This is the house blessing ritual I have used for many years to bless a home before or shortly after moving in. The purpose of this ritual is many layered: to clear away any energies which may be lingering in the house from previous inhabitants, to protect the space against unwanted intrusions in the future, and be on their way and to create a loving, harmonious space in which to live.
Everyone who will be living in the house should take part in the ritual. If they have friends and relatives who wish to be involved all the better as this will make all the more strength to the ritual through the power of their positive thoughts. Besides, I have never met a Pagan who does not like a reason for good food and a gathering.
Some might have you leave a door or a window open believing you need to have a way for negativity to escape, but for me I believe the fresh air entering the room is a positive thing all on its own. Whether it is day time or night time lower the lights and work by candle light, as your mind works better in the softness of candle light rather than the harshness of manmade light. If working at night, put out all lights except a single candle.
When you are all ready, create sacred space by casting a circle or envision a bubble begin to encompass the house until you are all securely contained within. If you decide to cast a circle, turn slowly around while staying within just one room envisioning the entire home as enclosed within the sacred space. This is something I have often done in ritual in the past if there are children present; it takes away parents worry that their children will somehow be disrupting the ritual by running in and out of circle. You may now call to the Elements or whatever other your method, you might prefer. If you wish to invoke a Pantheon for this ritual, a likely choice is to pair a domestic or hearth goddess, with a protective god to fill the needs of a house blessing.
Now proceed through the house deosil (clockwise), going into and out of each room, and smudging with a burning sage stick. It does not matter if you use Flat Cedar or White Sage, whichever you prefer will work just as well; remember to do the closets and each corner. Take the time to do all of the people who have gathered at the ritual as well.
Now for protection light dragons blood incense and go through the house a second time. Walk around the house deosil (clockwise), going into and out of each room. Stop at each window and say, "May no harm cross this portal." (You may choose to make the sign of the pentagram; I leave that up to you at each window and door.)
Continue through the door and when you leave the room stop again and repeat, "May no harm cross this portal." When all the rooms have been cleansed with dragons' blood, it will be time for the last part.
The third part of the ritual cleansing of the house is to set how the home will be lived in. A home of love and happiness, filled with joy and peace. In the center of each room lavender incense is burned. The owners of the home light the incense saying, "May our home be filled with love, happiness, and peace."
When everyone returns to the altar after lighting all the incense in each of the rooms, we share a small ritual meal and share our well wishes as a group. Then open the circle, and enjoy each other company for a bit longer.
A house blessing is many ways layered like an onion. There are layers, which are easy to see, and the ones you will not see unless you peel them away.