Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 12 January 2018 doi:10.20944/preprints201801.0116.v1 CONCEPT 1 Integrating solar energy in Rome’s built environment: A perspective for distributed generation on global scale Francesco Meneguzzo,*[b] Mario Pecoraino,[c] and Mario Pagliaro*[a] This article is dedicated to Professor Livio de Santoli, University of Rome La Sapienza, for all he has done to promote solar energy and energy efficiency in Italy’s and Rome’s historic built environment Abstract: Large-scale integration of solar energy technologies in consumption: more than 40% in European Union (EU) Rome’s built environment epitomizes the needed general adoption of countries,[2] and a similar percentage in China, where building distributed generation via functionalization of buildings of all size and energy consumption has increased at 7% annual rate since end use across the world, to become active energy generators and 2001.[3] no longer energy users only. This paper identifies selected technology solutions and critical policy and educational initiatives to Countries in Europe generally have limited or even no fossil fuel effectively achieve within the next decade (2018-2027) the resources, with oil production from the oil and gas reserves in widespread uptake of decentralized solar energy systems in the built the North Sea having decreased at fast pace since 1999 (for environment on a global scale. instance, the United Kingdom’s offshore oil production went from 398 million barrels in 1999 to 220 million barrels in 2007).[4] Keywords: solar energy • BIPV • energy transition • energy efficiency • photovoltaics In this context, aiming at saving oil and natural gas considered strategic for industry and transport sectors, it is perhaps not surprising that starting in the early 2000s the EU drafted increasingly tight legislation to promote energy efficiency in 1. Introduction buildings along with the use of renewable energy. Since 2002 first, and even more strictly since 2010, an Energy Performance A new model combining the competing dynamics of oil price, of Buildings Directive defines minimum criteria for the energy economic growth and extraction costs,[1] suggests that performance of new and refurbished buildings investments in new renewable energy power needs to be urgently increased to cope with the global consequences of the The 2010 EPBD, for instance, requires all new buildings to be resulting energy and economic scenario. nearly zero-energy by the end of 2020; and by 2018 for all new public buildings.[5] With the global population growing along the current trajectory, in the 2016-2025 decade about 800 million people will add to the New legislation resulted in a decrease in the consumption of world’s population. Correspondingly, in order to feed the “natural” energy by the residential sector from about 318 MTOE in 2000 growth of the gross domestic product (GDP) identified by the to 287 in 2014;[6] though half of the efficiency gains achieved above model, by 2025 the total energy consumption should through technological innovation in the household sector have increase by about 1,700 million tons of oil equivalent (MTOE) been offset by an increasing number of electrical appliances and per year. Even to keep the oil fraction in the energy mix at the larger homes.[2] 2015 level (around 33%), this means that more than 11 additional million barrels per day will have to be added to current Furthermore, action must be taken to improve the situation of production levels.[1] the existing building stock, since about 75% of buildings are truly energy inefficient and, depending on the country, only 0.4-1.2% Consuming energy for space and water heating and electricity of the stock is renovated each year.[7] for cooling, lighting and powering domestic appliances, buildings are responsible for a significant share of global energy Alone, the conflict between increasing specific dwelling consumption and increasing energy efficiency of buildings observed in the EU countries shows that energy efficiency alone [a] Dr. M. Pagliaro is not enough. The generation and use of renewable energy is of Istituto per lo Studio dei Materiali Nanostrutturati, CNR similar paramount importance. via U. La Malfa 153 90146 Palermo (Italy) E-mail: [email protected] The solar city concept, namely the use of surfaces in the entire urban built environment to generate electricity via solar [b] Dr. F. Meneguzzo photovoltaic (PV) modules,[8] is being actively explored in the Istituto di Biometeorologia, CNR via Madonna del Piano 10 context of the energy transition to renewable energy. Solar city 50019 Sesto Fiorentino (Italy) possibilities, for example, were lately considered for cities as E-mail: [email protected] large and as important as Amsterdam, London, Munich, New York, Seoul, and Tokyo.