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Fabric and ventilation heat loss calculator

Jeremy Harris

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7 hours ago, Gus Potter said:

Hiya all.


I totally get your enthusiasm.


But you are all spending a lot of time an effort juggling numbers, could be the JH spread sheet could be some nice high end software.. I too have some fancy software in my office but recognise that it's just a tool to give you a heads up. 


Some folk on BH actually think this will happpen in real life for no extra cost and you will be able to russle up a builder who will play the game.. you are living cloud cuckoo land.


The reality is that you need to be able to get a local builder to execute your output and get material off the shelf.. Honestly as a self builder if you get so anal at this stage you have little chance of making your self build a success. I have self built my self and also built houses for othe self builders..


My advice is to use your calculations as a concept model and then adapt to what can be built at a reasonable cost to your specification. A good 50% of the above looks good on paper but is complete bollock in real life.


If anyone has a problem with this then you can find my mobile number on my web site or just give me a call on 0771 308 1597.






Which aspects of the spreadsheet do

you think are inaccurate or not achievable? It sounds a bit defeatist to plan the construction of a build but ‘accept’ the quality required to bring that build to reality is not achievable? 

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Posted (edited)
On 08/06/2024 at 02:05, Gus Potter said:

Some folk on BH actually think this will happen in real life ... you are living cloud cuckoo land


I suppose you are right: we have been living in "cloud cuckoo land" for 7 years now.  And very comfortable it is.  😱 🤣🤣


Models are tools with limits and uses.  What you seem to forget in this polemic is that many of us live in builds that were the designed were tuned using such tools, and they worked for us.

Edited by TerryE
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On 05/06/2024 at 18:21, TerryE said:

... What is more important is that house has low energy loss, and a high internal thermal capacity, so it works well as a single zone and we can keep the whole living space at a pretty constant comfortable temperature 24×7.  No zones, no zone controls and valves; nothing complicated, pretty much no moving parts to go wrong and therefore no maintenance costs. 


In my case I have 4 power relays in my Consumer Unit Expansion and a Grundfos circulating pump, all of which are simple and cheap to replace on failure.   The system works well with Octopus Agile so the house is cheap to heat using resistive heating ...


This being said, my control system does cycle the UFH loops for 6 min every 30 min for two reasons: (i) to spread any solar heating from windows across the entire slab, and (ii) so that I can use the return flow temp as a proxy for the slab temp.  My Grundfos pump has just failed.  🙃

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