Search

Positive Energy Buildings (PEBs) represent a step forward from Net Zero Energy Buildings. In particular, theyshall contributeby decarbonizing the built environment, including surrounding buildings, exchanging energy among them or with the grid. Thus, they can reduce the energy grid congestion and provide a flexible energy asset thatallowsbuildings and energy communitiestoactasan integrated part of the energy system, while ensuring healthy and comfortable indoor environment, embracing occupants’ diversities and needs, supporting users’ energy-related practices and their flexibility and minimizing their own carbon footprint. In this direction, a consolidated definition is needed in order to enable the design, assessment, and documentation of PEBs in different contexts, climates, cultures, and markets. This paper aims to present a joint understanding of the essence and benefits of Positive Energy Buildings applied to the residential sector, as discussed within the three sister projects Cultural-E (https://www.cultural-e.eu/ led by Eurac Research), EXCESS (https://positive-energy-buildings.eu/ led by Joanneum Research), and syn.ikia (https://www.synikia.eu/ led by NTNU), which were funded under the Programme H2020-EU.2.1.5.2/Call topic2. The joint work also led to the identification of barriers and drivers for an increased acceptance and adoption of PEBs and to the definition of a list of recommendations for policy makers.

The building sector plays an important role in the transition to a climate-neutral society. The international interest in low, zero energy, or zero-emission buildings has grown as a potential means for this transition. A more ambitious step from zero energy buildings is the concept of Positive Energy Buildings (PEB), which are also contributing to the decarbonization of the surrounding built environment, not just minimizing their own carbon footprint. A shared PEB definition is needed in order to enable the design, assessment, and documentation of positive energy buildings. This article describes the ongoing discussions, concentrating on the most essential points.

ispartof: pages:1-8 ispartof: BS'2019 pages:1-8 ispartof: Building Simulation Conference 2019 location:Rome date:2 Sep - 4 Sep 2019 status: published

The ongoing energy system shift—from traditional centralized fossil fuel based to decentralized renewable energy sources based—requires a strengthened control of energy matching. Smart buildings represent the latest step in building energy evolution and perform as active participants in the cluster/energy infrastructure scale, becoming energy prosumers. In this framework, the IEA EBC Annex 67 introduces the concept of ‘Energy Flexible Building’, defined as a building able to manage its demand and generation in accordance with local climate conditions, user needs and grid requirements. Currently, there is no insight into how much flexibility a building may offer, and this study aims to overview the theoretical approaches and existing indicators to evaluate the Energy Flexibility of building clusters. The focus on cluster scale allows for the exploitation of the variation in energy consumption patterns between different types of buildings and the coordination of load shifting for the improvement of renewable energy use. The reviewed indicators can contribute to the definition of the Smart Readiness Indicator, introduced in the European Commission proposal for the EPBD revision, in order to test a building’s technological readiness to adapt to the needs of the occupants and the energy environment, as well as to operate more efficiently.

Energy Performance Certificates (EPCs) are expected to be a useful instrument for stakeholders (including final users), enabling to compare building energy performances within a purchasing/renting decision process. Thereby, EPCs should have a direct impact on the value of the properties, affecting the market attractiveness, as well as driving the investors in the energy renovations process. Nevertheless, a survey to real estate agents reveals a perceived low reliability of EPCs, representing one of the main barriers in their full implementation. The paper presents the EPCs impact in the building market and an analysis on energy efficient buildings in eight European countries.

Renovation Wave aims to boost the uptake of deep renovation towards the CO2 emission targets for 2030. In this perspective, there is the need of technologies and solution sets for improving the deep renovation process as well as demonstrating the performances for supporting the stakeholders in the decision-making process. To cope with the issue, this work presents a methodology for setting up a repository of building deep renovation packages that integrates industrialised facade technologies and more traditional solutions. The performances feeding into the repository have been evaluated by means of transient detailed simulations on a set of reference buildings in representative European climate conditions. The renovation packages are evaluated in terms of key performance indicators dealing with five areas: energy, comfort, pollutant emissions, cost, and renovation time. The defined repository includes 289 assessed technology packages and associated performances across Europe, providing a comprehensive support to identify the most effective solutions according to the user needs. The paper presents the application of the repository with two examples of stakeholders’ decision-making paths for selecting the deep renovation packages according to different priorities and expected targets.

