Michele Zinzi

Local climate change and urban heat island mitigation techniques – the state of the art

AbstractIncrease of the ambient air temperature in cities caused by the urban heat island phenomenon has a seri- ous impact on the economic and social system of cities. to counterbalance the consequences of the increased urban temperatures important research has been carried out resulting in the development of efficient mitigation technologies. the present paper aims to present the state of the art in terms of local climate change and urban heat island mitigation techniques. In particular, developments in the field on highly reflective materials, cool and green roofs, cool pavements, urban green and of other mitigation technologies are presented in detail, while examples of implemented projects are given.

Cool materials and cool roofs: Potentialities in Mediterranean buildings

Abstract The Mediterranean is a complex region, with differences in terms of environmental hazards, population growth, urban sprawl and economic development. The climate change affects all of the area and common risks are already detected. An urban heat island was monitored in a large and medium urban area. The energy end uses in buildings are another crucial point, even if with different situations and perspectives between European countries and North African and Middle East countries. The common trend is the dramatic increase of electricity consumption for cooling the buildings, a trend bound to increase in the next few years because of the energy demand of transition economies. Passive building technologies may be fruitfully applied to mitigate the cooling demand increase, reducing the energy consumption in cooled buildings and improving the thermal comfort in not-cooled buildings. Cool materials stay cool under the sun because of high solar reflectance and thermal emittance. A review of the products and technologies available on the market or in an advanced research state is performed. A study demonstrates the positive impact of the technology in terms of cooling and total energy savings as well as on the indoor thermal conditions in Mediterranean buildings.

Simplified algorithms for the Italian energy rating scheme for fenestration in residential buildings

Energy consumption in buildings is responsible for 40% of the energy end use in Italy. Most of the thermal and solar exchanges between the building and the external environment depend on fenestration. Rating schemes are useful instruments for classifying the energy efficiency of devices in many fields. For windows a rating system is largely utilised in some countries and is under study or development in many others. In Italy, single glazed units represent 80% of the total installed windows and the percentage of high quality products can be considered negligible. An energy-rating system would encourage efficient products onto the Italian market and would accelerate technical innovations in the glass and frame industries. The aim of introducing this scheme is to greatly reduce energy end use and, as a consequence, also CO2 emissions. The methodology, implemented for the residential sector, is based on the assessment of thermal performances of three reference buildings as a function of: window properties, climatic data and architectural characteristics. More than 1000 simulations, run with a building energy performance simulation code (TRNSYS), has made it possible to evaluate specific and percental heating, cooling and total energy savings as well as the reduction in CO2 emissions for the selected buildings. The simplified algorithms, which the energy-rating scheme for both cold and hot seasons is based on, have been taken from the analysis of previous results. Examples of cost–benefits analysis are presented to stress the economical and environmental advantages of the proper application of this instrument.

Preliminary studies of a cool roofs' energy-rating system in Italy

Energy saving in the building sector is one of the key issues to achieve environmental targets at national and European Union (EU) levels. Although characterised by a large number of different climatic conditions, Italy energy policies were aimed at reducing the energy consumption related to space heating in buildings, neglecting space cooling. The recent EU Directive for the State Members is to assess the energy quality of buildings taking into account all the relevant energy uses. Cool roofs are an old concept merged with new technologies that play a crucial role in the energy balance of buildings especially at Mediterranean latitudes. Reducing the solar gains thanks to a high solar reflectance, cool roofs tend to decrease the cooling demand and increase the thermal comfort. Energy rating and labelling are a quick solution to compare energy-related products. This paper presents the first studies aimed at the definition of an energy-rating scheme for cool roofs, starting from product properties and reaching building performances. Energy simulation results were used to find out simple linear regressions, expressing the energy performance of the building as a function of the roofs radiative properties and measuring the performance of the cool roof product.

Analisys of Daylight Availability in Italy Trough Different Louminous Efficacy Models

ISES Solar World Conference 2017, SWC 2017 and 5th International Conference on Solar Heating and Cooling Conference for Buildings and Industry 2017, SHC 2017

Technical advances in the EU-Cool Roof project

Cool materials keep the roof cool under the sun by reflecting the solar radiation away from the building and radiating the stored heat away during night time. The potential of the technology is very promising at EU level and, in particular, in the Mediterranean area. EU supports the Cool Roofs Project, where important technical actions are developed. The technical and scientific activities include: development of the first EU cool materials database; implementation of five case studies with different building typologies equipped with different cool materials; development and validation of a dedicated toolkit; production of the cool materials handbook. The paper summarises the most significant results achieved in the project.