The large, open spaces of a warehouse building or distribution centre require adequate illumination so items can be identified and workers can navigate through aisles easily, reducing the risk of accidents and damage to stored items. As a result, lighting may account for 50%-80% of onsite electric bills for warehouse and logistics facilities.
By installing a new energy efficient warehouse lighting system it is possible to make electricity savings up to 80% without compromising on the working lux levels. This is because a large amount of energy is wasted in old warehouse lighting systems by:
- Using outdated & inefficient lamps and/or light fixtures
- Using lighting at full brightness in areas where and when not required
Old lighting types
An older warehouse lighting system will consist of several ‘high bay’ or ‘low bay’ lighting fixtures using high intensity discharge (HID) bulbs – each rated at 250 Watts or 400 Watts. These HID bulbs could be either high-pressure sodium (a peachy-yellow coloured light) or metal halide (a white-bluish light); with the fixtures mounted 5 metres or higher from ground level. Older fluorescent strip lamp fixtures (using T8 or T12 tubes) are more common at lower mounting levels (e.g. under mezzanine floors).
Energy Losses With Older Lighting
A warehouse lighting system using the above outdated light fixtures will be inefficient due to a combination of the following factors:
- Hidden energy consumption – Older HID and fluorescent light fixtures have an addtional energy requirement for their magnetic control ballasts. This means an extra 5-20% of energy is consumed.
- Light ‘loss’ in older fixtures – Older lighting fixtures may be very inefficient at directing light where it is needed, preventing large levels of illumination reaching working surfaces. This means there may be more fixtures than required to achieve the required lighting levels.
- No control of lighting levels – The lighting in a warehouse may have default setting of full power in all areas during the working day.
Older HID and fluorescent lighting fixtures cannot be dimmed or switched in response to area occupancy or the existing daylight levels. Meaning energy is being needlessly wasted.
When these losses are added up, the annual energy wastage from an older warehouse lighting system can run into many thousands of pounds per year. The latest energy efficient warehouse lighting systems address the above issues and make it possible to achieve an 80% energy saving.
Overview of new lighting options for warehouses
An overview of T5, induction lamp & LED light technologies are given below:
- T5 fluorescent tube fixtures – These fixtures use 2, 4 or 6 T5 tubes mounted in a fixture with a polished reflector to direct all light downwards. The T5 tubes work on the same basic principle as older T8 & T12 tubes but with an electronic control ballast and a longer operational life of 12000-18000 hours. Some advantages include – a well established energy efficient technology, modest installation cost, the light fixture still produces acceptable light levels following the expiry of a single T5 tube.
- Induction lamp fixtures – These fixtures use induction lamp technology – this works on the same basic operational principles as fluorescent tubes (exciting gas in a glass tube to emit light). The key difference is not using an electrode to pass a current through the tube but the creation of an electromagnetic field around the tube. The advantages of induction are a very long operational lamp life (100000 hours) and high quality white light!
- LED lighting fixtures – These fixtures use a mounted cluster of high output Light Emitting Diode components that produce light when an electric current is passed through them. This solid state technology has a very big future in business lighting as performance continues to improve and cost is reduced. Some advantages include long lifetime (50000-80000 hours) and a unidirectional light source.
Advanced warehouse lighting control systems
An effective warehouse lighting control system should switch off or dim lights automatically when full illumination is not required. However, older warehouse lights cannot provide instantaneous full light output – HID lamps with magnetic ballasts have a ‘warm-up’ time (to reach 90% of full output) and an extended re-strike time (time needed for lamp to cool before switching back on). It is not uncommon for a warehouse lighting control system to be an absolute minimum – a default on setting for all lights, only deactivated at the end of working shifts.
The T5 fluorescent tube, induction lamp & LEDs fittings all have the ability to be dimmed and switched instantly – this allows very effective energy saving control systems to be designed around the warehouse construction & usage – for example:
- Lighting control in individual warehouse aisles – Occupancy detectors can be acoustic, infrared or microwave devices and may or may not be built into each individual light fixture. These can be used to detect the presence of people or approaching fork lift trucks and to control the lighting accordingly. An inbuilt time delay will prevent inappropriate ‘off’ switching if an occupant remains still. This means the individual warehouse aisles can be lit to full brightness only when in use
- Dimming control with existing daylight – Photo-electric daylight linked controls can be used to gradually dim up/down lighting levels. The controller is set so that the combination of daylight and electric lighting remains constant at a design illumination level. If the warehouse has in excess of 10% of the roof area as skylight panels then there may be no need for electric lighting at certain times of the day. This means the energy consumption of lighting can be eliminated at certain times of the day.
Operational benefits of new warehouse lighting
Lower maintenance costs – In warehouses, a scissor lift or cherry picker may be required to change expired lamps – which can be costly (as well as the disruption caused when an area remains unlit). Also, new environmental regulations mean that expired bulbs have to be carefully disposed of. New light fixtures use bulbs that last up to 50000-100000 hours; or 6-9 years continual operation. This means lighting maintenance and disposal costs can be almost eliminated.
Government financial assistance – Due to the level of energy & carbon saved, new warehouse lighting will usually qualify for Carbon Trust financial assistance – either through an interest-free loan or write off of investemtent against tax. This means a new lighting system could cost nothing to install as the savings are larger than payment installments (a positive cash flow) could be generated!
Improved light quality – The quality of light from older high-bay fixtures can be poor (especially from HPS lamps) – new lighting technologies can emit light that is close to daylight. This means beter colour recognition for product identification & picking and a safer working environment.
Improved light distribution – A poorly designed warehouse lighting system can can cause problems for workers – e.g. large shadows between high shelving making label reading/product picking difficult or forklift truck drivers experiencing high levels of glare. A new system can address these problems by fully considering the building users. This means better health & safety standards & productivity will be achieved.
Respond to the sustainability demands of your supply chain & customers – increasing awareness of environmental issues has put green issues high on business agendas. Energy saving warehouse lighting provides one of the most effective ways to significantly lower the carbon footprint of a business. This means a business gets a very visual display of their to sustainability commitment.
Which lighting system is best for your warehouse?
Some key points in considering a new energy efficient warehouse lighting system are:
- How often will the warehouse aisles be occupied?
- Is good access to daylight available in the warehouse via skypanels etc.?
- How critical is minimum maintenance of the lighting fixtures (lamp replacement etc.)
- Are there issues with the existing lighting system – poor colour rendition or light distribution (glare, shadows etc.)?
- Is there a set target for payback on any investment made in the new lighting?
- Is the installation dependent on qualification for the Carbon Trust financial loan scheme?
If you already have this information Salient can give you a head start on getting your warehouse project started, if not we’ll help you get started.