By Ned Heminger, PE, LEED AP, HBDP Vice President
I recently attended ASHRAE’s 2018 Winter Conference in Chicago, getting the opportunity to track the latest in industry trends, equipment and standards. One issue in particular caught my attention while I was there, and it’s one you might not assume has any connection to the MEP industry: cannabis.
As certain states have been legalizing growing cannabis for medical or recreational use, engineers are finding that the process is largely unregulated from an energy standpoint. With the energy codes focused on buildings, the industry is seeing a new high-energy user in these grow facilities. Because the classification of this type of facility is a process, there is not much in the energy code by which to restrict their energy use.
While one may expect that these facilities are utilizing greenhouses, many are not. It is common for these facilities to be placed in a warehouse with high-powered grow lights installed (approaching 70 watts/sq. ft.), giving them a power density similar to many data centers. Growers also utilize carbon dioxide (CO2) generators—normally fossil fuel-powered—to elevate the CO2 up to three times that of ambient levels. In order to maintain these elevated CO2 levels, sealing of the building is important. With a tightly sealed building and the high heat gain from the grow lights, a rather significant mechanical cooling system is needed to reject the heat in order to maintain space temperatures at an acceptable level for the plants (85F-95F).
Conversations began in Chicago to develop recommended HVAC practices for indoor plant growth facilities for this industry, which has taken off at a very rapid pace. At HAWA, we have yet to be approached about a project of this nature, but as culture shifts and legislation changes, we recognize the importance of keeping on top of new challenges the industry faces.