Here's a problem for the clever ones

[Mary Fisher]

From another group:

Does anyone have any tips on where I can look for details on how to go about
designing/specifying/building a passively-cooled larder for a kitchen? We
are having some structural work done, and being able to incorporate
something like this would be great.

He's in northern England, near the sea.


Mary

 

[Tuppence]

From another group:

Does anyone have any tips on where I can look for details on how to go
about
designing/specifying/building a passively-cooled larder for a kitchen? We
are having some structural work done, and being able to incorporate
something like this would be great.

He's in northern England, near the sea.


Mary

Forgive my ignorance, but what is the difference between a standard larder
(with high & low level ventilating air bricks on an outside wall) and a
passively cooled larder?

Regards,
Tuppence

 

[mike wilcox]

Forgive my ignorance, but what is the difference between a standard larder
(with high & low level ventilating air bricks on an outside wall) and a
passively cooled larder?

Regards,
Tuppence

About 100 pounds ;~)

 

[[email protected]]

... what is the difference between a standard larder (with high & low level
ventilating air bricks on an outside wall) and a passively cooled larder?

For starters, a passively-cooled larder might have insulation outside more
thermal mass, with vents above and a drain but no vents below, so warm air
can flow out and cold air can flow in at the top, but cool air is trapped
inside on a warm day. Thermal mass in containers of water that partially
freezes on the coldest nights can keep the larder contents from freezing,
with a vapor barrier between the ice and the larder compartment.

We can quantify this with more weather data. For instance, after a long
string of 40 F average days and an 80 F H-hour warm spell, a 4'x4'x8'
larder with 160 ft^2 of US R20 surface (4" of Styrofoam) and G = 160/20
= 8 Btu/h-F of conductance outside 16K Btu/F of thermal mass (eg 20K lb
of water in 4"x8' vertical PVC pipes) with RC = C/G = 16K/8 = 2000 hours
would warm to 50 F after H = -2000ln((50-80)/(40-80)) = 575 80 F hours,
ie a 24-day warm spell.

Nick