[9] [c] M. Pecoraino via C. Giacquinto 14 90135 Palermo (Italy) © 2018 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 12 January 2018 doi:10.20944/preprints201801.0116.v1 CONCEPT 2 When dealing with historic cities large-scale adoption of solar energy requires systematic architectural integration of the solar On the other hand, Italy’s new energy strategy for the period energy technology to combine historic preservation with efficient 2020-2030 (Strategia Energetica Nazionale - SEN) has identified generation of renewable energy. Preserving the architectural PV as one of the best options for increasing the share of integrity and historic value of old buildings, indeed, historic renewable energy in the country,[18] and to eliminate coal power preservation is as important as the generation of clean energy. production by 2025 by increasing the share of renewable energy sources to 27% in 2030. In detail, power production from PV is Hosting the largest historic heritage of the world,[10] and with expected to increase from 21.104 TWh in 2016 to 72 TWh by good to excellent solar irradiance levels,[11] Italy has pioneered 2030: an energy production target which requires new solar the development of building integrated photovoltaics (BIPV), a installations to exceed 3 GW per year. multifunctional technology that unifies the photovoltaic module with the overall building outer surface providing the building with For comparison, since the end of the Feed-in-Tariff (FiT) several other functions.[12] For example, an Italian-German incentives in mid 2012, Italy which had gone from 3 to 17 GW research and demonstration project (PVAccept) funded by the installed PV capacity in just 2 years, has installed only 2.7 GW European Commission between 2001 and 2004 developed while Australia, with a population about 35% of Italy’s, has over different marketable PV solar modules of innovative design for the same five years installed around 6 GW of rooftop PV.[19] their integration into old buildings, historical sites, the urban space and landscapes.[13] Referring to Rome as the city with the world’s largest historic heritage, this paper identifies selected technology solutions and Awarded the 2008 European Solar Prize for the category “solar critical policy and educational initiatives to effectively achieve architecture”,[14] Rome hosts on the rooftop of the “Paul VI” within the next decade (2018-2027) the needed widespread Audience Hall in the Vatican City an elegant PV array comprised uptake of decentralized solar energy systems in the built of 2,394 ad-hoc modules in crystalline silicon of 220 kilowatt environment on a truly global scale. peak (kWp) nominal power (Figure 1). Mario Pagliaro is a chemistry and energy scholar based in Sicily. His group’s research and educational achievements in chemistry, solar energy and the bioeconomy are reported in over 200 frequently cited research papers and 21 books. All work is developed in co-operation with leading researchers based in over 20 countries. Dr Pagliaro ranks amongst Italy's most cited scientists in nanotechnology and materials chemistry. In recognition of his "significant contributions to the chemical sciences" in 2014 he was designed Fellow of the Royal Society of Chemistry. Figure 1. The photovoltaic array on the rooftop of ‘Paul VI’ Audience Hall in A physicist at the Institute of Biometeorology the Vatican City is visible on the bottom part of the photograph. of Italy’s Research Council in Florence, Francesco Meneguzzo coordinates a research group active in numerous fields from Shortly afterwards, de Santoli, who designed the system, has energy to the bioeconomy. His recent explored the integration of new energy technologies for achievements include the development of an sustainability in Rome, from the analysis of energy savings entirely new brewing process based on [15] achievable through PV systems on school roofs, through hydrodynamic cavitation technology which energy savings achievable via the retrofitting of public housing has been called by the MIT Technology [16] dwellings from the 1940’s in an historic neighborhood. Review the “technology which is about to revolutionize beer-making”. Between 1996 Yet, still today neither the city of Rome nor Italy’s central or and 2002, as a weather forecaster, he has established Tuscany’s Regional regional governments have published guidelines with the criteria Met Service, later to become the well-known LAMMA weather forecast for incorporating solar PV and solar thermal (ST) technologies in centre. He has helped drafting the FiT law that made Italy in less than 3 the built environment. As a result, the use of solar modules and years one of the world’s leading countries in terms of installed PV power. thermal collectors in the historic center of cities like Rome, Florence, Venice, Catania and Naples is practically nihil. For comparison, in order “to find a proper balance between technical and aesthetic requirements”, several Swiss Cantons have guidelines for the integration of solar technologies in the building environment.[17] Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 12 January 2018 doi:10.20944/preprints201801.0116.v1 CONCEPT 3 2.