• Energy Research
• 15. Life on land close

Recently, Building Integrated Photovoltaic (BIPV) windows have become an alternative energy solution to achieve a zero-energy building (ZEB) and provide visual comfort. In Algeria, some problems arise due to the high energy consumption levels of the building sector. Large amounts of this energy are lost through the external envelope façade, because of the poorness of the window’s design. Therefore, this research aimed to investigate the optimum BIPV window performance for overall energy consumption (OEC) in terms of energy output, heating and cooling load, and artificial lighting to ensure visual comfort and energy savings in typical office buildings under a semi-arid climate. Field measurements of the tested office were carried out during a critical period. The data have been validated and used to develop a model for an OEC simulation. Extensive simulations using graphical optimization methods are applied to the base-model, as well as nine commercially-available BIPV modules with different Window Wall Ratios (WWRs), cardinal orientations, and tilt angles. The results of the investigation from the site measurements show a significant amount of energy output compared to the energy demand. This study revealed that the optimum BIPV window design includes double-glazing PV modules (A) with medium WWR and 20% VLT in the southern façade and 30% VLT toward the east–west axis. The maximum energy savings that can be achieved are 60% toward the south orientation by double-glazing PV module (D). On the other hand, the PV modules significantly minimize the glare index compared to the base-model. The data extracted from the simulation established that the energy output percentages in a 3D model can be used by architects and designers in early stages. In the end, the adoption of optimum BIPV windows shows a significant enough improvement in their overall energy savings and visual comfort to consider them essential under a semi-arid climate.

Abstract Irrigation of green spaces in cities helps to reduce thermal stress and building energy consumption in hot seasons, but requires an intricate balance between energy and water resource usage. While the objective for agricultural irrigation is focused on the yield of produces, urban irrigation needs a new paradigm. In this study, a cutting-edge urban canopy model is applied to assess the impact of a variety of controlled irrigation schemes for Phoenix. Results show that by increasing surface moisture availability for evapotranspiration, urban irrigation has a cooling effect on the built environment throughout the year. Maximum reduction in canyon air temperature can be more than 3 °C in summer as compared to the condition without irrigation. Among all investigated schemes, the soil-temperature-controlled irrigation is the most efficient in reducing the annual building energy consumption and the total cost. The total annual saving depends on the controlling soil temperature for irrigation activation, and can be up to about $1.19 m −2 wall area as compared to the current irrigation practice. In addition, the scheme can substantially enhance outdoor thermal comfort of pedestrians in summers.

Abstract In response to the burgeoning building integrated agriculture (BIA) discourse and industry, and assumptions of this land use form as a climate change adaptation strategy, this study considers the impact of rooftop greenhouses (RTGs) on the thermal performance of the built environment in current and future climate conditions. Based on empirical evidence, the study simulates the thermal impact of completely retrofitting an existing building in a Southern African urban context with passively controlled, non-integrated RTGs under current and future climate change affected climatic conditions. The study concludes that the current greenhouse technologies used in South African rooftop farms provide limited thermal modulation capacity for farmers, as well as generally negatively affecting the thermal performance of the associated buildings. Simulating both highly and poorly insulated buildings reveal contrasting impacts on the indoor thermal environment, with a 0.73 °C decrease and 0.55 °C increase in mean temperatures, respectively. Conversely, the highly insulated simulation reveals an annual energy consumption increase of 3.5%, which progressively worsens under higher climate change induced temperatures. These findings, based on current practices in the BIA industry, hope to inform both the choice of technology, as well as the development of appropriate greenhouse technologies to maximise their performance and enable co-benefits as often assumed in the industry.

Many cities around the world are facing immense pressure due to the expediting growth rates in urban population levels. The notion of ‘smart cities’ has been proposed as a solution to enhance the sustainability of cities through effective urban management of governance, energy and transportation. The research presented herein examines the applicability of a mathematical framework to enhance the sustainability of decisions involved in zoning, land-use allocation and facility location within smart cities. In particular, a mathematical optimisation framework is proposed, which links through with other platforms in city settings, for optimising the zoning, land-use allocation, location of new buildings and the investment decisions made regarding infrastructure works in smart cities. Multiple objective functions are formulated to optimise social, economic and environmental considerations in the urban space. The impact on underlying traffic of location choices made for the newly introduced buildings is accounted for through optimised assignment of traffic to the underlying network. A case example on urban planning and infrastructure development within a smart city is used to demonstrate the applicability of the proposed method.

