Building green covering for a sustainable use of energy

Nowadays the growth of the cities increased built and paved areas, energy use and heat generation. The phenomenon of urban warming, called urban heat island, influences negatively outdoor comfort conditions, pollutants concentration, energy demand for air conditioning, as well as increases environmental impact due to the demand of energy generation. A sustainable technology for improving the energy efficiency of buildings is the use of green roofs and walls in order to reduce the energy consumption for conditioning in summer and improve the thermal insulation in winter. The use of green roofs and walls can contribute to mitigate the phenomenon of heat island, the emissions of greenhouse gases, and the storm water runoff affecting human thermal comfort, air quality and energy use of the buildings. Recently, a number of municipalities started to adopt regulations and constructive benefits for renovated and new buildings which incorporate green roofs and walls. The aim of this paper is to describe the green roofs and walls plant technology.

Green roofs and green walls layouts for improved urban air quality by mitigating particulate matter

Global temperatures have continued to rise for decades, partly due to human-caused greenhouse gas emissions and subsequent urban heat island (UHI) effects. This current research examines the benefits of urban greenery by studying the impact of green roofs and walls of a building on thermal behavior and heat transfer in a warm and humid climate. This simulation study discusses the importance of greening systems in improving thermal comfort and minimizing the causes of UHI by assessing an integrated green building design. Using the simulation software DesignBuilder, the significance of greening systems, green roofs, and walls in enhancing thermal comfort and reducing the factors that contribute to UHI is investigated. The simulation results are based on the building’s energy usage in hot and humid regions while featuring green roofs and walls. The simulation results indicate a considerable positive impact of greening systems in improving the urban environment in hot and humid tropical climates. Air temperature, radiant temperature, humidity, and solar gain are decreased by urban greening. The total energy consumption and district cooling demand of buildings with green roofs and walls are reduced by 10.5% and 13%, respectively. The greening systems substantially improve air quality and building’s energy efficiency. Thus, the present study‘s findings can benefit urban designers and dwellers in devising strategies for establishing green spaces in congested urban environments by integrating green technologies and systems into built environments.

The impact of urban development on the natural environment creates unique challenges for architects and the need to seek a change in design strategies by building green and sustainable buildings. Designing and displaying green elements such as roofs and walls becomes an important element in this sense. Greenery plays a very crucial role in the city space. Green roofs and walls are the missing link between the built environment and the natural environment. They can complement urban greenery. This paper aims to show the possibilities of green roofs and walls solutions in the city, their aspects and impact on the environment and people. The research method is based on the analysis of selected existing objects with greenery solutions and showing their role in creating a sustainable city. The analysis shows that the green roofs and walls offers many environmental, social and economic benefits. They have the ability to improve the microclimate and increase air humidity. Thus, they affect the health and well-being of the city's inhabitants. This technology should be considered a valuable part of the design process to tackle climate change and the energy crisis. Green roofs and facades are passive techniques and provide benefits in reducing the energy requirements of buildings, among other things, but also play a role in shaping a better visual aspect of the city. In the 21st century, people are slowly beginning to realize the advantages of green architecture, which is considered a new perspective also for the urban heat island problem. Thus, the living roofs and walls are of major importance as part of a sustainable strategy for the urban environment. Sustainable cities will exist when society makes an informed choice to move towards a more sustainable lifestyle. The green roofs and walls these are the solution for the future, for better quality of life.

Experimental comparison of two extensive green roof designs in Northwest Mexico

Green roofs and walls can mitigate the environmental and climate change of a city. They can decrease the urban heat island (UHI), reduce greenhouse gas emissions, fix environmental pollutants, manage urban stormwater runoff, attenuate noise, and enhance biodiversity. This paper aims to analyse green roofs and walls in the possible mitigation of urban climate change and compare it by continent. Green roofs and walls might decrease the air temperature in a city up to 11.3 °C and lower the thermal transmittance into buildings up to 0.27 W/m2 K. Urban greening might sequester up to 375 g C·m−2 per two growing seasons and increase stormwater retention up to 100%. Urban greening might attenuate city noise up to 9.5 dB. The results found green roofs and walls of varied effectiveness in ameliorating climate extremes present in host continents. Results show urban planners might focus on green roofs and walls exposure to attenuate temperatures in hotter Asian cities and advise greening in cities in Africa and Asia. European and American designers might optimise runoff water capacity of green roofs and walls systems and use greening in old buildings to improve insulation. Recommendations are made based on the study to concentrate certain designs to have greater impact on priority climate challenges, whether UHI or stormwater related. This study provides information for decision and policymakers regarding design and exposure of green roofs and walls to mitigate urban environmental and climate change.

The rapid increase of the amount of impervious surfaces in urban areas has generated heat islands and other adverse environmental impacts that subsequently increase greenhouse gas (GHG) emissions. Local governments are now looking for an index to encourage building owners to increase green areas, including green roofs and green walls. Currently, several building green value (BGV) indices can be used to assess building greenness, including the green coverage ratio (GCR), biotope area factor (BAF), green factor (GF), and green plot ratio (GnPR). However, these indices use different sub-indexes and weights, such that the values they output vary significantly. To analyze their applicability, this study compares output values of the BGV indices and estimated GHG emission reductions for three typical buildings under three conditions: no green roof or green wall; a green roof; and a green roof and green walls. The GCR does not include green walls and thus cannot reflect reductions in GHG emissions from green walls. The BAF values are highly correlated to associated GHG emission reductions. The trend of GF values vs. associated GHG emission reductions is less consistent than that using the BAF method because the weights of GF are not consistent with associated thermal resistance improvements. The correlation between GnPR values and associated GHG emission reductions is the strongest among all BGV indices because the ratio of leaf area indexes for green roofs to that of green walls is close to the ratio of U-value reductions from green roofs and green walls.

