Passive Solar Solutions for Buildings: Criteria and Guidelines for a Synergistic Design

Passive solar system design is an essential asset in a zero-energy building perspective to reduce heating, cooling, lighting, and ventilation loads. The integration of passive systems in building leads to a reduction of plant operation with considerable environmental benefits. The design can be related to intrinsic and extrinsic factors that influence the final performance in a synergistic way. The aim of this paper is to provide a comprehensive view of the elements that influence passive solar systems by means of an analysis of the theoretical background and the synergistic design of various solutions available. The paper quantifies the potential impact of influencing factors on the final performance and then investigates a case study of an existing public building, analyzing the effects of the integration of different passive systems through energy simulations. General investigation has highlighted that latitude and orientation impact energy saving on average by 3–13 and 6–11 percentage points, respectively. The case study showed that almost 20% of the building energy demand can be saved by means of passive solar systems. A higher contribution is given by mixing direct and indirect solutions, as half of the heating and around 25% of the cooling energy demand can be cut off

An Innovative Enhanced Wall to Reduce the Energy Demand in Buildings

Energy saving in buildings is one of most important issues for European countries. Although in the last years many studies have been carried out in order to reach the zero-consumption house the energy rate due to passive solar heating could be further enhanced. This paper proposes a method for increasing the energy rate absorbed by opaque walls by using a two phase loop thermosyphon connecting the internal and the external façade of a prefabricated house wall. The evaporator zone is embedded into the outside facade and the condenser is indoor placed to heat the domestic environment. The thermosyphon has been preliminary designed and implanted into a wall for a prefabricated house in Italy. An original dynamic thermal model of the building equipped with the thermosyphon wall allowed the evolution of the indoor temperature over time and the energy saving rates. The transient behaviour of the building has been simulated during the winter period by using the EnergyPlusTM software. The annual saving on the heating energy is higher than 50% in the case of a low consumption building

Passive Solar Solutions for Buildings: Criteria and Guidelines for a Synergistic Design

Passive solar system design is an essential asset in a zero-energy building perspective to reduce heating, cooling, lighting, and ventilation loads. The integration of passive systems in building leads to a reduction of plant operation with considerable environmental benefits. The design can be related to intrinsic and extrinsic factors that influence the final performance in a synergistic way. The aim of this paper is to provide a comprehensive view of the elements that influence passive solar systems by means of an analysis of the theoretical background and the synergistic design of various solutions available. The paper quantifies the potential impact of influencing factors on the final performance and then investigates a case study of an existing public building, analyzing the effects of the integration of different passive systems through energy simulations. General investigation has highlighted that latitude and orientation impact energy saving on average by 3–13 and 6–11 percentage points, respectively. The case study showed that almost 20% of the building energy demand can be saved by means of passive solar systems. A higher contribution is given by mixing direct and indirect solutions, as half of the heating and around 25% of the cooling energy demand can be cut off

