as per agreement penalty clause agreed to be paid in the event of delay is Rs.5/- per sq ft you will be entitled to this amount only till possession from builder.
Issue a legal notice to the builder demanding this payment, if he complies with this demand good otherwise you will need to file a complaint before the District Consumer Court, New Delhi and seek this amount along with other amounts such as litigation costs, damages or compensation etc., if you are staying in a rented accommodation then enclose a copy of the latest rental agreement copy and seek compensation on this amount, court might grant it.