Multifamily residential sites (MRS) are practical alternatives for securing a carbon uptake source in urban areas where hardscape is dominant, as trees must be planted in the lot area, according to the current landscape-related ordinances in Korea. Tree planting contributes to sustainability of residential sites through carbon reduction. This study quantified direct and indirect carbon reduction from tree planting in MRS in Korea and explored sustainable design guidelines to maximize the carbon offset service of MRS. The total annual direct and indirect carbon reduction through tree planting in all the MRS was estimated to be about 101.1 kt/year. This carbon reduction equaled 3.3% of the total annual carbon emissions from the heating and cooling energy consumption of multifamily buildings. This study considered both direct and indirect carbon reduction from trees in MRS which was insufficient in previous studies. The results of this study can be useful internationally by sharing the information of sustainable residential design in enhancing carbon offset service.

Atmospheric moisture loading can cause a great impact on the performance and integrity of building exteriors in a tropical climate. Buildings can be highly impacted due to the changing climate conditions over the world. Therefore, it is important to incorporate the projected changes of moisture loads in structural designs under changing climates. The moisture index (MI) is widely used in many countries as a climate‐based indicator to guide the building designs for their durability performance. However, this was hardly considered in structural designs in Sri Lanka, even though the country is one of the most affected countries under climate change. Therefore, this study investigates future climate change impacts on the environmental moisture in terms of MI, which can be used in climate zoning, investigating indoor air quality, understanding thermal comfort and energy consumption, etc. The moisture index was found as a function of the drying index (DI) and wetting index (WI) to the whole country for its four rainfall seasons. The temporal and spatial distributions were plotted as MI maps and showcased under two categories; including historical MI maps (1990–2004) and future projected MI maps (2021–2040, 2041–2070, and 2071–2100). Future projected MI maps were constructed using bias‐corrected climatic data for two RCP climatic scenarios (RCP4.5 and RCP8.5). Results showed that the temporal and spatial variations of MIs are justifiable to the country’s rainfall patterns and seasons. However, notable increases of MIs can be observed for future projected MIs in two seasons, and thus a careful investigation of their impacts should be assessed in terms of the construction of buildings and various agricultural activities. Therefore, the outcome of this research can be essentially used in policy implementation in adapting to the ongoing climate changes in Sri Lanka.

It has been clear that the magnitude and character of a region's energy requirements are intimately related to the spatial configuration and mix of land use activities. To the degree to which they can shape the future configurations of residential, commercial, industrial, and transportation activities, local governments and their planners must give serious consideration to the energy implications of those configurations in the light of future social goals and requirements. This Planner's Energy Workbook describes a set of procedures that can be used to carry out community and regional energy analyses. The choice of land use activity parameters and their relation to energy use characteristics are associated with the normal planning concepts of land use density, type of residential development, commercial floorspace, industrial sales and employment, and shopping and work trip lengths. At the same time these energy related intensity coefficients are expressed in a form that permits the analysis of short-term conservation strategies such as the retrofit of insulation and the introduction of new technologies such as solar energy. An integrating framework is provided to construct total community or area energy consumption profiles and future needs; to examine compatibility between area requirements and the energy supply-distribution system serving themore » area; and to evaluate the implications for energy use of the physical configuration of urban, suburban and rural areas. Two cases illustrate the application of this Workbook. The Long Island area is representative of major suburban regions throughout the U.S. which have undergone major growth and development. A community redevelopment design in Tuscon, Arizona is typical of rapid and major land use development within the environs of an existing city.« less

