Privacy Policy
VentCalc · Last updated: June 2026 · UK GDPR compliant
1. Who We Are
VentCalc ("we", "us") operates the ventilation calculation tool at ventcalc.ai. We are the data controller for personal data processed through this Service.
Contact: info@ventcalc.ai
2. What Data We Collect
| Category | Examples | Purpose |
|---|---|---|
| Usage data | Pages visited, actions taken | Service improvement |
| Technical data | IP address, browser type, device | Security, performance |
| Payment data | Transaction reference (via Stripe) | Payment fulfilment |
| Uploaded drawings | Floor plans, M&E drawings (images/PDF) | Automated analysis to pre-fill form |
| Project inputs | Floor area, room counts, system type | Calculation engine |
We do not collect names, email addresses, or account credentials unless you contact us directly.
3. Legal Basis (UK GDPR Art. 6)
- Art. 6(1)(b) — Contract: Processing necessary to deliver the Service you have paid for
- Art. 6(1)(f) — Legitimate interests: Fraud prevention, security, service improvement
- Art. 6(1)(a) — Consent: Analytics cookies (where consent is given)
4. How We Process Your Data
Uploaded drawings are sent to OpenAI (GPT-4o) for automated analysis. They are processed in-memory and are not stored on our servers after the analysis response is returned. We do not retain drawing files.
Calculation inputs (floor area, room types, system selection) are processed server-side to generate results. Results are returned to your browser and stored temporarily in your browser session (sessionStorage) for the duration of your visit.
Draft progress is saved to your device's localStorage only — it is never uploaded to our servers. You can delete your saved draft or turn off draft saving at any time using the controls on the home screen. Drafts remain on your device until you delete them or clear your browser data.
Payment data is handled entirely by Stripe. We do not process, store, or have access to card numbers, CVCs, or full payment details. We receive only a transaction confirmation reference.
5. Automated Processing & Your Data
VentCalc uses automated analysis models to assist with drawing interpretation and calculation support. The following applies:
- Processing is automated — outputs are generated based on your inputs and assumptions
- Uploaded drawings are passed to Anthropic (Claude) or OpenAI (GPT-4) solely for extraction purposes
- Neither provider retains your drawings for model training under our enterprise agreements
- No guarantee is made of the accuracy, completeness, or suitability of automatically extracted data for specific projects
- All outputs are indicative and intended for early-stage feasibility and design support only
You should not upload drawings that contain sensitive personal data (names, addresses, occupier information) beyond what is necessary for ventilation sizing purposes.
6. Data Retention
| Data type | Retention period |
|---|---|
| Uploaded drawings | Not retained — in-memory processing only |
| Calculation results | Browser session only (cleared on tab close) |
| Draft progress | Your device only (localStorage) — never uploaded. Deleted when you clear it or your browser data. |
| Payment references | 7 years (UK financial records requirement) |
| Server logs | Up to 90 days for security and debugging |
7. Cookies & Analytics
We use essential cookies required for the Service to function (session state, payment flow). We do not load analytics or tracking scripts without your explicit consent.
On your first visit a cookie banner is shown. Analytics scripts load only if you click Accept all. If you click Reject, no analytics scripts are loaded or executed during that visit or future visits.
| Service | Purpose | Legal basis | Loaded without consent? |
|---|---|---|---|
| Session cookies (Supabase) | Authentication — keeps you signed in | Art. 6(1)(b) — Contract | Yes — essential |
| Google Analytics 4 (G-LKHF9LP77R) | Page views, session data, feature usage | Art. 6(1)(a) — Consent | No |
| Microsoft Clarity (xblze8qohb) | Session recordings, heatmaps | Art. 6(1)(a) — Consent | No |
Your consent choice is stored in your browser's localStorage under the key vc_consent. You can withdraw consent at any time by clearing your browser's localStorage or site data, which will cause the banner to reappear on your next visit.
8. Third-Party Services
- Stripe — payment processing (PCI-DSS compliant). Stripe Privacy Policy
- Anthropic — drawing analysis (Claude). Enterprise agreement; no model training on your data.
- OpenAI — PDF text extraction and analysis (GPT-4). Enterprise agreement; no model training on your data.
- Vercel — hosting and infrastructure. May log anonymised request metadata.
- Google Analytics 4 (Google LLC) — analytics, loaded only with consent. Google Privacy Policy
- Microsoft Clarity (Microsoft Corp) — session recording and heatmaps, loaded only with consent. Microsoft Privacy Statement
Each third party operates under its own privacy policy and data processing agreements. We select providers that offer appropriate UK/EU data protection standards.
9. Security
We implement appropriate technical and organisational measures to protect personal data, including TLS encryption for all data in transit, restricted access to infrastructure, and in-memory-only processing of uploaded drawings.
No internet transmission is completely secure. If you have concerns about a specific data security matter, contact us at info@ventcalc.ai.
10. Your Rights (UK GDPR)
You have the right to:
- Access personal data we hold about you
- Rectification of inaccurate data
- Erasure ("right to be forgotten") where applicable
- Restriction of processing in certain circumstances
- Data portability where technically feasible
- Object to processing based on legitimate interests
To exercise any right, contact: info@ventcalc.ai
You also have the right to lodge a complaint with the ICO (Information Commissioner's Office) at ico.org.uk.
11. Changes to This Policy
We may update this policy periodically. Continued use of the Service after changes are posted constitutes acceptance. Material changes will be clearly indicated.