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Part of Sustainability Annual Report 2019-2020

Annex 4 - technical appendix

This annex is intended to provide technical detail in line with the requirements of Her Majesty's Government annual public sector sustainability reporting guidance and make transparent our decision and methodologies.

Current Chapter

Current chapter – Annex 4 - technical appendix


This annex is intended to provide technical detail in line with the requirements of Her Majesty's Government annual public sector sustainability reporting guidance and make transparent our decision and methodologies.

Scope of reporting

An equity share approach has been taken to building utility reporting – electricity, gas and water. This means we have reported against our whole estate footprint rather than the partial reporting scope of the greening government commitments (GGC). Our GGC figures are shown in the table below.

Metric Unit 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20
Electricity kWh 4,492,733 3,683,799 3,912,435 5,590,629 5,574,130 5,952,435 6,345,507
Gas kWh 1,911,633 2,096,560 1,597,092 1,778,653 1,846,070 2,033,892 1,801,342
Water m3 10,543 10,387 10,923 12,935 17,321 17,231 14,417

Baseline year

Due to data quality and availability across all compulsory metrics we have chosen to re-baseline from the standard 09/10 period to 13/14. This is when NHS Digital was set up in its current form as the HSCIC and as such full data sets become available for all the constituent parts. This has made reaching our targets more ambitious as we have mirrored GGC targets which meant 4 years less to achieve them.

Normalisation metrics

Performance is generally reported in absolute terms as the nature of sustainability challenges means that the goal is zero net damage. In addition to this NHS Digital has grown significantly in terms of full-time equivalent (FTE) over the reporting period which makes absolute targets more challenging.

Whole estate Gross Internal Area (GIA) and FTE normalisation metrics are as follows if the reader would like to assess in more detail. FTE includes capitalised workers as well as permanent, temporary and secondees.

2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 2019/20
Full-time equivalent (FTE) 2,137 2,400 2,746 2,857 3,335 3,367 3,079
Gross internal area (GIA) in m2 18,397 21,439 20,835 20,508 21,872 21,595 20,622


In general materiality has been viewed through the carbon lens. Therefore, elements such as waste production and paper use are far less material and as such have received less focus.

Carbon analysis

Carbon analysis has taken place using GGC carbon conversion factors and further Department for Environment, Food and Rural Affairs (DEFRA) conversion factors where necessary.

Renewable electricity sources covered by Renewable Energy Guarantees of Origin (REGO) certificates have been reported as grid average carbon so that fair consumption-based comparison can be made with previous years. The savings noted in the report are indicative only and not included in the 44% carbon savings reported.

Data verification

Multiple internal and external audits have taken place on our data sets in 2018/19/20. These include audits by 3rd party independents for verification purposes and an internal process has been set up for annual verification with the finance team.

Data sources

Metric Accurate (A)/Estimate (E) Source
Generator fuel use A Invoices
Gas/electricity/water A Accounts, invoices, meter reads
Data centre electricity A Accounts, invoices, meter reads
Outsources data services E Extrapolated from data snippets
F-gas leak tests A Leak test certificates
Lease cars/grey fleet A Expenses system mileage claims
Taxi/Tube E Extrapolated from spend
Hotels/flights/trains A Travel bookings data
Virtual meeting use A MS Teams MI
Building waste E Estimated from volumes and frequencies
ICT waste A Contractual MI
Paper use A Printing quantity MI
ICT hardware E Estimations provided by suppliers
Hyperscale cloud E Estimations provided by suppliers

Data corrections and developments

Modest data corrections have taken place for consumption and carbon metrics against gas use, train travel and plane travel compared to previously submitted ARA data. This is due to errors being uncovered in the previous data sets.

New metrics are being added to the data set over time with recent inclusions being diesel use in generators and fugitive emissions from air conditioning systems.

External data storage has been a major area of data development during 19/20 with information added for outsourced data services in our baseline year and more recent impacts from co-location and cloud.

Co-location data has had major updates and is still in the process of updating due to new information on energy usage and PUE. Cloud information is starting to get more transparent and that data set is being built.

The 13/14 outsourced data services carbon estimation has been a crucial element, with a study occurring to cross check estimations of rack level energy use – the outcome was circa 2.7kW draw per rack in 13/14 compared to a circa 5kW draw in 19/20.

By 20/21 data should be available for broader procurement activities and at that point the data set will be nearing completion.

Last edited: 20 October 2020 1:28 pm