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HeatLens privacy policy

Version 2026-10-16c, last updated 16 October 2026.

1. Who we are

HeatLens is a trading name of Building Energy Consultants Ltd, a company registered in Scotland (company number SC652480). We are the controller of the personal data described in this policy. You can contact us about it at hello@heatlens.co.uk.

This policy covers visitors to heatlens.co.uk, people who apply to the partner programme or ask about free access, subscribe to our newsletter or write to us, installers we write to about HeatLens, and the professionals (installers, designers, assessors and others) who hold an account. It also covers homeowners taking part in a university research study that shares information about their home with us, and people whose homes are described in open research datasets we use (see section 2). It does not cover the personal data of an installer's customers: for that data the installer is the controller and we are their processor (see "Other notices" below).

2. What we collect, why, and our legal basis

We rely on the UK General Data Protection Regulation (UK GDPR) and the Data Protection Act 2018. The legal bases below are from Article 6(1) of the UK GDPR.

  • Account details: name, email address, company name, role, sign-in details, settings and preferences; a phone number if you verify one for WhatsApp alerts; a connection to your mailbox if you connect one
    • Why: To create and run your account, authenticate you, provide the Service and support you
    • Legal basis: Contract (Art. 6(1)(b))
  • Billing details: plan, payment status, invoices, VAT number if you give one. Card details are held by Stripe, not by us
    • Why: To take payment, issue invoices, keep accounts, and handle tax records
    • Legal basis: Contract (Art. 6(1)(b)); legal obligation (Art. 6(1)(c))
  • Partner programme and free-access applications: name, email, phone (optional), company, role, why you are interested, tools you use, projects per year, anything else you tell us
    • Why: To decide who to invite, contact you about the partner programme or free access and understand needs
    • Legal basis: Steps at your request before a contract (Art. 6(1)(b)); legitimate interests in running the partner programme and free access (Art. 6(1)(f))
  • Messages to us: email, forms, support requests
    • Why: To reply, resolve problems and keep a record
    • Legal basis: Legitimate interests (Art. 6(1)(f)); contract where you are a user
  • Newsletter: email address and name if you give it, which issues you receive
    • Why: To send the newsletter you asked for
    • Legal basis: Consent (Art. 6(1)(a)). You can withdraw at any time using the unsubscribe link
  • Business contact details of installers we write to: name, work email address, company name and role, and a record of our messages, any reply, and any request not to be contacted. We get them from public installer listings and trade networks' public installer pages that show your company's business contact details, through an introduction from a trade network or business contact, or because we already know you through work, and we write to a small number of heat pump professionals by hand. We only write this way to people at limited companies, limited liability partnerships and other corporate bodies. We do not send these emails to sole traders or partnerships unless they have agreed to hear from us
    • Why: To tell installers about a professional design and reporting tool relevant to their work
    • Legal basis: Legitimate interests (Art. 6(1)(f)). Our interest is introducing the tool to installers who may find it useful. We keep the number of messages small, identify ourselves in each one and give a way to opt out. You can object at any time (see section 8) and we will stop writing to you
  • Usage and technical data: pages and features used, errors, device and browser type, IP address in server logs, dates and times
    • Why: To run, secure and improve the Service and prevent abuse, including a record of which pages signed-in users open, kept by our hosting platform, and to run the partner programme, including weekly counts of each partner's use
    • Legal basis: Legitimate interests (Art. 6(1)(f))
  • AI usage records: which AI feature was used, when, and how much, linked to your account
    • Why: To control cost, monitor quality and investigate problems
    • Legal basis: Legitimate interests (Art. 6(1)(f))
  • Your project content: property details, rooms, documents and reports you create, including anything that identifies your customers
    • Why: To provide the Service to you
    • Legal basis: See "Customer data" below
  • Cylinder specifications you upload, and any offer to the library: the file, the figures read from it and confirmed by you, whether you offered it, when, and which version of the wording you agreed to
    • Why: To let you use the cylinder in your designs and, if you choose, to add its figures to the shared library
    • Legal basis: Contract (Art. 6(1)(b)) for your own use. Your consent for the offer; you can withdraw it until we finish checking (Art. 6(1)(a))
  • Research study data: when a university research partner runs a study that tests our heat-loss calculation against real homes, a description of each home taking part (such as floor areas, walls, roof, floors, windows, insulation, heating system and room sizes), at most the first part of its postcode and, once our calculations for the study have been fixed, the heat use and heat pump performance measured at that home. Each home is identified only by a study number that the university assigns. We do not receive names, addresses, full postcodes or details about the people who live there
    • Why: Only to test our heat-loss calculation against measured data from real homes and to develop a published method for doing so. We do not use it for marketing, sales, profiling or any other purpose. We do not link it to other data or try to identify or contact anyone. We publish results only as totals, or in a form that does not identify any home
    • Legal basis: Consent (Art. 6(1)(a)), which the homeowner gives through the university for sharing with us. Homeowners withdraw through the university (see section 8)
  • Open research datasets: data about homes and heat pumps that others have published openly for research, such as the Electrification of Heat trial data, and the system records that owners publish on HeatpumpMonitor.org. These do not list the names of the people who live there, but a row can describe a particular home in detail, including its general location and how its heat pump performed
    • Why: To design and check our validation study, for example which building details our calculation can read and which are missing. We keep only the files and columns the study needs. We do not link them to the EPC register or any other data, we do not match them to study data from a research partner, and we do not try to identify or contact anyone. We also use HeatpumpMonitor.org records to calibrate and test our heat pump calculations. A script reads the individual records and keeps only totals, such as medians and ranges. We do not keep copies of the records, we do not publish anything about an individual system, we do not link them to other data, and we do not contact the owners
    • Legal basis: Legitimate interests (Art. 6(1)(f)) in testing our calculation against real homes. You can object by emailing hello@heatlens.co.uk (see section 8)
  • Plan sharing: when you share your home heating plan, a record of the share, the email address of anyone you invite by email, when you invited them and when they last opened it, and when the plan was last opened through the share. We send each person you invite one email from HeatLens, saying someone shared a plan, with your first name only if you have given one. It has no free text from you and none of your plan, figures or address. We count invitation emails using a one-way code made from the address, to limit how many one address can be sent. We get the address of a person invited to a plan from the person who shared it. If someone you invited asks us not to send them invitations, we keep a one-way code made from their address, and not the address, so that we do not send to them again
    • Why: To let you share your plan
    • Legal basis: Legitimate interests (Art. 6(1)(f)), in letting you share your plan with the people you choose. The person you invite gets only that one email, and is not added to any mailing list. They can email hello@heatlens.co.uk to report it or object (see section 8), and we then stop sending them invitations
  • Survey voice recordings and transcripts: if you use voice notes during a survey, the audio you record, the written transcript we make from it, how long it is and when it was recorded, linked to the job and room. A recording can pick up other voices and anything said aloud, including your customer's details. We do not use voiceprints or identify anyone from their voice
    • Why: To turn what you say during a survey into a written transcript and into suggested survey entries that you review one by one. Nothing in the survey's measurements or settings changes until you accept it
    • Legal basis: Contract (Art. 6(1)(b)), for providing the voice note feature to you. Where a recording or transcript contains your customers' details, see "Customer data" below. Please tell people in the property before you record, and do not record anyone who objects
  • Advertising cookie (only if you accept it)
    • Why: To measure how people find HeatLens
    • Legal basis: Consent (Art. 6(1)(a)); see section 6

