| Energair Ltd | Newry | 2011 |
| Energee Cubes Limited | South Uist | 2022 |
| Energen Biogas Limited | Cumbernauld | 2008 |
| Energetech Operations Limited | London | 2020 |
| Energetix Solutions Limited | Manchester | 2023 |
| Energi Generation Ltd | Lytham | 2015 |
| Energi Savings Limited | Feltham | 2018 |
| Energia (NW) Ltd | Liverpool | 2020 |
| Energia Customer Solutions NI Limited | Belfast | 1999 |
| Energia Hydrogen Limited | Belfast | 2019 |
| Energia Renewable Solutions Limited | Daventry | 2022 |
| Energiekontor UK Ltd | London | 1999 |
| Energiekontor UK Management Limited | Leeds | 2019 |
| Energize (UK) Limited | Bognor Regis | 2012 |
| Energized Electrics Limited | Clevedon | 2010 |
| Energy Project Support Ltd | Carlisle | 2022 |
| Energy & Engineering & Construction ( UK ) Ltd | Greater Manchester | 2015 |
| Energy & Power Limited | West Midlands | 2025 |
| Energy 19 Limited | Ballymoney | 2024 |
| Energy 4 Businesses (U.K) Limited | Coventry | 2021 |
| Energy 4 Life Enterprise Ltd | Cardiff | 2020 |
| Energy 52 Ltd | Mildenhall | 2026 |
| Energy Air Storage Ltd | London | 2017 |
| Energy Alliances Group (H2-C) Ltd | London | 2025 |
| Energy Analytics Ltd | Chorley | 2025 |
| Energy and Leisure Limited | Llanfyrnach | 2011 |
| Energy Assessment Ireland Limited | Enniskillen | 2023 |
| Energy BEE Ltd | Manchester | 2023 |
| Energy Bill Solutions Limited | Southampton | 2025 |
| Energy Bloom Marketing Ltd | Barking | 2020 |
| Energy BU Ltd | Poole | 2014 |
| Energy Buzz Limited | Leicester | 2015 |
| Energy Check Poland Ltd | London | 2019 |
| Energy Choice 4 U (UK) Ltd | London | 2013 |
| Energy Connect Global Limited | Stockport | 2026 |
| Energy Contractor Hub Ltd | Billingham | 2018 |
| Energy Cooling Limited | Portsmouth | 2012 |
| Energy Coop Limited | Lichfield | 2009 |
| Energy Cooperative Limited | Pynes Hill | 2023 |
| Energy Demand & Response Limited | Hull | 2016 |
| Energy Developments (UK) Limited | Towcester | 1996 |
| Energy Direct Consultants Limited | Cardiff | 2017 |
| Energy for Future SCE Limited | Glasgow | 2019 |
| Energy for Life Ltd. | Barry | 2011 |
| Energy FOX Contracts Limited | Ashford | 2014 |
| Energy Future Generation Ltd | London | 2017 |
| Energy G Ltd | Poole | 2014 |
| Energy Group Supplies Limited | Chester Le Street | 2021 |
| Energy Guide Limited | Preston | 2018 |
| Energy Infrastructure Networks Limited | London | 2022 |
| Energy Investors Limited | Twickenham | 2022 |
| Energy IS Ltd | London | 2022 |
| Energy L Ltd | Poole | 2014 |
| Energy Land & Waste Limited | Borehamwood | 2018 |
| Energy Link GAS Connections Limited | Newcastle Upon Tyne | 2011 |
| Energy Link Solution Limited | Oldham | 2026 |
| Energy Management Workshop Ltd | Ashford | 2015 |
| Energy Marketing and Trading Ltd | Edinburgh | 2018 |
| Energy Masters UK Limited | Bury | 2024 |
| Energy Merchants (Wellington) Ltd | Motherwell | 2010 |
| Energy Mine Ltd | London | 2023 |
| Energy Neom Ltd | Leeds | 2015 |
| Energy Network Partners Ltd | Mildenhall | 2024 |
| Energy Observe Limited | Rotherham | 2009 |
| Energy on Clyde Limited | Edinburgh | 2024 |
| Energy Online Ltd. | Horsham | 2000 |
| Energy PAL Limited | Henley-On-Thames | 2020 |
| Energy Plus Management Ltd | Liversedge | 2009 |
| Energy Portfolio (UK) Ltd | Knutsford | 2023 |
| Energy Portfolio Ltd | Knutsford | 2012 |
| Energy Price Compare Limited | Rochester | 2016 |
| Energy Price Limited | Birmingham | 2021 |
| Energy Price Saver Ltd | Carnforth | 2018 |
| Energy Quest International Limited | Ilkley | 2001 |
| Energy Renewal Services Limited | London | 2016 |
| Energy Sales Services Limited | London | 2012 |
| Energy Sanctuary Ltd | Cardiff | 2011 |
| Energy Saver Hub Ltd | London | 2025 |
| Energy Saving Guru Ltd | Glasgow | 2019 |
| Energy Science Limited | Stockport | 2026 |
| Energy Search Ltd | Bolton | 2014 |
| Energy Secure Systems Ltd | London | 2026 |
| Energy Service Solutions Ltd | Chester | 2019 |
| Energy SHY Ltd | Cardiff | 2018 |
| Energy Smart Consultancy Ltd | Birmingham | 2011 |
| Energy Solutions & Design Limited | Steyning | 2014 |
| Energy Storage Africa Ltd | Staplefield | 2018 |
| Energy Storage Technologies Limited | Ruislip, | 2025 |
| Energy Strategy Services Limited | London | 2012 |
| Energy Supply Ltd | London | 2021 |
| Energy Team (Midlands) Ltd | London | 1994 |
| Energy Trade Centre Ltd. | London | 2025 |
| Energy Trades Ltd | London | 2017 |
| Energy Trading International Ltd | Belfast | 2019 |
| Energy Trading Ireland Limited | Belfast | 2012 |
| Energy Utilities Ltd | Manchester | 2020 |
| Energy Warriors Limited | Harrogate | 2015 |
| Energy Watch Limited | Birmingham | 2017 |
| Energy Works (Hull) Limited | London | 2011 |
| ENERGY24 Limited | Thornaby | 2006 |