[Greenbuilding] Passive solar in hot, humid climate

[YankeePerm at aol.com]

In a message dated 11/6/06 11:33:17 AM, ian at remmler.org writes:

[snip]
> 
> I've thought about putting an 8 foot deep porch along the entire
> south wall.  Yes, this will prevent much direct gain in the
> winter, but I'm wondering if it would be worth it to keep cool
> in late summer / early fall (and spring sometimes).  I've only
> found a couple of references that recommend this approach, but
> before air conditioning it was a common feature of the local
> architecture.  So does it make sense to block all direct gain
> when it's hot at the expense of some winter heating (which is
> really only needed for about two months around here)?
> 
> Please share your thoughts and experiences.
> 
> Thanks,
>     - Ian.
> 
> 
> 
That makes sense to me, though I'd also consider a food-producing hedge, 
windbreak for the same purpose.   Where I live in Florida, increasing roof 
overhang would just provide more purchase for hurricanes and tornados to rip the roof 
off. So I'm glad to have the porch idea in this connection. (Of course there 
is no defense against a direct hit by a tornado that is on the ground, but we 
get them a bit above the ground often.)   A vegetation shelterbelt of some 
sort also reduces convection, if somewhat permeable (40-60 percent), and provides 
some cooling through transpiration.   It is also cheaper than a wall and 
self-repairing from most damage.   If thick enough, you can include ornamental 
elements such as rose-of-Sharon, where there is a view, e.g., outside a window.   
If you are not using roof catchment rainwater storage, you can dig a swale 
beside the hedge and increase the amount of water available for transpiration.

Dan Hemenway



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