• Energy Research

Abstract The use of building materials with high moisture buffering capacity is a well-recognized strategy to moderate the variation of indoor moisture loads. Many researchers investigated the ability and potential of finishing materials and furniture for the reduction of the amplitudes of indoor relative humidity by characterising their Moisture Buffering Value. Nevertheless, the recent and widespread building practice, which is increasingly trying to reduce the air permeability and thermal transmittance of the envelope, is likely to even worsening indoor humidity conditions, with consequences for durability of materials and inhabitants’ comfort and health. Very performing materials are then needed to act as buffering and quickly dampen high moisture loads. This paper proposes the design of a building internal counter wall equipped with an "active" moisture buffering device. This is able to measure the indoor relative humidity and consequently increase the adsorbing capacity of a porous material through an air-flow. Experimental activities were carried out on different prototypes with the combination of granular Sepiolite with two different pore structures and nonwoven fabrics. The devices effectiveness in terms of MBV has been dynamically tested in a climate chamber according to the DTU Nordtest method. Different “activation” times against several humidity levels were set in order to assess the best solution in different scenarios.

Abstract The use of building materials with high moisture buffering capacity is a well-recognized strategy to moderate the variation of indoor moisture loads. Many researchers investigated the ability and potential of finishing materials and furniture for the reduction of the amplitudes of indoor relative humidity by characterising their Moisture Buffering Value. Nevertheless, the recent and widespread building practice, which is increasingly trying to reduce the air permeability and thermal transmittance of the envelope, is likely to even worsening indoor humidity conditions, with consequences for durability of materials and inhabitants’ comfort and health. Very performing materials are then needed to act as buffering and quickly dampen high moisture loads. This paper proposes the design of a building internal counter wall equipped with an "active" moisture buffering device. This is able to measure the indoor relative humidity and consequently increase the adsorbing capacity of a porous material through an air-flow. Experimental activities were carried out on different prototypes with the combination of granular Sepiolite with two different pore structures and nonwoven fabrics. The devices effectiveness in terms of MBV has been dynamically tested in a climate chamber according to the DTU Nordtest method. Different “activation” times against several humidity levels were set in order to assess the best solution in different scenarios.

Abstract In the aftermath of catastrophic events, lightweight construction systems are often used to build temporary emergency architectures. However, if suitable environmental control systems are not present, as may occur in post-disaster scenarios, these buildings provide poor indoor thermal conditions, especially in hot climates, which may jeopardize the occupants’ physical and mental health in case of longer periods of occupations. In these contexts, passive cooling techniques are the preferred strategies to improve the indoor thermal environment. However, only a few papers evaluated the effectiveness of these measures on emergency buildings, also considering calibrated simulations, different climates, costs, and operational feasibility. In this work, the thermal performance of a novel emergency construction system, still not sufficiently studied in the literature and based on the assembly of 3D-reinforced EPS panels, is examined. First, a numerical model of an experimental unit is calibrated on experimental data. Then, the thermal performance in hot and temperate climates of a reference building, recently adopted in emergency scenarios, is numerically evaluated and improved through passive cooling measures, i.e. shading, thermal buffering, natural ventilation, and cooling materials. Results show high summer thermal discomfort in all climates. The efficacy of the different measures depends on climatic contexts, with natural ventilation, combined with cool roof materials or blinds (for temperate and hot climates, respectively), providing the best trade-off between thermal comfort, costs, and feasibility. However, the summer indoor thermal discomfort cannot be completely reduced. This study helps decision-makers and people to correctly improve the living conditions and sustainability of emergency architectures.

