A review of mitigating strategies to improve the thermal environment and thermal comfort in urban outdoor spaces

Based on United Nations Environment Program (UNEP), building sector accounts for 40% of total energy consumption. In European countries, 36% of total greenhouse gas emissions is attributed to buildings. In this respect, green roofs are considered to be one of the most appropriate sustainable solutions to resolve the urban heat island-related issues. Roofs account for nearly 20–25% of overall urban surface areas. Energy saving, thermal insulation, shading and evapotranspiration features highlight the key role of green roofs in overall thermal performance of buildings and microclimatic conditions of indoor environments. Within the scope of this research, the concept of green roofs and facades is comprehensively analysed in a holistic and thematic way. Following a historical overview of the technology, the research is split into various subfields such as energy saving in buildings through greenery systems, multifunctional thermal benefits including evapotranspiration, thermal insulation, shading and thermal comfort features, evaporative cooling for reducing cooling demand and minimising wind driven convection losses. The results achieved from the literature survey clearly indicate that green roofs and facades are key solutions to mitigate building-related energy consumptions and greenhouse gas emissions. According to the previous works, heat flow through the building roofs in summer can be reduced by approximately 80% via green roofs. The green roofs are reported to consume less energy in the range of 2.2–16.7% than traditional roofs during summer time. A similar tendency is observed for the winter season depending on regional and climatic conditions. The temperature difference between conventional and greens roofs in winter is found to be about 4 °C, which is remarkable. Energy demand of buildings in summer is highly dependent on the plant intensity as it is reported to be 23.6, 12.3 and 8.2 kWh/m2/year for extensive, semi-intensive and intensive greenery surface, respectively. Greenery systems are also capable of providing thermally comfortable indoor and outdoor conditions. It is underlined that the annual average accumulation of CO2 reaches the level of 13.41–97.03 kg carbon/m2 for 98 m2 of vertical greenery system. The results of this research can be useful for dwellers, builders, architects, engineers and policy makers to have a good understanding about the potential of green roofs and facades to mitigate building-related energy consumptions and carbon emissions in a renewable, sustainable, energy-efficient and cost effective way.

Green roofs and facades: A comprehensive review

The United Nations' Sustainable Development Goals (SDGs) provide guide-posts to society as it attempts to respond to an array of pressing challenges One of these challenges is energy; thus, the SDGs have become paramount for energy policy-making Yet, while governments throughout the world have already declared the SDGs to be 'integrated and indivisible', there are still knowledge gaps surrounding how the interactions between the energy SDG targets and those of the non-energy-focused SDGs might play out in different contexts In this review, we report on a large-scale assessment of the relevant energy literature, which we conducted to better our understanding of key energy-related interactions between SDGs, as well as their context-dependencies (relating to time, geography, governance, technology, and directionality) By (i) evaluating the nature and strength of the interactions identified, (ii) indicating the robustness of the evidence base, the agreement of that evidence, and our confidence in it, and (iii) highlighting critical areas where better understanding is needed or context dependencies should be considered, our review points to potential ways forward for both the policy making and scientific communities First, we find that positive interactions between the SDGs outweigh the negative ones, both in number and magnitude Second, of relevance for the scientific community, in order to fill knowledge gaps in critical areas, there is an urgent need for interdisciplinary research geared toward developing new data, scientific tools, and fresh perspectives Third, of relevance for policy-making, wider efforts to promote policy coherence and integrated assessments are required to address potential policy spillovers across sectors, sustainability domains, and geographic and temporal boundaries The task of conducting comprehensive science-to-policy assessments covering all SDGs, such as for the UN's Global Sustainable Development Report, remains manageable pending the availability of systematic reviews focusing on a limited number of SDG dimensions in each case

https://iopscience.iop.org/article/10.1088/1748-9326/aaafe3/pdf

Connecting the Sustainable Development Goals by their energy inter-linkages

Spend your time even for only few minutes to read a book. Reading a book will never reduce and waste your time to be useless. Reading, for some people become a need that is to do every day such as spending time for eating. Now, what about you? Do you like to read a book? Now, we will show you a new book enPDFd weather data that can be a new way to explore the knowledge. When reading this book, you can get one thing to always remember in every reading time, even step by step.

Weather data

Building envelope parameters and geometric configurations can considerably influence the building energy performance. However, determining the best trade-offs of different building shape and envelope configurations to yield near-optimal design alternatives with respect to their energy performance is not a straight-forward task. Consequently, different methods have been utilized to optimize building envelope parameters and geometric configurations to achieve better energy performance. The objective of this paper is to provide an extensive review of the optimization methods and their application in energy-efficient architectural building design to better identify the potentials and applicability of different optimization methods. This paper reviews the optimization research, where building envelope parameters and geometric configurations are considered remarkably as the optimization independent variable(s) and building energy consumption/demand is included as an objective in the optimization process. The associated derivative-free and derivative-based optimization methods and their application in energy-efficient building design are included in this review. In addition, decision-making approaches are discussed for multi-objective optimizations. Current optimization tools are demonstrated. Finally, crucial considerations, including limitations and suggestions for the related future studies are concluded.

