Use Of Green Roofs Research Articles

Simulating the Hydrological Impact of Green Roof Use and an Increase in Green Areas in an Urban Catchment with i-Tree: A Case Study with the Town of Fontibón in Bogotá, Colombia

Urbanization has produced various social, environmental, and hydrological impacts, such as reduced biodiversity, increased urban temperatures, ecosystem degradation, air and water pollution, changes to hydrological processes, groundwater recharge alterations, increased prevalence of floods, vegetation removal, and potential increases in unstable soils. Finding solutions to mitigate the impacts of urbanization is of vital importance in the development and planning of cities, and particularly so for developing countries. One strategy gaining momentum is the use of green roofs and larger green areas (greater green cover under trees, with the purpose of increasing the permeable area) for runoff control. In this study, a simulation was carried out using the i-Tree Hydro software that involved the urban basin in the Fontibón area of Bogotá, Colombia, with the aim of observing the hydrological benefits of trees, green areas, and permeable zones. Five scenarios were proposed in which green roof coverage was implemented (20% and 50% increases in green areas in Scenarios 1 and 2), coverage under existing trees was enhanced (50% and 100% increase in Scenarios 4 and 5), and finally a complete removal of green zones in Fontibón was simulated (Scenario 3). The town is relatively susceptible to a reduction in its existing green areas, with an increase in total flow of more than 50% for one scenario considered. Thus, an increase in the permeable coverage under trees (50% and 100% increased coverage under existing trees) provided the best strategy for mitigating the impacts of urbanization by reducing the total, maximum, and average impervious flow by 3%, 4%, and 8%, respectively. Finally, an increase in permeable zones corresponding to plants was proposed via the implementation of green roofs. However, this strategy showed a response to the reduction in the lowest total flow at 1%.

Costs and Benefits of Green Roof Types for Cities and Building Owners

Increasing urbanization and the effects of climate change will bring new challenges for cities, such as energy saving and supply of renewable energy, preventing urban heat islands and water retention to deal with more frequent downpours. A major urban surface, the surface of roofs, is nowadays hardly exploited and could be used to make cities more ‘future proof’ or resilient. Many Dutch municipalities have become aware that the use of green roofs as opposed to bituminous roofs positively contributes to these challenges and are stimulating building-owners to retrofit their building with green roofs. This study aims at comparing costs and benefits of roof types, focused on green roofs (intensive and extensive) both on building- and city scale. Core question is the balance between costs and benefits for both scales, given varying local conditions. Which policy measures might be needed in the future in order to apply green roofs strategically in regard to local demands? To answer this question the balance of costs and benefits of green roofs is divided into a public and an individual part. Both balances use a strengths, weaknesses, opportunities and threats framework to determine the chance of success for the application of green roofs, considering that the balance for green roofs on an individual scale influences the balance on a public scale. The outcome of this combined analyses in the conclusion verifies that a responsible policy and a local approach towards green roofs is necessary to prepare the city sufficiently for future climate changes. http://dx.doi.org/10.13044/j.sdewes.d6.0225

Hydrological Performance Assessment for Green Roof with Various Substrate Depths and Compositions

Low Impact Development (LID) techniques have been drawing an increasing attention in recent years as efficient ways of stormwater management. These methods try to mimic nature by providing pervious area which has been decreased due to urbanization. One of the most efficient practices of LID is the use of Green Roof (GR) systems. Although GRs have been traditionally used in the past, their engineering design and construction is a recent trend. Since GR systems, similar to other LID techniques, are supposed to endure local climate and environmental conditions, their design should be accomplished regarding the conditions of the area where they will be installed. In order to systematically examine, design, and construct various LID techniques for Korean climate and environment, the LID & GI Center of Korea is built in Pusan National University. This center tries to hire hardware and software facilities to study and design LID practices; Hydrological Performance Tester for Green Roof (HPT-GR) and Korea Low Impact Development Model (K-LIDM) are made for this purpose. In order to examine the performance of a Green Roof (GR) system composed of layers with different material and size, five trays were made at LID & GI Center of Korea. The size and composition of these trays were: (A) plant + soil + drainage mat with total depth of 15 cm, (B) plant + soil + sand with total depth of 15 cm, (C) plant + soil + sand with total depth of 9 cm, (D) a bare soil with total depth of 15 cm, and (E) a concrete with total depth of 15 cm. All the trays were examined under different uniform precipitations with rates of 50, 80, 100 and 150 mm/h using HPT-GR. The results showed that the use of drainage mat in tray A could significantly improve the performance of the GR by increasing its storage capacity up to 40% of the rainwater, decreasing its saturation rate, and reducing its discharge peak value. Then, as the first use of K-LIDM for simulating a green roof, all the experimental GRs were numerically simulated using this model; the numerical hydrographs were compared to those achieved from the experiment. The results showed that K-LIDM can be used for performance prediction of GR systems with slightly conservative but acceptable results. With an increase in the rainfall intensity, the discharge peak values increased and their times decreased in both numerical and experimental scenarios; however, the peak values were slightly higher in simulation results than those of the corresponding experimental ones.

