How Many Downlights & Lighting Design
If you’re planning a new downlight installation for your home or business, one of the first things you’ll need to find out is how many downlights you’ll need.
LED downlights are now available in different light outputs (measured in lumens and also known as luminous flux). They have different beam angles ranging from 25 to 90 degrees. If you plan your project wisely you can choose the right downlights for your room size. If you have a large room such as a living room it’s better to choose brighter LED downlights with wider beam angles. This allows you to spread them further apart from each other and means that you don’t need to buy or install as many.
Smaller rooms like bathrooms may not require brighter downlights, you can often go for lower output downlights and they will provide enough light.
Here are some golden rules to consider for new installations:
- What type of room are you illuminating? Not all rooms need to be illuminated to the same lux levels. Lux is measured in lumens per square metre. Kitchens require a minimum of 300 average lux. Living rooms and bathrooms require 150 average lux and bedrooms only need to have an average of 100 lux. An office requires a brighter 500 average lux, more light is required in rooms that you’re performing more complicated tasks in.
- It’s best to choose the type of downlight you prefer first then figure out how many you’ll need for each room, as each room is different.
- Some downlights are available in different beam angles. Downlights with wider beam angles can be spread further apart but the beam is less intense as it is not as focused.
- Uniformity, there’s no point having overly bright areas of a room and dark patches in other areas. You want to make sure that you have a nice even light across the room.
- Grid layout, a square room looks better with a square grid layout of downlights. If your room is 9x9 metres having a 2x2 grid or 3x3 will look fine, compared to 2x2 and 1 in the middle.
Lighting Guidance from Aurora
As a guide to allow you to achieve the right lux levels and uniformity, these helpful 'ready reckon-er' lux planners from Aurora Lighting can give you a good idea about how many downlights you should install for various room sizes.
- Dimensions are in metres
- Based on 2.5M ceiling height
- Average surface reflectance’s are floor 20%, ceiling 70% and walls 50%
- Working plane measured at 750mm (based on a kitchen worktop).
- Maintenance factor of 0.85
- No allowance made for UGR compliance for office use
Using the Aurora Enlite E5
Using the Aurora Enlite E6 Pro
Using the Aurora Enlite E8
Using the Aurora M10
Using the Aurora MPRO
If you’re replacing existing downlights were the holes and wires are already in place, it’s likely you’ve got 50 watt halogens. If you have, then the calculations have already been made, so just replace them with new LED downlights that have an equivalent light output.
A 50 watt GU10 halogen has a light output of at least 345 lumens and a 50 watt MR16 low voltage halogen is at least 620 lumens. Just make sure that you choose an LED downlight or LED lamp that offers the equivalent light output or your room won’t be as bright.
These lumen outputs are in accordance with DIM2 Compliance which came into effect in November 2013. The Dim2 Compliance table which can be found below gives consumers an idea of how to compare an LED to a halogen.
Comparing the wattage of an LED to a halogen isn’t accurate. LEDs are becoming more and more energy efficient, early GU10 LEDs on the market that were 7 watt and marketed as 50 watt equivalents only had a 300 lumen output, so they didn’t quite meet the lighting expectations of a 50 watt halogen and nowhere near a 50 watt low voltage halogen.
LED lighting offers a clearer lighting effect than halogen and differences in colour temperatures can make it a appear clearer and brighter even though the lumens of a halogen and LED are comparable.
This video from Philips Lighting explains more about luminous flux:
Lighting Design Service
Not all rooms are square or rectangular in shape, if you want something more accurate than these guides offer, or want to use a different type of downlight, we can offer a bespoke lighting design service.
Using Relux we can calculate exactly how many downlights you need for your own room, provide you with the lux levels, uniformity and spacing information.
We have a minimum charge of £20 +VAT per room. Full houses or more technical drawings cost more depending on the amount of work involved. We can quote on these on a case by case basis.