Les « toits froids » réfléchissants solaires absorbent moins de lumière solaire que les toits sombres traditionnels, ce qui réduit le gain de chaleur solaire et diminue la quantité de chaleur transférée dans l'atmosphère. L'adoption généralisée de toits froids pourrait donc réduire les températures dans les zones urbaines, atténuant partiellement l'effet d'îlot thermique urbain et contribuant à inverser les impacts locaux du changement climatique mondial. Les impacts des toits froids sur le climat mondial restent débattus par les recherches antérieures et sont incertains. À l'aide d'un modèle sophistiqué du système terrestre, les impacts des toits froids sur le climat sont étudiés à l'échelle urbaine, continentale et mondiale. Nous constatons que l'adoption mondiale de toits froids dans les zones urbaines réduit les îlots de chaleur urbains partout, avec une diminution annuelle et mondiale moyenne de 1,6 à 1,2 K. Les diminutions sont statistiquement significatives, à l'exception de certaines régions d'Afrique et du Mexique où la fraction urbaine est faible, et de certaines régions de hautes latitudes pendant l'hiver. L'analyse du budget énergétique de surface et de TOA dans les régions urbaines à l'échelle continentale montre que les toits froids provoquent des augmentations du rayonnement solaire quittant le système Terre-atmosphère dans la plupart des régions du monde, bien que la présence d'aérosols et de nuages compense partiellement les augmentations du rayonnement ascendant. Les aérosols atténuent les augmentations induites par le toit froid du rayonnement solaire ascendant, allant de 4 % aux États-Unis à 18 % en Chine plus polluée. L'adoption de toits froids entraîne également des réductions statistiquement significatives des températures de l'air de surface dans les régions urbanisées de la Chine (−0,11 ± 0,10 K) et des États-Unis (−0,14 ± 0,12 K) ; l'Inde et l'Europe montrent des changements statistiquement insignifiants. Bien que les recherches antérieures ne soient pas d'accord sur la question de savoir si l'adoption généralisée de toits froids refroidirait ou réchaufferait le climat mondial, ces études manquent d'analyse sur la signification statistique des changements de température mondiale. La recherche présentée ici indique que l'adoption de toits froids dans le monde entier entraînerait des réductions statistiquement insignifiantes de la température moyenne mondiale de l'air (−0,0021 ± 0,026 K). Ainsi, nous suggérons que si les toits froids sont un outil efficace pour réduire la consommation d'énergie des bâtiments dans les climats chauds, les îlots de chaleur urbains et les températures de l'air régionales, leur influence sur le climat mondial est probablement négligeable. Los "techos fríos" reflectantes solares absorben menos luz solar que los techos oscuros tradicionales, lo que reduce la ganancia de calor solar y disminuye la cantidad de calor transferido a la atmósfera. Por lo tanto, la adopción generalizada de techos fríos podría reducir las temperaturas en las zonas urbanas, mitigando parcialmente el efecto de isla de calor urbano y contribuyendo a revertir los impactos locales del cambio climático global. Los impactos de los techos fríos en el clima global siguen siendo debatidos por investigaciones anteriores y son inciertos. Utilizando un sofisticado modelo de sistema terrestre, se investigan los impactos de los techos fríos en el clima a escala urbana, continental y global. Encontramos que la adopción global de techos fríos en áreas urbanas reduce las islas de calor urbano en todas partes, con una disminución media anual y global de 1.6 a 1.2 K. Las disminuciones son estadísticamente significativas, excepto en algunas áreas de África y México donde la fracción urbana es baja, y algunas áreas de latitudes altas durante el invierno. El análisis de la superficie y el presupuesto energético de TOA en regiones urbanas a escala continental muestra que los techos fríos causan aumentos en la radiación solar que sale del sistema Tierra-atmósfera en la mayoría de las regiones del mundo, aunque se encuentra que la presencia de aerosoles y nubes compensa parcialmente los aumentos en la radiación ascendente. Los aerosoles amortiguan los aumentos inducidos por el techo frío en la radiación solar ascendente, que van desde el 4% en los Estados Unidos hasta el 18% en una China más contaminada. La adopción de techos fríos también causa reducciones estadísticamente significativas en las temperaturas del aire superficial en regiones urbanizadas de China (-0,11 ± 0,10 K) y los Estados Unidos (-0,14 ± 0,12 K); India y Europa muestran cambios estadísticamente insignificantes. Aunque las investigaciones anteriores no han estado de acuerdo sobre si la adopción generalizada de techos fríos enfriaría o calentaría el clima global, estos estudios han carecido de análisis sobre la importancia estadística de los