Looks interesting. You might want to reconsider the name "Nano", though, as there is already an "official" Arduino Nano, of course.
Is the mini "shield" with the DHT22 designed to fit on the (unpopulated) 8x2 male header? Do you also have the RTC on the shield?
Looks like you have had a few made up. How many did you get made up, and how much did it cost you to get an initial batch run? Or did you solder these up yourself?
I like the fact it is Serial/ICSP programming only -- I feel the usb programming capability adds too much to the cost and complexity of design, and is a waste for a board destined to actually go into the field. I'd even simplify further and get rid of the DTR reset circuitry, and make it ICSP programming only. Why do you need more than ICSP for a deployment board?
And did you design these so that two small relays could be mounted directly on the board, or are they just providing two relay actuation outputs?