Porous skirt at the foundation. The downwind drift sits away from the building face. Wind is from the right.
Construction of a 5.5m high snow fence at Baker Lake, Nunuvut.
Street and subdivision planning can reduce, but not solve snowdrift problems in Arctic communities. Since the mid-eighties, RWDI has been involved in the planning and design of snow fences to protect entire Arctic communities and subdivisions. The snow fences typically seen along highways in more temperate regions are about 1m high, whereas these Arctic monsters range from 3m to nearly 6m in height (above) and are upwards of several kilometres in length. Arctic community snow fences are currently used in the Alaskan communities of Kaktovik, Point Hope,Wainwright, Barrow and Atqasook, and in the Nunavut com- munities of Baker Lake, Chesterfield Inlet, Cambridge Bay and Rankin Inlet. The aerial photo of Baker Lake (below) shows the snow collection capabilities of Arctic snow fencing. Over 1.5 km of Arctic snow fencing has been constructed in Baker Lake and has significantly reduced drifting problems in the community. The snow fence shown is 5.5m high and collects a drift nearly 7m in depth.
A solid skirt at the foundation. The downwind drift is pressed against the building face. Wind is from the right.
These two pictures illustrate snowdrift conditions downwind of a build- ing with an open (porous) wire mesh foundation skirt and a building with a solid (non-porous) plywood skirt. The porous skirt (above, top) allows wind to flow under the building, which blows the snow away from the downwind building face (an ideal location for a wind sheltered, drift-free entrance). Conversely with a solid skirt (above) , a downwind drift forms against the building face blocking doors and windows. The performance of the air space underneath a building, in terms of drift for- mation, depends on the height of the air space, the building’s exposure to the wind. severity of drifting conditions expected, the local terrain, the presence of exposed understructure and floor area. Wind exposure and a clean path under the building are perhaps the most important details as field observations indicate that even small gaps work.
Drift control measures such as snow fencing and subdivision layout are large scale solutions. On a smaller scale it is necessary to consider the orientation and design of individual buildings. In most Arctic regions, buildings must be thermally isolated from the ground to avoid thawing the underlying permafrost, which would result in foundation settlement problems. Buildings are typically constructed on steel pipe piles with a 500 - 800mm air space separating the underside of the building from the ground surface. The perimeter opening of this air space is typically skirted with wire mesh, plywood or siding. The snow drift performance of buildings changes drastically according to the porosity of the founda- tion skirt.
Aerial view of the 5.5m high snow fence under construction at Baker Lake. The recently com- pleted sections have no drifts.
On Site review 11
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Spring 2004
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