Data logger

Utilising Data loggers to Diagnose Damp Issues:

This guide is for ORIA Wireless Thermometer Hygrometer, but is similar for most hygrometer data loggers


Data loggers have become instrumental in identifying the root causes of damp within properties, by continuously monitoring the environment and logging data over time. A notable device in this realm is the ORIA Wireless Thermometer Hygrometer, currently available on Amazon at £17.49 for a pair. This guide outlines the setup, usage, and analysis of data from the ORIA data loggers to understand and resolve damp issues.

Data loggers for Identifying the Root Cause of Damp

Data loggers, especially hygrometer data loggers, are crucial for collecting relative humidity and temperature within a building over time. Over the past five years, the emphasis on data-driven analysis to understand the genesis of damp has grown significantly. By deploying one or more data loggers before an onsite damp survey, it’s possible to gain insights into the production, ventilation, and distribution of water vapour, thereby enabling a more targeted approach to resolving damp issues.

Setting Up Your Data logger the First Time

Setting up your data logger is a straightforward process on a smart phone or table. These instructions are for the ORIA Wireless Thermometer Hygrometer.

  1. Download “Sensor Blue” app from the app store and activating bluetooth, for Oria it is called SensorBlue.
  2. Device Activation: Pull the plastic battery saver to activate the device. The sensor may automatically register itself on your smart phone, in which case go to 5. below.
    Pairing: Pair the device with your phone by pressing the bottom centre.
  3. Device Selection: Select your device (marked with a red dot).
  4. Data Sync: After 10 minutes, press between °C and %RH to sync data (allow about 1 minute per month of data to sync).
  5. Data Export: To export data, press the “box” icon, top right, and follow through to export as CSV.
  6. It can take 1 minute per month of data to sync. First time you export data there will be a tip on how to you the data on your screen.
  7. To export data, press “box” icon, top right.
  8. Press again top right to export data.
  9. Press Export – CSV. If this doesn’t work or you don’t have an email set up, then press Open – CSV.
    A CSV data file will show and either an option to send from various email providers or save the file to a folder.
    From there select you preferred provider or drop into a file and import and send, or import and use Excel it is currently too complicated for Google Sheets).
  10. Either send data to me to evaluate (members only). Put enough information so that each property and device can be tracked easily. Here is an example Excel spreadsheet: – it should be self explanatory, if not cut and past from logger 1, normally damp wall into data 1, likewise from logger 2. You may need to remove ‚ÑÉ from Apple device and may have to change to % ages in Android devices.

Positioning Your Data loggers

  1. Primary Position: Place one data logger on or near the main damp patch, ideally on the coldest part of the wall.
  2. Secondary Position: Place another in the nearest source of vapour, often a kitchen or bathroom, ideally out of the way like above a door frame.

Dew Point Formula

Processing the data to find the Dew point (a proxy for vapour pressure) can be done using the formula provided in Excel or any other spreadsheet software. Dew point helps in understanding where vapour is being produced and when it’s being removed.

Examples of Data logger Usage

Example 1: Condensation

In a top floor modern flat with mould issues, data from four data loggers unveiled a flaw in the ducting from two extractor fans. Post remedial measures like installing back-flow shutters and improving loft insulation, a noticeable drop in relative humidity was observed, showcasing the effectiveness of the intervention.

Example 2: Mould

In another property, a dehumidifier was deployed to combat mould, with data loggers providing evidence of improvement post late November. Further refinements led to even better conditions without the need for additional equipment.

Other Data logger Options

  • ORIA’s Brifit Wireless Thermometer Hygrometer: Comes with a display and Bluetooth 5.0, priced at £13.
  • Smart Hygrometers: Useful for measuring sub-floor humidity, priced around £16 for two.
  • Govee WIFI Connected Hygrometer: Recommended for landlords for remote monitoring, priced around £42.


The ORIA Wireless Thermometer Hygrometer, along with other data logger options, provides a robust method for understanding and tackling damp issues. By accurately logging environmental conditions and allowing for data analysis, these devices are instrumental in devising effective solutions to maintain a healthy and damp-free living environment.

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