Triggering a connection to a database server is resource intensive for the application server, the database server, and, potentially, for the network. Do not use the database if the application doesn’t need it.

Electricity consumption
The Quality of Service (QoS) and the Service Level Agreement (SLA) must be outlined with the website or online service’s users. For example, there is no reason to host the service in a high-availability data center (Tier IV) if the users are prepared to accept an availability of equal to or under 99% for a non-critical service. With equal energy efficiency, the more data center hosting the website or online service is available, the larger its overall environmental footprint. This is primarily because everything is mirrored and active, with dual-powered electricity and dual-powered cooling systems, etc.