[Strawbale] Forced air

[Robert Tom]

On Tue, 08 Jan 2008 15:06:07 -0500, Mark BP / Low Energy Design Ltd  
<mark at lowenergydesign.ca> wrote:

> Yes, Rob, indoor humidity is lower here, but you exaggerate the effect
> by disregarding the principal sources of water vapour in a dwelling -
> not the external conditions but (i) human activities in the kitchen,
> (ii) human activities in the bathroom, and  (iii) people breathing.  In
> Britain (as per the building regs document I sent you, Rob)


I must confess that I've not taken the time to download the Brit  
regulations simply because
I can already guess what Brit "ventilation" (such as is) standards are...  
that is, where a ventilation scheme exists, it's probably some variation  
of a primitive, exhaust-only, passive inlet ventilation system (EOPIVS)  
... hit or miss at best and for the most part, unworkable in Canadian  
conditions.

In my previous message, it was assumed that in winter, anywhere in Canada  
(ie not just arid SK), any interior humidity would be interior-sourced (ie  
humans and their activities) rather than non-existent-in-winter, ambient  
atmospheric humidty.

I'm not a particularly big fan of forced air heating systems either. (I  
heat with radiant sources in my own home (ie direct gain slab, wood  
stove). But I do have a forced air furnace (essentially a big electric  
toaster that has only been turned on once, to test it after installation)  
with air-handling system installed as the Code-required automatic heating  
system .)

The thing about radiant heating energy is that it obeys the law of inverse  
squares -- that is, the sensible warmth decreases as the distance between  
the radiant source and the receptor increases, in a proportion that is the  
inverse of the square of the separation distance ... so obviously beyond   
a relactively short distance, the effects of the radiant energy will no  
longer be relevant and any sensation of warmth will be due to warmed air.
ie Most people don't spend their time hugging their radiant heat floors or  
walls.

Hence, the effectiveness of radiant heating sources is usually enhanced  
where there is also a means in place to move warmed air around, which  
incidentally also has the effect of increasing the heat exchange rate  
bewteen the radiant source and the air in the vicinity of the radiant  
source.


-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at chaffY a h o o  dot  c a >
manually winnow the chaff from my edress in your reply