Nearly all retail locations use ventilation and cooling systems to ensure adequate air exchange for health reasons and indoor comfort temperatures. These systems can run for over 2,000 hours per year and we expect that average operating hours will continue to rise across Europe because of the continued trend towards longer opening hours and increased number of opening days. Shopping malls often enclose large open spaces and atria with high solar and internal gains that can drive ventilative cooling. This paper presents the ventilative cooling strategy proposed, analysed and implemented in one of the three demo cases of the project: Mercado del Val, the historic market of the city of Valladolid. Once we determined the climate suitability, we defined a ventilative cooling strategy that exploits openings in the facade and in the skylight to promote stack effect ventilation. Considering that indoor spaces of a shopping centre highly interacts among each other, a multizone based analysis of airflows is needed to evaluate the ventilative cooling strategy effectiveness and to assess potential energy savings. We sized openings area and location on the facade, taking into account design constraints, and we assessed their performances in terms of energy, thermal comfort and indoor air quality. Results show the potential cooling load reduction, with the achievement of acceptable thermal comfort due to the ventilative cooling in the shopping mall. The analysis performed supported the design decision process towards cost effective low energy shopping centre.

In the perspective of the Net Zero Energy Buildings as specified in the EPBD 2010/31/EU, we propose the concept and design of a modular unglazed solar thermal (UST) facade component for facilitating the installation of active solar facades. The renovation of existing buildings offers an opportunity to improve the energy efficiency when using such a system and a novel design methodology tackled via a parametric approach is here proposed. We analysed a variety of building typologies as potential application targets of the UST collector, properly sizing the collector field for each typology to match the heat loads profile. We investigated the thermal behaviour of the novel thermal facade component and the energy potentiality in covering the heat demand using the TRNSYS software’s model of the UST collector field as a part of a combisystem. We concluded with the definition of rules of thumb for early design stage. The work here presented demonstrates that the low-cost, the versatile modularity and the easy installation make this active solar facade an innovative and promising technology for the building stock transformation, despite of the low quality of the produced energy due to the low outcome temperature of the unglazed collector.

Decisions taken during the early design of facade retrofits have a major influence on the final performance of buildings. However, current procurement procedures do not promote the evaluation of how facade systems design affects the overall building performance, which includes energy efficiency, comfort, cost and their complex interactions. Tenders are commonly based on single values which describe single properties of facade components like thermal transmittances and solar gain factors and do not consider interrelation between these components, the dynamic behavior of buildings and specific local climate. This paper presents a concept to drive public procurement processes based on overall building performance criteria. The methodology is operationalized by a user-friendly tool (FIT) predicting the overall performance according to facade design variations. These performance criteria are integrated into tenders by calculating a total score for every design proposal. This approach sensitizes designers and contracting authorities to consider the overall performance of a facade from the very early design and helps in making informed design decisions. An application in a simulated case study of a public school building shows its potential to guide public procurement processes and that further research and validation in actual procurement procedures is needed.

Urban systems de-carbonization is achievable if supported by measures for energy efficiency and integration of renewable energy sources (RES). In this context, a key role can be played by shopping malls. They are usually identified as “icons of consumer society,” but they also have a huge energy retrofitting potential. Moreover, they can have an active role in the future smart grid, connecting buildings and energy infrastructures. Photovoltaic (PV) and energy storage systems (ESS) play a fundamental role in exploiting such potential, and can very quickly become a cost effective solution contributing to emissions reduction, as demonstrated in the presented case study. Considering the short economic perspective of investors, the capital expenditure associated with retrofitting could be a barrier, and the evaluation of suitable economic indicator of primary importance to choose among several retrofitting strategies. Despite the fact that overall legislative frameworks and regulations do not promote shopping centers as key energy and social infrastructures to achieve ambitious targets in the ongoing urban transformation, energy-efficient shopping malls massively using RES and ESS can actually become the backbone of the city of tomorrow.

