Search Results (15)

Plug-in distributed energy resources (DERs), such as balcony solar, backfeed power to the home through a standard plug. These systems may represent the future of residential solar and storage, particularly as recent net metering policies have reduced the economic appeal of rooftop solar. While plug-in DERs have seen widespread success in Europe, their U.S. market is stagnant. This paper reviews the technical, interconnection, and regulatory barriers hindering the adoption of plug-in DERs. We first discuss the technical barriers, which include touch safety, breaker masking, and bidirectional ground-fault circuit interrupters. We then examine utility perspectives on plug-in DERs and strategies for navigating interconnection challenges. Finally, we discuss regulatory hurdles related to UL standards and the National Electrical Code. Full article

In 1944, the architect Antonio Gómez Davó designed and built a new house for Mr. Ferrer at Rocafort in the suburbs of Valencia (Spain). In this same year, Europe, America, Russia and even Japan were still at war and Spain was recovering from its own intestine conflict. Therefore, architectural innovations and influences were scarce, as was the circulation of specialized journals on the matter. Still, many creations were occurring, like ceramic vaults and the brise-soleil; further, the architect Le Corbusier had stated his profound nostalgia for the Mediterranean, a sea that he had come to appreciate in his travels to the “East”. In the case of Gómez Davó, having been born and raised in a prominent family of Valencia, he could not remain indifferent to the design features that appeared in the vernacular architecture of the area, especially the type of inclined louvers of Arabic descent, that covered bow-windows and balconies and which have come to be known in Spain as the Majorcan louvers; these are currently even employed by prominent architects like Rafael Moneo at the extension of the Painter Miro Foundation. However, with so many difficult circumstances surrounding him, Gómez Davó could not get to the point of producing a ground-breaking design based on solar assumptions for the whole façade of the house he was building; instead, when providing an entrance porch apt for living life in the pure Mediterranean tradition, he ventured to construct a surprising perforated wall oriented to the south in order to control radiation in the winter and provide shade in the summer while affording excellent light and superb conditions of ventilation. By means of self-devised simulation tools, we have analyzed the conditions of the house and especially of his innovative brise-soleil, which are at times reminiscent of Alvar Aalto’s solutions for day-lit roofs, and which he intuitively adapted to the latitude of Valencia with the help of incipient notions of solar geometry. By outlining such unknown and bold precedent and assessing the house’s proper climatic performance, we contribute to revitalizing the early and daring pioneers of solar architecture in peripheral Spain and Europe during the birth of critic regionalism, a fact often disregarded in the conventional history of Modern Architecture. Full article

Rapid urbanization exacerbates the urban heat island effect, raising local temperatures and endangering residents’ health and well-being. The decreasing green spaces resulting from urbanization necessitate global action focused on reducing heat island intensity and addressing heat stress. Urban green infrastructure (UGI) offers solutions for enhanced comfort and reduced pollution through passive methods. Various large-scale UGI projects have been implemented to regulate temperature and improve air quality in urban areas. More research on smaller green spaces is essential to improve the microclimate in space-constrained urban cities. This experimental study examines the thermal effectiveness of potted plants located on balconies of a mid-rise residential building in Chennai, India. The study aims to enlighten balcony greening’s role in reducing heat stress by monitoring temperature and humidity indoors and outdoors, with and without potted plants at similar solar radiation. Potted plants significantly lowered indoor air and surface temperatures by about 3 °C. Thus, balconies offer untapped potential for green interventions that are often unnoticed in tropical climates like India. The challenges in the installation and maintenance of UGI hinder the widespread adoption of UGI even though UGI positively influences residential well-being. The significant findings benefit urban planners and architects, enlightening strategies to enhance urban thermal comfort and mitigate heat stress through small-scale and cost-effective green interventions. This research contributes to sustainable urban development in tropical climates, aligning with several UN Sustainable Development Goals (SDGs), including SDGs 3, 7, 11, 13, and 15. Full article

