This one can be tough sometimes. Depends on how bad the negativity is.
This may or may not sound strange to you, but it is what I do.
Take a bottle of olive oil, bless it in the name of the Father, Son and Holy Spirit. Put a drop on your forehead and bless yourself. Also, bless your house and command every bad and negative thing in it to leave in the name of Jesus.
Sorry, I don't have any fung shui solutions.
Well you have answered your own question it is their negative energy/personality so really you don't have to worry about it do you...unless you believe/let it rub off on you for lack of a better term.....but I like tamarinds answer better since I don't believe in the stars and placement of objects making life better or worse....that would mean that inanimate objects rule my life instead of the Creator and letting someone or something else be my God is not my idea of being in control understanding we are each our own individual under the guidance of the Lord God who is control of all things even down to the next breath we take.....so I would rather ask him to take care of it and not have to think about what is going to make my day(clint eastwood)
When they start their negative attitude, just start talking positive about them. Keep talking positive about them until, they start talking positive about themselves. Ignore negative energy also. Reward positive energy by a smile, a laugh, a comment and a discussion. Negative energy can not exist in a positive atmosphere. You and your spirit can block it by the positive side of things. It works....try it.