The Effectiveness of PCM Wallboards for the Energy Refurbishment of Lightweight Buildings

Abstract In order to compensate for the small storage capacity of lightweight buildings, that usually suffer from pronounced overheating in summer, the incorporation of Phase Change Materials (PCMs) into the opaque envelope can be an effective way to enhance thermal inertia and to improve the thermal comfort. In particular, PCM wallboards are recommended during refurbishment, as they have a small thickness and can be easily applied on the inner surface of both the walls and the ceiling. In this paper, a comprehensive study is presented about the effectiveness of PCM wallboards for improving summer thermal comfort in existing lightweight buildings. The study is based on dynamic simulations carried out with the software EnergyPlus on a sample office building. The analysis is repeated in four different locations, ranging from Southern Europe (Catania, Italy) to Northern Europe (Paris, France). The results of the simulations may help designers to make the correct choices in terms of position of the PCM wallboards, scheduled rate of nighttime ventilation and value of the peak melting temperature for the specific PCM

The role of shading devices to improve thermal and visual comfort in existing glazed buildings

Abstract Buildings with large glazed surfaces may show severe thermal and visual discomfort issues, as an effect of the large incoming direct solar radiation. In order to avoid excessive solar gains and glare issues to the occupants, it is necessary to adopt suitable solutions that limit the incoming solar radiation, such as highly reflective coatings or movable shading devices. However, such devices must be accurately selected, according to the building location and to the exposure of the glazed facades, while also taking into account possible regulatory measures. This paper evaluates the effectiveness of a series of shading devices applied to an existing office building in Southern Italy. The building shows large glazed surfaces and has no overhangs, thus significant thermal discomfort is perceived in summer by the occupants. The aim is to identify those solutions that allow to improve thermal comfort while also keeping a sufficient illuminance level indoors, without disregarding the compliance with Italian regulations about the installation of shading devices and, of course, the need to keep costs on a reasonable level. The analyses are repeated for different building orientations, in order to provide general information

A review of daylighting strategies in schools: state of the art and expected future trends

The study of daylight conditions within educational buildings has been a topic of interest since the nineteenth century in western countries, and European ones in particular. Although it has been argued that providing a view outside—or even using daylight instead of more stable and manageable artificial light—could reduce students’ performance without providing a pleasant and healthy environment, nowadays it seems that a large consensus upon the need to design well daylit spaces is being reached. This paper reviews how the research community has tackled the task of understanding and solving the complex relationships amongst local climate, users’ needs and design constraints in school buildings by showing the different approaches used and technological solutions suggested. The reported case studies, based either on experimental measurements or on simulations, highlight the need of a comprehensive approach to the topic to fully understand the non‐trivial requirements of a daylit educational environment

Refurbishing an existing apartment block in Mediterranean climate: towards the Passivhaus standard

The Passivhaus standard, although widely appreciated in cold regions, is seldom regarded as a reference in the energy renovation of existing buildings in warm countries. This paper evaluates the effectiveness of a series of strategies for the energy refurbishment of an existing apartment block in Southern Italy, based on dynamic energy simulations. The paper aims to show that, in warm Mediterranean areas, a building refurbishment must not be oriented towards an excessive insulation level. Conversely, if aimed to comply with the Passivhaus standard, the renovation must look above all at those strategies that mitigate the energy needs for space cooling and improve thermal comfort in summer

application of a mapping tool to plan energy saving at a neighborhood scale

Abstract This study proposes the application of a model for the evaluation of the overall energy demand of existing urban neighborhoods, which can be useful when planning energy enhancement strategies at urban scale. The application of this model can be interconnected with the use of a GIS software tool, thus providing the opportunity to perform the energy mapping of city neighborhoods. In the proposed model, the overall energy demand of existing urban neighborhoods is evaluated by considering the three most energy intensive sectors: buildings, transport and urban lighting. However, in this paper the application of the model is only focused on the assessment of the energy demand in the building sector. The proposed methodology is applied to a neighborhood of the municipality of Catania in Southern Italy. The preliminary results are reported in this study: first, the existing energy consumption for space heating and electric appliances is assessed, then the effectiveness of a series of energy-saving strategies is considered, thus providing a tool to implement effective energy planning policies at urban scale

uhi effects and strategies to improve outdoor thermal comfort in dense and old neighbourhoods

