Project: Willy Naessens – LED high bays and LED panels

Industrial construction company Willy Naessens replaced 32 mercury vapour lamps of 400W in its 3,000 m² storage hall in Tessenderlo (Belgium) with 32 LED high bays of 200W, switched by motion sensors. The light level went from 300 to 500 lux at half the power. In the offices, the old ceiling lighting made way for LED panels 60×60 with switchable colour temperature.

Project facts

Client	Willy Naessens, industrial construction
Location	Tessenderlo, Belgium
Building	Storage hall, approx. 3,000 m², with offices
Completed	2024
Old lighting (hall)	32 × 400W mercury vapour
New lighting (hall)	32 × LED high bay 200W
Offices	LED panels 60×60, switchable colour temperature
Mounting	8 m, on chains
Control	Motion sensors
Illuminance	300 lux before, 500 lux after
Planning	DIALux light study

The starting point

Willy Naessens stores building materials, profiles and components on pallet racking in a hall of around 3,000 m², with large sectional doors for loading. The hall was lit by 32 mercury vapour lamps of 400W each: a total of 12,800W.

Not enough light and failing lamps

With around 300 lux on the floor, the hall was workable but not bright enough for picking and checking materials quickly. More and more lamps had failed, and mercury vapour lamps have been phased out in the EU since 2015, so replacements were becoming hard to find.

High consumption

12,800W running 2,800 hours a year adds up to 35,840 kWh: more than €11,000 a year for lighting the hall at €0.31/kWh, often burning in parts of the hall where nobody was working.

The solution

Light study first

Before ordering, we made a DIALux light study of the hall. It showed that every old fitting could be replaced one for one by an LED high bay, raising the light level to 500 lux.

32 LED high bays 200W at 8 m

All 32 positions now carry an LED high bay, hung on chains at 8 m. The luminaire can be set to 120W, 160W or 200W; here it runs at 200W. With 210 lm/W and a 90° beam, it puts a lot of light on the floor at half the power of the old lamp. The high bays are IP65 rated and 0-10V dimmable. More on choosing wattage and beam in our LED high bay guide.

Motion sensors

The high bays are switched by motion sensors, so they only burn where and when someone is working in the hall. LED gives full light instantly and is not harmed by frequent switching, which makes it ideal for sensor control.

Offices: LED panels 60×60

In the offices, the ceiling grid now holds LED panels 60×60 of 36W. Each panel replaces a 4×18W fluorescent fitting, gives even, glare-free backlit light and lets the colour temperature be switched between warm, neutral and cool white to suit the space. See all options in our LED panels collection.

LED luminaires used in this project

Energy savings in figures

The figures below cover the storage hall. The office panels are not included, so the total saving is higher.

	Before	After	Difference
Luminaires	32 × 400W mercury vapour	32 × 200W LED high bay	one for one
Connected load	12,800W	6,400W	−50%
Load per m²	4.3W/m²	2.1W/m²	−2.1W/m²
Consumption per year	35,840 kWh	17,920 kWh	−17,920 kWh
Electricity cost per year	€11,110	€5,555	−€5,555
CO2 per year	5.4 t	2.7 t	−2.7 t
Average illuminance	300 lux	500 lux	+67%

How we calculated this

• Before: 32 × 400W = 12,800W × 2,800 h = 35,840 kWh per year.
• After: 32 × 200W = 6,400W × 2,800 h = 17,920 kWh per year.
• Cost: 17,920 kWh × €0.31/kWh = €5,555 per year.
• CO2: 17,920 kWh × 0.15 kg/kWh = 2.7 t per year.

The extra saving from the motion sensors and ballast losses of the old lamps are not included, so the real saving is higher.

Investment and payback

At current webshop prices, the 32 LED high bays cost €2,814. Half of the investment was covered by an energy-efficiency subsidy, leaving €1,407. With €5,555 saved per year, the high bays paid for themselves in about three months. Installation, sensors and the office panels are not included in that figure.

Calculate the savings for your hall

The calculator below is pre-filled with the Willy Naessens hall figures. Change the values to see what a switch to LED would save in your own building.

The result

• More light at half the power: from 300 to 500 lux with 6,400W instead of 12,800W.
• Light only where needed: motion sensors switch the high bays on when someone is working.
• No more failed lamps: no warm-up time and no more searching for discontinued mercury vapour lamps.
• Comfortable offices: glare-free LED panels with switchable colour temperature.
• Lower running costs: €5,555 less on electricity every year in the hall, plus the sensor and office savings.

Frequently asked questions

Can a 200W LED high bay replace a 400W mercury vapour lamp?

Yes. A mercury vapour lamp produces only around 50 lm/W, and part of that light is lost in the reflector. An LED high bay at 210 lm/W sends its light where it is needed. At Willy Naessens the light level went from 300 to 500 lux, while the power per fitting was halved.

Why combine LED high bays with motion sensors?

In a storage hall, people rarely work everywhere at once. Motion sensors switch the light only where it is needed. LED gives full light instantly and is not harmed by frequent switching, so the two work well together.

What does a switchable colour temperature panel do?

A CCT-switchable LED panel can be set to warm, neutral or cool white. That way the same panel fits a meeting room, an open-plan office or a reception area, without ordering different versions.

How was the saving of €5,555 per year calculated?

The old hall installation drew 12,800W, the new one 6,400W. At 2,800 operating hours a year that is 17,920 kWh less. Multiplied by €0.31/kWh, that gives €5,555 a year. The extra saving from the motion sensors and the office panels is not included.

Can you make a free light plan for my hall and offices?

Yes. Send us a floor plan or a few photos with the ceiling heights. We make a free DIALux light study for the hall and the offices, and send a non-binding quote at direct-import prices.