Ventilated rainscreen cladding: A study of the ventilation drying process

Falk, Jørgen; Sandin, Kenneth

doi:10.1016/j.buildenv.2012.11.015

Cited by 24 publications

(9 citation statements)

References 6 publications

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“…A further study by Falk and Sandin [39] explored the connection between air cavity design, air change rate, and ventilation drying processes. Calculations and mathematical models were employed and compared to field studies from the previous article from Università di Napoli Federico II.…”

Section: Façadesmentioning

confidence: 99%

Microclimate of Air Cavities in Ventilated Roof and Façade Systems in Nordic Climates

2022

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Accurate values for the climatic conditions in an air cavity, hereby called the microclimate, are crucial when calculating and simulating the performance of a ventilated roof and façade system. The climatic stress of its components and their mould and rot potential influence the long-term durability of the roof or façade. A scoping study is conducted to gain an overview on research and the scientific literature on the microclimate of air cavities in ventilated roofing and claddings in Nordic climates. From the body of the research literature, 21 scientific works were of particular interest, and their findings are summarized. The review shows that only a limited number of studies discuss the microclimate of air cavities. Roofs are discussed to a greater and more varied degree compared to façades and air cavities behind solar panels. However, the results cannot be compared and validated against each other to generally describe the microclimate of air cavities, as the surveyed papers approach the subject differently. This knowledge gap indicates that calculations and simulations can be performed without knowing whether the results represent reality. If the structure of ventilated roof and façade systems are only designed based on experience, it can be difficult to be proactive and adapt to future climate changes. Further studies are needed to determine the relation between the exterior climate and the air cavity microclimate, so that future climate predictions can be used to simulate the long-term performance of ventilated roof and façade systems.

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Section: Façadesmentioning

confidence: 99%

Microclimate of Air Cavities in Ventilated Roof and Façade Systems in Nordic Climates

2022

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“…where h r is the heat transfer coefficient of radiation (W/m 2 K) and R int is the R value between the wind barrier surface and indoor air (m 2 K/W). The convective heat transfer coefficient between cavity surfaces and cavity air is estimated with equation (A.10) (Falk and Sandin, 2013b):…”

Section: Fundingmentioning

confidence: 99%

Factors affecting the performance of ventilation cavities in highly insulated assemblies

Viljanen

Lü

Puttonen

2021

Journal of Building Physics

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The article presents experimental studies of typical Finnish highly insulated (HI) envelopes with thermal resistance values ( R value) for the wall and roof inside the ventilation cavity between 7.7 and 8.1 m2K/W and 13 m2K/W, respectively. The conditions in the ventilation cavities were studied by using typical and increased R values for the exterior part of the cavity, which were 0.18 m2K/W and 1.57 m2K/W in the walls, and 0.13 m2K/W and 2.13 m2K/W for the roof. With higher exterior R values of 1.57 m2K/W and 2.13 m2K/W, the cavity temperature increased only after closing the inlet gap of the cavities. If the cavity inlet was closed, the restriction of the outlet gap from 20–25 mm to 10 mm had no significant effect on the temperatures. A closed ventilation inlet resulted in increased absolute humidity in the cavity, which indicates that the restriction of cavity ventilation should be made with care to avoid impairing the drying-out ability. The computational analysis showed that the optimal air change rates in the wall and roof cavities of HI structures were 4–40 1/h and 20 1/h, respectively. The conventional 22-mm-thick wood cladding enables safe cavity conditions in HI walls if the vapor barrier is vapor tight and other moisture sources are low. A lower heat flux and additional heat loss caused by cloudless sky at night support the observation that HI roofs have a higher moisture risk. In HI roofs, a conventional exterior R value of 0.13 m2K/W should at least be increased to the range of 0.3–0.4 m2K/W, which is achieved, for example, by a 20-mm-thick mineral wool board under the roofing. The use of mold-resistant materials in the ventilation cavity is recommended to mitigate the possible ramifications of the moisture behavior of HI roofs.

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“…The coefficient K represents the ratio of the velocity measured in the middle the cross section to the average velocity (K = 0.89). A similar approach is presented in [18] and leads to values ranging from 0.6 to 0.9, depending on the duct geometry and on the airflow rate. .…”

Section: Estimation Of the Global Airflow Ratementioning

confidence: 99%

Experimental assessment of a PCM to air heat exchanger storage system for building ventilation application

Labat

Virgone

David

et al. 2014

Applied Thermal Engineering

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International audienceThis paper presents a heat exchanger prototype containing PCM material designed to provide a 1kW heating power during 2 hours (i.e. energy storage of 2kWh). The exchanger is tested in a closed-loop wind tunnel, used to provide constant airflow rates with temperature changes selected so that the PCM is allowed to melt, then to solidify. Temperature and air velocity measurements are achieved for eight airflow rates and the heating power is estimated. The second objective of this work is to provide detailed results suitable with the validation of numerical models. Therefore, the geometry of the exchanger is detailed and the uncertainty associated with the heating power measurement is given. Results show that enough energy is stored in the exchanger, yet the heating power is lower than 1kW before 2 hours because of the use of a of constant airflow rate during the tests. On the other hand, the global behaviour of the heat exchanger is rather simple, which gives confidence in using a simplified approach in further work and help with optimising the current prototype

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Ventilated rainscreen cladding: A study of the ventilation drying process

Cited by 24 publications

References 6 publications

Microclimate of Air Cavities in Ventilated Roof and Façade Systems in Nordic Climates

Microclimate of Air Cavities in Ventilated Roof and Façade Systems in Nordic Climates

Factors affecting the performance of ventilation cavities in highly insulated assemblies

Experimental assessment of a PCM to air heat exchanger storage system for building ventilation application

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