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Ask Erik: Staying Cool After You Get the Power Bill ^Featured

Written by Erik Biksa
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Ask Erik: Staying Cool After You Get the Power Bill

Q: Where I live, it’s going to take some serious cooling to be able to grow indoors this summer. Even at night, the outside temperature can be 85°F, and the humidity needle spikes during rainy weeks. Other growers in the area say that in/out just isn’t an option around here. As a matter of fact, a lot of them shut down their grows entirely and start again in the fall when things cool off. Power isn’t cheap. I want to run about eight 1000W HID lamps and keep things cool and happy for my crop. I don’t mind spending a little on the gear; my biggest concern is keeping the power bill down. Any help?

A: Relying on air conditioning as the only source of cooling is going to run up your power bill unless you combine it with a few tactics to help keep the growing environment optimal indoors when it’s hot outside:

Isolate and remove the heat

Well-designed air-cooled grow lamp reflectors like the MelonHead (pictured) keep hot running lamps separate from the growing environment with a glass tube or lens. Connected duct work allows fans to transfer the heated air surrounding the lamp, significantly limiting grow room temperature increases related to lighting. By using AC shades, you only need about 1500 BTUs of cooling from your AC per 1KW of grow lighting (versus 4500+ BTU capacity without). The result? Needing only a third of the power draw from energy-intensive air conditioners

Cool Feet

A hydroponics system that doesn’t lose lots of water to evaporation and that runs with a good depth of solution, like an Under Current for example, provides a great buffer and insulator against warmer grow rooms. If you chill your plants directly at the roots (maintaining 65°F), your plants will still be able to flourish in slightly warmer-than-optimal air temperatures. Cooler solutions hold a lot more oxygen, helping to promote faster growth and curtail pathogens like root rot.

Spot-cool

Air-cooled reflectors are a great example of putting cooling power where it is needed. Some growers even use a small AC to blast very cold air through their air-cooled shades, in some cases negating the need for AC room cooling.
Water-cooled heat exchanges can also help to accomplish this. Use water-cooled CO2 generators (water cooling takes about 90% of the heat away that is associated with hot-running gas-fired CO2 generators). Keep your ballasts outside the growing area too, as they can generate lot of heat.

TIP:

High-quality digital ballasts run quite a bit cooler than their core-and-coil predecessors, so you can reduce the heat generated by the ballasts by around 50% here as well.