The short version
Tiang shows you no ads, and sells nothing about you. It does carry one piece of advertising machinery: if you installed Tiang after seeing an ad for it, a Meta component inside the app tells Meta that the install happened, and reads your device’s advertising ID so Meta can match it to the ad. You can delete or reset that ID yourself in Android’s own settings. Nothing is sold, and nothing goes to a data broker. The app also sends anonymous usage data about itself, described below, so we can tell what to improve. Your drawings live on your phone; they are copied to our server only while you are signed in with Tiang Pro, so you can reach them from another device — a free account downloads what the server already holds for it and uploads nothing. A floor plan you scan never leaves your phone at all. You can delete your account, and everything synced to it, from inside the app.
What we collect
Your account
When you sign in with Google we receive your name, email address, profile picture and Google account ID, which is how we know a returning device is you. If you set your own display name in the app, we store that instead of Google’s.
You do not need an account to draw. Signing in is what turns on backup, sharing and subscriptions.
Your projects
While you are signed in and subscribed to Tiang Pro, your saved designs are backed up to our servers. A backed-up project holds the name you gave it, the building geometry, the materials and build-ups you chose, the country you picked for it, the map location and its place label, and your recent undo history. A signed-in account without Pro only downloads: it receives whatever the server already holds for it — from an earlier subscription, or from another device — and sends none of its designs up. A project you delete on a free account is deleted on that phone; the server copy, if there is one, is removed the next time the account is subscribed, or when you delete the account.
Whether or not you subscribe, when you run a simulation the design it is run on is sent to our server for that run. We keep your latest simulation inputs and results so re-running is fast, and any runs you explicitly saved for the Compare tab.
Where you put the building
You pin the building on a map so the simulations can use the weather for that place. The latitude and longitude you choose are sent to our server and to the weather services below. This is a place you point at, not your device’s GPS — the app never asks for location permission and never reads where your phone is.
Floor plans you scan — these stay on your phone
If you import a PDF or a photo of an existing floor plan, the file is opened by Android’s own file picker, which hands the app that one file and nothing else. The image is traced entirely on your device and is never uploaded to us or to anyone else. If you keep the plan as a backdrop to draw over, the picture is stored locally on your phone; it is not part of the backup, and uninstalling the app removes it.
Subscriptions
If you buy Tiang Pro, the purchase itself is handled by Google Play. We never see or store card or payment details. We use RevenueCat to keep track of subscriptions: your Tiang account ID and account email are sent to them so a purchase can be matched to your account and restored on a new phone. Our own server stores only whether your subscription is active and when it runs out.
How much you have used
The free tier includes a monthly allowance of runs, so our server keeps a count per account per month. It is a number, not a history: we record that a run happened, not what it was of. The size of the allowance depends on the version of the app, so each request carries the app’s version number and each queued simulation keeps the version that asked for it — an older app keeps the allowance it was installed with.
The same allowance is also counted per installation, so that signing in with a second account does not simply reset it. To do that the app makes up a random code when it is installed and sends it with those requests. It is not your phone’s identity: the app invents it, it is not taken from the hardware and it is not the advertising ID described below, it cannot be matched to you anywhere else, and reinstalling gives you a new one.
How the app is used
The app sends anonymous usage data so we can work out what to improve. It carries no identifier: nothing in it is linked to you, to your account, or to anything else you send us, and one phone cannot be told from another. It does not include your designs, anything you type, or your location. You can turn it off in Settings → App settings → About Tiang.
Ads that brought you here
We advertise Tiang on Facebook and Instagram. To know whether that money is doing anything, the app includes Meta’s measurement component — the facebook-core library from the Facebook SDK for Android (version 18.0.3), registered under our Meta app ID 1013978131237918. It tells Meta when the app is installed and when it is opened, and sends your device’s advertising ID so Meta can connect that to an ad you were shown. With those events go basic device and app details of the kind any such component reports: the Android version, the device model, the app’s package name and version, and the language and time zone the phone is set to. Meta’s own use of what it receives is governed by Meta’s privacy policy.
This is the one genuinely advertising-related thing in the app, and it is why the old promise never to touch an advertising identifier is gone from this policy.
What it does not send: your designs, your simulations, anything you type, your account, your email address, or where you pinned the building. Meta’s component can also report purchases — that part cannot attach to the payment library Tiang uses, so no purchase or subscription information reaches Meta.
The advertising ID is yours to control, outside this app: Android Settings → Privacy → Ads lets you reset it or delete it, and switch off ad personalisation. Delete it and Meta receives nothing it can match. There is no switch for this inside the app: the component starts with the app, and the advertising ID is the only thing it sends that could identify a device — which is why the choice sits with Android rather than with us.
Support messages
If you use “Contact us”, your email app opens a message to tiangbuildingapp@gmail.com. We then have your email address and whatever you wrote. The message is pre-filled with your app version and language so we can reproduce the problem — delete those lines before sending if you would rather not. We keep support mail only as long as it takes to sort the problem out.
Technical logs
Our servers record ordinary things like IP address, request times and app version, for security and for working out why something broke.
What we never collect
Your contacts, your photo library, your messages, or your device’s GPS position. The app requests no location permission, no camera permission and no storage permission — scanning uses the system file picker, which needs none.
What we do with it
- Create and manage your account, and keep you signed in.
- Run the simulations you ask for — temperature, humidity, electricity and solar, and WiFi — against the place and the building you chose.
- Back up a Tiang Pro subscriber’s projects and make them available on their other devices; deliver a free account the projects the server already holds for it.
- Keep the service running, secure and debuggable.
- Apply the free tier’s monthly allowance, and honour a subscription if you have one.
- Work out whether advertising Tiang is worth paying for.
Who else sees anything
Only the services it takes to run the app:
- Verifies your sign-in.
- Open-Meteo
- Receives the coordinates you pinned — latitude and longitude only, with nothing identifying you attached — and returns the weather for that place.
- PVGIS
- The same coordinates, on the same terms. Operated by the European Commission’s Joint Research Centre, and used only as a fallback when Open-Meteo cannot answer.
- OpenStreetMap
and Nominatim - Map tiles, and turning coordinates into a place name. These requests go straight from your phone, so those services also see your IP address and the area you are looking at.
- RevenueCat
- Your account ID and email, if you subscribe, so the subscription follows you to a new phone.
- Meta
- If you installed Tiang after seeing one of our ads, Meta is told the install happened and receives your device’s advertising ID so it can match the two, with the basic device and app details listed above. Nothing about your designs, your account, your purchases or your location goes with it.
- People you invite
- If you share a project, the people you invite can see it — its name, its design and its map location — and, while you are working on it together, the email address on your account. You choose who, and you can revoke it at any time.
Meta is the only advertiser we share anything with, and only the install signal described above. We share nothing with data brokers, and we never sell or rent your data.
Keeping and deleting
We keep your account while it exists. You can delete it, and everything synced to it, from inside the app under Profile → Delete my account. That removes your projects, your saved and cached simulations, your undo history, your usage counts and any shares, immediately.
You can also ask us by email at api.tiang.app/delete-account. We finish those within 30 days, apart from the few records the law requires us to hold.
Deleting your Tiang account does not cancel a Google Play subscription. Cancel that first in Google Play → Subscriptions, or you will keep being charged for an account that no longer exists.
Security
Everything between the app and our servers is encrypted in transit over HTTPS.
Children
Tiang is meant for people aged 13 and over. It is not directed at younger children and we do not knowingly collect their data.
Changes
We may update this policy. When something material changes, the effective date at the top changes with it.
Contact
Questions about this policy or about your data: tiangbuildingapp@gmail.com.