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ECO4 Geotagged Photos for UK Site Evidence

Elvis · Sep 11, 2026

Date and geo stamped photos are site photographs that show when and where they were taken, usually with the date, time, address and GPS coordinates visible on the image. UK energy-efficiency schemes and building control rules ask for them so that installation, inspection and retrofit evidence can be checked against the correct property and stage of work.

Where date and geo-stamped photo rules come from

Several schemes and guidance documents refer to photo evidence with a date, time and location. The exact instruction matters, so always follow the latest guidance for your scheme, funder or energy supplier.

For geotagged photos ECO4 work, the key wording is in Ofgem's ECO4 guidance. It says that all photos used to support eligibility or compliance must be date and geo-stamped, and that evidence should be supplied as standalone files, in PDF format where possible. ECO4 Phase 4 runs from 1 April 2025 to 31 December 2026.

For geotagged photos building regulations evidence in England, building control operational standards rule 3.10 says inspection evidence must be date/time marked and images geo-tagged. Rules 3.8 and 3.9 also cover inspection reports and supporting evidence for the work inspected.

For Boiler Upgrade Scheme photos, Ofgem describes time-stamped and geo-tagged installation photos as best practice for audit support. It is a recommendation rather than a stated requirement in the installer guidance.

Why site photo evidence gets questioned

A clear photo of good work is useful, but it may still be difficult to rely on if it does not show the basic context.

Common issues include:

  • No visible date, time or location on the image.
  • A timestamp based only on a phone clock that can be changed.
  • Location held only in hidden photo metadata.
  • Location data disappearing after a photo is shared through a messaging app or upload tool.
  • Evidence that is not clearly tied to a property, measure or job.
  • Photo details that appear to have been changed or tampered with.

Many messaging apps and some upload tools remove hidden image metadata, including EXIF location data. A stamp printed directly on the image remains visible even if that hidden metadata is removed.

How to take geotagged photos with Timemark

Timemark is a free camera app for iPhone and Android that prints the date, time, address and GPS coordinates directly on each photo. It can also print optional notes and your company logo.

1. Download Timemark before arriving on site

Download the app from the Timemark download page. Make sure your phone has location access enabled for the app before taking evidence photos.

2. Set up a useful note for the job

Add a short note that makes the photo easy to identify later. Useful details can include:

  • Job number
  • Property reference
  • Measure type
  • Installation stage
  • Room or elevation
  • Plot, block or unit reference

For example:

Job 2048 | Loft insulation | Front elevation | Pre-install

Keep notes practical and consistent across the job. This helps an assessor, coordinator, site manager or auditor understand what the image shows without guessing.

3. Make sure Photo Code is turned on

Before taking the photo, make sure Photo Code is turned on.

4. Take the photo in Timemark, not in your normal camera

Open Timemark and take the photo through the app. Timemark prints the following directly onto the image:

  • Date
  • Time
  • Address
  • GPS coordinates
  • Optional note
  • Optional company logo

Photos taken with Photo Code turned on also carry a Photo Code that can be checked.

The Timemark time comes from the network rather than the phone clock, so changing the phone clock does not change the time shown on the stamp.

5. Capture the views your scheme or inspection needs

Take the photos requested by your scheme, funder, energy supplier, coordinator or building control process. Make sure the relevant work is visible, well lit and in focus.

Check that the stamp is readable and that the address, coordinates and note match the property and work being photographed before moving on.

6. Keep the Photo Code visible

Photos taken with Photo Code turned on carry a printed Photo Code. A recipient can enter that code in Timemark Photo Verification to check that the photo is genuine.

TrustMark photo evidence and retrofit assessor records

For TrustMark photo evidence, clear, well-lit photos with the date, time and location make it easier to show what was completed and where. Salix Finance's Social Housing Decarbonisation Fund Wave 2 photo tips state that photos should be geotagged and include the date, time and location.

The Energy Trust guidance on photo evidence for retrofit assessors says all evidence should be date stamped and geo-tagged. It lists Timemark as one option for doing this.

For photo evidence for retrofit assessors, use notes that connect each image to the dwelling and assessment or installation record. A property reference, measure and location within the property can make a set of images much easier to review.

Sending and organising photo evidence

Ofgem's ECO4 guidance says evidence should be provided as standalone files, in PDF format where possible. Check the current submission instructions from your energy supplier, scheme or funder before sending anything.

A practical approach is to:

  1. Keep the original stamped image files.
  2. Organise photos by property, person, date and measure.
  3. Export a PDF report where a PDF is requested or useful.
  4. Send evidence through the specified submission route.
  5. Avoid relying only on images forwarded through messaging apps, as hidden location metadata can be removed.

Timemark Teamspace automatically collects team members' photos and organises them by project, person and date. You can also create photo reports as PDFs for a more structured evidence pack.

Checklist before submitting evidence

  • The photo clearly shows the relevant work or inspection point.
  • The date, time, address and GPS coordinates are visible and readable.
  • The Photo Code is visible on the photo.
  • The note identifies the job, property or measure where useful.
  • The image is clear, well lit and in focus.
  • The photo is filed with the correct property and stage of work.
  • You have followed the latest scheme, funder, energy supplier or building control instructions.
  • You have retained the required standalone files or PDF report.

Frequently asked questions

What are date and geo-stamped photos?

They are photos that show when and where they were taken. A useful visible stamp can include the date, time, address and GPS coordinates, alongside a note identifying the job or measure.

Are date and geo-stamped photos required for ECO4?

Ofgem's ECO4 Delivery Guidance says all photos used to support the eligibility or compliance of a measure must be date and geo-stamped, and that their details should remain accurate and not be tampered with. See paragraph 8.30 of the guidance.

Are Boiler Upgrade Scheme photos mandatory?

Ofgem's installer guidance says time-stamped, geo-tagged photos are best practice during installation to support audit purposes, particularly desk audits. The guidance presents this as a recommendation, not a stated requirement. See the Boiler Upgrade Scheme installer guidance.

How do I take geotagged photos on a phone?

Use a camera app that has location access and prints the required information visibly on the photo. In Timemark, take the image in the app and add a note such as a job number, measure or property reference.

Will using Timemark guarantee my evidence is accepted?

No. Timemark helps you create visibly stamped photo records, but acceptance depends on the current requirements and review process of your scheme, funder, energy supplier or building control body. Always follow their instructions.