I rather like the look of the next generation smart air-con's from Samsung. They can pull 1L of water out of the air per hour and can be controlled remotely via wi-fi. There is an added benefit in that you could in theory have your telescope down to night time operating temperature as soon as you open the observatory which is the way professional observatories get around the issue of thermal mass inducing local seeing.
Being that they use inverter technology, the power consumption is 20% of the heat actually being removed by the head unit.
http://www.samsung.com/au/air-condit...9FSSSBWK1.html