INVESTIGATING SOLAR ENERGY APPLICATION IN BUILDINGS: OPTIMIZATION OF PASSIVE CONFIGURATIONS AND ACTIVE SYSTEMS

Since it arrived in the caves thousands of years ago, man has looked at energy to set proper living conditions. Originally, men relied on nature: fire, wind, and sun were the only sources to provide the energy requested. Passive design sinks its roots in the attempt to maximize available resources, by optimizing urban layouts, building shape and orientation, materials, and developing techniques to further exploit, store and distribute natural energy flows. With technological advancement, attention to natural elements has been overtaken by new systems based on new energy vectors, fossil fuel, first, and electricity later. The growing number of essential services, due to a growing demand for comfort, have considerably pushed forward energy consumption, recklessly and without control, the environmental impact is the main consequence, later noted. To reduce the carbon footprint related to the civil sector, and save the planet, the pursuit of sustainable solutions, as to preserve the resources available for future generations, gave a decisive boost to the development and dissemination of renewable energy systems. In the civil sector, this mainly translates into photovoltaic systems, whose diffusion has been driven by the electrification of building loads, the decreasing technology cost, and intrinsic characteristics such as ease of installation. This kind of technology is particularly suitable as it is locally related to energy demand, as the system, and its production, are directly located where the consumption occurs: as a result, energy losses are reduced and direct utilization of energy is promoted. These achievements come at a price, menaces that prevent a deeper integration of photovoltaic technology in the energy pie of the building sector. Two kinds of challenges, systemic and technical, threaten the rational use of photovoltaic energy production. The systemic issue is related to the intermittent nature of the source; the technical limits lie in both architectural constraints for building integrated photovoltaic systems, and the not dispatchable nature of the system. In conclusion, the challenges are related to system design: the effectiveness of this kind of renewable energy system depends on time matching between consumption and production, which is directly affected by system size and the design of auxiliaries. The thesis goal is to deliver optimized scenarios for passive and active solar energy exploitation. The purpose is to determine sizing criteria for professionals, practitioners, and designers, to promote a rational development and diffusion of passive solar design and photovoltaic systems. The final scope is to provide general guidelines for both passive solar solutions integration in different kinds of buildings, and photovoltaic and electrical storage size, according to the different objective functions, from the definition of self-consumption schemes to reduce the pressure on the national electrical grid and maximize the direct use of energy produced, to energy sharing configurations, to enhance a deeper penetration of renewable energy systems at urban scale at high efficacy. The novelty of the thesis lies both in its scope and approach, a bottom-up methodology based on monitored data under real operating conditions, supported by simulated scenarios. The methodology is based on two different approaches, data-driven and simulation-based, over three main correlated topics. The path of the thesis followed a rising path, moving from the analysis of solar radiation to passive and active solar systems on a single-building scale, and finally to aggregated buildings and district-level energy models. The methodology mostly relied on monitored data, through collected data on solar irradiation, photovoltaic production, and building electricity consumption. Based on these data, in a bottom-up approach calibrated models have been developed and analyzed in a single and aggregated configuration. In the absence of a direct source of data, passive solar design and district cluster final analysis is essentially based on energy simulation results. Firstly, the energy source, solar radiation, has been investigated, through the analysis of locally monitored time series. The investigation concerned the evaluation of the intermittent nature of solar radiation and the reliability of nominal, average data, commonly used in the pre-sizing methodology of solar-based devices. Data have been clustered according to different day types based on daily average values, and compared to monthly evaluation to determine the reliability of standard monthly solar irradiation values, according to the established uncertainty criteria and mean relative and absolute error and relative root mean square error. Time series clustering techniques, based on the dynamic time warping method, and K-Means, have been applied to 5-minute monitored yearly data to detect potential clusters and the minimum number of referenced day types and series to effectively represent an annual trend of solar irradiation. As a first design step, the performance of passive solar configurations has been investigated over residential and office buildings. Once the effectiveness of passive solar design, from simple to complex configurations, has been determined, a wide sensitivity analysis has been run to determine design guidelines and the impact of design parameters on the final results. Variables of the general investigation over five different passive schemes include orientation, thermal properties of the construction involved, and optic characteristics of the glazed surfaces. Simulation results have been compared to plot trends and behaviors that suggest the best configurations in different building scenarios. Finally, a methodology to exploit the achieved has been outlined over two test cases, residential and office buildings, analyzing the energy performance, to maximize, and the impact over the building design and potential costs of implementation, to minimize. The integration of a transdisciplinary approach, analyzing the impact of an adaptive comfort model, showed the importance of a combined point of view, due to different elements interacting in synergy in the definition of the final energy performance. As a second step, the focus moved to active photovoltaic systems. Data have been collected from monitoring activity of different kinds of buildings, including traditional homes, residential nZEB, schools, and food stores. Through a bottom-up approach, monitored data have been analyzed to determine current system behavior. Calibrated energy models have been developed according to collected data to define optimal configuration, in terms of photovoltaic system size, based on different objective functions. Trends have been detected in the different types of buildings. The case study of food stores has been more carefully analyzed, being a mainly electrical-fueled kind of building with high and constant loads: different scenarios have been investigated to use the energy locally produced, including building-to-vehicle strategies. Finally, the last scenario included building cluster analysis. The assumption, moving from an individual building to cluster and district level, was to exploit potential complementary loads, to achieve a better production-to-load and grid interaction performance of the photovoltaic system and reduce the relative size. Firstly, the calibrated models based on monitored data have been used to investigate potential effective clusters based on the building aggregated energy demand. Full self-consumption and net-zero-energy clusters have been pursued, through the combination of high energy-intensive buildings, as food stores, as prosumers, and low energy-intensive buildings, as homes, as main consumers. Lastly, a methodology, based on two developed key performance indicators is proposed to determine optimal building clusters within urban districts, with an assumption of searching for local clusters that can rely on a dedicated electrical grid. The methodology is then tested on simulation-based results of an optimal district in the case study of the city of Fribourg, Switzerland. A multi-objective analysis, with techno-economic indicators, has been run to determine the results achievable in terms of energy performance and saving of PV power installed. Results highlighted the impact of solar radiation clustering to represent and summarize yearly trends for sizing applications, with summer showing high reliability. A minimum set of four-day types can properly represent the overall annual dataset. The contribution of passive solar design can achieve 10-15% in total energy savings even in existing buildings, up to 65% including adaptive comfort models. The optimization process on the photovoltaic system determine consistent sizing criteria among analyzed buildings, while district-level analysis showed how either full self-consumption or net zero energy cluster can be achieved and identified in a city

