Sustainability, renewal energy

 Energy Efficiency  (EE) is defined as "the relation between the useful output and energy consumption" by ITU-T L.1330 :cite:p:`itutl1330` for telecommunication networks and ETSI EN 303 471 :cite:p:`etsien303sp471` for NFV, the useful output being a metric which represents the capacity provided by the service whose energy efficiency is assessed.

As an example, the useful output of a traffic forwarding function can be the data volume forwarded (e.g., measured in Byte) and the assessment of its energy efficiency is then based on the ratio between this volume and the energy consumed for processing it (e.g., measured in Watt.hour) : Energy Efficicency (B/Wh) = Traffic Volume / Consumed Energy

The method for assessing energy efficiency depends on the service targeted and the objectives. For NFV, ETSI proposes a method for production environment in ETSI EN 303 471 :cite:p:`etsien303sp471` and another one for laboratory one in ETSI ES 203 539 :cite:p:`etsies203sp539` (which is a common work with ITU-T which published as ITU-T L.1361 :cite:p:`itutl1361`).

Whatever the method and the service, it requires the cloud infrastructure to provide some energy consumption metrics for different parts of the infrastructure hardware (server, CPU etc.) as included in :ref:`chapters/chapter04:internal performance measurement capabilities`. These metrics can be an amount of consumed energy (measured in Joule or Watt.hour) or a real-time power utilisation (measured in Watt or Joule/second) as proposed by DMTF Redfish DSP0268 2022.2 :cite:p:`dmtfredfish` which specifies metrics EnergykWh and PowerWatts for this purpose.

Some relevant information regarding NFV energy efficiency can also be found in Open RAN Technical Priority - Focus on Energy Efficiency (March 2022) :cite:p:`oranenergyeff` and QuEST Forum - NFV Workload Efficiency Whitepaper (October 2016) :cite:p:`questnfvwlenergyeff`.

Sustainability , green energy and optimizing the efficiency of Telecom Networks is key requirement for all current and ongoing Network transformations and it should be enabled on each layer of the Network stating from Hardware infrastructure , Cloud and CaaS Systems , Applications and above all use of Data and ML/AI to optimize the energy use in real time

The key aspect of Optimizing energy efficiency is to enable smart observability which means that KPI are available at each layer and further they can  be co-related across a closed loop system to intelligently monitor and optimize the energy use 

Energy Savings in Hardware:

• 1. Application functionality or application control requires infrastructure components beyond RM profiles or infrastructure configuration changes beyond APIs specified by RA. Generally, such an application is tightly coupled with the infrastructure which results in an Appliance deployment model (see :ref:`common/glossary:cloud platform abstraction related terminology:`).
• 1. Application control using APIs specified by RA finds nodes (already configured in support of the profiles) with the required infrastructure comp

Energy Savings in Cloud layer:

Energy Savings through Orchestration and Intelligence:

Energy Savings in Applications:

Most of the Telecom applications currently are seldom designed by keeping energy KPI's and measures in place . With 5G Release17 there had been a lot of work and emphasis on Energy optimizations as can be refereed  in 

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