The best way to describe a Yin house is to remember back when you were young, walking home from school with your friends and you'd walk past the 'haunted scary' house. The house that had the overgrown garden and dirty windows and more than likely a large front fence - that is a Yin house.
Inner city apartment blocks could also be Yin deficient as they generally have small windows due to council building regulations to do with overlooking/privacy of a neighbouring property.
If your window to wall ration is less than 10% I believe you are living in an excessively Yin house. Occupants living in such homes may feel unmotivated, sluggish, tired and suffer from fatigue.
To remedy this we need to allow as much natural light as possible in to your home. Remove heavy window furnishings, trim or remove tress and bushes, you may even want to change your front fence to something smaller.
If you live in an apartment creating more natural light can be a harder task. I suggest leaving curtains and windows open as often as possible, change all light globes to the highest wattage and you may even consider changing your furniture to feature more bright and vibrant colours.
Having natural sunlight in your home creates good Feng Shui.