TL;DR:<\/strong><\/p>\n Visit Delta First<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n Before you calculate anything, collect these figures for the space you are assessing:<\/p>\n The core energy saving formula is: (existing wattage minus proposed wattage) multiplied by number of fittings, divided by 1,000, multiplied by operating hours, multiplied by the kWh tariff. This gives your annual energy saving in pounds. Add to that the maintenance saving, which usually comes from fewer lamp changes, less need for access equipment such as scissor lifts, and reduced call-out labour, since LED fittings typically outlast fluorescent tubes by a wide margin.<\/p>\n LED upgrades can cut lighting energy use by a large margin compared with older fluorescent technology<\/strong>, according to government lighting guidance<\/a>, which gives you a sense of the ceiling on savings before you run your own site numbers.<\/p>\n Take a conservative worked example: 50 fittings currently at 150W, replaced with 55W LED equivalents, running 10 hours a day, 260 days a year, at 20p per kWh. That is (150-55) x 50 \/ 1,000 x 2,600 x \u00a30.20, which comes to \u00a32,470 a year in energy savings alone. Add some reduction in maintenance costs and you have a total annual benefit before incentives are even considered.<\/p>\n Generic ROI calculators are a useful starting point but rarely tell the whole story. They tend to be accurate on inputs you control directly, such as kWh tariff and estimated operating hours, but far rougher on installation cost, controls integration and existing baseload assumptions, which vary enormously between sites.<\/p>\n Before you trust a calculator\u2019s output enough to take to a budget holder, work through this checklist:<\/p>\n Pro Tip:<\/strong> Treat any online calculator result as a draft business case, not a final figure, until it has been checked against a site survey and a supplier\u2019s itemised quote.<\/em><\/p>\n Several site-specific factors move the payback calculation more than people expect, and most are within your control at the design stage.<\/p>\n Simple payback tells you how many years it takes to recover your outlay, but it ignores energy price inflation, the time value of money and what happens to the asset after payback. Net present value, or NPV, addresses this by discounting future savings back to today\u2019s terms, which is why the Carbon Trust recommends NPV and life-cycle costing<\/a> over simple payback for accurate appraisal.<\/p>\n Use whole-life costing when the decision involves multi-site procurement, long-term asset planning, or when the upgrade is one part of a wider refurbishment. Simple payback is usually sufficient for a small, low-risk, single-area project.<\/p>\n To build a life-cycle cost, work through these additions to your simple payback figure:<\/p>\n As an illustration, a project with a four-year simple payback and a ten-year asset life might show a materially stronger NPV once ten years of discounted energy savings are included, rather than just the initial four.<\/p>\n A projected saving only becomes a real one once it is measured. Carbon Trust commissioning guidance recommends pre and post-installation metering, agreed measurement and verification protocols, and ongoing monitoring to confirm that a project delivers what was promised.<\/p>\n Pro Tip:<\/strong> Build a remediation clause into your contract so any shortfall against agreed savings triggers a supplier review, not a dispute.<\/em><\/p>\n The biggest false economy in lighting upgrades is treating the retrofit as a one-off transaction rather than an asset decision. We approach every lighting upgrade as part of a building\u2019s ongoing performance, starting with a site survey and LED lighting design, upgrade and retrofit<\/a> service that produces a whole-life costing appraisal before any commitment is made.<\/p>\n Because Delta First delivers electrical installation and planned preventative maintenance<\/a> through the same accountable team, there is no handoff between the contractor who installs the fittings and the one who maintains them afterwards. That reduces the risk of savings eroding through neglected servicing, and it means handover reporting and verification data sit with the same partner you can return to if performance needs checking.<\/p>\n \u2014 Ashley<\/em><\/p>\n<\/blockquote>\n A site survey checks operating hours, current tariff, existing wattage and fitting condition, then builds a whole-life costing model with a draft payback figure before you commit to anything.<\/p>\n Visit our LED lighting design, upgrade and retrofit page to request a quotation or a planned maintenance survey, and ask for an itemised business case alongside a measurement plan so you know exactly how savings will be confirmed once installation is complete.<\/p>\n For further reading beyond this guide, the Carbon Trust\u2019s lighting overview guide covers appraisal methods in more depth, while the government ETL leaflet lists qualifying products and typical savings ranges. A real project example worth reviewing is Dorset Council\u2019s Canford manufacturing LED case<\/a>, which shows a net project cost of about \u00a37,000 repaid in just over two years. Non-energy benefits, including staff wellbeing, are covered in this workplace lighting and productivity article.