A review on optimization methods applied in energy-efficient building geometry and envelope design

Scarcity of resources and environmental issues caused by human activities stimulate designers and policy makers to search for energy efficient strategies for sustainable development. A considerable amount of energy consumption and CO2 emission comes from the building sector which today accounts for 40% of the world’s energy use. Greenery systems are considered as a promising solution for making buildings more energy efficient. However, energy saving is one among multiple benefits that a greenery system can offer to a building. The most common places in a building that can be used to accommodate vegetation include roof greening, vertical greening, terrace planting and sky gardens (indoor and outdoor) especially in the design of high-rises. Therefore, the main aim of this paper is to provide a literature review for all different greening systems with respect to their energy impact. The role of indoor planting on thermal comfort and indoor air quality (IAQ) will also be discussed. Furthermore, the suitability of different greenery systems for different climate types is summarized.

/pdf/the-impact-of-greening-systems-on-building-energy-1bhrd6ekxv.pdf

The impact of greening systems on building energy performance: A literature review

An assessment of energy-saving solutions for the envelope design of high-rise buildings in temperate climates: A case study in the Netherlands

Decisions made at early stages of the design are of the utmost importance for the energy-efficiency of buildings. Wrong decisions and design failures related to a building’s general layout, shape, facade transparency or orientation can increase the operational energy tremendously. These failures can be avoided in advance through simple changes in the design. Using extensive parametric energy simulations by DesignBuilder, this paper investigates the impact of geometric factors for the energy-efficiency of high-rise office buildings in three climates contexts: Amsterdam (Temperate), Sydney (Sub-tropical) and Singapore (Tropical). The investigation is carried out on 12 plan shapes, 7 plan depths, 4 building orientations and discrete values for window-to-wall ratio. Among selected options, each sub-section determines the most efficient solution for different design measures and climates. The optimal design solution is the one that minimises, on an annual basis, the sum of the energy use for heating, cooling, electric lighting and fans. The results indicate that the general building design is an important issue to consider for high-rise buildings: they can influence the energy use up to 32%. For most of the geometric factors, the greatest difference between the optimal and the worst solution occurs in the sub-tropical climate, while the tropical climate is the one that shows the smallest difference. In case of the plan depth, special attention should be paid in the case of a temperate climate, as the total energy use can increase more than in other climates. Regarding energy performance, the following building geometry factors have the highest to lowest influence: building orientation, plan shape, plan depth, and window-to-wall ratio.

Early-Stage Design Considerations for the Energy-Efficiency of High-Rise Office Buildings

This paper investigates the potential use of natural ventilation strategies to reduce the energy demand for cooling and mechanical ventilation for high-rise buildings in summer. A 21-storey office building was selected to represent a mechanically ventilated high-rise design in temperate climates. Six natural ventilation scenarios were developed for the base design and the CFD package in DesignBuilder was used to predict their flow pattern under two summer conditions. Afterwards, the Operative temperature and the total fresh air changes per hour were calculated with EnergyPlus and were compared accordingly with European comfort standards. The percentage of discomfort hours indicates when a natural ventilation system would need active cooling or mechanical ventilation. Natural ventilation strategies can provide comfort conditions for up to 90% of the occupancy time in summer and therefore can save a significant amount of energy that is generally needed for the operation of traditional mechanical ventilation and air-conditioning systems.

/pdf/natural-summer-ventilation-strategies-for-energy-saving-in-ukviu6qd3h.pdf

Natural summer ventilation strategies for energy-saving in high-rise buildings: a case study in the Netherlands

Tall buildings are being designed and built across a wide range of cities A poorly designed tall building can tremendously increase the building’s appetite for energy Therefore, this paper aims to determine the design strategies that help a high-rise office building to be more energy efficient For this purpose, a comparative study on twelve case buildings in three climate groups (temperate, sub-tropical a tropical) was performed The exterior envelope, building form and orientation, service core placement, plan layout, and special design elements like atria and sky gardens were the subject of investigation effectiveness of different design strategies for reducing the cooling, heating, ventilation and electric lighting energy usage Finally, lessons from these buildings’ were defined for the three climates Furthermore, a comparison of building energy performance data with international benchmarks confirmed that in temperate and sub-tropical climates sustainable design strategies for high-rise buildings were performing well, as a result leading to lower energy consumption However, for the tropics the design of high-rise buildings needs additional consideration

Babak Raji

Papers

The impact of greening systems on building energy performance: A literature review

An assessment of energy-saving solutions for the envelope design of high-rise buildings in temperate climates: A case study in the Netherlands

Early-Stage Design Considerations for the Energy-Efficiency of High-Rise Office Buildings

Natural summer ventilation strategies for energy-saving in high-rise buildings: a case study in the Netherlands

A comparative study: design strategies for energy-efficiency of high-rise office buildings