Integrating conventional and green roofs for mitigating thermal discomfort and water scarcity in urban areas

This paper aims to evaluate the possibility of using the roofs of habitations in Caruaru city in the semiarid region of Pernambuco, Brazil, for two purposes: as green roofs to mitigate extreme temperatures inside the houses and for rainwater harvesting and storage for potable purposes. For this, a preliminary study was carried out with inside and outside temperature monitoring of rooms with a green roof and conventional roof to verify the thermal variation in a real situation. Furthermore, the potential of rainwater harvesting for Caruaru city was evaluated based on precipitation data provided by the Water National Agency and an estimation of the available roof area (buildings and houses). In this context, two scenarios were analysed: (scenario 1) the whole roof surface was used for rainwater harvesting and saving and (scenario 2) green roofs were implanted in part of the roofs.The results of this preliminary study indicated that the use of green roofs resulted in lower temperature variations throughout the day, decreased internal temperatures, and decreased thermal amplitude in relation to a conventional roof (with tiles). Regarding the reduction of the catchment area because of the recommended use of green roofs in a semiarid region, considering green roof application just over the bedrooms (which was considered to cover 16 m2 in total), the water saving potential of the public supply system decreased, with a monthly average of 23.13% versus 28.43% (without green roofs). Implanting green roofs in part of the roofs of houses, although there is a reduction in the rainwater volume that can be harvested, can result in an increase in thermal comfort, whereas this is not feasible with the use of the entire roof area to harvest potable water. Thereby, the results indicate that the simultaneous use of the two kinds of roofs (conventional and green) is feasible even in a semiarid climate.

Green Roof Design Techniques to Improve Water Use under Mediterranean Conditions

Green roof typology can vary depending on buildings structure, climate conditions, substrate, and plants used. In regions with hot and dry summers, such as the Mediterranean region, irrigation plays an essential role, as the highest temperatures occur during the driest period of the year. Irrigation might reduce the heat island effect and improve the cooling of buildings during this period, however, the added cost of maintenance operations and additional energy consumption could outrun the benefits provided by the project. Moreover, in situations where water is scarce or primarily channelled to other uses (e.g., domestic, agriculture or industry) during drought occurrence, it is advisable to implement green roof projects with the lowest use of water possible. The objective of the present work is to investigate solutions to optimize water use in green roofs under Mediterranean conditions, such as those of southern Europe. Two case studies are presented for Portugal, and potential techniques to reduce irrigation requirements in green roofs were tested. These addressed the use of native plant species, including the extreme type of a non-irrigated green roof (Biocrust roof) and techniques for plant installation. Plant drought tolerance was found to be an advantage in green roofs under these climatic conditions and, for the species studied, aesthetic value could be maintained when irrigation decreased.

Pluvial flooding in urban areas across the European continent

Pluvial flooding is a result of overland flow and ponding before the runoff enters any watercourse, drainage system or sewer, or cannot enter it because the network is full to capacity, usually caused by intense rainfall. River and coastal floods get the most attention since they are largest and last the longest, while pluvial floods are relatively marginalized in research. Therefore, the main goal of this research was to show risk posed by pluvial floods, their connection to current global climate change processes, present effects of flooding in European cities, as well as what we can expect in the future. Furthermore, the aims were to present and get more familiar with scientific projects, strategies, directives and measures devised both on national and international levels, that deal with urban pluvial flood issues across the European continent. Climate change projections indicate that there will be an increase in the frequency and intensity of rainfall events throughout Europe and along with ongoing urbanization, the problem of pluvial flooding will most certainly require more attention, which it is starting to receive. Some countries have already developed their strategies and initiatives and implemented both structural and non-structural measures, such as spatial planning, constructional measures, information systems, reducing land sealing through policies, building codes and standards, on-site improvement of retention, infiltration, evaporation, and rainfall water recycling with the use of green roofs, permeable or porous pavements, rain gardening or urban rainwater harvesting. At the same time, there are numerous research papers, studies, conferences and workshops devoted to the problem of pluvial flooding and its management carried out in an attempt to properly deal with this hazard.

What are the root causes hindering the implementation of green roofs in urban China?

It is worldwide accepted that green roofs have a variety of environmental, economic, and social benefits. China, which is experiencing rapid urbanization, has great potential to gain the benefits of green roofs, yet which are not commonly seen in the existing or new buildings. Understanding its root causes is important for promoting the larger-scale implementation of green roofs. Previous studies have studied the barriers of implementing green roofs in developed urban areas but ignored developing countries or regions, whose implementation of green roofs is still at the initial stage. To fill the research gap, this study aims to investigate the root causes that impede the implementation of green roofs in urban China through a practical survey and case study. The root causes are identified as the increase of maintenance cost, increase of design and construction cost, poor arrangement of the use of green roofs, and lack of incentives towards developers. Policy implications are proposed, which provide valuable references for decision-makers to improve the green-roof-related codes, policies and incentives.