A typical problem of Building Integrated Photovoltaic (BiPV) is the power loss due to temperature increase caused by limited cooling compared to free standing photovoltaic (PV) systems. Higher operating temperatures have a negative effect both on the efficiency and lifetime of the PV system. Decreasing the PV operating temperature in BiPV applications is thus a crucial aspect to both enhance the system efficiency and to decrease the temperature-induced degradation process. This study investigates the effectiveness of a passive low-cost strategy to improve the PV performance of BiPV systems by decreasing the module temperature. It consists in the application of an heat sink system on the PV module back side to enhance the PV cooling. An experimental investigation was performed on a wooden BiPV facade prototype and the results show that this strategy could lead to a temperature reduction up to 5.2 °C, meaning a possible power output increase of 2.3% of the PV nominal power. Considering a South facing facade application in Agrigento (South of Italy) climate, this strategy could enhance the annual PV energy generation for an extent of 1.2% and the total PV energy generation over the whole module life-time for an extent of 31% due to a longer life-time (considering some assumptions reported in the paper).

Only 1.2% of the EU building stock is renovated every year, and the rate is even lower in case of deep renovation (i.e., savings exceed 60% compared to pre-renovation levels), since such interventions are often too expensive. To answer these challenges, 4RinEU will define robust, cost-effective, tailorable deep renovation technology packages supported by usable methodologies, feeding into reliable business models. The project will manage different stages of the deep renovation process, from the preliminary audit up to the component end-of-life, and will provide information on energy, comfort, users’ impact, and investment performance. The 4RinEU deep renovation strategy is based on 3 pillars: (i) technologies, to decrease net primary energy use (60 to 70% compared to pre-renovation), ant to reduce the life cycle costs over 30 years (15% compared to a typical renovation); (ii) methodologies to support the design and implementation of the technologies; (iii) business models to enhance the level of confidence of deep renovation investors.

Nearly Zero Energy Buildings (nZEBs) represent the backbone to achieve ambitious European goals in terms of energy efficiency and CO2 emissions reduction. As defined in the EPBD, by 31 December 2020, all of the new buildings will have to reach a target of nearly zero energy. This target encourages the adoption of innovative business models as well as the technology development in the building sector, aimed at reducing energy demand and exploiting local renewable energy sources (RES). Assessing the share of implementation and the performance of technologies in new or renovated nZEBs is strategic to identify the market trends and to define design guidelines with the most effective solutions according to the context. In this regard, this paper analyses the construction features of a set of nZEBs, collected in 17 European countries within the EU IEE ZEBRA2020 project, with a special focus on the influence of the boundary conditions on the technologies adopted. The results show a general high insulation level of the envelope and recurrent specific technologies in the Heating Ventilation Air Conditioning (HVAC) system (i.e., heat pumps and mechanical ventilation), while the climatic conditions do not drive significantly the design approach and the nZEB features.

Policy makers need scientific support to set ambitious yet realistic environmental targets for the transition to energy efficient buildings and to develop cost-effective policies to meet these targets, but comprehensive, manageable procedures to this aim are still lacking. Our proposed method ranges from baseline creation to transition scenarios depending on annual retrofit budget and specifies the buildings to renovate according to location, size, and age, and the energy efficiency measures to apply based on cost and energy saving. We show how to extrapolate a baseline from few available data, determine retrofit costs, and create calibrated models to estimate energy savings. Retrofits are ranked by levelized cost of saved energy, which ensures that for any budget allocated to retrofit maximum energy savings are obtained at minimum cost to society. The results are summarized in an energy efficiency cost curve enabling policy makers to estimate potential costs and energy savings. We demonstrate the method on a housing stock in northern Italy and show that facade insulation of old buildings in colder climates can compete with gas heating. About 60% baseline energy consumption can be saved doubling current investments, while a maximum saving of 75% requires over three times the current investments.

We present a study of natural ventilation design during the early (conceptual) stage of a building's design, based on a field study in a naturally ventilated office in California where we collected data on occupants' window use, local weather conditions, indoor environmental conditions, and air change rates based on tracer-gas decay. We performed uncertainty and sensitivity analyses to determine which design parameters have most impact on the uncertainty associated with ventilation performance predictions. Using the results of the field study along with wind-tunnel measurements and other detailed analysis, we incrementally improved our early-design-stage model. The improved model's natural ventilation performance predictions were significantly more accurate than those of the first draft early-stage-design model that employed model assumptions typical during initial design. This process highlighted significant limitations in the EnergyPlus software's models of occupant-driven window control. We conclude with recommendations on key design parameters including window control, wind pressure coefficients and weather data resolution to help improve early-design-stage predictions of natural ventilation performance using EnergyPlus.

