Evaluation of thermal conductivity in air permeable concrete for dynamic breathing wall construction

Wong, Jim Min; Glasser, F. P.; Imbabi, M.S.

doi:10.1016/j.cemconcomp.2007.04.008

Cited by 61 publications

(36 citation statements)

References 11 publications

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“…The first step has been the evaluation of the porosity ε. After preparing some dedicated samples with the same features of the Breathing Wall previously described, the Archimedes method was used, as suggested in [21]. The obtained result is ε=(30±2)%.…”

Section: Air Permeable Concrete and Wall Samplementioning

confidence: 99%

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Experimental investigation of the steady state behaviour of Breathing Walls by means of a novel laboratory apparatus

Alongi

Angelotti

Mazzarella

2017

Building and Environment

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Breathing Walls are envelope components, based on porous materials, crossed by a natural or forced airflow. Since they behave both as recovery heat exchangers and active insulation, reducing the conductive heat flux, they represent a promising envelope technology, allowing to reduce energy consumption in buildings.From the modeling point of view, an analytical model can be found in literature, describing heat and mass transfer across Breathing Walls in steady state conditions. However, to the best of the authors' knowledge, the model lacks an exhaustive experimental validation. Therefore, in this paper, the novel laboratory apparatus named Dual Air Vented Thermal Box developed at Politecnico of Milano is presented. The apparatus is used to experimentally investigate the steady state behavior of a 1 m 2 Air Permeable Concrete sample, crossed by an airflow at different velocities up to 12 mm/s.The temperature profile inside the sample, measured in different positions, is compared with the model predictions. While in the central portion of the wall a very good agreement is found, the experimental results at the top and at the bottom of the wall suggest a non-uniform velocity field entering the sample. A qualitative confirmation of this hypothesis is provided by CFD simulations on the apparatus, clearly showing a mixed convection regime on both sides of the wall. The results lead to state the validity of the one-dimensional analytical model in literature, although a careful application should take into account adjusted boundary conditions, consisting in an airflow velocity possibly variable with height.

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Section: Air Permeable Concrete and Wall Samplementioning

confidence: 99%

“…This material, also known as Air Permeable Concrete (APC) [21], is a cement based mixture produced without using small diameter aggregates. The final result is a highly porous hardened solid matrix, with highly interconnected pores.…”

Section: Air Permeable Concrete and Wall Samplementioning

confidence: 99%

Experimental investigation of the steady state behaviour of Breathing Walls by means of a novel laboratory apparatus

Alongi

Angelotti

Mazzarella

2017

Building and Environment

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“…Additionally, Wong et al (2007) and Sommerville et al (2011) identify that variation in the pore size of NFC walls also influences the thermal performance of the wall. The nominal void size in a NFC wall ranges from 1.89 to 6.57 mm (Sommerville et al, 2011).…”

Section: Nfc Homes Thermal Performancesmentioning

confidence: 98%

No‐fines concrete homes: atypical thermal performances

Craig

Sommerville²,

Charles³

2013

Structural Survey

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Purpose -This paper is a continuation of "No-fines concrete in the UK social housing stock: 50 years on" published in Issue 4 of Volume 29 of this journal. It identifies the thermal performance of existing, un-refurbished no-fines concrete (NFC) walls; as about 33,000 NFC homes exist in Scotland. A majority of these properties are owned by social housing providers (SHPs) and are being upgraded to current building standards. Literature identifies the thermal performance (U-value) of NFC walls ranging from 1.1 W/m 2 K to 2.0 W/m 2 K depending on the build-up of the structure. The homes are classified as "hard to treat" and, as a result, the occupants experience "fuel poverty". SHPs currently adopt a range of measures to refurbish NFC properties and adopt a broad brush approach, refurbishing a range of non-traditional (NT) constructed dwellings under similar refurbishment packages. The purpose of this paper is to call for a re-think in terms of such refurbishment approaches when seeking to improve the thermal performance of NFC properties. Design/methodology/approach -Various cores were extracted from NFC homes in the West of Scotland to explore the heterogeneity of NFC construction. To measure the thermal performance of existing NFC homes, in situ u-value calculations were undertaken through case studies and fieldwork. Findings -The findings of this research highlight the heterogeneity of NFC construction. The paper discusses the different approaches adopted by SHPs and identifies the variations between individual NFC elements resulting from workmanship and build issues. Practical implications -The findings expose the heterogeneity of individual NFC elements and further suggest that any decision to adopt a refurbishment approach must be based on a detailed consideration of the existing characteristics of the property including location and orientation of the property. Originality/value -This paper is the first to discuss the in situ u-values of NFC properties in the last 20 years. It will be of interest to SHPs planning to refurbish such properties.

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“…Wong et al [42] reported that the thermal conductivity coefficients of pervious concrete with normal aggregate ranged from 0.19 to 1.49 W/m K depending on the degree of filling and water to cement ratio of cement paste. Zaetang et al [24] and Chindaprasirt et al [40] reported the thermal conductivities of 0.15-0.27 W/m K for pervious concrete with porous lightweight aggregate.…”

Section: Thermal Conductivitymentioning

confidence: 99%