Cannabis market price compression across the country has pushed cultivators to explore new strategies to increase output and reduce operational costs. Power consumption is one of the leading contributors to those operational costs and, therefore, a clear target for identifying savings. Although access to capital and the state of financial markets has made it difficult for many producers to secure funding for facility upgrades, many of the states most impacted by low market prices offer significant incentives and rebates through local utility providers or governmental agencies for energy-efficient equipment purchases like high-efficiency LED lighting and HVAC units. Especially when combined with financing solutions, which urban-gro can help source for their customers, these programs allow legacy cultivation facilities to retrofit light fixtures at little to no out-of-pocket cost.
New, efficient LED fixtures provide cultivators the option to either maintain previous light levels while reducing energy usage or to increase light intensity while matching their previous wattage. While most cultivators simply compare their crop value and electrical costs when facing this decision, both retrofit strategies have significant implications for environmental conditions.
When considering lighting system retrofits, it is important to evaluate the sensible load (heat generated) from lighting that needs to be removed by HVAC cooling systems, and cultivators must also account for how a change in lighting will affect their ability to manage the latent load (moisture) created through plant transpiration. Put simply, lighting changes typically result in necessary adjustments to dehumidification requirements, and reducing the wattage of cultivation lighting will often make the environment more difficult to control, despite a reduction in heat within the room.
So, for example, imagine a room in which cooling systems run at full power all day, without ever shutting off, to achieve a desired temperature setpoint. Upgrading to more efficient lighting that operates at lower wattage will reduce sensible load and likely result in the cooling units operating more efficiently and shutting off for periods of the day once the setpoints are reached. HVAC units remove a significant amount of latent load while operating (through condensation on the cooling coil), so shutting down these systems will lead to higher humidity within the room, despite target temperatures being achieved more efficiently. The detriment to crop health from this lack of control over humidity will almost always offset any benefit from lower energy costs.
Alternatively, cultivators that choose to increase light intensity by matching the wattage of their current lights with more efficient solutions often face similar humidity challenges due to increased transpiration. As the plants absorb more light for photosynthesis, transpiration rates also typically rise and increase latent load within the space, even though the sensible load remains the same.
Every HVAC system will have different operating characteristics, so understanding how your specific equipment will respond to a change in cultivation lighting requires an in-depth analysis, and the optimal retrofit strategy will look different for every facility.
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