Odp: [Strawbale] At what point (R value) do we reach 'enough' insulation?

[henryk czachor]

Hi Andre and Coralie,
Could you explain how did you get the curve of thermal resistance R vs thickness of straw layer x? Can you send me the data obtained in your experiment?
You suggest that R value is not proportional to x. Possible reasons : 1)not uniform properties of straw, ( for example higher moisture content in the exterior part of bale), 2) error in experimental procedure. That why I ask you for additional data.
I guess that the answer at the question At what point (R value) do we reach 'enough' insulation?  depends on prices of buildig materials and labour and on the cost of energy for heating  (cooling) you would find acceptable. 
Amities Henryk Czachor

-----Original Message-----
From: Coralie & Andre de Bouter <m.ep at laposte...>
To: ESBN <strawbale at amper....muni.cz>
Date: Monday, June 24, 2002 10:27 AM
Subject: [Strawbale] At what point (R value) do we reach 'enough' insulation?


    a question : 
    
    When we draw the relation between insulation in cm and the thermal resistance obtained we obtain a curve.
    
    For example:
    0 cm insulation > 0 thermal resistance
    5 cm insulation > x thermal resistance 
    10cm insulation > 3x thermal resistance 
    
    curve starts to slow down...
    
    50 cm insulation > 30x thermal resistance 
    100 cm insulation > 40x thermal resistance 
    
    So at some point it is as good as useless to increase the insulation because it hardly adds up to increased performance.
    
    ***The the million dollar question is: At what point (R value) do we reach 'enough' insulation?*** 
    I guess this is relative to the climate, is there any objective way of calculating this? 
    
    I ask this because other ecological/natural building systems do not offer R6 (R=m².C/W), but I would like to form an idea on at what point we can say it is well enough insulated. rather that bluntly stating that SB has the best R value. (a bit like saying a Ferrari can do 300km an hour, when 100 km an hour is enough)
    
    I know that some other building systems fonction in a different way (storing the heat or cold in thick high mass walls for instance) but I'm only looking to the insulation approach here.
    
    Greetings,
    André
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