Determination of thermal characteristics of standard and improved hollow concrete blocks using different measurement techniques. (September 2017)

• Record Type: Journal Article
• Authors: Caruana, C.; Yousif, C.; Bacher, P.; Buhagiar, S.; Grima, C.
• Is Part Of: Journal of building engineering. Volume 13(2017)
• Page Start: 336
• Page End: 346
• Publication Date: 2017-09
• Subjects: U-value Value of thermal transmittance (W/m2 K) -- HCB Hollow concrete block -- HVAC Heating, ventilation and air-conditioning -- ARX-model Autoregressive model with exogenous inputs -- HFM Heat flow meter method -- IRM Infrared method -- OA Orthogonal array -- LECA Lightweight expanded clay aggregate -- EPS Expanded polystyrene -- q Heat flux (W/m2) -- k Thermal conductivity (W/m K) -- DT Temperature differential (K) -- L Thickness of material (m) -- G Global solar radiation (W/m2) -- ACF Auto-correlation function -- CCF Cross-correlation function -- H Sum of UA-value and convection losses (W/K) -- UA-value Value of the product of the U-value and the area perpendicular to the direction of heat transmittance (W/K) -- A Area perpendicular to the direction of heat transmittance (m2) -- HLC Total heat loss coefficient (W/K); Hollow-core concrete block -- Heat flow -- Infrared -- Insitu -- Building envelope -- Malta; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2017.09.005
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: The lighter weight, improved thermal properties and better acoustic insulation of hollow-core concrete blocks are few of the characteristics that one encounters when comparing them to traditional Maltese globigerina limestone solid blocks. As a result, hollow concrete blocks have recently been in greater demand. However, their transmittance, or U-value, is still quite high and does not meet the minimum energy requirements for constructing new buildings. This paper is focused on the investigation of the thermal properties of a new building block, developed as part of a nationally-funded research project ThermHCB, with the aim of improving the U-value of such blocks without changing their compressive strength, physical dimensions or manufacturing process. Measurement techniques were applied to obtain comparative values of the thermal transmittance for standard and improved HCBs, using different EN and draft standards. Compressive testing was carried out concurrently in order to ensure that the minimum benchmark compressive strength was reached. The comparison between these results provides information on the reliability of the methodologies used to determine the thermal properties of building elements in-situ, without having to conduct such tests in a laboratory hot box setup. Highlights: A thermally improved hollow concrete block has been manufactured and tested. Thermal improvement of 21% was achieved without affecting compression strength. The block is 24% lighter by mass, thus reducing labour costs and construction time. Insitu and laboratory tests differed by an average of 6%.