Wall Thermosyphon: un innovativo sistema di riscaldamento passivo per il Florence Cultural Centre

L’edilizia è uno dei settori più rilevanti in termini di produzione di ricchezze e di occupazione ma, al contempo, è anche responsabile di significativi consumi di risorse naturali e impatti ambientali. In particolare, essa incide in misura rilevante sul bilancio energetico e sullo scenario emissivo di gas serra in Europa: si stima infatti che, nell'Unione Europea l’edilizia sia responsabile del 40% del consumo delle risorse energetiche disponibili e tale percentuale è inevitabilmente destinata a crescere se non si provvede all'avvio di strategie ed azioni orientate alla riduzione dei consumi di combustibili fossili e alla promozione delle risorse rinnovabili. In tale contesto, il risparmio di risorse primarie, l’impiego di fonti energetiche rinnovabili, l’uso di materiali eco-compatibili, il ricorso a nuove tecnologie costruttive e l’applicazione di sistemi efficienti di climatizzazione dello spazio confinato sono diventati, negli ultimi anni, gli obbiettivi principali da perseguire nella progettazione, nella costruzione ex novo e nella ristrutturazione degli edifici. Uso del suolo e consumo di energia costituiscono gli impatti principali del settore dell’edilizia, imputabili ai processi di costruzione di nuovi edifici e delle relative infrastrutture, ai processi di estrazione delle materie prime, alla lavorazione e trasformazione dei materiali ed infine allo smaltimento. Tuttavia un contributo rilevante al consumo di energia proviene dalla fase d’uso di un edificio ed, in particolare, dalla climatizzazione invernale ed estiva degli spazi confinati. Ecco che, allora, obiettivo finale di tecnici e progettisti diventa la realizzazione di “case a consumo zero” (NZEB), anche conosciute come “case passive”, come primo passo verso lo sviluppo di “case attive”, che riescano a produrre più energia di quella che consumano. Si tratta di edifici a misura d’ambiente, costruiti con il chiaro obiettivo di ridurre i costi energetici ed eliminare gli sprechi. Le strategie per ridurre la richiesta di energia degli edifici sono molteplici: il controllo dell’orientamento e della ventilazione, l’impiego di materiali isolanti sempre più preformanti, l’efficienza impiantistica. Tra queste, uno dei metodi più impattanti è lo sfruttamento dell’energia solare passiva. L’energia complessivamente trasferita dal sole ad un’abitazione può essere divisa in due categorie: la quota direttamente fornita all'edificio attraverso le porzioni trasparenti dell’involucro, che è decisamente preponderante, e la quota ceduta attraverso le pareti opache. In quest’ultimo caso, il sole riscalda gli strati esterni della parete ed il calore riesce difficilmente ad essere trasferito all'interno dell’edificio per effetto della massa e della resistenza termica dei vari strati costituenti la parete, spesso tutt'altro che trascurabile. D’altra parte, la normativa attuale, al fine di contenere al minimo le dispersioni, impone valori sempre più restrittivi per la trasmittanza termica delle strutture opache verticali. La soluzione proposta nel presente lavoro di tesi risolve questa apparente contraddizione, incrementando la quota di energia solare proveniente dagli elementi opachi senza comprometterne la capacità di isolamento. L’idea è quella di inserire nelle pareti d’involucro di un edificio, un dispositivo a due fasi in grado di stabilire un ponte termico, tra le due facce, interna ed esterna, delle pareti stesse. In verità tale dispositivo sfrutta i principi della fisica che regolano il cambiamento di fase dei materiali, mentre la forza gravitazionale costringe il flusso di calore a scorrere esclusivamente in nel verso in ingresso nell’edificio, bloccando quello opposto. A ben vedere, dunque, il comportamento del dispositivo è assimilabile a quello, non di un ponte termico, ma di un diodo termico. Considerati il punto di installazione ed il