Thermal design optimization of lightweight concrete blocks for internal one-way spanning slabs floors by FEM

• Published in: Energy and buildings Vol. 41; no. 12; pp. 1276 - 1287
• Main Authors: DEL COZ DIAZ, J. J, GARCIA, P. J, DOMINGUEZ HERNANDEZ, J, SUAREZ SANCHEZ, A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.12.2009; Elsevier
• Subjects: Applied sciences; Buildings; Buildings. Public works; Concrete products; Concretes. Mortars. Grouts; Construction (buildings and works); Energy savings; Exact sciences and technology; External envelopes; Finite element modelling; Floor. Ceiling; Internal hollow block; Lightweight concrete; Lightweight concretes; Materials; Non-linear complex heat transfer; Thermal optimization; Thermal optimization; Finite element modelling; Internal hollow block; Lightweight concrete; Non-linear complex heat transfer; Energy savings; Construction materials; Hollow block; Modeling; Precast concrete block; Optimal design; Geometry; Finite element method; Thermal properties; Numerical simulation; Product development; Mathematical model; Slabs; Precast concrete; Heat transfer
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2009.08.005

In the present work, numerical thermal analysis is used in order to optimize the lightweight hollow block design for internal floors with respect to the energy saving, by the finite element method (FEM). From an initial block design with 0.57 m × 0.25 m × 0.20 m constant external dimensions, other five different configurations were built varying the number the vertical and horizontal intermediate bulkheads. Besides, five different compositions of lightweight concrete have been taken into account, giving place to sixty different configurations of the floors, thirty per each heat flow direction: upward and downward heat flows. Based on the non-linear thermal analysis of the different configurations, it is possible to choose the best candidate block from the CTE rule requirements. Mathematically, the non-linearity is due to the radiation boundary condition inside the inner recesses of the blocks. Also, the temperature distribution and thermal characteristic values of the floors, both for downward and upward heat flows, are provided. From the numerical results, we can conclude that the main variables in the thermal performance are: the number of the horizontal intermediate bulkheads and the material conductivities. Therefore, increasing the number of horizontal intermediate bulkheads and decreasing the material conductivities, the best thermal efficiency is obtained. Optimization of the floors is carried out from the finite element analysis by means of the average mass overall thermal efficiency and the equivalent thermal conductivity. In order to select the appropriate floor satisfying the CTE rule requirements, detailed instructions are given. Finally, conclusions of this work are exposed.