The accurate assessment of heat transfer via unheated spaces is an important aspect of calculating the heating load of a building and mitigating its energy consumption and carbon emissions. Currently, the majority of international and national standards employ the correction factor method for the calculation of heat transfer via unheated spaces, categorized into three types: detailed temperature correction factors (b), simplified b-values, and a correction factor (a) of thermal resistance. In order to provide an accurate and efficient evaluation of heat transfer through unheated spaces, this paper conducts a comparative analysis of these three methods using on-site measurements, TRNSYS (version 18) simulations, and analytical calculations. The findings indicate that the use of simplified b-values results in inaccurate predictions of correction factors and heat transfer via unheated balconies, yielding relative discrepancies within the ranges of 0.065 to 0.527 and 12.2% to 111.3%, respectively. Detailed temperature correction factors offer a more precise prediction, exhibiting relative discrepancies of −0.161 to 0.11 and 0.1% to 33.5%. However, the complexity of the calculation process, influenced by dynamically changing climates and solar radiation, necessitates a steady-state assumption to streamline calculations. The use of detailed correction factors of thermal resistance yields more accurate predictions, with relative discrepancies ranging from −0.176 to 0.11 and 0.3% to 33.1%, and it is recommended as the main method for predicting heat transfer via unheated spaces. In addition, it is advised to enhance the thermal resistance correction factor method by considering the influence of radiative heat transfer via transparent envelopes. Full article

To mitigate greenhouse gas emissions responsible for global warming and climate change, governments have undertaken concerted efforts and established goals to restructure production and consumption patterns within the current global economy. The construction sector, which in Europe has significant energy use and related greenhouse gas emissions, recognizes adopting passive heating and cooling systems for buildings as a viable solution. The revival of vernacular passive solar strategies emerges as opportune within this context. Through dynamic simulations, this study aims to analyze and quantify the potential contribution of glazed balconies, a traditional passive heating system, to improve contemporary constructions’ thermal behavior and comfort conditions in mild temperate climates, such as in northern Portugal. Results indicate that this system can significantly enhance a building’s energy efficiency, reducing energy needs for heating and cooling by up to 47% while extending periods of thermal comfort indoors by nearly 900 h per year compared to buildings with non-glazed balconies. Proper use of natural ventilation and shading devices is essential to ensure optimal system performance and prevent overheating. This research underscores the potential of glazed balconies as a sustainable solution for enhancing contemporary buildings’ thermal-energy performance and comfort, contributing to the transition towards carbon-neutral constructions. Full article

In sunspaces, there is an observable temperature rise above the external air temperature, caused by solar gains and the buffering effect of their enclosure. In addition, their external partitions form a barrier preventing the direct influence of the external environment and delaying the natural deterioration of elevation surface. In the paper, the temperature rise in a glazed balcony attached to a typical flat in a multifamily building, together with the energy demand in the living zone, were assessed with the use of dynamic computer simulations. Ten variants of the sunspace casing were analysed, with different thermal and solar energy transmittance of the glazing (which is a novel subject in the research area). This enabled us to evaluate average values of the temperature reduction factor during the year and to choose the most efficient variant of the sunspace external partitions. It turned out to be an insulated, double-glazed casing with a spectrally selective coating (type O 21), combining high insulative properties with high solar transmittance. These features allowed the temperature in the sunspace to rise by almost 10°C (compared with the external air) and lower total energy demand in the flat by 33% (compared with a flat with an open balcony). Full article

Based on an extensive literature review on passive building designs for tropical climates, seven energy-efficient building design principles for tropical climate areas were deduced. These are: 1. To orientate a building design in such a direction that it protects from excessive solar radiation; 2. To accommodate for indoor natural ventilation; 3. That it makes maximal use of indirect instead of direct natural light; 4, That it reduces the amount of heat transmission through the roof as much as possible by natural ventilation between roof and ceiling and by lowering the roof surface temperature; 5. By preventing the use of high thermal mass materials; 6. By reducing through the exterior walls as much as possible heat transmission by e.g., preventing direct sunlight on the external walls and applying reflective paints on the external walls and; 7. By creating outdoor and transition spaces such as balconies, terraces atriums and corridors. The insights from the literature review were used as input to conduct a field study to evaluate the practice of applying passive building design principles. To this end, for 626 buildings on the Caribbean island Curaçao, it was investigated to what extent the recommended passive design principles for tropical climates were actually applied. Based on the results of the field study, several recommendations are made to improve the practice of applying passive building principles. Full article

