Tinytag data logger used for Post-Occupancy Evaluation in Irish Passive House

  • 26 Aug 2021

Design-focused architectural practice Mark Stephens Architects used a Tinytag temperature and relative humidity data logger to evaluate the post-occupancy performance of a new-built house designed to Passive House calculations.

Construction on a new low-energy build in County Mayo, West of Ireland, was complete in October 2019. Straightaway, Mark Stephens, partner of Mark Stephens Architects, set out to assess the performance of the building with a Post-Occupancy Evaluation.

In the case of the County Mayo house, the Post-Occupancy Evaluation was also important for assessing whether the Passive House (Passivhaus) temperature and over-heating calculations met the actual data ‘in-use’.


A key component of the Post Occupancy Evaluation came in the form of a Tinytag Ultra 2 TGU-4500 temperature and relative humidity data logger. Temperature and humidity levels are integral to indoor occupant comfort. Measuring these parameters was vital for understanding the ‘real’ performance of the building.

The data logger was placed next to one of the main rooms, and measured continuously for the year-long period of evaluation from October 2019 to October 2020.

At the end of the monitoring period saw the removal of the data logger. The data was then downloaded and analysed.

At the same time, the occupants were given a questionnaire to assess their perception of the building’s performance.

The data from the data logger revealed a number of things:

1. The average indoor temperature for the year was 20.5°C, which matches Passive House requirements.

2. The minimum and maximum humidity levels registered were 28.25% and 69.20% (both slightly outside the recommended level of between 35% and 55%). However, the average humidity was a comfortable 47.40°C.

3. For most of the year, the building remained within ‘comfortable’ temperature and humidity levels.

Occupants reported the house overheated during summer, but data revealed this only occurred for a smaller percentage of the time.

The data was also cross-referenced with data from a local weather station. This was to aid understanding of the building’s response to outdoor temperature fluctuations.

The data logger has been crucial for understanding how the building works in practice – in real, lived-in conditions, and not just in theory or calculations.

Mark Stephens comments: “The data that we have achieved with the Tinytag has been excellent. We are able to see if the performance of the Passive House we designed matched the calculations and whether the relative humidity of the house throughout the year was comfortable. In both cases we are pleased to report success!”

In future projects, Mark says he would like to use more data loggers to cover more rooms in a building. This would help to construct a more accurate and detailed picture of conditions across the whole build. He would also utilise an outdoor data logger to understand more precisely the relationship between indoor and outdoor temperatures.

Tinytag data loggers are ideal for indoor monitoring in domestic properties. Unwired and compact design makes Tinytags an easy-to-install and discreet option for monitoring in occupied spaces. Long battery life and large internal memory enables extended monitoring periods without interruption or inconvenience to building occupants.

Gemini Data Loggers,
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Terminus Road,
West Sussex,
United Kingdom,
PO19 8UJ

Phone: 01243 813000
Fax: 01243 531948

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