Create a blue print of the house you live in below. Include every room, wall and closet. Once you have drawn the walls, locate and mark the heating vents or wall heaters, and the air return if you have one, and fireplaces. Also, include any fans built into the home, such as ceiling fans, bathroom fans, and kitchen fans. If your home has more than one floor, diagram each floor separately.
Use these symbols on your blue print. Do not include furniture.
Door:____/ ___ (looks like an open door)
Stairs: dashed, parallel lines in the location of the staircase
Closet: outline it and write a C in the center of the closet
Vent: small rectangle with parallel lines inside
Fan: a five leg fan
Air return: this is usually found on the ceiling in the hall. It looks like a large vent.
Fireplace: outline it and write an F in the center
You can see simple blueprints at these sites as examples:
one story: http://eugenemodern.org/ellendale/images/blueprint001.gif
two story: http://house-blueprints.net/images/mf/7637_house_mf_plan_blueprint.jpg