We do not sell personal data. We do not use your information to make decisions about you that have a legal or similarly significant effect without a person being involved.

3. Customer data you put into HeatLens

If you add your customers' details (names, contact details, property addresses, EPC data, job records), you are the controller and we are your processor. We process that data only on your instructions, as set out in Schedule A of the installer terms at /installer-terms. The notice your customers see is at /enquiry-privacy. Please do not put special category data (such as health information) into free-text fields.

4. Artificial intelligence

4.1 Some features use AI to read documents such as EPCs and floor plans, to draft text and to answer questions. We treat the output as a proposal for a person to review. Please do not rely on it without checking.

4.2 To do this, text and files you submit are sent through our hosting platform to AI providers. See "Who we share data with".

4.3 If you ask HeatLens to find a photo of a property, the property address is used to search the web, and an image may be fetched from a third-party website.

4.4 We ask you not to enter special category data or other sensitive information into AI features unless you need to.

4.5 Cylinder specifications offered to the library. If you offer a cylinder to the shared library, we check it using AI before anything is added. The check compares the make, model and figures with the maker's own published document, which we find on the web. Only the make, model and figures are sent for the check: not your file, your name or your account. The AI we use for this step is Anthropic's, used directly by us and not through our hosting platform, so section 4.2 and "Model training" do not apply to it.

5. Who we share data with

We use the following providers to run HeatLens. Except where stated below, they process data on our behalf under written terms. We do not allow them to use it for their own marketing. Base44's use of data for model training is described under "Model training" below.

