway finders or for steps, you can choose ones that are shielded on the top and have directional light. This will also facilitate better vision at night. Glare guards / baffles fitted to the lamps can help direct the light where it is needed and can offer a lovely effect.

5. Light colour (wavelength of the light)

   Most white LED lighting have harmful/ disrupting blue light content that adversely affects wildlife and human behaviour and physiology. Therefore, avoid white LEDs with a high blue content and  select lamps that are 2700K or less. These are often known as warm warm white (2700K). There are now new to the market lamps that are 1800K - and offer an even warmer, comforting light perfect for spotlighting downwards on a tree - if it needs to be lit at all. For reference, the old sodium street lights are/were 2200K. 

6. Dark areas and Buffer Zones

   Be mindful of areas outside your house boundaries that offer wildlife habitats and try to ensure that the light from your outside fittings do not spill over into these areas - particular into hedgerows and waterways. Better still leave a 10 m buffer zone in which light should not spill. Within your garden, leave as large an area as possible unlit to provide dark refuges for wildlife and include areas with lots of plant cover. Also make sure that these dark areas areas are connected to allow passage of wildlife around and through your garden.

Further Resources:

Landscapeplus - supply all your landscape lighting, garden irrigation, pond products, structural wiring, tools and site essentials to trade professionals.

International Dark-Sky Association

Videos demonstrating the best types of lighting design and placement and their effects by Chris Hudson of Hudson Lighting.

Dark sky: Episode 2 - Which garden lights are worse for wildlife?

Dark sky: Episode 3: If you have to use uplighting, how do you limit the effects?

Dark sky: Episode 4: Which lighting works best for gardens where we want to protect the wildlife?