There is growing attention to the use of greenery in urban areas, in various forms and functions, as an instrument to reduce the impact of human activities on the urban environment. The aim of this study has been to investigate the use of green roofs as a strategy to reduce the urban heat island effect and to improve the thermal comfort of indoor and outdoor environments. The effects of the built-up environment, the presence of vegetation and green roofs, and the urban morphology of the city of Turin (Italy) have been assessed considering the land surface temperature distribution. This analysis has considered all the information recorded by the local weather stations and satellite images, and compares it with the geometrical and typological characteristics of the city in order to find correlations that confirm that greenery and vegetation improve the livability of an urban context. The results demonstrate that the land-surface temperature, and therefore the air temperature, tend to decrease as the green areas increase. This trend depends on the type of urban context. Based on the results of a green-roofs investigation of Turin, the existing and potential green roofs are respectively almost 300 (257,380 m2) and 15,450 (6,787,929 m2). Based on potential assessment, a strategy of priority was established according to the characteristics of building, to the presence of empty spaces, and to the identification of critical areas, in which the thermal comfort conditions are poor with low vegetation. This approach can be useful to help stakeholders, urban planners, and policy makers to effectively mitigate the urban heat island (UHI), improve the livability of the city, reduce greenhouse gas (GHG) emissions and gain thermal comfort conditions, and to identify policies and incentives to promote green roofs.

Chapter 5: Law and regulation

Life cycle assessment (LCA) is used to evaluate the benefits, primarily from reduced energy consumption, resulting from the addition of a green roof to an eight story residential building in Madrid. Building energy use is simulated and a bottom-up LCA is conducted assuming a 50 year building life. The key property of a green roof is its low solar absorptance, which causes lower surface temperature, thereby reducing the heat flux through the roof. Savings in annual energy use are just over 1%, but summer cooling load is reduced by over 6% and reductions in peak hour cooling load in the upper floors reach 25%. By replacing the common flat roof with a green roof, environmental impacts are reduced by between 1.0 and 5.3%. Similar reductions might be achieved by using a white roof with additional insulation for winter, but more substantial reductions are achieved if common use of green roofs leads to reductions in the urban heat island.

Green roofs (GRs) have emerged as an essential component for the sustainability of buildings, as they reduce the need for cooling energy by limiting heat transmission into building space. The benefits of implementing GRs are appropriate in tropical regions with hot temperatures. The entire Association of Southeast Asian Nations (ASEAN) is located in a tropical climate and receives about 12 h of sunlight every day throughout the year, which offers excellent opportunities to install GRs. This research reviews the literature on GR knowledge in ASEAN countries over the past decade (2012–2022) and discusses two main points including (i) GR development level status and (ii) GR performance regarding drivers, motivations, and barriers. The review reveals that Singapore and Malaysia are two among ten countries with significant developments in GRs. Barriers to expertise, government regulations, and public awareness of green roofs represent the most challenging aspects of GR implementation in ASEAN countries. Although research regarding the use of green roofs has been conducted widely, ASEAN countries still need to investigate regulatory breakthroughs, incentives, and technology applications to encourage the use of GRs. The review recommends promoting the use of GRs, which have the potential to reduce energy consumption by up to fifty percent, outdoor surface temperature up to 23.8 °C, and room temperature to 14 °C. The use of GRs can also mitigate runoff issues by up to 98.8% to avoid the risk of flooding in ASEAN countries, which have high rainfall. In addition, this review sheds new insights on providing future potential research to improve GR development in the ASEAN region.

Evaluating the Thermal Performance of Retrofitted Lightweight Green Roofs and Walls in Sydney and Rio de Janeiro

Mitigating urban heat and air pollution considering green and transportation infrastructure

Bio-Facades; An Innovative Design Solution Towards Sustainable Architecture in Hot Arid Zones

This paper reports a literature review of the large-scale ecosystem services (ESS) which green roofs and walls can provide for cities. A short overview of 17 ESS’s is given. Much research has been done on ESS’s meeting immediate physical human needs and providing long-term physical and socioeconomic security. Services meeting social and psychological needs have been less studied. In general, ground-level urban vegetation like parks can provide a higher level of ESS’s than green roofs and walls, but the latter are a valuable addition where ground-level room is scarce. Of roof and wall types, intensive green roofs provide the highest level of ESS’s. Extensive green roofs mainly satisfy physical needs, and green walls mainly satisfy social and psychological needs. Green roofs and walls can probably contribute the most to the reduction of the Urban Heat Island effect, and to the processing of annual rainfall. It is not possible yet to translate all ESS’s into a financial value, for easy comparison of their impact. Recent research points to health benefits and savings on energy and emissions as candidates for the largest effects of green roofs and walls in financial terms