Passive House is a voluntary standard for energy efficiency in buildings. Buildings designed in accordance with Passive House standards typically have an ultra-low rate of energy usage, making them more environmentally-friendly than buildings that rely on active heating and cooling. For a new, domestic ‘Passive House’ in County Mayo, West of Ireland, temperature and relative humidity monitoring with a Tinytag data logger was crucial to understanding how the building performed in real, lived-in conditions.
Construction on a new low-energy build in County Mayo,
West of Ireland, was completed in October 2019.
Straight-away, Mark Stephens, partner of
Mark Stephens Architects, set out to assess the
performance of the building with a Post-Occupancy Evaluation.
Post-Occupancy Evaluation (POE) is important
for understanding how a building performs while it is in use. It
helps architects, designers and builders to understand, in
practice, how a building's design impacts on running costs and,
crucially, how it impacts on the comfort of those who use the
In the case of the County Mayo house, the Post-Occupancy
Evaluation was also important for assessing whether the
Passive House (or 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, the data logger was
removed, and the data was 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:
- The average indoor temperature for the year was
20.5°C, which matches Passive House requirements.
- The minimum and maximum humidity levels registered were 28.25%
and 69.20% (both slightly outside the recommended level of between
35% and 55%) but the average humidity was a comfortable
- For most of the year, the building remained within
'comfortable' temperature and humidity levels.
The occupants reported in the survey that the house overheated
during the summer, but the data revealed that this only occurred
for a smaller percentage of the time.
The data was also cross-referenced with data from a local
weather station to aid understanding of how the building
responded 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. "The data that we have
achieved with the Tinytag has been excellent," says
Mark Stephens. "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
In future projects, Mark comments that 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 more precisely understand 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.
For more information on the innovative work of Mark Stephens
Architects on the County Mayo build, and on the results from the
Post-Occupancy Evaluation, check out their
With thanks to Mark Stephens Architects www.markstephensarchitects.com,
Architects & Passive House Consultants.
Images courtesy of Mark Stephens Architects.