Reexamining roof ventilation.


Moisture in the roofs of cold storage buildings.

The low-slope roofs of ten cold storage buildings in the Dallas area were examined visually and thermo graphically (Tobiasson and Korhonen 1985) from above and below. Two inch (51 mm) diameter cores were taken to verify infrared findings and to determine moisture contents for estimating wet thermal resistances (Tobiasson et al. 1991 ). Twelve inch (0.3 m) square specimens of many of the insulations were removed for laboratory studies of their thermal properties and structure.

Application of a new type of air and vapour retarder in a self drying dloped roof with a cathedral ceiling.

In cool and cold climates, sloped roofs with cathedral ceilings are quite sensitive to moisture damages caused by built-in moisture and prolonged concealed condensation of water vapor produced inside. Conventional solutions are to leave a cavity between the thermal insulation and the sheathing and vent it with outside air and/or to include a vapor barrier below the insulation layer. An alternative, however, is the self-drying roof. This concept was evaluated experimentally.

Case study - ice dam remediation for Northeast ski area condominiums.

This is a case study describing the procedures for locating, prioritizing, and repairing the causes of ice dam formation at a complex of over one hundred Northeast ski-area condominiums. The testing, performed on four typical units, was commissioned by the Owners Association to prove the feasibility of preventing ice dam formation without replacing all of the existing roofs and to determine the costs of this approach. Ice dam formation is one of the predominate problems for buildings in cold climates.

Experimental testing of a ventilated roof component for energy saving in cooling.

A Ventilated roof component was built and tested in the outdoor testing facilities (Test Cells) of CRES, Greece. A conventional Greek roof structure of the same area was also installed in the roof of the Test Cell allowing simultaneous measurements in order to perform a comparative study of the performance of the two parts. Different configurations in the Ventilated roof were investigated, like ventilation air gap height and application of a radiant barrier. The tests carried out under summer weather conditions will be discussed in this paper.

Roof design for natural cooling.

A recent European project explored combinations of radiative and evaporative cooling processes involving the roof for application in the Mediterranean region. The paper introduces the experimental applications which were built and tested as part of the project and the design considerations and applicability data derived from simulation models validated with the experimental results

Roof ice dams. It's not really a roofing problem.

     Nothing highlights construction shortcomings like severe winter storms. Too often, possible problems are neglected during the construction season when winter and its bad weather seem far removed. The winter of 1999 produced many ice dams on shingle roofs in central and eastern Canada. The resulting leaks caused widespread damage to ceilings, walls and interior .furnishings of many homes.     

Greenhouse natural ventilation by buoyancy forces.

Convective transfers mainly determine the energy and mass balances which regulate the micro-climate inside a greenhouse. Air flow and temperature patterns induced by natural ventilation through greenhouse roof openings are only considered here. Flow visualizations were performed on a half scale test cell simulating the absorption of solar radiation at the floor surface of a single-span greenhouse. Temperature and air flow patterns were observed in a steady regime i) with a single sided roof vent and ii) with two symmetrical one.