An algorithm was developed for predicting the rates of airflow and heat flow in an inclined air space heated from above or from below. The algorithm yields the mass flow rate and the temperature rise of the thermally induced flow rate. The flow and convective heat transfer are very similar to those occurring in inclined cooling ducts formed by offset roof-mounted photovoltaic installations. The algorithm is useful for predicting the free laminar convection heat transfer prevalent in roofs elevated from the roof deck. The routine was implemented in an attic simulation code and validated against thermal field data for stone-coated metal roofs equipped with above-sheathing ventilation.

Presented at Thermal Performance of Exterior Envelopes of Whole Buildings X – December 2007

Units: I-P