<\/p>\n Depreciation schedules vary by accounting policy and jurisdiction, so there is no single fixed figure that applies universally. For appraisal purposes, most facilities teams pair the asset\u2019s expected working life with a whole-life costing model, as recommended in Carbon Trust guidance, rather than relying on depreciation alone.<\/p>\n Coverage depends heavily on ceiling height, fitting type and the light level required for the task, so there is no single area figure that applies to every space. A site survey measures actual lux levels against the relevant task requirement rather than working from lumen output alone.<\/p>\n Simple payback divides the net project cost by the total annual savings from energy and maintenance combined. For a more accurate long-term figure, the Carbon Trust recommends using NPV or life-cycle costing, which accounts for energy price changes and the asset\u2019s full working life.<\/p>\n Running cost depends on the fitting\u2019s wattage and your electricity tariff, so it is calculated by multiplying wattage in kilowatts by hours run and by the tariff in pence per kWh. Sector guidance has shown a 150W LED costing considerably less annually to run than an equivalent 150W discharge fitting at the same tariff, illustrating the scale of savings from switching technology.<\/p>\n Site focused guidance for UK facilities teams to calculate, verify, and lock in lighting upgrade ROI using surveys, NPV, and measurement.<\/p>\n","protected":false},"author":2,"featured_media":556,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","footnotes":""},"categories":[12,13],"tags":[154,303,251,117,29],"class_list":["post-555","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-energy-efficiency","category-facilities-management","tag-asset-management","tag-building-energy-efficiency","tag-energy-efficiency","tag-facilities-managers","tag-led-lighting-upgrades"],"blocksy_meta":[],"uagb_featured_image_src":{"full":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels.jpeg",1280,720,false],"thumbnail":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels-150x150.jpeg",150,150,true],"medium":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels-300x169.jpeg",300,169,true],"medium_large":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels-768x432.jpeg",768,432,true],"large":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels-1024x576.jpeg",1024,576,true],"1536x1536":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels.jpeg",1280,720,false],"2048x2048":["https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789773796_Engineer-measuring-warehouse-lighting-levels.jpeg",1280,720,false]},"uagb_author_info":{"display_name":"Delta First Editorial Team","author_link":"https:\/\/www.deltafirst.co.uk\/blog\/author\/deltaeditor\/"},"uagb_comment_info":0,"uagb_excerpt":"Site focused guidance for UK facilities teams to calculate, verify, and lock in lighting upgrade ROI using surveys, NPV, and measurement.","_links":{"self":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/555","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/comments?post=555"}],"version-history":[{"count":3,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/555\/revisions"}],"predecessor-version":[{"id":687,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/posts\/555\/revisions\/687"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/media\/556"}],"wp:attachment":[{"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/media?parent=555"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/categories?post=555"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deltafirst.co.uk\/blog\/wp-json\/wp\/v2\/tags?post=555"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\n
\nTable of Contents<\/h2>\n
\n
Step-by-step calculation: energy savings, maintenance savings and total annual benefit<\/h2>\n
\n
![\"Worked](\"https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789711535_Worked-example-of-annual-LED-energy-savings.jpeg\")
<\/p>\nHow to use online calculators safely and what they miss<\/h2>\n
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Key factors that materially change ROI: controls, hours and product quality<\/h2>\n
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Whole-life costing and NPV: the right way to appraise a lighting project<\/h2>\n
![\"Illustration](\"https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/10\/1790789819777_Illustration-of-discounted-lighting-project-savings.jpeg\")
<\/p>\n\n
Verify and lock in savings: monitoring, measurement and contractual protections<\/h2>\n
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Delta First perspective: how we protect your projected ROI<\/h2>\n
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Request a site survey or LED lighting quotation<\/h2>\n
![\"Delta](\"https:\/\/www.deltafirst.co.uk\/blog\/wp-content\/uploads\/2026\/07\/1783116648075_deltafirst.jpg\")
<\/p>\nSources<\/h2>\n
\n
FAQ<\/h2>\n
What is the depreciation life of lighting?<\/h3>\n
How much area will 2,000 lumens cover?<\/h3>\n
How do I calculate the ROI rate on a lighting upgrade?<\/h3>\n
How much does it cost to run an LED light for 24 hours?<\/h3>\n
Recommended<\/h2>\n
\n