Abstract In the aftermath of catastrophic events, lightweight construction systems are often used to build temporary emergency architectures. However, if suitable environmental control systems are not present, as may occur in post-disaster scenarios, these buildings provide poor indoor thermal conditions, especially in hot climates, which may jeopardize the occupants’ physical and mental health in case of longer periods of occupations. In these contexts, passive cooling techniques are the preferred strategies to improve the indoor thermal environment. However, only a few papers evaluated the effectiveness of these measures on emergency buildings, also considering calibrated simulations, different climates, costs, and operational feasibility. In this work, the thermal performance of a novel emergency construction system, still not sufficiently studied in the literature and based on the assembly of 3D-reinforced EPS panels, is examined. First, a numerical model of an experimental unit is calibrated on experimental data. Then, the thermal performance in hot and temperate climates of a reference building, recently adopted in emergency scenarios, is numerically evaluated and improved through passive cooling measures, i.e. shading, thermal buffering, natural ventilation, and cooling materials. Results show high summer thermal discomfort in all climates. The efficacy of the different measures depends on climatic contexts, with natural ventilation, combined with cool roof materials or blinds (for temperate and hot climates, respectively), providing the best trade-off between thermal comfort, costs, and feasibility. However, the summer indoor thermal discomfort cannot be completely reduced. This study helps decision-makers and people to correctly improve the living conditions and sustainability of emergency architectures.

AbstractMany countries, for aesthetic purposes, offer economic advantages (tax deductions, incentives, etc..) for the installation of building integrated photovoltaic modules (BIPV), with water-tightness capability and adequate mechanical resistance in order to substitute tile covering or part of it. Nevertheless, poor or absent ventilation under BIPV panels could cause them to overheat and reduce their efficiency.It is well established that the presence of an air gap between a photovoltaic (PV) module and roof covering facilitates ventilation cooling under the device and consequently reduces cell temperature and improves its performance.In this study, we investigated the thermal performance of PV modules installed in a real scale experimental building over a traditional clay tile pitched roof in Italy for almost one year (from August 2009 to June 2010). One PV module was rack-mounted over the roof covering with a 0.2 m air gap; the others were fully integrated and installed at the same level of the roof covering (one with an air gap of 0.04 m, the other mounted directly in contact with the insulation). Temperature and heat flux measurements for each panel, and environmental parameters were recorded.Experimental results demonstrate that even though the rack-mounted PV module constantly maintains cell temperature below that of the other full-building integrated modules, due to the presence of a higher air gap, the difference in the energy produced by the PV modules estimated for the entire monitoring period is less than 4%.

AbstractMany countries, for aesthetic purposes, offer economic advantages (tax deductions, incentives, etc..) for the installation of building integrated photovoltaic modules (BIPV), with water-tightness capability and adequate mechanical resistance in order to substitute tile covering or part of it. Nevertheless, poor or absent ventilation under BIPV panels could cause them to overheat and reduce their efficiency.It is well established that the presence of an air gap between a photovoltaic (PV) module and roof covering facilitates ventilation cooling under the device and consequently reduces cell temperature and improves its performance.In this study, we investigated the thermal performance of PV modules installed in a real scale experimental building over a traditional clay tile pitched roof in Italy for almost one year (from August 2009 to June 2010). One PV module was rack-mounted over the roof covering with a 0.2 m air gap; the others were fully integrated and installed at the same level of the roof covering (one with an air gap of 0.04 m, the other mounted directly in contact with the insulation). Temperature and heat flux measurements for each panel, and environmental parameters were recorded.Experimental results demonstrate that even though the rack-mounted PV module constantly maintains cell temperature below that of the other full-building integrated modules, due to the presence of a higher air gap, the difference in the energy produced by the PV modules estimated for the entire monitoring period is less than 4%.

Abstract The aim of this study was to assess the influence of thermal mass placed on the inner side of the building envelope, described as the dynamic internal areal heat capacity (International Standard ISO 13786), on the summertime thermal comfort in buildings characterised by high internal heat loads. To that aim, simultaneous monitoring was carried out on rooms with high internal heat loads (school classrooms), varying the internal inertia of the envelope through the introduction of an insulating panel on the interior side. Analytical assessment was performed in order to include different inertia values and combinations of both external and internal heat loads. The study allowed the threshold values of internal areal heat capacity to be determined with respect to the different periodic transmittance values of the walls, assessed according to the adaptive thermal comfort model described in Standard EN15251. These values could be adopted in energy saving regulations which, being based on semi-stationary calculation models, tend to consider the performance of building envelopes as analogous even if there is different thermal inertia.