House facing and your main door
Every house or apartment building has a sitting and a facing direction and in most cases, we can intuitively differentiate them. The facing is usually the side with allow the maximum qi energy into your house.
How to determine which site allow the most qi energy?
First, you must remember that we all bring in the most qi energy into the house when we walk through the main door
Take an example, you stay in a condominium where there are on-going construction nearby and you pass by the construction site every time you want to go home. You will definitely bring along all the killing qi "sha" into your house once you open your main door and walk in. You are not climbing into your condo through the balcony. Your family members are more prone to sickness.
Take another example. This is a truth story. Mr. David Lee was staying in a double storey house. He have a large glass door on the ground floor facing south and his balcony also facing south and his main door is facing west. You might want to conclude that his house facing is South. There was a huge construction site in front of his house not far away. Mr. Lee thought that by not using the glass door and balcony (and also by having curtains) will block all the killing qi. However, he used to pass by the construction site whenever he want to go home. He entered his house using his south facing door. This means he was bringing all the killing qi into his house.
Thus, the site that allow the most qi entering your house is the most frequently used door. Therefore, you can conclude that the facing direction is the facing of your main door.
You should take the compass reading standing inside your house facing your main door. For example by doing this you get your house facing as 248 degree.