Lemnis Lighting and the Impact of Hydronic Cooling
by Dan Gustafik, President & CEO, Hybrid Tech LLC
Cannabis cultivators have been stuck in a battle in growing for the last two decades: how to eliminate the heat that is generated in cultivation facilities. Many clients have tried to solve this problem with 20-ton air handler units, 48-inch ducts and polytubes penetrating into their greenhouses and indoor spaces. Unfortunately, this has been the price to be paid for a sealed, controlled-environment agriculture facility. This battle is partially due to conventional lighting technology depositing its entire sensible load into a conditioned space. (Sensible heat is the heat imparted to the cultivation environment by lights and sun.) But, we now have a new tool in our toolbox that removes two-thirds of the sensible load from the cultivation chamber—the hydronically-cooled LED fixture.
Around six months ago, Hybrid Tech began a casual conversation with a representative of Lemnis lighting solutions. As one of the few cannabis-specific licensed design and engineering firms, Hybrid Tech receives many requests from clients for review and recommendations for lighting solutions. The usual response is “Please send any data you have and we will review it.” Lemnis Lighting Solutions followed up with hard engineering data.
The data involved an elegant piping detail for a hydronically-cooled LED with 2.7 Umol/joule efficacy, which is the highest we had ever seen. It also has 0-10 V dimming for active daylight harvesting and sunrise/sunset mimicking, with five spectrums to choose from. However, all that data paled in comparison to the cooling data: The fixture imparts up to 61.7% of its energy into the cooling circuit. The cooling data made us leap up and call Lemnis immediately. Here’s why: Being an engineering firm with a robust mechanical division we are absolutely amazed at what hydronically-cooled LEDs mean for system engineering in contrast to radiantly-cooled LEDs.
Let’s start with a brief explanation of how chiller plants operate: A chiller plant is a liquid chiller inside the facility, mated with a cooling tower outside, which is cooled using water as the refrigerant. The cooling tower deposits the thermal load outside, potentially for just the cost of a pump and a fan. Inside, the chiller plant compresses the remaining load before sending the water through all the cooling and dehumidification systems. Chillers can be as efficient as 0.5 KW/ton and are one of the most energy-efficient technologies in existence. However, the chiller must be mated with appropriately-sized air handlers in each chamber, which are expensive and cumbersome. Now, what if 60% of the heat is gone from the chamber? We then have 60% fewer air handlers, and that is just the start.
With the removal of 60% of the heat from cultivation chambers, a host of new system designs are available on larger projects. For greenhouse clients, systems can be undersized, need less cooling overall and can have active heat recovery from vegetation areas. For indoor clients, multilayer rolling canopies can finally be deployed without massive ducting or full-sized air handlers. The remaining heat can be mitigated by the dehumidification system using specialized coils, without having every air handler outfitted at high cost. With the fixture temp at 105℉ on average, the light can be placed far closer to the canopy without damage. Another area that can benefit from this technology is geothermal cooling.
Geothermal cooling is transferring heat energy with the earth for very low cost and amazing efficiency. With hydronically-cooled LEDs, it’s very easy to use. Having a light that displaces its heat into water allows that heat to be shuttled wherever it is needed. Obviously, most clients would prefer the heat to go outside the cultivation space, but once outside the heat needs to be dropped before coming back in. With geothermal, ground loops—laid horizontally or vertically into ponds and lakes can be used to mitigate the entire thermal load at the cost of just a pump! A curtate cycloid AKA “slinky” low-cost geothermal loop system can also be used. The implication is a low-operational-cost system that can outperform even chillers. Hydronically-cooled LEDs are not just useful for massive greenhouse and indoor facilities, though.
Often finding a good HVAC contractor and being able to afford engineering design work is out of the reach of small cultivators; a hydronically-cooled light is much simpler. On our demo fixture from Lemnis, we set up a micro-chiller and pump and run one light in our booth. This incredibly simple design uses standard hoses and a bucket. Rather than having high-pressure refrigerant and an HVAC contractor, the whole system uses standard flex tubing and water that can be assembled by anyone. Placing the micro-chiller outside also deposits the heat outside the cultivation area. We are currently working on smaller pre-engineered designs that will be available in the next few months for cultivators. The pre-engineered solutions should be available about the same time as our white paper study on hydronically-cooled LEDs.
Moving forward, Hybrid Tech will soon have an ASME white paper coming out, along with quite a few other offerings. The Lemnis engineering team is working on an additional spectrum to supplement the current five spectrums they offer. Our American Society of Mechanical Engineers (ASME) white paper study will explore the complete implications of hydronically-cooled LEDs in controlled environment agriculture (CEA) systems. The white paper will reveal precisely why we are so excited about this technology and why it will transform the cannabis industry. Stay tuned; it’s an exciting time for innovation in cannabis!