Rather than a Dehumidifier, consider a whole house ventilator or an air-to-air heat exchanger.
By the way, the "Problem" is not that your house is "TOO TIGHT". That is a very persistant myth. However, when you build a tight, enegy efficient house, you need to manage the indoor air quality. This usually gets overlooked. This is both a structural & a health concern. Both of the above suggestions account for this. A dehumidified does not.