I agree with Miss Lydia. A life confined to a dog house would not be fair to the ducks or good for their health.
First things first, they are messy with water. So if you left them in a dog house all night and all day, you would HAVE to have water in there for them. Which means you would have to clean the dog house out daily as they tend to empty all water and splash and make a mess.
Also, how many ducks do you have? Because they need enough space to be able to lay down, stretch their legs and wings, and walk around comfortably. If you have a small dog house with more than 2-3 ducks in it, its going to be too crammed even just for them to spend the night in, let alone all day too.
And to be fair, ducks are meant to be outside. Even if they are penned and not necessarily out on grass, at least they have access to fresh air and sun. Cooped in a dog house will limit their sun which could, in turn, limit their egg laying or stop production all together.
My suggestion would be to build them a pen and let them out during the day. Give them food and water before you leave and again before you turn them in for the night. Then they won't be so cooped and crammed as leaving them in a dog house all night and for 8-10 hours during the day is pretty much their whole life. Even 1-2 hours out to free range is unfair to them.
In all honesty, if you can't do that and have to keep them in the dog house all night and day, then you probably should take another look at being a duck owner. If you can't give them a good life, and devote enough of your own time to ensuring they are properly cared for, then maybe having ducks is not such a good idea at this point in time in your life.