ASHRAE Journal - April 2010 - 55

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Photo 2: Frost Heaving in the Lab. (A sequence of photos courtesy of the American Physical Society from a paper by Ozawa, H. 1997. “Thermodynamics of frost heaving: A thermodynamic proposition for dynamic phenomena,” Physical Review E 56(3):2811 – 2816).

Frost heave, when it happens, can be huge. Frost heaving is due to the growth of ice crystals not due to a change in the volume of frozen water. The ice crystals under freezing conditions draw water from the surrounding soil and develop into ice lenses.‡ The growth of ice lenses can be quite phenomenal. At the freezing plane, water is turned into ice, desiccating the soil beneath it. More water is drawn to that location to replace the liquid water that was removed due to a concentration gradient and, according to Penner, “pressure is developed so that the ice and soil above it are lifted.” How high can frost heave lift

the soil? In the lab, it’s not so high (Photo 2). But in the real world where nature is involved? It’s impressively high. Read on. Frost heave can be so impressively high in Canada that we have a special name for it: “pingo,” and we put it on our stamps (Photo 3). Pingo is an Inuit word for the conical hills caused by frost heave typical to the Mackenzie River Delta in the Northwest Territories near Tuktoyaktuk. A pingo is frost heave where nature decides to show us puny humans a thing or two. The Ibyuk Pingo is thought to be the largest on earth and is approximately 150 ft (46 m) tall (Photo 4). Think of it as a giant dirt-covered snow cone.

Photo 3: Canadian Stamp. Tuktoyaktuk, Northwest Territories, land of the pingo. Who else but Canadians would revere frost heave enough to put it on a stamp?

As impressive as frost heave can be, as far as buildings go, who cares about how

*	Only	in	building	science	can	a	connection	be	made	between	Shakespeare	and	the	lingo	about	pingos.	First,	apologies	to	William	Shakespeare.	The	actual	quotation	is:	Double, double toil and trouble, Fire burn, and caldron bubble.	A	discussion	about	pingos	follows.	Yes,	pingos.	Not	dingos,	which	are	Australian	creatures	 of	rather	ill	repute,	but	Canadian	ice	mounds. †	 Once	again	I	am	citing	a	performance	metric	based	on	my	experience	and	the	experience	of	a	bunch	of	other	folks	who	have	been	around	and	paying	attention	for	long	time.	In	the	early	80s	I	was	part	of	what	we	members	thought	was	an	“elite	flying	squad	of	construction	experts”	whose	job	it	was	to	investigate	any	 reported	incidents	of	basement	frost	damage	due	to	basement	insulation.	Energy,	Mines	and	Resources	Canada	was	promoting	full	height	basement	insulation	 and	was	nervous	enough	to	form	a	task	force	to	evaluate	risks.	We	flew	around	the	country	investigating	“incidents.”	I	was	the	representative	from	the	Housing	and	 Urban	Development	Association	of	Canada.	Over	the	years	of	its	existence	the	task	force	never	actually	found	a	basement	that	was	frost	damaged	due	to	basement	 insulation.	Oh,	there	were	frost	damaged	foundations,	but	we	never	found	one	due	to	basement	insulation.	In	each	and	every	case	where	foundations	were	frost	 damaged,	the	foundations	that	were	damaged	were	unheated.	Most	were	also	uninsulated.	This	makes	sense	when	you	consider	what	a	young	Master’s	student	 figured	out.	He	is	not	so	young	anymore	and	is	now	a	full	professor	at	my	Alma	mater,	the	University	of	Toronto.	Professor	Pressnail’s	observations	are	further	 discussed	elsewhere	in	this	rant.	Back	then	he	was	fun	to	hang	out	with,	even	though	he	skied	with	the	wrong	crowd.	In	any	event,	the	task	force	was	disbanded	 because	no	frost	damage	due	to	the	addition	of	basement	insulation	was	ever	found.	But	there	were	rumors.	Just	like	Project	Blue	Book	and	Roswell	and	Area	51.	 Ok,	not	quite	like	those	rumors,	there	really	was	an	alien	crash	at	Roswell,	but	there	were	no	insulation-induced	frost	damaged	foundations	found	in	Canada. ‡	 E.	Penner,	“Ground	Freezing	and	Frost	Heaving,”	Canadian Building Digest 26,	Division	of	Building	Research,	National	Research	Council	of	Canada,	February	 1962.	What	a	beautiful	read.	It’s	online	and	it’s	free.	 §	 K.D.	Pressnail	and	J.	Timusk,	“Adfreezing	of	insulated	residential	basements:	a	hypothesis,”	Canadian Journal of Civil Engineering,	1987.	Nice	job	Kim.	To	the	folks	 in	ASHRAE	land	this	work	was	Professor	Pressnail’s	Master’s	Thesis.	His	advisor	was	(and	is)	an	equally	impressive	fellow—now-retired	Professor	John	Timusk. #	Figley,	D.A.	and	L.J.	Snodgrass,	“The	Effect	of	Basement	Insulation	on	the	Depth	of	Frost	Penetration	Adjacent	to	Insulated	Foundations,”	National	Research	 Council	of	Canada,	Division	of	Building	Research,	Saskatoon,	SK,	published	in	the	Journal of Thermal Insulation,	Volume	7,	April	1984.

April	2010	

ASHRAE	Journal	

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ASHRAE Journal - April 2010

Table of Contents for the Digital Edition of ASHRAE Journal - April 2010
