Hey Macnasty, don't sweat it (AC joke yuk yuk),the 10k AC windowless is going to be just fine if the outside temps are only going up to 23C at night when you run your lights.
That 10k would at least equal a 6500-7000k window unit, you only need to cool 3400+ BTUs of the lights.....and you can let the room temp reach 25-26C to be in a real sweet spot.

Night time is the best time, :thumbsup: higher levels of ambient CO2.

Chiller systems are water based systems that use a resivior of water and water to air heat exhcanges to cool the lights and even the room. Most times a small compressor chiller is used to keep water temps cool, tho sometimes there are other ways.

Just recently I changed my personal grow's mom/veg room layout and needed more light and went to a 600w MH, talk about a heat producer. I bought a Icebox heat exchager (made by Hydro Innovation) that fits on the hood and an inline fan on the other side of the hood, blowing thru the bulb area and out the heat exchanger. It's like a car's heater core in a plastic box with 6" (or 8") flanges on each side. In the next room, utility area, sits a 30 gallon plastic olive drum filled with water. Inside this drum I have a coil of 3/4" soft copper tubing that has the output of my well diverted thru it. My well water is 52F degrees year round, and anytime water is used in my house that water runs thru the coil and keeps the resivior cold. Small pump runs when lights are on to circulate cold water to the icebox/light/fan combo. Pretty cool set up.

OM