The increasing global energy demand, the foreseen reduction of available fossil fuels and the increasing evidence off global warming during the last decades have generated a high interest in renewable energy sources. However, renewable energy sources, such as wind and solar power, have an intrinsic variability that can seriously affect the stability of the energy system if they account for a high percentage of the total generation. The Energy Flexibility of buildings is commonly suggested as part of the solution to alleviate some of the upcoming challenges in the future demand-respond energy systems (electrical, district heating and gas grids). Buildings can supply flexibility services in different ways, e.g. utilization of thermal mass, adjustability of HVAC system use (e.g. heating/cooling/ventilation), charging of electric vehicles, and shifting of plug-loads. However, there is currently no overview or insight into how much Energy Flexibility different building may be able to offer to the future energy systems in the sense of avoiding excess energy production, increase the stability of the energy networks, minimize congestion problems, enhance the efficiency and cost effectiveness of the future energy networks. Therefore, there is a need for increasing knowledge on and demonstration of the Energy Flexibility buildings can provide to energy networks. At the same time, there is a need for identifying critical aspects and possible solutions to manage this Energy Flexibility, while maintaining the comfort of the occupants and minimizing the use of non-renewable energy. In this context, the IEA (International Energy Agency) EBC (Energy in Buildings and Communities program) Annex 67: “Energy Flexible Buildings” was started in 2015. The article presents the background and the work plan of IEA EBC Annex 67 as well as already obtained results. Annex 67 is a corporation between participants from 16 countries: Austria, Belgium, Canada, China, Denmark, Finland, France, Germany, Ireland, Italy, The Netherlands, Norway, Portugal, Spain, Switzerland and UK. ispartof: Energy and Buildings vol:155 pages:25-34 status: published

Nowadays, one of the main goals of the building industry and architecture is to exploit the solar source for the air‐conditioning of buildings. Over the last years many activities have started to develop new building and plant technologies oriented to energy saving by improving indoor comfort and reducing pollution emission. The guidelines deriving from various world conferences (Kyoto 1997, Buenos Aires 1998) are known. Industrial countries have committed themselves to try and carry out new strategies to reduce both energy consumption and air‐pollution. These aims have increased research works oriented to find materials, components and systems able to use energy gains from the environment, in particular from the sun. During the study carried out at ITC on the subject, two envelope technologies have been studied and realised. The paper describes such technologies and the methods used for their characterisation. It also reports on the most meaningful results obtained from the experiments carried out.

The paper analyses the benefits of the application of energy analysis in the early-stage building design, in particular for large commercial buildings. The research highlights the barriers that prevent this early integration and finally proposes the development of a methodology tailored around the optimization of energy efficiency during early-stage design. In general, the research aims to identify (a) the accuracy obtainable through progressive simplifications of the building model, (b) the most significant building parameters with respect to the model result accuracy and (c) the maximum number of simplifications able to ensure the respect of time requirements dictated by early-stage building design and to maintain an acceptable level of correctness. Here, as detailed example of simplification process, a case study of a large multi-storey office building is modelled starting with a previous detailed simulation performed through EnergyPlus and Openstudio software. The detailed model is then analyzed and progressively simplified. At each progressive simplification step, a comparison with the detailed results is given in terms of building energy needs and power curves of the system. The analysis is performed based on three different system hypotheses: a single-zone system and a variable air volume system with and without humidity control. The quantitative differences between detailed and simplified model are analyzed to determine the quality of the results of the simplified model.

A major advantage of the Net Zero Energy Building (Net ZEB) approach is claimed to be the absence of energy performance indicators, hence avoiding the need to set internationally agreed limits. Nevertheless, if the rationale is to endorse the design of environmentally friendly buildings that promote sustainable development, then reasonably strict requirements on energy efficiency should be satisfied while providing high levels of indoor environmental quality and consequent users comfort. Otherwise, the risk is that poorly designed buildings could achieve the definition of Net ZEB simply by means of oversized generation systems. The purpose of this paper is to provide an overview of existing international standards and/or design best practices based on comfort and energy efficiency requirements that can be taken as general recommendations for the design of Net ZEBs.