fatto che all’interno del circuito si instauri una circolazione convettiva per effetto della sola differenza di densità tra volumi di fluido date temperature diverse, al dispositivo si è dato nome di Wall Thermosyphon (WT), termosifone in parete. Il progetto scaturisce dalla collaborazione del Dipartimento di Ingegneria dell’Energia, dei Sistemi, del Territorio e delle Costruzioni (DESTEC) dell’Università di Pisa con il Dipartimento di Ingegneria Meccanica dell’Università Federale di Santa Caterina (UFSC). Il circuito-termosifone applicato alla parete, infatti, è simile al termosifone progettato e sperimentato nel 2010 da Milanez&Mantelli, i quali hanno prestato la loro collaborazione alla messa a punto del nuovo dispositivo. Una parete similare è stata appena studiata da Sun et al. nel 2014 e testata da Zhang et al. nel 2015 per il clima cinese. L’elevata prestazione in termini di trasferimento di calore della suddetta parete-termosifone consente di ridurre il carico di riscaldamento fino al 15% durante un tipico inverno nella città di Jinan. Muovendo da quest’idea, il presente lavoro di tesi si articola in due parti, occupandosi: • in prima fase della progettazione dell’impianto costituito dall’innovativo circuito termosifone, si da integrarlo all’interno della struttura di una parete prefabbricata, per unire, in questo modo, ai noti vantaggi dell’edilizia prefabbricata gli alti standard energetici che il mercato e la sensibilità costruttiva attuale richiedono. La validazione della progettazione passa attraverso lo studio della prestazione energetica di un edificio prototipo sul quale si ipotizza installato il dispositivo. Il comportamento dell’edificio è stato analizzato al variare del numero e dalla disposizione dei dispositivi installati in parete nonché al mutare delle condizioni climatiche esterne, in modo da poter confrontare i risultati in termini di risparmio energetico e stabilire la configurazione più vantaggiosa. Il comportamento termico transitorio dell’edificio è stato studiato con il software di simulazione energetica degli edifici EnergyPlus™. In definitiva, lo scopo è stato quello di progettare il dispositivo e di testarne l’efficacia su un edificio campione nell’ottica che l’esito positivo o negativo di questo studio preliminare avrebbe deciso rispettivamente il successivo sviluppo o abbandono di quest’idea; • in seconda fase dell’integrazione del sistema in una proposta progettuale architettonicamente compiuta: rispondendo alle richieste del bando emesso dal Comune di Firenze, la proposta progettuale concerne la realizzazione di un nuovo centro museale polifunzionale, il “Florence Cultural Centre”, riorganizzando gli spazi del Largo Pietro Annoni, sito nel cuore del capoluogo toscano

Energy Sustainability of Food Stores and Supermarkets through the Installation of PV Integrated Plants

Food stores and supermarkets are buildings, often with rather similar structures characterized by large surfaces and a single floor, that are particularly energy intensive. The energy uses associated with them are mainly electrical, in connection with air conditioning and food refrigeration. These buildings are particularly interesting for a systematic application of photovoltaic (PV) generation technology. After an analysis of the main energy consumption parameters and of the most common benchmarking approaches, standard solutions for the sizing of photovoltaic systems are proposed based on different design objectives, highlighting the potential of each solution proposed. Two specific indicators are defined for the sizing processes. The methodology is tested with reference to two different stores under the zero grid-injection restriction. The results showed how the degree of self-sufficiency for a supermarket obtained with a PV plant can be of the order of 20% in cases without storage system and can be increased over 50% and up to 70–75% but only using relevant battery storage dimensions

