How many downlights?
If you're looking for the short answer to this, you can install 1 downlight per square metre, leaving 1 metre spacing's between each downlight and a distance of 1/2 a metre from the walls. This would generally get you the correct, bright and even lighting results. But this is more of a question of how many downlights per square metre? And does not account for other variables.
The one downlight per square metre formula usually provides sufficient lux levels for the majority of installations. Many contractors and installers have used this method successfully for many years and adapted it to different room shapes and applications. But LED downlighting technology has surpassed halogen, you can get LED downlighters that are much brighter than 50W GU10 mains voltage halogens and 50W MR16 low voltage halogens. You can use brighter downlights with wider beam angles and spread them out further. Rather than cramming lots of downlights together, you can install fewer. This looks better and saves you money on not only having to buy more downlights but also on the installation costs.
For example if you have a brighter LED downlight such as the Collingwood H2 Pro, it has a light output of 550-850 lumens and a wide 55 degree beam angle. You could easily space these 1.5 metres apart and 0.75 metres from the walls; or what about 2 metres apart and 1 metre from the walls? You can certainly get away with the 2 metre spacings in living rooms and bedrooms especially if you've got a wider beam angle. This particular downlight has a wattage switch that goes from 5W at 550 lumens to 7W at 850 lumens as well as a colour temperature switch.
However, rooms are used for different purposes and require different levels of brightness (lux). For example; in a kitchen it would be better to have a higher lux level to allow you to see what you're doing better. For kitchens we recommend an average of 300 lux. Whereas in a lounge where you're only watching TV, you may only require an average of 150 lux.
For some unknown reason there are no industry set recommendations for lux levels in homes. Specific lux levels are only used for commercial buildings, for example an office should be set at a minimum of 500 lux. Anything else you read on the internet etc. is a matter of opinion not fact.
Many Variables to Consider
As there are many variables to consider with lighting design, ranging from obvious ones such as the brightness (lumen output) of the downlight you want to install; to more complicated ones like uniformity, maintenance and reflectance factors, we offer a lighting design service to take away the guessing and make it more accurate. We charge a fee of £20+VAT per room, our lighting design service is available on request, please email details of your project including your room dimensions, plans, drawings and any other information you've got. We can then send a link for payment. Our £20+VAT charge is per room, not per building. If you have a large property with lots of rooms, please contact us for a quotation. Some room types are quick and easy to do, but some rooms with lots of cupboards and furniture to add, or rooms with apex ceilings or awkward shapes take considerably longer for us to do.
We can then provide you with your own personal lighting plan, using our lighting design software and done by our dedicated Relux and Dialux lighting designer. He's hungry for work, so please do get in touch, no matter if you've got a small bathroom or an entire house. If you have a commercial property we can also arrange for site visits, energy saving advice and cost of ownership analysis. We usually do this in partnership with one of our commercial lighting manufacturers such as Ansell Lighting, Aurora Lighting and Collingwood Lighting who specialise in site visits.
We're happy to make recommendations for the best downlights to use, and advise you on the advantages of using energy saving downlights which will also help you to comply with the latest Building Regulations.
If you don't want a lighting design and just need a bit more guidance, we have 5 golden rules to consider:
- 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.
- Choose a downlight - 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.
- Which beam angle? 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's not as focused.
- Uniformity, there’s no point having overly bright patches in certain 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 3x3 metres (9M²) having 9 downlights in 3x3 grid will look neat but your ceiling will be cluttered with downlights. A 2x2 grid, might leave a dull patch in the middle, but adding 1 downlight in the middle won't look right. This is why having a lighting design can be really useful as you can compare different grid layouts with different downlights before committing to the purchase or cutting holes.
Here are some useful tables from Aurora Lighting that shows you what lux levels you will achieve with some of their best selling downlights with various room sizes.
Lighting Design Criteria
- 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 MPRO
If you're interested in our lighting design service to discover how many downlights you need, please email details of your project and we'll be in touch. Or follow this link to view our latest range of kitchen lighting products.