  • Base44 (a Wix.com company) hosts HeatLens, stores its data, runs authentication and provides AI features. Its published data processing agreement lists service providers that include OpenAI and Anthropic (AI models), MongoDB, Render, Google Cloud, Supabase, Datadog and SendGrid, and Wix.com Ltd. Base44's servers and providers are mainly in the United States, and Wix.com is in Israel.
  • Stripe processes card payments where you buy a paid plan.
  • Google supplies an advertising tag that loads only if you accept advertising cookies. Google uses the data it collects under its own privacy policy.
  • Google (Gmail) or Microsoft (Microsoft 365), only if you connect your own mailbox, to send messages from it.
  • Meta Platforms (WhatsApp Business Platform), only if you turn on WhatsApp alerts, to send alerts to your phone.
  • Public data services: postcodes.io (a postcode), the European Commission's PVGIS and Open-Meteo (an approximate location), to look up location, solar and weather data. We do not send them names or contact details.
  • Research study data and open research datasets (section 2) are kept in a private folder on a computer we use to run the study, separate from the HeatLens app. They are not sent to Base44, so the "Model training" paragraph below does not apply to them. The study is run by a script that does not send the data to any AI provider. HeatpumpMonitor.org records are read by a script on the same computer. It does not send the records to any AI provider, and we do not keep copies of them (see section 7). We do not share this data with anyone else.
  • Transcription of voice notes: when a recording is transcribed, whether automatically after it uploads or when you ask again, HeatLens sends that one recording, through a short-lived link (it works for 5 minutes), to the transcription service built into Base44. Base44's documentation does not say which company processes the audio or where, so we cannot name them yet. We will update this policy when we can. Base44's published data processing agreement, described above, is the only terms we have for it. We do not know whether the audio or transcript is kept by the service or used to train AI models. Until we do, treat a recording as possibly covered by the "Model training" paragraph below
  • Slack, for our internal alerts.
  • Email delivery and newsletter tools used to send you messages you asked for or that relate to your account, and the invitation email when someone shares a plan with you.
  • Professional advisers (accountants, lawyers, insurers) and authorities where we have to, for example to comply with the law.

Model training. Base44, our hosting provider, states that unless an organisation is on its Enterprise plan, data processed through its platform may be used to train AI models. This can include project content and customer details you enter into HeatLens. Schedule A of the installer terms at /installer-terms sets out this term for customer data. We will update this policy if our plan changes.

International transfers. Base44, Inc., our hosting provider, is in the United States. It is certified under the UK Extension to the EU-U.S. Data Privacy Framework (the "UK-US data bridge"), and we rely on the UK's adequacy regulations for the United States for transfers to it, for as long as that certification stays active. Base44 is responsible under that framework for onward transfers to its own providers. We check the certification on the official list and will update this policy if it lapses. Wix.com Ltd is in Israel, which is covered by UK adequacy regulations. For the other providers we use directly outside the UK (Stripe, Google, Meta, Microsoft and Slack), transfers to each rely on the safeguards in that provider's terms. If a provider changes where it processes data, we will update this policy.

6. Cookies and similar technologies

6.1 Strictly necessary. HeatLens stores small items in your browser to keep you signed in, remember settings and make the site work. These do not need your consent.

6.2 Advertising. We use a Google Ads tag to measure how people find HeatLens. It is off unless you accept it. If you reject it, or change your mind, no tag loads (or it is removed). You can change your choice at any time by opening "Cookie settings" on the site.

6.3 We do not use other advertising cookies or third-party analytics cookies. Our hosting platform records page use inside the Service as described in section 2.

7. How long we keep data

We keep personal data while we need it for the reasons in section 2. We do not delete data that is still in use in an active account, except personal data we must remove to comply with the UK GDPR, for example when you ask us to erase it or when it is no longer needed.

