Punyahavachana

We perform punyaha to purify (shuddhi) our soul and house.
We perform this especially during house opening ceremony that is gruha pravesha, jathasoucha(during birth of the infant) and mruthasoucha(during death)
Before construction of house, we dig the earth which causes disturbance in the life of simple organisms and plants which results in dosha.
So we perform punyahavachana for dosha nivarana.