If you want to heat your premises energy efficiently, the best way is to utilize the heat sources that are already there! Either after heated up with heat pumps or direct use, the warm water can be used to save in energy costs elsewhere.
Using modern high temperature heat pumps, you can use your excess heat for heating of the other locations with a great PUE and cooling the source medium!
Heat recovery can be utilized either directly or indirectly.
Direct heat recovery means that the heat can be used directly in the destination, without a process in between that heats up the medium. Indirect heat recovery on the other hand means a process that has a part in the process that changes the medium temperature between the heat source and the destination.
Direct heat recovery can be executed for example with process water. After using the fresh process water for cooling, the water can be delivered to the process usage, leading to the water being warmer and therefore needing less heating in the later parts of the process.
Indirect heat recovery can be done with heat pumps, either with so called high temperature heat pumps or by using the heated process water as a source medium for a normal water-water heat pump.