The role of specific heat capacity on building energy performance and thermal discomfort

The key role of the building and construction sector, in terms of sustainability and decarbonization, has led building codes to tighten mandatory requirements related to buildings energy performance. Envelope quality, beyond light efficiency or the renewable energy contribution, is a key factor since the highest percentage of energy consumption is produced by thermal losses through enclosures. Therefore, building codes have significantly increased the mandatory benchmarks for equivalent thermal transmittance. However, the specific heat capacity (SHC) has commonly been overlooked in the discussion. Thus, in order to estimate the impact of such parameter in the energy consumption and thermal comfort of residential and non-residential buildings, a building model has been simulated by means of Transfer Functions Methods and the Finite Difference Methods. A traditional double brick façade has been considered and the SHC of bricks has been varied from 800 to 1800 kJ/kg K. The thermal behavior of the building has been assessed at several locations in accordance with the Spanish building code. In addition, building orientation has also been shifted from north to south. Although passive strategies have not been considered, the results show significant energy savings (i.e. up to 20%) and a reduction of thermal discomfort (i.e. up to 20%), depending on the type of building and its location

Replacement of Natural Sand with Expanded Vermiculite in Fly Ash-Based Geopolymer Mortars

Increasing the thermal insulation of building components to reduce the thermal energy loss of buildings has received significant attention. Owing to its porous structure, using expanded vermiculite as an alternative to natural river sand in the development of building materials would result in improvement of the thermal performance of buildings. This study investigates the properties of fly ash (FA)-based geopolymer mortars prepared with expanded vermiculite. The main aim of this study was to produce geopolymer mortar with lower thermal conductivity than conventional mortar for thermal insulation applications in buildings. A total of twelve batches of geopolymers were prepared for evaluating their different properties. The obtained results show that, at a given FA and expanded vermiculite content, the geopolymers prepared with a 10 molar NaOH solution exhibited a higher flowability, water absorption and porosity, as well as a lower dry unit weight, compressive strength, ultrasound pulse velocity and thermal conductivity compared with those prepared with a 15 molar NaOH solution. As is also shown, the geopolymers containing expanded vermiculite (15%) developed a lower flowability (~6%), dry unit weight (~6%), compressive strength (~7%), ultrasound pulse velocity (~6%) and thermal conductivity (~18%), as well as a higher apparent porosity (~6%) and water absorption (~9%) compared with those without expanded vermiculite at a given FA content and NaOH concentration. The findings of this study suggest that incorporating expanded vermiculite in FA-based geopolymer mortar can provide eco-friendly and lightweight building composites with improved sound and thermal insulation properties, contributing toward the reduction of the environmental effects of waste materials and conservation of natural sand

Properties of lightweight concrete blocks with waste zeolitic tuff

El artículo presenta el estudio de los efectos de la ceniza volcánica en las propiedades mecánicas y térmicas de blocks de concreto ligero

Materiales de reciclo y su uso en el mejoramiento del concreto

Atendiendo a la regla de las “tres erres” (reducir, reciclar y reusar), cuya meta consiste en establecer una sociedad orientada al reciclaje, en este capítulo se aborda la problemática de los materiales de desecho y su uso en el mejoramiento del concreto, abriendo un panorama hacia la sustentabilidad del mismo, al producir un concreto ambientalmente amigable

Polymer concrete reinforced with luffa fibers: effect of gamma radiation

The interest of many research groups regarding manufacture of composite materials by using natural fibers is increasing world-wide. The main objectives involve the improvement of mechanical properties, mainly those related to resistance and elasticity. In the present study in a first stage, polymer concrete specimens were elaborated by using an unsaturated polyester resin, silica sand and luffa fibers; after, they were gamma irradiated at different doses and their mechanical properties were evaluated. Two different silica particle sizes (0.15 mm and 0.6 mm), and four different luffa fiber concentrations (0.3, 0.6, 0.9 and 1.2 wt%) were used, as well as 50 and 100 kGy of radiation dose. The results show a gradually diminution of compressive strength and modulus of elasticity when adding luffa fiber concentration. Nevertheless, such mechanical features are increasing when polymer concrete is gamma irradiated.Autonomous University of the State of Mexico (UAEM), Grant 3408/2013M (Megaproyecto

Microstructure and physical properties of clayey-ceramic materials with lightweight mineral additives

Low density ceramic structures have an important place in application areas such as heat, noise and noise insulation. Besides, being durable and inexpensive is also a demand for producers and consumers. In this study, it is aimed to produce lightweight insulation ceramic materials from a binder clay containing diatomite and vermiculite raw materials in different proportions which is a local and natural mineral raw material source for low temperature applications. For this purpose, firstly, powdered raw materials is characterized for particle size distribution, chemical composition (x-ray fluorescence, XRF), thermal behavior (thermal gravimetric analysis, TGA), morphological structure (scanning electron microscope, SEM) and crystal phase structure (x-ray diffraction, XRD). Specific prescriptions were then prepared and pellet samples were obtained using the pressing method. The bulk density and porosity, dimensional changes, thermal conductivity coefficients and microstructural properties of the samples fired at temperatures between 900, 1000 and 1100 °C were compared. As a result of the study, the porosity of the ceramic samples containing 60% diatomite, 10% vermiculite and 30% binder clay increased up to 47%, while the bulk density values were obtained at 1.3 g/cm3 and the thermal conductivity coefficient was at 0.439 W / mK