Literature Review on Building Envelope, Heating and ... - Beeshive.org

• Incorporate expansion joints to compensate for structural movement due to large
temperature variations from winter to summer.
• Install triple-glazing, low-e coating windows with insulated fibre reinforced plastic
frames.
• Avoid stepped roofs, offsets, nooks, or parapet walls to prevent the accumulation of
snowdrifts. Use a sloping roof section to connect two roof levels. Metal roofing has
performed satisfactorily. Skylights are not recommended unless designed to control
condensation. Eaves minimum projections are 200 to 600 mm (8 to 24 in.) below the
tree line and 100 to 200 mm (4 to 8 in.) above the tree line. Below the tree line,
ventilated roof systems perform well. Above the tree line, roof venting is problematic.
It is difficult to avoid snow infiltration through vents. Incorporate drains for melted
snow.
• Incorporate strategies to minimize the impact of the building on the thermal
equilibrium of the permafrost and also to reduce snowdrift accumulation. A common
strategy is elevating the building about 0.9 to 1.2 m (3 to 4 ft.) above the ground. A
Swedish study concluded that a 1.8 m (6 ft.) elevation worked well in Antarctica.
• In winter, strategies to harness any daylight available include large windows,
clerestory windows, and strategically placed skylights to allow natural light to
penetrate into living spaces. In summer, latticed window screens block the continual
oblique rays. Scale and spacing of the slats of window shading devices may be
optimized using solar angle calculations to block excessive daylight and solar heat of
the high summer sun while maximizing the entry of low winter sun.
• Considerations are given to the availability of labour and equipment, speed of
construction, and methods that encourage local participation.
Heating and Ventilating Strategies
Load estimation computations are modified for northern conditions, as temperatures stay
at design conditions for long periods and solar gains do not subside in summer nights.
Easily maintained and reliable systems are preferred, because transportation is expensive
and sometimes not available in bad weather. Ensure air supply and exhaust openings can
withstand wind and snowdrifts.
Ventilation
An indoor relative humidity of 20% is considered optimum during an arctic winter.
Occupants’ discomfort might increase at a relative humidity of less than 20%. Relative
humidity above 20% could lead to condensation and mould growth. Mechanical
ventilation is preferred. Defrosting surfaces of the heat exchanger of the HRV is a critical
design consideration to minimize ice buildup. Avoid high intake air velocities, because
they could entrain snow and rain. The reverse is true for exhaust openings, as high
exhaust velocities propel moist air away from the opening before frost buildup.
PERD-079: Task 2 - <strong>Literature</strong> <strong>Review</strong> 92