After several complaints and accidents it was decided to upgrade the warehouse lighting.

The 400w High Pressure Sodium Fittings are replaced with 185w LED High Bay Fittings

The new lighting improves staff safety and saves over £8300 per year, see below for details.

The warehouse lighting is on for an average of 12 hours per day, 7 days a week, 52 weeks a year. Replacing fifty High Pressure Sodium lamps with LED High Bay fittings on a 1-for-1 basis improves lighting levels, saves energy and reduces maintenance costs, see note 3.

150w LED High Bay fitting 400w High Pressure Sodium lamp
Fitting/Lamp projected lifespan (hrs), see note 4 40,000 15,000
Cost for 50 LED fittings including installation compared to maintaining 50 High Pressure Sodium lamps, see note 1 £33,063 £6,926
Fittings/Lamps needed to last 40,000 hours 50 133
kWh used per year 32,760 87,360
Cost of electricity per year (@ £0.11 / kWh), see note 2 £3,604 £9,610
Electricity savings per year £6,006 (9610 – 3604)

Energy Reduction and Cost Saving

Replacing fifty 400w High Pressure Sodium lamps with 150w LED High Bay fittings in a warehouse reduces energy costs by an average of 62% or £6,006 per year.

The cost of replacing High Pressure Sodium with LED High Bay will be paid back in 3-4 years by reduction in cost of energy and replacement High Pressure Sodium lamps.

Furthermore after payback the annual savings are approximately £8,314 (electricity saving £6,006 plus High Pressure Sodium lamp replacement £2,308).

If energy prices rise the savings will be higher and payback sooner!


1. This is a typical price for an Aurora 150w LED High Bay fitting
This is a typical price for a Phillips 400w High Pressure Sodium Lamp
2. http://www.electricityprices.org.uk/average-electricity-bill/
3. Maintaining a High Pressure Sodium lamp will involve more costs than an LED fitting. Based on usage of on an average of 12 hours per day, 7 days a week, 52 weeks a year LED High Bay fittings would be replaced every 9 years whereas High Pressure Sodium lamps would be replaced every 3 years. Each time lamps are replaced there is potential disruption in the work place and high labour cost due to the height at which the lamps are located.
4. Although manufacturers specify that the typical lifespan of an LED lamp is 50,000 hours this can vary depending upon the environment it is installed in. This should be taken in consideration when installing any new lighting.