How many LED panels do I need for an office?

LED panels are the standard for offices: they give plenty of light, use little electricity and fit exactly into a suspended ceiling. But how many panels do you need? That depends on the size of the room, the work done there and the wattage of the panel. In this article you will read how many lux each room needs, how to calculate the number of panels and what to look out for when choosing. With two worked examples you can apply it straight away.

How many lux does an office need?

The European standard for workplace lighting, EN 12464-1, requires 500 lux on the working surface for desk work and screen work. A meeting room also needs 500 lux, a reception about 300 lux, a canteen or break room 200 lux and a corridor 100 lux. For technical drawing or precision work, 750 lux is common. If in doubt, choose a little more light with a dimmable driver; you can always turn it down later.

How to calculate the number of panels

The formula is: lux times m² divided by the useful light per panel. Not all the light from a panel reaches the desk: part of it falls on walls and cabinets, and the light output decreases slightly over the years. So calculate with about half of the lumens on the rating plate. A 40-watt panel with 120 lumens per watt gives 4,800 lumens and therefore about 2,400 useful lumens on the working surface.

Table: m² per LED panel

Panel	Lumens	Useful lumens	300 lux	500 lux
60x60 cm, 30 watts	3,600	approx. 1,800	6 m²	3.6 m²
60x60 or 30x120 cm, 40 watts	4,800	approx. 2,400	8 m²	4.8 m²
60x120 cm, 60 watts	7,200	approx. 3,600	12 m²	7.2 m²

Divide the floor area of the room by the figure in the table and round up. Then choose a regular pattern so that the light falls evenly across the room.

Worked example 1: a 24 m² office for three people

An office of 6 by 4 metres needs 500 lux. That is 500 times 24 divided by 2,400, so 5 panels of 60x60 cm and 40 watts. For a regular pattern you choose 2 rows of 3, so 6 panels. That gives about 600 lux. With a dimmable driver you set the light to exactly 500 lux and save electricity at the same time. The total wattage is 240 watts.

Worked example 2: a 120 m² open-plan office

An open-plan office of 12 by 10 metres needs 500 lux: 500 times 120 is 60,000 useful lumens. With 60x60 cm panels of 40 watts that makes 25 panels, in 5 rows of 5, together 1,000 watts. With larger 60x120 cm panels of 60 watts you need 17; in a regular pattern of 3 rows of 6 that becomes 18. That gives about 540 lux at 1,080 watts, with fewer fittings to install.

What to look for in office panels

For screen work, the glare rating UGR must be below 19. Panels with UGR<19 have a special diffuser that spreads the light so you do not see annoying reflections on your screen. Also choose a colour rendering of at least CRI 80 and flicker-free drivers, because flicker causes headaches and tired eyes. For workstations, 4000 kelvin, neutral white, is the best colour temperature; in a reception or meeting room 3000 kelvin can feel more welcoming.

Recessed or surface-mounted?

If you have a suspended ceiling, first measure the grid: most ceilings take 60x60 cm, but some older ceilings have 62x62 cm. With a plasterboard or concrete ceiling you use a surface-mounting frame, so the panel is screwed against the ceiling. In an office with a ceiling height of 2.7 metres, the spacing between panels is usually 2 to 2.5 metres.

Advice for your office

Send the dimensions of your rooms, the ceiling height and the type of ceiling to info@dimay.com. We will calculate the number of panels and the layout for you. Also see our LED panels, the panels with UGR<19 and the 60x60 cm panels, and read what the UGR value means, which colour temperature to choose and how many lumens you need.

Frequently asked questions about LED panels in an office