An Illuminating Example
In a recent energy audit for a large warehouse, lighting was found to be the biggest energy consumer. This might be as expected but the options for reducing energy on site are typically limited because the lighting used are high bay lights. These do not function well with movement sensors or light level sensors because of the time it takes to warm up and then cool down before it can be turned on again. In addition, in older warehouses, the lighting circuits were simple. All on or all off.
We looked at several initiatives. These included;
- Installing voltage management equipment. From past experience these units can save about 30% on high bay lights.
- Developing a virtual switch board so that lighting could be switched off or on depending on need. The development work was done for this option and if installed, the lights could be controlled from an ipad which displayed a floor plan and a touch button for each light. Lights could be individually controlled or controlled in pre defined banks.
- LED replacement
- A high tech version of T5 lighting designed as a high bay replacement.
The last option progressed to a detailed design stage and quotation from the supplier.
“After less than 2 years the savings go straight to the bottom line”
The lighting units include movement detectors and daylight sensors. When the lights are not needed they gently dim to a low level and if needed later gently ramp up intensity to the level required. Similarly if light levels from sky lights provide adequate lighting the lights dim down and eventually turn off. Importantly the dimming process does not waste energy in the form of heat, a common problem with other dimming technologies.
Replacing all high bay lights is an expensive operation but due to the efficiency of the system the payback period was just under 2 years. This means, once the system is paid off from the savings, the savings, equivalent to around half the cost of the lights, went straight to the bottom line as reduced cost and increased profit every year thereafter.