Ventilated rainscreen cladding: Measurements of cavity air velocities, estimation of air change rates and evaluation of driving forces
(2013) In Building and Environment 59. p.164-176- Abstract
- To analyse the moisture performance of wall systems with a ventilated rainscreen cladding, the air change rate per hour (ACH) is required. However, the average ACH and its variation depend on many factors. This study focuses on performing field measurements of air velocities and temperatures in south oriented wall cavities characterised by either vertical wooden battens or horizontal vented metal battens. A physical cavity airflow model together with laboratory test of loss factors were used to analyse the data and interpret the results. With vertical battens, findings estimated the average ACH during a measurement period to be 230-310 ACH. In the cavities with horizontal battens, the ACH was 60-70% lower. The daily variations were... (More)
- To analyse the moisture performance of wall systems with a ventilated rainscreen cladding, the air change rate per hour (ACH) is required. However, the average ACH and its variation depend on many factors. This study focuses on performing field measurements of air velocities and temperatures in south oriented wall cavities characterised by either vertical wooden battens or horizontal vented metal battens. A physical cavity airflow model together with laboratory test of loss factors were used to analyse the data and interpret the results. With vertical battens, findings estimated the average ACH during a measurement period to be 230-310 ACH. In the cavities with horizontal battens, the ACH was 60-70% lower. The daily variations were considerable and hours with solar radiation and clear skies resulted in ACH that exceeded the average values 2-3 times. In contrast to airflow induced by thermal buoyancy, wind-induced airflow was irregular with frequent changes in both velocity and direction. This pattern was observed independent of the angle between the wind and the cladding. The frequent changes in flow direction significantly reduced the efficiency of wind-driven airflow to create air exchange. The wind-induced airflow in wall cavities with a pronounced non-linear relationship between the driving force and the air velocity is suppressed in the presence of buoyancy. For rainscreen claddings exposed to many hours of solar radiation, this effect increases the possibility of accurate estimations of ACH. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/3166673
- author
- Falk, Jörgen LU and Sandin, Kenneth LU
- organization
- publishing date
- 2013-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Air change rate, Batten configuration, Cavity airflow model, Driving force, Loss factor, Ventilated cavity
- in
- Building and Environment
- volume
- 59
- pages
- 164 - 176
- publisher
- Elsevier
- external identifiers
-
- wos:000314371900017
- scopus:84870446352
- ISSN
- 1873-684X
- DOI
- 10.1016/j.buildenv.2012.08.017
- language
- English
- LU publication?
- yes
- id
- ec9db466-b111-4e13-bdc9-0e423d305970 (old id 3166673)
- date added to LUP
- 2016-04-01 14:28:03
- date last changed
- 2022-03-14 06:04:29
@article{ec9db466-b111-4e13-bdc9-0e423d305970, abstract = {{To analyse the moisture performance of wall systems with a ventilated rainscreen cladding, the air change rate per hour (ACH) is required. However, the average ACH and its variation depend on many factors. This study focuses on performing field measurements of air velocities and temperatures in south oriented wall cavities characterised by either vertical wooden battens or horizontal vented metal battens. A physical cavity airflow model together with laboratory test of loss factors were used to analyse the data and interpret the results. With vertical battens, findings estimated the average ACH during a measurement period to be 230-310 ACH. In the cavities with horizontal battens, the ACH was 60-70% lower. The daily variations were considerable and hours with solar radiation and clear skies resulted in ACH that exceeded the average values 2-3 times. In contrast to airflow induced by thermal buoyancy, wind-induced airflow was irregular with frequent changes in both velocity and direction. This pattern was observed independent of the angle between the wind and the cladding. The frequent changes in flow direction significantly reduced the efficiency of wind-driven airflow to create air exchange. The wind-induced airflow in wall cavities with a pronounced non-linear relationship between the driving force and the air velocity is suppressed in the presence of buoyancy. For rainscreen claddings exposed to many hours of solar radiation, this effect increases the possibility of accurate estimations of ACH.}}, author = {{Falk, Jörgen and Sandin, Kenneth}}, issn = {{1873-684X}}, keywords = {{Air change rate; Batten configuration; Cavity airflow model; Driving force; Loss factor; Ventilated cavity}}, language = {{eng}}, pages = {{164--176}}, publisher = {{Elsevier}}, series = {{Building and Environment}}, title = {{Ventilated rainscreen cladding: Measurements of cavity air velocities, estimation of air change rates and evaluation of driving forces}}, url = {{http://dx.doi.org/10.1016/j.buildenv.2012.08.017}}, doi = {{10.1016/j.buildenv.2012.08.017}}, volume = {{59}}, year = {{2013}}, }