The daylighting contribution in the electric lighting energy uses: EN standard and alternative method comparison

The standard EN 15193: 2007. Energy performance of Buildings. Energy requirements for lighting includes a comprehensive method, which takes into account the daylighting contribution in the calculation procedure. Such contribution is obtained through several approximations. An alternative approach is developed, where the daylighting contribution is based on the availability of outdoor illuminance data and an explicit procedure. The methods are tested on a standard office building, whose lighting requirements are calculated for different visual tasks, observation positions and climatic zones. The results show discrepancies among the methods and address the need of a more accurate estimation of the lighting energy service

Climate Mitigation and Adaptation Strategies for Roofs and Pavements. A Case Study at Sapienza University Campus

The progressively emerging concept of urban resilience to climate change highlights the importance of mitigation and adaptation measures, and the need to integrate urban climatology in the design process, in order to better understand the multiple effects of combined green and cool technologies for the transition to climate responsive and thermally comfortable urban open spaces. This study focuses the attention on selected mitigation and adaptation technologies; two renovation scenarios were designed and modeled according to the minimal intervention criterion. The study pays attention to the effect on surface temperature and physiological equivalent temperature (PET) of vegetation and high albedo materials characterizing the horizontal boundaries of the site. The Sapienza University campus, a historical site in Rome, is taken as a case study. These results highlight the importance of treed open spaces and the combination of permeable green pavements associated with cool roofs as the most effective strategy for the mitigation of summer heatwaves and the improvement of outdoor thermal comfort

Global energy performance of residential buildings: the role of the urban climate

Abstract The energy performance of buildings are strongly dependent on climatic conditions. Climatic data are acquired by measuring stations, generally located outside of the city, hence their reliability in reproducing the thermal conditions inside the urban environment should be carefully addressed. This paper deals with the analysis of the urban climate in Rome, city characterized by a composite urban texture and a high variability of the residential building stock. Air temperature and relative humidity were monitored in different neighborhoods of the city and in a microclimatic station placed in a countryside area for one year in 2015. The monitoring allowed to quantify relevant microclimatic indicators and to use the data as input to predict the impact on the energy performance of a reference building. It was found that UHI is uniform in winter, while it is zone dependent in summer. UHI hourly intensities reached 10.5 and 7.8°C in winter and summer, seasonal UHI reched 1.5°C in city centre. Urban cooling and heating degree days showed relevant variations up to 26% respect to the countryside area. In terms of predicted energy performance, UHI causes a winter reduction up to 36% and a summer increase up to 42%

Urban Overheating - Progress on Mitigation Science and Engineering Applications

The combination of global warming and urban sprawl is the origin of the most hazardous climate change effect detected at urban level: Urban Heat Island, representing the urban overheating respect to the countryside surrounding the city. This book includes 18 papers representing the state of the art of detection, assessment mitigation and adaption to urban overheating. Advanced methods, strategies and technologies are here analyzed including relevant issues as: the role of urban materials and fabrics on urban climate and their potential mitigation, the impact of greenery and vegetation to reduce urban temperatures and improve the thermal comfort, the role the urban geometry in the air temperature rise, the use of satellite and ground data to assess and quantify the urban overheating and develop mitigation solutions, calculation methods and application to predict and assess mitigation scenarios. The outcomes of the book are thus relevant for a wide multidisciplinary audience, including: environmental scientists and engineers, architect and urban planners, policy makers and students

Lighting Implications of Urban Mitigation Strategies through Cool Pavements: Energy Savings and Visual Comfort

Cool materials with higher solar reflectance compared with conventional materials of the same color are widely used to maintain cooler urban fabrics when exposed to solar irradiation and to mitigate the Urban Heat Island (UHI). Photo-catalytic coatings are also useful to reduce air pollutants. Many studies related to these topics have been carried out during the past few years, although the lighting implication of reflective coatings have hardly been explored. To investigate these aspects, reflective coatings were applied on portions of a road and intensely analyzed in a laboratory and on the field. The applied cool coatings were found to have much higher solar and lighting reflectance than the existing road, which lead to lower surface temperatures up to 9 °C. Non-significant variations of chromaticity coordinates were measured under different lighting conditions. However, these materials showed a relevant variation of directional properties depending on the lighting and observation conditions with respect to conventional pavements. The optical behavior of these materials affects the uniformity of visions for drivers and requires ad-hoc installation of light sources. On the other hand, potential energy savings of up to 75% were calculated for the artificial lighting of a reference road

On the Solar Reflectance Angular Dependence of Opaque Construction Materials and Impact on the Energy Balance of Building Components