The reduction of air-conditioning energy consumptions is one of the main indicators to act on when improving the energy efficiency in buildings. n the case of advanced technological buildings, a meaningful contribution to the thermal loads and the energy consumptions reduction could depend on the correct configuration and management of the envelope systems. In recent years, the architectural trend toward highly transparent all-glass buildings presents a unique challenge and opportunity to advance the market for emerging, smart, dynamic window and dimmable daylighting control technologies (Lee et al., 2004). A prototype dynamic glazing system was developed and tested at ITC-CNR; it is aimed at actively responding to the external environmental loads. Both an experimental campaign and analyses by theoretical models were carried out, aimed at evaluating the possible configurations depending on different weather conditions in several possible places. Therefore, the analytical models of the building-plant system were defined by using a dynamic energy simulation software (EnergyPlus). The variables that determine the system performance, also influenced by the boundary conditions, were analysed, such as U- and g-value; they concern both the morphology of the envelope system, such as dimensions, shading and glazing type, gap airflow thickness, in-gap airflow rate, and management, in terms of control algorithm parameters tuning fan and shading systems, as a function of the weather conditions. The configuration able to provide the best performances was finally identified by also assessing such performances, integrating the dynamic system in several building types and under different weather conditions. The dynamic envelope system prototype has become a commercial product with some applications in facade systems, curtain walls and windows. The paper describes the methodological approach to prototype development and the main results obtained, including simulations of possible applications on real buildings. (C) 2009 Elsevier Ltd. All rights reserved.

Progettare e costruire edifici con elevato livello di sostenibilità ambientale significa ridurre l'uso di risorse, aumentare il comfort ed ottimizzare l'integrazione dell'edificio stesso nel territorio, anche a livello funzionale e sociale. In questo contesto ampio e articolato, l'ITC è impegnato nella definizione di metodi e strumenti di valutazione capaci di fornire informazioni consistenti a tutti i soggetti coinvolti e, in primo luogo, agli utenti finali. A livello internazionale si trovano numerosi sistemi di valutazione del livello di sostenibilità ambientale, nati e sviluppati con approcci e finalità distinti; i più diffusi sono LEED, esempio di sistema di "auto-referenziazione" voluto dai progettisti, BREEAM sviluppato da un ente certificatore e finalizzato a verificare il livello dei progettisti e SBTool realizzato nell'ambito di un processo internazionale di R&D. A partire da quest'ultimo sono nati una serie di strumenti nazionali tra cui, in Italia, il protocollo ITACA, approvato dalla Conferenza deiPresidenti delle Regioni italiane nel gennaio del 2004 ed attualmente impiegato in diverse regioni a supporto di politiche volte a promuovere l'edilizia sostenibile. Il protocollo ITACA, inizialmente indirizzato agli edifici residenziali, è al momento in fase di estensione verso altre tipologie edilizie. Grazie al supporto diretto della Regione Marche, l'ITC sta sviluppando un vero e proprio software che implementerà l'aggiornamento del protocollo. Tuttavia molte tematiche rimangono ancora aperte, come la modalità di attribuzione dei pesi, il benchmarking, la definizione di indicatori prestazionali quantitativi per tutti i criteri i dei relativi strumenti di calcolo, la determinazione di un protocollo di indagine per la misura in opera. L'ITC ha inoltre partecipato alla conduzione di numerosi casi studio (e altri sono in corso d'opera) con risultati attesi su più fronti: la definizione di strumenti di valutazione dedicati a contesti specifici, la verifica di interventi di retrofit su edifici esistenti compiuti con lo scopo di elevarne le prestazioni energetico-ambientali. L'attività di ricerca e sviluppo e la possibilità di confrontarsi con le realtà internazionali e con casi studio concreti permette di migliorare metodi e strumenti di valutazione in direzione di una sempre maggiore oggettività, efficacia e concretezza scientifica.