SECR is part of a package of changes (announced in the March 2016 budget) which aims to reduce the administrative burdens of the current overlapping suite of reporting requirements (CRC, ESOS, MGHG etc.) while further incentivising energy efficiency and reducing carbon emissions. SECR will deliver a simpler reporting requirement than the current CRC energy efficiency scheme and align with existing reporting mechanisms such as mandatory reporting of greenhouse gas emissions by listed companies. SECR will be introduced from April 2019 to coincide with the end of the current CRC Energy Efficiency Scheme.
From April 2019 onwards, large (SME defined) unquoted businesses in the UK will have to report on annual energy use, carbon emissions and implemented energy efficiency measures via annual reports. This is associated with scopes 1 & 2 emissions, with scope 3 being voluntary.
Essentially, any organisation that was or is in CRC and/or ESOS needs to consider this, if not already working on some aspects of this.
https://www.gov.uk/government/consultations/streamlined-energy-and-carbon-reporting
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/729586/SECR_Govt_response_Final__1_.pdf