Why is a South-facing house bad?
It is not always bad. That is why you see some people terribly suffering in a S-facing flat and others seem quite ok with it. Ancient texts have given specific divions of all the directions in which the main entry could be taken.
But this is possible only if one has the liberty and space to design such a house. We hardly have that today.
The cure: We can use certain pyramids and metals to solve this problem. I am not going into the details because they won't help a layman. It would only confuse one on how these things work.
Now, South-facing entry: As I said above, only the morning Sunrays are beneficial to us, what is ultraviolet to the body is the same thing we need for the Agya Chakra which when activated takes us to the higher planes of consciousness. It is the same bluish colour, the colour of Saturn, the deity governing spiritual growth.
The Sun has all the colours with all their positive and negative aspects. What is positive can become negative depending on the coordinates of time and space. And I am not speaking physics here, I am still sticking to metaphysics which is physics and beyond.
So, the Sun which is Pran in the East becomes the Yama when it comes to the South. Our scriptures have given 12 names to the Sun one of which is also Yama or the messenger of death. The Sun stream coming from the South, and as I said above, it is in the south at and after the noon, the radiation is very harmful.
In Yoga Shastra, the South stream is called Yama Pravah, the Pingala or Surya Nadi or which is the right side breath in Pranayam. It is considered bad because it will heat up the house like a furnace when your all your French windows are in the South or a huge entry is in the South.
And these are merely thermodynamical reasons. The cosmic and esoteric reasons are many and for the moment are not part of this discussion. These reasons will explain why certain S-facing houses bring in death, decay, destruction, defamation and distress for the dwellers