The Igloo

A Dome of Many Wonders

Outline

• Igloo basics

• Igloo science

• Construction of an igloo

• An igloo in Hyde Park

What is an igloo?

• Comes from Inuit word for house

• Usually means a dome-shaped dwelling made of snow

• Not a quinzhee

Igloo Culture

• Igloos were built by Inuit in the Canadian central arctic and Greenland’s west shore

• Used mainly as temporary shelter on hunting trips

• Larger semi-permanent igloos were also built that could house several families

• Design of igloos varies between Inuit cultures

Igloo Physics

• A hemisphere is not a good dome shape

• Ideal dome shape is a catenary – Innuit design is very close to this ideal

• Height/Diameter = 0.3 for minimal stress

• But compression shrinking so it’s best to make H/D > 0.3

• Theoretical maximum size of igloo is:D = 34 ft., H = 12 ft.

Igloo Physics

• A hemisphere is not a good dome shape

• Ideal dome shape is a catenary – Innuit design is very close to this ideal

• Height/Diameter = 0.3 for minimal stress at base

• But compression shrinking so it’s best to make H/D > 0.3

• Theoretical maximum size of igloo is:D = 34 ft., H = 12 ft.

More Igloo Physics

• Rate of heat flow through igloo given by

where Q/t = heat flow per unit time, k = thermal conductivity, A = area of interior/exterior of igloo, Ti = interior temperature, To = exterior temperature, L = thickness of igloo

• Can calculate Q/t in the interior making simple assumptions about people

• Using reasonable values, temperature difference between inside and outside can be about 60 C

L

TTkA

t

Q oi )(

Construction of an Igloo

• Snow must be packed

• Cut wedge shaped snow blocks using snow saw

• Lay blocks in helical pattern, cutting block thinner as you go up

• Dig a trough leading into igloo and cover with snow blocks

• Terrace interior to so that inhabitants are elevated

• Cut ventilation holes

Block laying pattern

Construction of an Igloo

• Snow must be packed

• Cut wedge shaped snow blocks using snow saw

• Lay blocks in helical pattern, cutting block thinner as you go up

• Dig a trough leading into igloo and cover with snow blocks

• Terrace interior to so that inhabitants are elevated

• Cut ventilation holes

Igloo Side View

Igloos of the Future

Building an Igloo in Hyde Park

• Problem: snow is not well packed– Solution: pack it into buckets

• Problem: snow is cold and not fun to touch– Solution: buy a shovel

• Problem: people throwing shit at your igloo– Solution: none

The location: 60th and Drexel

Igloo

Nick

STAGE 1: COMPLETE

The Finished Igloo!