march 03, 2010 10:40am

The results are in, the jury is out...

It was surely an achievement to be awarded Passivhaus certification, but to me it only has any lasting merit if monitoring supports the calculated performance.

A new build can take 6 months to fully dry out and settle, even with a conventional heating system, so I had not really expected to have definitive measurements until this time next year.

However, this winter has been the coldest (and wettest) in the last 30 years. It seems obvious that if our actual space heating requirements for recent months were low enough it would at least prove the cold weather performance.

Multi-room monitoring is not up and running yet but I do now have 24/7 temperature and relative humidity data logged from mid January onwards. The indoor sensor is located in the main open-plan living area. I have 5 other thermometers located in different rooms for my manual records. These determined the location of the 24/7 logging sensor. Comparing measurements show that the logged data is reliable and a very fair reflection of the overall temperatures in the house.

I also found another local weather station that gives a good comparison with my outdoor temperature and humidity readings:

The climate model used for our PHPP calculations is a triangulation of 3 meteo stations, 2 in Wales and one in England. It is of course based on long term monthly averages, and winter 2009-2010 has been a long way away from the November-February averages.

So, what is the conclusion so far:

Adjusting for actual mean temperatures, Y Foel used:
January: 88% of the kWh predicted by PHPP for space heating.
February: 80%

More on this soon I hope...

Posted By: MarkTiramani

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