  • Account details and project content you create: While your account is open, or until you delete them. Deleting a job removes the records linked to it as described in the installer terms
  • Closed accounts: Within 90 days of closure. We record the closure when you ask us to close your account; there is no close button in the app yet. Within 90 days of closure, we delete the account's jobs and the records linked to them, its draft invoices, its customer enquiries, its contacts (including any marked "do not contact"), contact notes and follow-ups, the notices we showed it about changes to its calculations, its company settings, the team invites it sent, its enquiry form address, and then the account record itself. A closed account that has been reopened, or that signed in after it closed, is not deleted. We keep invoices that have been issued, accounting records, quote requests, message send logs, our billing records with Stripe and product feedback, which are covered by their own lines in this section or have no fixed period. Uploaded files are not deleted with the account, as the next line explains
  • Uploaded files: Files you upload or we generate, such as documents, EPCs, report PDFs and photos, are not deleted when we delete the record they belong to. We do not yet have a way to delete them automatically. Email hello@heatlens.co.uk to ask us to remove them, and we will tell you what we can remove and when
  • Survey voice recordings and transcripts: The transcript, the suggested entries and the link to the job and room are deleted when you delete the job and when a closed account is deleted, as described above. The audio file itself is not deleted with them. It stays in storage, as for all uploaded files in the line above, because Base44 gives us no way to delete a file; we keep only a bare reference to it so we can delete it once that is possible. Email hello@heatlens.co.uk to ask us to remove it, and we will tell you what we can remove and when
  • Plan sharing: A share lasts while you keep it. The email address of a person you invited is deleted when you remove them, when you end the share, and when their invitation runs out after 14 days. A share that nobody has opened for 12 months is ended, and the addresses on it are deleted. Everything about your shares is deleted when you delete the home or your account is closed. The one-way code we keep to count invitation emails is deleted with the send logs, after 90 days. The one-way code we keep for someone who asked us not to send them invitations is kept until they withdraw that request
  • Cylinder specifications and the shared library: Your upload and your offer record are kept as for project content above, and are deleted when your account is deleted. Figures we have added to the shared library hold only the cylinder's make, model and figures, with the maker's document we checked them against. They are not linked to your account and are not deleted with your account. We cannot find them by account, so we cannot remove them on request. We may correct or remove an entry ourselves. You can withdraw an offer until we finish checking it
  • Quote requests: As set out at /quote-privacy
  • Invoices and accounting records: 6 years after the end of the financial year, as the law requires
  • Partner programme and free-access applications: 12 months after the application was accepted, rejected or withdrawn (counted from the last change to it), if the applicant has no HeatLens account. Applications we have not decided are kept
  • Research study data: 12 months after the study's final report, then deleted. If a homeowner withdraws, we delete their home's data within five working days of the university telling us. A home cannot be removed from totals that have already been calculated or published
  • Open research datasets: The copies we download for the validation study are deleted 12 months after the study's final report
  • HeatpumpMonitor.org records: We do not keep copies. We keep the totals we calculate, and a list of the systems whose owners have objected, so that we leave them out in future
  • Installer outreach contact details and replies: We do not yet delete these automatically. We keep them only as long as we need them, delete them on request where the law says we should, and keep only your email address on a suppression list if you ask us not to write to you again
  • AI usage records: Deleted once they are 24 months old and neither the account nor the job they relate to still exists. While the account or job exists, we keep them, except when a closed account is deleted, as above
  • Messages on a job: Messages on a job in HeatLens are deleted 2 years after they were sent, unless the job is still in an active account
  • Messages to us, product feedback, billing records with Stripe, usage and technical data in server records, and other server records: We have no fixed deletion period for these. We keep them only as long as we need them and delete them on request where the law says we should
  • Newsletter subscription: Until you unsubscribe, then your address is kept only on a suppression list so we do not email you again
  • Message send logs, digest records and phone verification codes: 90 days, then deleted automatically
  • Customer enquiries and other installer-controlled records: As set out in the retention schedule linked from Schedule A

8. Your rights

You have the right to ask for a copy of your personal data, to have it corrected or deleted, to restrict or object to certain uses, to receive data you gave us in a portable form, and to withdraw consent at any time. To use these rights, email hello@heatlens.co.uk. We will answer within one month. We may need to confirm who you are first.

Withdrawing an offer to the shared library works only until we have finished checking it (section 7).

If we have written to you about HeatLens as an installer, you can tell us at any time to stop, by replying to our message or emailing hello@heatlens.co.uk. We will stop, and keep only your email address on a suppression list so we do not write to you again.

If you are not happy with how we handle your data, please tell us first so we can put it right. You can also complain to the Information Commissioner's Office at ico.org.uk or on 0303 123 1113.

If your personal data is held in an installer's account, ask the installer in the first instance; we will help them respond.

If you take part in a university research study that shares information about your home with us (section 2), the university holds the link between you and your home's study number. Please withdraw, or make any other request, through the university. If you write to us instead, we will pass your request to the university so it can tell us the study number, and we will then act on it. We will not try to identify you ourselves. To object to our use of an open research dataset (section 2), email hello@heatlens.co.uk. If we can find the row about your home from what you tell us, we will delete it from our copy and stop using it, and tell the publisher where that is appropriate. To object to our use of your HeatpumpMonitor.org record, email hello@heatlens.co.uk with the link to your system's page. We will leave it out of future calculations and remove any mention of it from our documents within 30 days. Totals already calculated or published cannot be changed.

9. Security

We use access controls, encrypted connections and the security measures of our hosting platform, and we limit who can see personal data. No online service is completely secure. If a personal data breach affects you, we will tell you and the ICO where the law requires.

10. Children

HeatLens is for professionals and is not aimed at anyone under 18. We do not knowingly collect data from children. Our free homeowner advice service requires users to be 18 or over.

11. Other notices

  • Installers' customers and enquirers: /enquiry-privacy
  • The free homeowner advice service: /ask/privacy
  • Typical battery prices: /price-data-privacy
  • Customer data processed for installers: Schedule A at /installer-terms

12. Changes to this policy

We will update this policy when our practices change and show the new version number and date at the top. If a change is significant we will tell you by email or in the Service.

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