Ventilated rainscreen cladding: Measurements of cavity air velocities, estimation of air change rates and evaluation of driving forces

Experimental analysis of cavity ventilation behind rainscreen cladding systems: A comparison of four measuring techniques

“…This issue of the overestimation of the anemometer results was already addressed by Falk and Sandin [20]. They derived for predominant upward flow conditions (sunny periods with low wind velocities) an overestimation ratio of the air change rate based on anemometer measurements of 5e40%.…”

“…Sandin [20]) have documented air change rates based on similar smoke injection tests, the authors of the article at hand stress the inaccuracy of this method for three reasons: a) replacing the inner group of materials by plexiglass to visualise the smoke influences the driving potentials, b) at low air change rates the smoke distributes across the cavity, impeding its localisation and c) the smoke is injected at a different temperature influencing the flow pattern. Therefore this method is not included in the present work as a measuring method.…”

“…Refs. [20,26,27]]. This steady-state method basically divides the problem in a sequence of air resistances.…”

“…Refs. [20,28,29]]. In this paper the experimental data of Falk and Sandin [20] is applied in which the relation between the loss factor and averaged velocity is given by: Fig.…”

“…[3,20]]. A very detailed study was performed by Falk and Sandin [20] who studied cavity ventilation by measuring the air velocity in the middle of the cavity with an omnidirectional anemometer. The authors derived in this study a method to quantify the driving potentials related to thermal buoyancy and wind differential pressures.…”