An LED lighting upgrade provides most of its savings as reduced energy consumption, and the long service life of the technology translates into maintenance savings, since plenty of lamp replacements are avoided.
However, LED fixtures also have a lower heat emission than less efficient types of lighting, and in air conditioned spaces this translates into additional savings, since the cooling load is reduced.
LED upgrades are often analysed considering only energy savings, and the resulting payback period may not seem too attractive. However, for a realistic assessment of the project, maintenance savings and cooling load reduction must also be considered.
Air Conditioning Savings with LED Lighting
Fluorescent lighting is frequently used in commercial and corporate buildings, and 32-watt T8 tubes are especially common. However, there are now equivalent LED tubes that offer the same lighting output for a power consumption of 20 watts or less, which represents savings of more than 37 percent. However, this is considering only the direct reduction in lighting power.
Since an LED upgrade results in the same lighting output, the difference in power consumed is reflected as a reduction in the heat radiated by lighting fixtures. Consider the following example:
- A facility has 6000 fluorescent tubes, with a power consumption of 32 watts each, distributed among 2000 fixtures.
- Assume all 6000 tubes are replaced with equivalent LED lamps, with a power consumption of 20 watts each.
- Each tube now emits 12 watts less of heat, for a total of 72 kilowatts if all 6000 tubes are considered.
- The air conditioning system must no longer remove these 72 kilowatts of heat from the building.
Assuming the AC system removes three kilowatts of heat for each kilowatt of electricity consumed, a total of 24 kW would be saved on cooling power. If this value is added to the direct savings of the lighting savings, a total of 96 kW is obtained. In other words, this LED upgrade provides 33 percent more savings than if it had been installed in a facility with no air conditioning.
LED Lighting in Cold Storage Facilities
LED lighting is an even more attractive investment in cold storage facilities, which often operate 24 hours a day and where lamp replacements are more difficult to carry out than in commercial spaces. Also, consider that HID lighting is common in cold storage applications and it is less efficient than fluorescent lighting; hence, there is a greater opportunity to save energy with LED lighting.
An HID fixture with a power consumption of 450 watts can typically be replaced with an LED fixture consuming 200 watts or less, which results in energy savings of more than 50 percent, before accounting for the cooling load reduction. LED lighting is even more beneficial in new projects: since the cooling load is reduced from the design stage, refrigeration equipment can be sized with a slightly lower capacity, which reduces the initial investment.
LED lighting can achieve great synergy with air conditioning or refrigeration equipment, since the lighting power reduction also reduces the cooling load. If there are also plans to upgrade air conditioning or refrigeration equipment, it can be specified with both a smaller nameplate capacity and a higher energy efficiency.