Abstract The solar reflectance of the surfaces is a property that varies according to spectral and angular distribution of the incident solar radiation which in turn depends on orientation and latitude. In this paper, an optical characterization was conducted on some typical opaque building materials, generally used as roof covers: shingles, membranes, bricks and tiles. The measurements were carried out through an experimental factory equipped with a large integrating sphere which allows to measure the spectral reflectance at different incidence angles of the light beam on the sample. Thus it was possible to create a function that linked reflectance values with the incidence angle. The results obtained were included within a dynamic software in order to optimize the calculation of solar gains in the energy balance of a building

On the Implementation of an Innovative Energy/Financial Optimization Tool and its Application for Technology Screening within the EU-project School of the Future☆

Abstract A tool for the energy & financial optimization of the renovation of school buildings was developed based on an existing tool - ASCOT. The tool combines an energy calculation with a LCC-analysis, which are calculated simultaneously. The tool was then used for the screening of energy saving measures in school buildings in four European countries: Denmark, Germany, Italy and Norway. For Italy, the screening was carried out for three climates

Energy and Environmental Monitoring of a School Building Deep Energy Renovation in Italy

Abstract The Tito M. Plauto school in Cesena is the Italian case study in the FP7 School of the Future project. Objective was the energy renovation of school buildings with high energy and indoor environment targets, to be demonstrated by monitoring before and after the retrofit. Measures involved envelope components and energy systems, including renewable. The energy monitoring started in January 2014 and included thermal and electricity uses; as well the electricity produced by the PV plant. Data were compared to those registered for the 2008-2010 period. The environmental quality was addressed by thermal comfort and CO 2 concentration instrumental monitoring

Urban temperature analysis and impact on the building cooling energy performances: an Italian case study

Climate changes and urban sprawl are dramatically increasing the heat island effect in urban environments, whatever the size and the latitude are, affecting these latter parameters the effect intensity. The urban heats island is a phenomenon observed since the last decades of the XIX century but demonstrated at large scale only one century later, characterised by the increase of air temperature in densely built urban environments respect to the countryside surround cities. Many studies are available, showing urban heat island intensities up to 12°C. This thermal stress causes social, health and environmental hazards, with major consequences on weaker social classes, as elderly and low income people, it is not by chance that survey demonstrated the increase of deaths in such categories during intense and extended heat waves. This study presents the firs results on the observation of air temperature measures in different spots of Rome, city characterised by a typical Mediterranean climate and by a complex urban texture, in which densely built areas are kept separated by relatively green or not-built zones. Six spots are monitored since June 2014 and include: historical city centre, semi-central zones with different construction typologies, surrounding areas again with various urban and building designs. The paper is focused on the analysis of summer temperature profiles, increase respect to the temperature outside the cities and the impact on the cooling performance of buildings. Temperature datasets and a reference building model were inputted into the well-known and calibrated dynamic tool TRNSYS. Cooling net energy demand of the reference building was calculated, as well as the operative temperature evolution in the not cooled building configuration. The results of calculation allow to compare the energy and thermal performances in the urban environment respect to the reference conditions, usually adopted by building codes. Advice and recommendation of suitable technologies to mitigate such conditions are finally given

Retrofit of an Existing School in Italy with High Energy Standards

Abstract The Tito Maccio Plauto school was built in Cesena during late sixties and, conformingly to the period construction technologies and standards, is characterized by poor energy performances. The retrofit of the school is implemented in the framework of the School of the Future Project, funded by 7th Framework Programme. The objective is demonstrating the technical economical feasibility of deep energy renovation for public buildings, bound to last several decades after, avoiding the land use for new construction and improving the energy performances of the existing building stock. The actual consumptions for the different energy services were monitored and the occupancy profile of the school zones was analyzed. Starting from the preliminary monitoring it was possible to design the most suitable energy to achieve the initial targets: reduction of factor 4 of space heating energy uses, reduction of factor 3 of the overall energy uses. The measures involved: external insulation of facades and roof, partial insulation of the ground floor, replacement of windows with external moveable shading devices, complete renovation of the heating system, design and installation of a remote energy management system for the municipality schools, installation of a PV plant on the roof, mechanical ventilation system for classrooms. The last measure was implemented to fulfill the improvement of the indoor environment quality, another crucial issues the EU Project had to couple with. Detailed analyses, carried out with dynamic and national reference calculation tools, demonstrated the efficacy of the implemented measures, since all the relevant target were reached, as will be monitored during the monitoring phase of the project