/library/oar/handle/123456789/470 2025-11-09T01:17:07Z 2025-11-09T01:17:07Z Caruso, Luca Buhagiar, Vincent M. /library/oar/handle/123456789/138914 2025-09-11T07:42:30Z 2024-06-01T00:00:00Z

Title: The Double C Block project : hot box studies deploying heat flux method inside the hot box apparatus to enhance the measurement of the block’s thermal transmittance Authors: Caruso, Luca; Buhagiar, Vincent M. Abstract: The Double C-Block (DCB) is an innovative Concrete Masonry Unit (CMU) with embedded insulation developed to provide, through its geometry, both thermal and acoustic performance, apart from its established load bearing capacity. The DCB is a proven faster construction process as it eliminates the need for external/internal insulation cladding. The first load-bearing prototype developed at the University of Malta was made of two concrete C-shaped skins bonded with sprayed polyurethane foam (PUF) as the insulation layer. Earlier studies through full-scale in-situ test cells reported thermal transmittance value UDCB of 1.47 W/m2K, already outperforming the local building energy code. When running steady-state simulations Finite Element Method (FEM), results persistently showed a difference in U-values, when compared to field studies. The methodology was therefore revisited to combine these field studies with hot-box apparatus as well as performing a new set of steady-state FEM simulations by using experimental values of concrete and PUF’s thermal conductivity (TC). The latest U-value is now proven to be 1.40 W/(m2K) thanks to the use of Heat Flux Method (HFM) inside a hot box apparatus. This brings the performance gap down from 51% to a more precise 11%. This establishes the DCB as an alternative to the standard hollow core blocks plus insulation cladding. These results now push it up the technology readiness levels scale(TRL), from TRL4 to TRL6, thus lined up for commercial production.

2024-06-01T00:00:00Z Bonello Ghio, Alexia Caruso, Luca Buhagiar, Vincent M. /library/oar/handle/123456789/138913 2025-09-11T07:35:03Z 2024-06-01T00:00:00Z

Title: Acoustic performance of the Double C-Block : the tune of sustainable design Authors: Bonello Ghio, Alexia; Caruso, Luca; Buhagiar, Vincent M. Abstract: Hollow Concrete Blocks (HCB) greatly under-perform, from an acoustical point of view, due to loss of solid mass negatively impacting the wall’s acoustic and thermal performance. An innovative Double C-Block (DCB) aims to offer a competitive technology able to replace the HCB, with a design that inhibits noise transmission, by virtue of its unique geometry and embedded triple layered, S-shaped polyurethane foam. Acoustic performance of the two blocks was compared by in-situ testing of two identical test cells, as well as a laboratory testing of two comparative elements in a hermetically insulated ‘hot-box’, and calculating their respective sound reduction indices (SRI), all in line with established ISO standards. For the DCB, a maximum value of 30dB was estimated using the Mass Law theory. Although there is scope for improvement, the results are highly promising, with the DCB already exceeding in acoustic (and thermal) performance over the HCB. This should augur well for the use of the DCB in facades to mitigating traffic noise as well as domestic noise between third party walls. The purpose of this article is to disseminate scientific evidence in favour of the DCB's acoustic performance, with a potential upgrade from technology readiness level TRL4, as laboratory-grade prototype testing, to TRL6, lined up ready for full-scale production.

2024-06-01T00:00:00Z Sacco, Jeremy Micallef, Daniel Borg, Simon Paul /library/oar/handle/123456789/138182 2025-08-19T10:57:09Z 2025-01-01T00:00:00Z

Title: Passive barriers for improved air quality in pedestrian zones at adult and child breathing height Authors: Sacco, Jeremy; Micallef, Daniel; Borg, Simon Paul Abstract: Pedestrians are increasingly affected by air pollution, primarily due to vehicular emissions in densely populated areas. This issue motivates the exploration of passive solutions to improve air quality in pedestrian zones at heights relevant to adults and children. Existing literature indicates a significant gap in understanding the effectiveness of low lying barrier configurations in mitigating pollutant concentrations within pedestrian zones. This study aims to address this gap by investigating the impact of different barrier designs at both adult and child breathing levels and to assess whether their inclusion applies to both the leeward and the windward pedestrian zones. We employed a Computational Fluid Dynamics (CFD) methodology, validated with site measurements, to simulate the aerodynamic effects of various barrier configurations on gaseous (NO2 ) pollutant dispersion in a typical urban street canyon. The barriers examined include fully vegetative, mixed solid-vegetative barriers and their segmented variants. Key results from our simulations indicate that fully vegetative barriers significantly reduce pollutant concentrations at both child and adult breathing heights by 70% and 50%, while partly solid barriers cause stagnation points that are detrimental particularly to children. The impact of this research is particularly relevant to urban planners seeking to implement effective green infrastructure in street canyon-like urban zones.

2025-01-01T00:00:00Z Caruso, Luca Rochman, Arif Buhagiar, Vincent Michael /library/oar/handle/123456789/138077 2025-08-12T11:19:05Z 2025-01-01T00:00:00Z

Title: Thermo-mechanical behaviour of fossil-based and bio-based polyurethane foams for building construction Authors: Caruso, Luca; Rochman, Arif; Buhagiar, Vincent Michael Abstract: Polyurethane foams (PUF) are well-known materials in building construction. Innovative biobased polyurethane foams (BPUF) offer competitive alternatives to fossil-based formulations with the ongoing research driven by environmental and health concerns. In this paper, a comparison between an off-the-shelf fossil-based PUF and a custom-made BPUF was conducted. BPUF is based on a chemical formulation that replaces up to 70% of the main fossil-based reactants—polyol and isocyanate— with non-fossil alternatives. Both foams were embedded in the cavity of loadbearing composite masonry units as their insulation layer and binding agent. It was observed that while the density of fossil-based PUF inside the block completely changed from free-foamed declared values, the density of BPUF instead remained consistent to declared values. BPUF has also more (but smaller) number of pores than PUF detected by the microscope. Both types of foam samples were extracted from the block cavities and via dynamic scanning calorimetry (DSC) they were not undergoing any post-curing effects within the temperature working range of interest (10 °C−40 °C) hence they both perform at their best. The combination of such analyses with the results obtained from dynamic mechanical analyzer (DMA) shows that a carefully manufactured, custom-made mid density BPUF can outperform, in average, the mechanical properties of an all-purpose fossil-based PUF in both shear and tensile mode. The latter are stresses applied to the foam when the area of the block is either partially or fully loaded in compression mode. BPUF reached averages of E’ of 33.4 MPa (30 times higher than PUF) at 10 °C and 29.23 MPa (43.62 times over PUF) at 40 °C. In shear mode averages of G’ of 9.27 MPa (12.19 times higher than PUF) at 10 °C and 8.12 MPa (18.45 times higher than PUF) at 40 °C. Furthermore, both types of foam reached the lowest values of elastic modules in tensile and shear mode at their respective glass transition temperature measured by the DSC.

2025-01-01T00:00:00Z