Lightweight concrete containing phase change materials (PCMs): A numerical investigation on the thermal behaviour of cladding panels

open4siThe use of phase change materials (PCMs) in building elements has gained increasing popularity in recent years because of the potential energy savings that result from the heat stored during variable temperature–time histories. This paper describes the results of non-linear numerical analyses on sandwich panels characterized by different geometry and consisting of an innovative concrete, i.e., lightweight concrete with aggregates containing PCMs. The amount of embedded PCMs has no equal in the literature, and this calls for a detailed assessment of its thermal performance within a typical building element. The heat transfer process inside the panels is modelled via finite elements in order to evaluate the effectiveness of the addition of PCMs with regard to insulation. The results show that adding PCMs may significantly reduce (by up to 20%) the energy required for cooling in the hot season, while the reduction of the energy required for heating in the cold season is lower (up to 10%). Moreover, there is a significant reduction in the instantaneous power required, both for heating and cooling.openP. Bamonte, A. Caverzan, N. Kalaba, M. Lamperti TornaghiBamonte, P.; Caverzan, A.; Kalaba, N.; Lamperti Tornaghi, M

Computational study on prestressed concrete members exposed to natural fires

The present paper is aimed at investigating the structural behaviour in bending of prestressed concrete members exposed to natural fires, i.e. fires with a heating and a cooling phase. The fire scenarios considered are characterized by a heating phase that coincides with the ISO834 standard fire and a linear cooling branch. To accurately track the structural behaviour, the usual constitutive models for concrete, ordinary and prestressing steel at high temperature are adapted to account for the different behaviour of the materials upon unloading and cooling. Parametric analyses are carried out on typical prestressed sections (an I-girder and a double-tee), in order to highlight the detrimental effect of longer fire durations (up to 120 min) and lower cooling rates (3 °C/min) as well as the variability of the structural behaviour with the variation of the load level. The results show that in members characterized by massive sections (I-girder in the present study) and exposed to natural fires, limiting the attention to the heating phase is not sufficient, as the maximum temperature in the prestressing steel may be reached long (even hours) after the onset of cooling (in accordance with tests reported in the literature), leading to delayed failure. Moreover, within the range of variation of the cooling rate (3–10 °C/min, ranging from slow to fast cooling) and load level (M/M u = 0.15–0.30, ranging from low to high load ratio), the structural behaviour exhibits significant variations in the cooling phase of the fire, from an almost complete recovery of the initial configuration to runaway failure

Lightweight Concrete containing Phase Change Materials (PCMs): A Numerical Investigation on the Thermal Behaviour of Cladding Panels

Buildings use 40% of the total European Union (EU) energy consumption and generate 36% of the Union’s CO 2 emissions. Indeed, according to U.S. Department of Energy (DoE) estimates the building envelope typically impacts 57% of a building’s thermal loads. More than 20% of the energy consumed in the EU literally flows out of building envelopes and with a similar iimpact in terms of greenhouse gases. Hence claddings are a key mechanism by which to address the decarbonisation of the European economy by 2050, where the challenging objective of reducing CO2 emissions by at least 80%, and energy consumption by as much as 50%, must be met. Innovative concepts for new building materials which also increase thermal inertia were proposed in the E4iBuildings project. E4iBuildings aimed to develop and assess an innovative concrete lightweight aggregates containing embedded Phase Change Materials (PCMs). This concrete may be used to manufacture innovative cladding systems (wall panels and blockwork).JRC.E.4-Safety and Security of Building