Search

The acronym BIPV (Building Integrated Photovoltaics) refers to the installation of photovoltaic systems which, in addition to convert solar energy into electrical energy, have a high level of architectonical integration with the built environment, becoming a real architectural cladding to be installed over the buildings in place of traditional envelope systems. Many typologies of BIPV have been developed, however their thermal characteristics such as g and Ug-value are not well evaluated and require more detailed analyses considering that they could replace large extension of traditional building envelope. A first approach to address this problem is proposed in this work. A mathematical model based on a finite differences scheme for the estimation of the thermal parameters g and Ug-value has been developed and tuned using experimental value measured on sample BIPV with a Hot Plate and a Solar Calorimeter. The results of the model show that the introduction of solar cells in a laminated glass or in a double glass leads to a reduction of energy parameters modifying winter and summer energy balance of the building system. [ABSTRACT FROM AUTHOR]

Abstract: The vernacular Mediterranean architecture was characterised by passive solutions able to ensure thermal comfort conditions in the built environment during the hot season. The use of light colours to redirect most of the incident solar radiation was based on these traditional solutions. Cool roofs are a mix of ancient concepts and modern technologies; their application in new and existing buildings can significantly improve the energy efficiency during the cooling season and throughout the year. The paper reports the results of a large application in an office/laboratory building belonging to a school campus in Trapani, on the west coast of Sicily. The experiment was carried out in two phases. The building was continuously monitored during the first phase from late April to late September 2009: indoor and outdoor air temperatures, relative humidity and solar radiation were acquired. The monitoring was carried out before and after the cool eco-friendly white paint application, characterised by high solar reflectance and thermal emittance. The monitored data were used to calibrate the building model input into a dynamic simulation tool, used to evaluate the building performance with a number of variants. The analysis gave interesting results on the potential of this technique for the southern European climatic conditions. [Copyright &y& Elsevier]

Abstract: The increase of peak and energy demand during the cooling season is becoming a crucial issue, as well as the intensification of the urban heat island effect. This trend is observed at several latitudes, including areas where overheating was unknown at building and urban levels. This phenomenon involves different issues: reduction of greenhouse gases, quality and comfort in outdoor and indoor environment, security of energy supply, public health. The building sector is directly involved in this change and adequate solutions can provide great benefit at energy and environmental levels. Roofs in particular are envelope components for which advanced solutions can provide significant energy savings in cooled buildings or improve indoor thermal conditions in not cooled buildings. Cool materials keep the roof cool under the sun by reflecting the incident solar radiation away from the building and radiating the heat away at night. Roofs covered with vegetation take benefits of the additional thermal insulation provided by the soil and of the evapo-transpiration to keep the roof cool under the sun. These two technologies are different in: structural requirements, initial and lifetime maintenance costs, impact on the overall energy performance of buildings. This paper presents a numerical comparative analysis between these solutions, taking into account the several parameters that affect the final energy performances. By means of dynamic simulations, the paper depicts how cool and green roofs can improve the energy performance of residential buildings in different localities at Mediterranean latitudes. [Copyright &y& Elsevier]

Abstract: Cooling down buildings and cities is becoming a priority as a consequence of global increase of air temperatures. This effect determines the growing of energy consumption for cooling, as well as the spread of urban heat island effect. Cool materials are characterised by high solar reflectance and high infrared emissivity. These two properties allow the material to stay cool under the solar radiation. Cool materials are deserving attention to mitigate surface temperatures in buildings and urban materials. This paper presents the first results of the potential benefits of cool materials applied on solar protection devices. Shutters are used for security and for solar shading in Mediterranean countries. These components are generally characterised by high solar absorbance, due to the colours traditionally used. An experimental campaign was carried out to measure and compare the optical and thermal properties of conventional and cool coloured materials. The results were used as input to assess the impact of these products in Italian dwelling, taking into account several variables: climatic zone, insulation level, and operative conditions. The cooling energy demand and the thermal comfort conditions were calculated with an hourly heat balance building simulation tool. [Copyright &y& Elsevier]

Focuses on a study which proposed an energy rating scheme for fenestration in residential buildings in Italy. Definition of simplified algorithms used in the study; Details of a cost-benefit analysis; Conclusions.