India is one of the richest countries to possess maximum numbers of heritage monuments. Temple architecture is one of those. Most of these structures are more than 400 to 500 years old. They have been able to sustain the wrath of nature but have failed to cope up with the misbehaving of people.
Renovation, restoration, preservation, and conservation stages of dealing with heritage structures. Specialised processes are followed while conserving the old structure. Many temples are now listed as heritage structures by UNESCO and other national authorities. The terms and conservation guidelines are very carefully and precisely drafted and stated by each authority.
Similarly, the ancient literature of Bharat- Agam Shastra very specifically deals with the various aspects of temple architecture. Temple design, restoration, and conservation are in terms of jirnodhhar of the temple. The term Agama primarily means tradition; Agama represents the previously oriented practices generally held in regard (Agama loka-dharmanaam maryada purva-nirmia – Mbh 8.145.61).
Jīrṇoddhāra (जीर्णोद्धार) refers to the “renovation of the temple” as described in the Śaivāgamas.
The Anukarmavidhi of Kamikāgama explains it thus: If the temple is decayed but still has regular pūjā, it can be said to be in a good state. But if there are no pūjās, then it is said to have fallen into a bad state. If jīrṇoddhāra or renovation is performed, it bestows the highest results on the kartā. This is because both the performing of worship and not performing of worship at a decayed temple result in ill effects. Therefore, for the general welfare, renovation should be performed according to the śāstra. The Anukarmavidhi also has elaborate rules and instructions for the proper renovation of temples. (Shrinivasa Rao in the encyclopedia of temple architecture)
Striking differences in the conservation norms and those of jirnodhar terms mentioned in Agama Shastra are noticed. The first principle of conservation is to restore the structure as it is without making any changes. Minimal intervention is considered to be the best way of conservation.
Whereas in Jirnodhar, the most important aspect is the restoration of the Idol of deity. Being able to perform Puja is more important.
Temple without a deity cannot be considered to be a temple.