Mini-solar photovoltaics, which are installed on apartment balconies, are rapidly spreading in Seoul, South Korea. Seoul has implemented a policy to diffuse mini-solar photovoltaics in apartments for energy transition since 2012. The policy considers compact land use and a large population of the city. This study examines a variety of variables in relation to the adoption of mini-solar photovoltaics. In particular, we focus on peer effects, namely, those of spatially adjacent, previously installed mini-solar photovoltaics. As apartment characteristics, four variables are selected to assess both within and between apartment complexes: one for the density of adopters as a within-complex variable and three for the number of adopters in the 500 m, 1 km, and 1.5 km radius of apartment complexes as between-complex variables. A major finding is that peer effects significantly contribute to the new adoption of mini-solar photovoltaics. Implications of this finding are discussed in an urban context. Full article

Solar photovoltaics (PV) deployment is not easy in dense urban areas because there is little space for the installation. Furthermore, tenants have few incentives to install PV panels because they frequently relocate, and most PV facilities are nonremovable. To address these factors, this study reports on an innovative model that collectively installed 260 W of mini-PV on the balconies of almost all the households in two high-rise apartment complexes in Seoul, South Korea. This project was unique in that it established energy commons in a community using private space. This study found that economic and social factors significantly influenced community-internal or micro factors, which in turn affected the success of the community energy project. Economic factors such as the expected economic benefit and residents paying no direct installation costs shaped the initial conditions for the commencement of the project. Leadership played a key role by speeding up the process, relieving residents’ concerns and distrust. This study introduced an innovative community energy model that can be referenced by megacities and communities. It provides opportunities for enhancing awareness of energy transition via on-site energy production using renewable energy and allows even communities that have insufficient common space to build energy commons. Full article

The built environment remains a strategic research and innovation domain in view of the goal of full decarbonization. The priority is the retrofitting of existing buildings as zero-emission to improve their energy efficiency with renewable energy technologies pulling the market with cost-effective strategies. From the first age of photovoltaics (PV) mainly integrated in solar roofs, we rapidly moved towards complete active building skins where all the architectural surfaces are photoactive (Building Integrated Photovoltaics - BIPV). This change of paradigm, where PV replaces a conventional building material, shifted the attention to relate construction choices with energy and cost effectiveness. However, systematic investigations which put into action a cross-disciplinary approach between construction, economic and energy related domains is still missing. This paper provides the detailed assessment of a real multifamily building, taking into account retrofit scenarios for making active the building skin, with the goal to identify the sensitive aspects of the energetic and economic effectiveness of BIPV design options. By assuming a real case study with monitored data, the analysis will consider a breakdown of the main individual parts composing the building envelope, by then combining alternative re-configurations in merged clusters with different energy and construction goals. Results will highlight the correlation between building skin construction strategies and the energy and cost parameters by identifying the cornerstones for enhancing efficiency. The outcomes, related to the total life cost, self-consumption/sufficiency, in combination with different building design options (façade, roof, balconies, surface orientations, etc.), provide a practical insight for researchers and professionals to identify renovation strategies by synergistically exploiting the solar active parts towards lower global costs and higher energy efficiency of the whole building system. Full article

In South Korea, we are aiming for net zero energy use apartment home structures. Since the apartment structure in South Korea is generally a high-rise of 10 or more floors, the types of renewable energy applicable are limited to photovoltaic (PV) panels, solar collectors installed on the wall, or a photovoltaic thermal (PVT) hybrid panel combining both. In this study, the effect of PV, ST (Solar Thermal), and PVT systems on greenhouse gas reduction was analyzed using TRNSYS18. All three systems showed maximum CO₂ reductions at 35° facing south. PV, ST, and PVT showed CO₂ reductions of 67.4, 114.6, and 144.7 kg_CO₂/m²·year, respectively. Compared to those values, when installed on a wall (slope of 90°), CO₂ reduction is about 35–40% less and about 20% less at a slope of 75°. ST and PVT installed on the vertical wall have a greater greenhouse gas reduction effect than the PV installed at the optimal slope of 35°. Since the CO₂ reduction difference among SW, SE, and azimuthal S is within 10%, ST and PVT are recommended for installation on high-rise apartment structure walls or balconies with the azimuthal angle of ± 45° with respect to south. Full article