Passive solar systems for buildings: performance indicators analysis and guidelines for the design

Data from the International Energy Agency confirm that in a zero-energy perspective the integration of solar systems in buildings is essential. The development of passive solar strategies has suffered the lack of standard performance indicators and design guidelines. The aim of this paper is to provide a critical analysis of the main passive solar design strategies based on their classification, performance evaluation and selection methods, with a focus on integrability. Climate and latitude affect the amount of incident solar radiation and the heat losses, while integrability mainly depends on the building structure. For existing buildings, shading and direct systems represent the easiest and most effective passive strategies, while building orientation and shape are limited to new constructions: proper design can reduce building energy demand around 40%. Commercial buildings prefer direct use systems while massive ones with integrated heat storage are more suitable for family houses. A proper selection must consider the energy and economic balance of different building services involved: a multi-objective evaluation method represents the most valid tool to determine the overall performance of passive solar strategies

The potential of building integrated Photovoltaic (BIPV) systems for reducing the energetic impact of Italian supermarkets

In the perspective of sustainable cities, urbanist and planners have to deal with a constantly increasing penetration of renewable energy systems (RES) in the urban structure: in tertiary sector, retail and supermarket stores as particularly energy-intensive compounds play a core role in this scenario, as they are often characterized by similar kinds of structures mostly, large surfaces and a single floor, and analogous composition of energy loads. Most of the current research focuses on energy efficiency, but these buildings are particularly interesting for a systematic application of PhotoVoltaic (PV) generation technology as the energy uses associated with them are mainly electrical, in connection with air conditioning and food cooling. This article analyses the energy consumption in the supermarket sector for the sale of food. After an analysis of the main energy consumption parameters, standard solutions for the sizing of PV systems are proposed based on different design objectives, highlighting the potential of each proposed solution. Results show that a high percentage of self-consumption can be achieved, and that a battery storage set at a mean daily PV potential production level (4 kWh/kW in the case) perfectly suits to reach a self-sufficiency between 50-70%. Retail and food stores have proven to be a perfect promoter for PV diffusion either in a high self-consumption configuration, or turning them into energy hub for mobility to building or energy sharing policies

Valorization of agro-industry residues in the building and environmental sector: A review

Environmental pollution has become a relevant issue as the population rises and resources decrease. Reuse and recycling still have the greatest potential as they turn the waste into a new resource, representing the ‘closed-loop’ step of a circular economy (CE). Looking for new applications for agro-industry waste represents both an environmental issue, as its incorrect disposal is a cause of pollution, and a chance to exploit zero-cost natural wastes. The present review, with around 200 articles examined, focuses on possible reuses of these residues in (a) building construction, as additives to produce thermal and acoustic insulation panels, and (b) in water treatments, exploited for removal of pollutants. The selected materials (coconut, coffee, corn, cotton and rice) have industry production wastes with suitable applications in both sectors and huge worldwide availability; their reuse may thus represent a new resource, with an impact based on the production rate and the possible replacement of current inorganic materials. Along with possible implementation of the selected materials in the building industry and environmental engineering, a brief description of the production and supply chain are provided

A review on alternative binders, admixtures and water for the production of sustainable concrete

To keep its leading role, the concrete industry must face the environmental issues linked to the manufacturing, by increasing the energy efficiency and adopting alternative fuels or raw materials. The present work analyses physical, mechanical, and environmental performances of concrete products incorporating waste from four main sources (construction and demolition waste, residues from waste treatment, metallurgical industry by-products and other sources), as substitutes of one of the three main components of concrete (binder, admixtures and water). The binder is the easiest component to be replaced in terms of number of alternatives, with the highest impact on concrete properties, while water easily reaches a full replacement level. Ground granulated blast furnace slag (GGBFS) showed the highest potential for the overall performance, with positive effects on compressive strength, durability, and workability of concrete samples, along with electric arc furnace dust (EAFD) and ceramic powder