Sure, It's good to have a storage problem (aka, more ammo than before is a good thing).
Generally Ammo stored in a house will be just fine. It's not too hot, not to cold, not too wet, and not to dry(usually).
Efficient? It's hard to beat the compact storage efficiency of a well loaded ammo can (or stacks of them
I won't bother addressing in any laws regarding storage in your area. I love the ammo can's, but have a carboard box of many calibers that I keep as handy stock when the family and friends come by to shoot.