Abstract Modelling techniques have received growing attention as a tool to investigate the thermal comfort within a city, on the basis of which decision makers can set-up appropriate mitigation strategies. This research aims at studying the effectiveness of strategies for reducing the urban heat island-associated effects in dense and old neighborhoods considering, in particular, green roofs, cool roofs, cool pavements, green areas and urban renewal actions. Computer simulation was selected as the major methodology in this research; ENVI-met software was used under different scenarios for a case study consisting in an old neighborhood in the city of Avola. The investigation focused on evaluating the efficacy of each strategy for a condition corresponding to a typical summer heat wave. The results highlight that the cool pavements allow relevant improvements at the height of 1.50 m, with a temperature decrease up 1.15°C, whereas the other scenarios, given the relatively high density of the buildings, are able to improve outdoor conditions only at higher elevations. Reported results represent a guideline for the choice of UHI mitigation method that can help stakeholders involved in new urban assessment of old neighborhoods in Mediterranean climate

Mitigation of environmental noise in urban streets through lightweight transparent screens

AbstractNoise pollution is one of the main environmental stressors in urban areas. In particular, strong noise pollution can be experienced at nighttime in downtown areas with intense anthropic activities: here, dwellers may suffer from disturbance to their rest, which induces stress and – in turn – adverse effects on health.Usually, local authorities implement actions to tackle noise pollution, e.g. limiting the time allowed for outdoor events. However, these measures are often inadequate because the noise annoyance comes directly by the shouting of people spending time outdoors till late night.In this framework, this study proposes a procedure to optimize the shape of customized lightweight transparent noise screens that can be applied to façades in order to reduce noise disturbance in urban canyons. The case study of the "movida" area in the downtown of Marina di Ragusa (Southern Italy) is discussed to test the applicability of the proposed procedure.The results of this analysis allow defining the shape and the size of the noise screens that minimize the noise annoyance perceived by residents. The proposed mitigation approach can be applied in cities affected by significant noise pollution

Different strategies for improving summer thermal comfort in heavyweight traditional buildings

In order to exploit the passive energy potential of the building envelope, it is important to provide a right combination of insulation thickness, heat capacity and night-time ventilation. In this paper, this issue will be tackled with reference to an historic building in Catania (Southern Italy). The building was built at the end of the XIX century, and its opaque envelope is entirely made with lava stones, which is typical of traditional architecture in this area. Starting from the current configuration of the building, many hypotheses for refurbishment are considered, combined with different strategies for passive cooling, such as night-time ventilation, use of shading devices and adoption of highly-reflective coatings. The effectiveness of each solution in terms of summer thermal comfort is evaluated through dynamic thermal simulations carried out with EnergyPlus. The results show the synergic effect of these strategies, as well as their individual impact, and allow to draw some general conclusions about the behaviour of heavyweight buildings under moderately hot weather conditions

Exergy Analysis of Energy Systems in Buildings

The performance of space heating and cooling systems in buildings is usually measured by applying the first law of thermodynamics, which makes it possible to quantify the energy losses of the single components and to measure their energy conversion efficiency. However, this common approach does not properly consider that different forms of energy have different potentials to produce useful work, the latter being a function of the temperature at which energy is made available. As a result, it is not possible to properly address how the “quality„ of energy is exploited or conserved in the different processes. On the contrary, the second law of thermodynamics is able to do that by introducing the concept of exergy: This is the maximum amount of work that can be produced through an ideal reversible process evolving until a full condition of equilibrium with the environment is attained. Exergy is; thus, a possible way to measure the “quality„ of an energy flow or an energy source. This perspective is particularly relevant when dealing with buildings and their energy conversion systems, which usually deliver thermal energy at a temperature level that is close to the environmental temperature. This means that the users require “low-quality„ energy; notwithstanding, this energy comes from the depletion of “high-quality„ energy sources, such as fossil fuels and electricity. The exergy analysis helps with identifying such irrational use of the energy sources, which cannot come to light from the energy analysis. In this paper, a literature review identifies methods and metrics commonly used to carry out the exergy analysis of buildings and their energy technologies, while also underlining discrepancies and open methodological issues. Then, the review discusses the main lessons learned from selected works, providing significant advice about the rational use of energy in buildings as well as the most effective technological solutions

SIMULATION OF A LOW CAPACITY ABSORPTION COOLING SYSTEM FOR INDOOR AIR-CONDITIONING

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