Ascend Cannabis Grow Facility
Colorado is recognized as one of the leading pioneers in marijuana legalization and has made significant strides since the Medical Use of Marijuana Initiative (Amendment 20) kicked off in 2000 and recreational marijuana successfully passed in 2012 (Amendment 64) with sales opening in 2014. All jokes aside, Colorado’s cannabis industry is a blooming one where revenue exceeds more than $1.9 billion in 2020, growing more than $1.75 billion in 2019. Retail is often the face of the cannabis industry; however, storefronts are fueled by grow facilities across the state. Delineated by different classes or tiers, these facilities are licensed and heavily regulated; and many are in need of the professional services BG provides. Ascend Cannabis Grow Facility is located west of Pueblo in open rangeland. BG is working with the owners’ passion to operate the greenest grow facility with precision environmental controls. BG was retained by Economy Air-Conditioning & Heating, the mechanical sub-contractor, to help concept and design systems for the multi-building site – (10,000 SF existing building, 5,000 SF utility building, and 33,000 SF new cultivation building with a 13,000 SF indoor cultivation area and 20,000 SF of greenhouse space).
There were several challenges at the existing site including 1) limited electric utility service sized at 75kVA; 2) well water was near capacity and required filtration and treatment for optimal production; 3) gas heating systems were fed by propane tanks requiring frequent refilling; and 4) two diesel generators powered lighting systems that were intensive to maintain, operate, and failed often. The latter routinely damaged the components because of poor power quality. In the end, the environmental and lighting system failures caused potential costly and time-consuming detriment to the horticultural lifecycle. Expansion of the existing site to support larger operations required more water and a larger, more reliable energy source. Marrying the owner’s desires of a sustainable facility and solving existing conditions, BG served in a lead MEP design role. This included coordinating with a myriad of consultants, designers, equipment manufacturers, and vendors to develop a trigeneration system concept, which is where electric generation systems also provide heating and cooling, all from one source.
BG’s first step organized the existing and planned site loads for the Ascend Cannabis Grow Facility site, including future expansions, confirmed lighting operation cycles, and developed a power capacity study to determine site power requirements for a primary power source. The result was a megawatt, modular, power turbine array, with ability to expand in the future for additional array capacity. The turbine array is powered by compressed natural gas that is transported to the site. Array combustion gases utilize heat-exchanger stack recovery to generate heating hot water for building systems. Chilled water for building cooling systems is created by two hot-water-drive, absorption chillers to complete the trigeneration concept.
Plant power system reliability is provided within the modular array arrangement with a backup boiler and redundant pumping strategies. Power capacity is monitored and if it approaches peak, lighting systems will dim to reduce load on the array. The multiple chillers provide part capacity in the event of component failure, and the chilled water system is also equipped with integrated water-side economizing for pre-cooling of return water. Site water systems were enhanced with an additional well, and secondary treatment systems, configured for crossover (allowing partially treated water flow in the event of well or treatment system failure), and collected into on-site (treated) water storage tanks. The cleaned water is distributed to the building systems.
Inside the new, cultivation building, state-of-the-art environmental control systems allow temperature and humidity control. The LED lighting systems installed are controlled by light intensity, limiting power consumption. The indoor grow rooms a dedicated air handling unit located outside each room, capable of recirculation (for CO2 dosing) and economizing and direct exhaust. Destratification fans, with internal UV-c treatment clean the air and promote constant air motion to enhance plant growth. Smaller 4-pipe fan coils serve breeding rooms, maintained at negative pressure to the surrounding space similar to strategies used in hospital surgical rooms to minimize spread of contaminants.
The greenhouse systems are a mixture of gas-fired unit-heaters, evaporative cooling walls, and supply and exhaust fans supplied as part of the greenhouse vendor equipment package. Additional radiant, plant-bench heating systems connected to the central plant, and LED lighting systems were designed and integrated into the space by BG. Lighting systems are configured to only operate when the solar intensity does not provide the desired lighting levels. Radiant bench heating systems will provide a uniform and even temperature in the greenhouses as greater air transfers occur. BG’s work truly created a “circle of life” with the system’s hot water creating refrigeration of cold water to distribute and control humidity levels. This process helped curate an optimal environment for the grow rooms and recirculate carbon to feed the plants.