The increase in global environmental problems requires more environmentally efficient construction. Vernacular passive strategies can play an important role in helping reducing energy use and CO₂ emissions related to buildings. This paper studies the use of glazed balconies in the North of Portugal as a strategy to capture solar gains and reduce heat losses. The purpose is understanding thermal performance and comfort conditions provided by this passive heating strategy. The methodology includes objective (short and long-term monitoring), to evaluate the different parameters affecting thermal comfort and air quality, and subjective assessments to assess occupants’ perception regarding thermal sensation. The results show that the use of glazed balconies as a passive heating strategy in a climate with cold winters is viable. During the mid-seasons, the rooms with balcony have adequate comfort conditions. In the heating season, it is possible to achieve comfort conditions in sunny days while in the cooling season there is a risk of overheating. Regarding indoor air quality, carbon dioxide concentrations were low, but the average radon concentration measured was high when the building was unoccupied, rapidly decreasing to acceptable values, during occupation periods when a minimum ventilation rate was promoted. Occupants’ actions were essential to improving building behavior. Full article

Rapid and uncontrolled urbanization is continuously increasing buildings’ energy consumption and greenhouse gas emissions into the atmosphere. In this scenario, solar energy integrated into the built environment can play an important role in optimizing the use of renewable energy sources on urban surfaces. Preliminary solar analyses to map the solar accessibility and solar potential of building surfaces (roofs and façades) should become a common practice among urban planners, architects, and public authorities. This paper presents an approach to support urban actors to assess solar energy potential at the neighborhood scale and to address the use of solar energy by considering overshadowing effects and solar inter-building reflections in accordance with urban morphology and building characteristics. The approach starts with urban analysis and solar irradiation analysis to elaborate solar mapping of façades and roofs. Data processing allows assessment of the solar potential of the whole case study neighborhood of Sluppen in Trondheim (Norway) by localizing the most radiated parts of buildings’ surfaces. Reduction factors defined by a new method are used to estimate the final solar potential considering shadowing caused by the presence of buildings’ architectural elements (e.g., glazed surfaces, balconies, external staircases, projections) and self-shading. Finally, rough estimation of solar energy generation is assessed by providing preliminary recommendations for solar photovoltaic (PV) systems suited to local conditions. Results show that depending on urban morphology and buildings’ shapes, PV systems can cover more than 40% of the total buildings’ energy needs in Trondheim. Full article

Singapore’s high dependence on imported energy and food resources, and the lack of available land requires an efficient use of the built environment in order to increase energy and food autonomy. This paper proposes the concept of a productive façade (PF) system that integrates photovoltaic (PV) modules as shading devices as well as farming planters. It also outlines the design optimization process for eight PF prototypes comprising two categories of PF systems: Window façade and balcony façade, for four orientations. Five criteria functions describing the potential energy and food production as well as indoor visual and thermal performance were assessed by a parametric modelling tool. Optimal PF prototypes were subsequently obtained through the VIKOR optimization method, which selects the optimal design variants by compromising between the five criteria functions. East and West-facing façades require greater solar protection, and most façades require high-tilt angles on their shading PV panels. The optimal arrangement for vegetable planters involves two planters located relatively low with regard to the railing or window sill. Finally, the optimal façade designs were adjusted according to the availability of resources and the conditions and context of the Tropical Technologies Laboratory (T² Lab) in Singapore where they are installed. Full article

Solar passive strategies that have been developed in vernacular architecture from different regions are a response to specific climate effects. These strategies are usually simple, low-tech and have low potential environmental impact. For this reason, several studies highlight them as having potential to reduce the demands of non-renewable energy for buildings operation. In this paper, the climatic contrast between northern and southern parts of mainland Portugal is presented, namely the regions of Beira Alta and Alentejo. Additionally, it discusses the contribution of different climate-responsive strategies developed in vernacular architecture from both regions to assure thermal comfort conditions. In Beira Alta, the use of glazed balconies as a strategy to capture solar gains is usual, while in Alentejo the focus is on passive cooling strategies. To understand the effectiveness of these strategies, thermal performances and comfort conditions of two case studies were evaluated based on the adaptive comfort model. Field tests included measurement of hygrothermal parameters and surveys on occupants’ thermal sensation. From the results, it has been found that the case studies have shown a good thermal performance by passive means alone and that the occupants feel comfortable, except during winter where there is the need to use simple heating systems. Full article