Upstairs heating options for passivehaus - electric or wet systems; looking for advice

[JohnMo]

18 minutes ago, Thorfun said:

i keep harking on like a stuck record but we have loads of glass all over and suffer from overheating but we get to look out at the garden and surrounding trees and the sun and sky and stuff.

 

i'd hate to block all that off so we just turn on the AC and enjoy our house without the fear of sweating buckets. 🤣

We are the same - but no AC. We are NE Scotland and no one needs Aircon in Scotland do they?

 

Our UFH cooling went on mid May and was switched off in Mid September last year. Not as effective as AC, but makes life bearable. Without cooling in the first year, we got lounge temps in the late 20s any day the sun came out - don't matter if it was cold or hot outside. As soon as we had building sign-off, I installed a heat pump purely for cooling the floor.

[Gone West]

36 minutes ago, Mike said:

As opposed to the climate data sheet in my PHPP, which just says 'To enter new data, fill in yellow cells'!

That brings back memories! I was using PHPP2007 in 2009/2010 and I found the results were very sensitive to which of the climate data files I used.  IIRC the example data file for SE England was from Heathrow. I got data from the Met Office for Manston, I lived eight miles away at the time, and then got a free version of Meteonorm. The data Meteonorm created was very close to the Manston data so I used the Manston data in my calculations. The Heathrow data produced very different results, as did a data file I got for Vlissingen.

[Mike]

28 minutes ago, Gone West said:

That brings back memories! I was using PHPP2007 in 2009/2010 and I found the results were very sensitive to which of the climate data files I used.

Yes, I was using the same version in 2008 and had a similar experience with the climate data, though I don't recall trying anything as exotic as Vlissingen!

At the time I didn't think about getting data for the future climate; nobody then was expecting much of an impact from climate change this century, at least not among the general public. And the forecast data probably wouldn't have been available anyway.

[SteamyTea]

I thought I would have a look at some high quality weather data from Reading University.  It is daily mean air temperatures going back to 01/01/1971.

I split it into decades, so >=1971 to <1981 and so forth.

As air temperatures follow a normal distribution pretty well, I decided to model it from the decadal  means and standard deviations.  While this is not perfect, the fit is pretty good, good enough for calculating the need for heating and cooling.

While this data is only from one place, the same technique can be used with other datasets.

 

So here is the chart.

 

 

The reasons you cannot see two of the lines 2001-2011 and 2011-2020 is because there is not enough difference in the variation to worry about.

But, this is only part of the picture.  When it comes to cooling, generally, anything over 24°C mean daily temperature can cause discomfort.  In the 1971 to 1981 decade, there were 36 days that breached that limit, this jumped to 60 days during the 1980's and has been stead at 64 days since (I have not included the data since 2021).

So basically you can expect the OAT to cause problems for 1 week a year, with probably 4 nights with very excessive temperatures.

It is nice to see that the mean temperature has gone up every decade, which confirms past models.  The standard deviation, which is really the weather, rather than the climate, is always going to be variable, and just mathematically, the bigger the range of number i.e. max temp minus min temp, the greater you would expect the variations to be, which is happening (0.0134/decade).

So the mean air temperature is increasing (in Reading), the variation is getting greater and the number of cooling days is currently constant, things can change.