cambios de temperatura global. La investigación presentada aquí indica que la adopción de techos fríos en todo el mundo conduciría a reducciones estadísticamente insignificantes en la temperatura media global del aire (-0,0021 ± 0,026 K). Por lo tanto, sugerimos que, si bien los techos fríos son una herramienta efectiva para reducir el uso de energía de los edificios en climas cálidos, islas de calor urbano y temperaturas del aire regionales, su influencia en el clima global es probablemente insignificante. Solar reflective 'cool roofs' absorb less sunlight than traditional dark roofs, reducing solar heat gain, and decreasing the amount of heat transferred to the atmosphere. Widespread adoption of cool roofs could therefore reduce temperatures in urban areas, partially mitigating the urban heat island effect, and contributing to reversing the local impacts of global climate change. The impacts of cool roofs on global climate remain debated by past research and are uncertain. Using a sophisticated Earth system model, the impacts of cool roofs on climate are investigated at urban, continental, and global scales. We find that global adoption of cool roofs in urban areas reduces urban heat islands everywhere, with an annual- and global-mean decrease from 1.6 to 1.2 K. Decreases are statistically significant, except for some areas in Africa and Mexico where urban fraction is low, and some high-latitude areas during wintertime. Analysis of the surface and TOA energy budget in urban regions at continental-scale shows cool roofs causing increases in solar radiation leaving the Earth–atmosphere system in most regions around the globe, though the presence of aerosols and clouds are found to partially offset increases in upward radiation. Aerosols dampen cool roof-induced increases in upward solar radiation, ranging from 4% in the United States to 18% in more polluted China. Adoption of cool roofs also causes statistically significant reductions in surface air temperatures in urbanized regions of China (−0.11 ± 0.10 K) and the United States (−0.14 ± 0.12 K); India and Europe show statistically insignificant changes. Though past research has disagreed on whether widespread adoption of cool roofs would cool or warm global climate, these studies have lacked analysis on the statistical significance of global temperature changes. The research presented here indicates that adoption of cool roofs around the globe would lead to statistically insignificant reductions in global mean air temperature (−0.0021 ± 0.026 K). Thus, we suggest that while cool roofs are an effective tool for reducing building energy use in hot climates, urban heat islands, and regional air temperatures, their influence on global climate is likely negligible. تمتص "الأسطح الباردة" العاكسة للشمس أشعة الشمس أقل من الأسطح المظلمة التقليدية، مما يقلل من اكتساب الحرارة الشمسية، ويقلل من كمية الحرارة المنقولة إلى الغلاف الجوي. وبالتالي، فإن اعتماد الأسطح الباردة على نطاق واسع يمكن أن يقلل من درجات الحرارة في المناطق الحضرية، ويخفف جزئيًا من تأثير الجزر الحرارية الحضرية، ويسهم في عكس الآثار المحلية لتغير المناخ العالمي. لا تزال آثار الأسطح الباردة على المناخ العالمي موضع نقاش في الأبحاث السابقة وهي غير مؤكدة. باستخدام نموذج نظام أرضي متطور، يتم التحقيق في تأثيرات الأسطح الباردة على المناخ على المستويات الحضرية والقارية والعالمية. نجد أن التبني العالمي للأسطح الباردة في المناطق الحضرية يقلل من الجزر الحرارية الحضرية في كل مكان، مع انخفاض سنوي وعالمي من 1.6 إلى 1.2 ألف. الانخفاضات ذات دلالة إحصائية، باستثناء بعض المناطق في أفريقيا والمكسيك حيث الجزء الحضري منخفض، وبعض المناطق ذات خطوط العرض العالية خلال فصل الشتاء. يُظهر تحليل ميزانية الطاقة السطحية وطاقة TOA في المناطق الحضرية على المستوى القاري أسطحًا باردة تسبب زيادات في الإشعاع الشمسي تاركة نظام الغلاف الجوي للأرض في معظم المناطق حول العالم، على الرغم من العثور على وجود الهباء الجوي والغيوم لتعويض الزيادات جزئيًا في الإشعاع التصاعدي. يخفف الهباء الجوي من الزيادات الناجمة عن السقف البارد في الإشعاع الشمسي التصاعدي، والتي تتراوح من 4 ٪ في الولايات المتحدة إلى 18 ٪ في الصين الأكثر تلوثًا. يؤدي اعتماد الأسطح الباردة أيضًا إلى انخفاضات ذات دلالة إحصائية في درجات حرارة الهواء السطحي في المناطق الحضرية في الصين (-0.11 ± 0.10 كلفن) والولايات المتحدة (0.14 ± 0.12 كلفن )؛ تظهر الهند وأوروبا تغيرات ضئيلة إحصائيًا. على الرغم من أن الأبحاث السابقة اختلفت حول ما إذا كان اعتماد الأسطح الباردة على نطاق واسع من شأنه أن يبرد أو يسخن المناخ العالمي، إلا أن هذه الدراسات تفتقر إلى التحليل حول الأهمية الإحصائية للتغيرات في درجات الحرارة العالمية. يشير البحث المقدم هنا إلى أن اعتماد الأسطح الباردة في جميع أنحاء العالم من شأنه أن يؤدي إلى انخفاضات ضئيلة إحصائيًا في متوسط درجة حرارة الهواء العالمية (-0.0021 ± 0.026 كلفن). وبالتالي، فإننا نقترح أنه في حين أن الأسطح الباردة هي أداة فعالة للحد من استخدام طاقة البناء في المناخات الحارة والجزر الحرارية الحضرية ودرجات حرارة الهواء الإقليمية، فمن المحتمل أن يكون تأثيرها على المناخ العالمي ضئيلًا.