Telhados verdes: uma análise da influência das espécies vegetais na retenção de água de chuva

Com o aumento da população urbana mundial, problemas urbanos passam a ser recorrentes, como por exemplo, as inundações em decorrência da precipitação. Ações que minimizem os impactos ambientais do processo de urbanização passam a ser necessárias, uma dessas ações é a aplicação de telhados verdes, que devido as suas propriedades retém parte da água da chuva e ainda retardam o escoamento dessa água. Alguns estudos demonstram a capacidade de retenção dos telhados verdes, entretanto, sem vincular ao tipo de vegetação. O objetivo da presente pesquisa é verificar a influência da espécie vegetal, utilizada em telhados verdes, na retenção e água de chuva na cidade de Curitiba. Através do estudo em seis espécies vegetais diferentes Bulbine frutescens, Tradescantia zebrina variação Purpusii, Sedum mexicanum, Callisia repens, Arachis Repens e Zoysia tenuifolia. Com esta análise pode-se perceber que existe uma variação de retenção significativa em função da espécie vegetal, sendo que a espécie Bulbine frutescens apresentou o melhor desempenho entre as espécies analisadas.

Reduction of energy consumption in residential buildings with green roofs in three different climates of Iran

ABSTRACTIn the current study, the modelling and simulation of energy consumption for a two-story building with green roof in three different climates of Iran (Bandar Abbas: hot and humid, Tehran: mild and dry, and Tabriz: dry and cold) have been performed. A typical building with asphalt roof and a complete identical building with vegetation on its roof instead of asphalt, on its last layer, has been simulated. Heat pumps have been used to provide heating and cooling loads on the building. The results of the simulation indicated that by the use of green roof, the annual baseline electricity consumption for heating and cooling loads was reduced up to 16.3%, 12.5% and 23% in Tehran, Tabriz and Bandar Abbas, respectively. Use of green roofs in the tropical regions (Bandar Abbas) is more efficient compared to cold regions (Tabriz). The reason behind this phenomenon is the effect of the green roof as a cooler on the performance of the studied building's cooling system. Payback time for the initial construction of green roofs, due to energy savings, is 11, 10 and more than 40 years for Tehran and Bandar Abbas, respectively.

Energy, environmental and economic assessment of electricity savings from the operation of green roofs in urban office buildings of a warm Mediterranean region

Green roofs are an important technique to efficiently mitigate adverse environmental impacts of buildings. This study focuses both on energy conservation and sustainability related aspects of two alternative green roof solutions applied to a typical urban office building in representative climatic areas of Cyprus in the Eastern Mediterranean. Simulations regarding the buildings’ energy demand were conducted using EnergyPlus software. Based on these results and using an in-house developed algorithm, the primary energy consumption for each alternative solution was computed, assuming variable refrigerant flow air-to-brine heat pump as heating and cooling system, coupled with a calculation of the associated emissions of carbon dioxide, nitrogen oxides and sulphur dioxide. The analysis shows a reduction in primary energy consumption up to 25% in heating and up to 20% in cooling operation, thanks to the use of green roofs, and a corresponding reduction in emissions. The economic viability of the proposed green roof solutions was also examined, taking into consideration both monetary and environmental costs. The results show that the green roof solutions increase the lifetime cost up to 40,000 €, however they can lead to additional environmental and economic benefits which are hard to quantify.

TAMAN KOMUNITAS DENGAN PENDEKATAN GREEN ARCHITECTURE DI KOTA SOLO

<em>Public space is an urban facility that serves as a forum for interaction and recreational activities of the community. However, the existence of Solo City’s public space which serves as an area of interaction, recreation society and urban green space become degraded. Until 2014 Solo City’s public green space reached 12.02% of the total is to be achieved by 20%. The impact of vandalism of Solo City’s public space reducing facial aesthetics and lowering the interest of the public to visit. As a problem-solving strategies, takes a public space planning that can accommodate recreational activities and community interaction and optimize its potential as a green open space that can preserve environmental sustainability. With the phenomenon of people's appreciation of community interest and talent of Solo City is high enough, it can be a potential concept of public space that can accommodate groups of community interaction and public recreation. The formulation of the problem in this design is how to plan and design a community park as efforts increase green open space that can accommodate groups of community interaction and recreation community in Solo with Green Architecture approach . Thus it can be formulated Taman Komunitas planning objectives aligned with the Rencana Strategis (RENSTRA) Dinas Tata Ruang Kota Surakarta Tahun 2011–2015 to realize the addition of green open space which serves as the lungs of the city at the same time facilitate the activities of community interaction and recreation . Tangible public space planning to optimize its potential as a park with green open spaces are supported by a strategic approach to the concept of Green Architecture in order to achieve the target. The applied aspects of Green Architecture refers to the Greenship criteria set by the Green Building Council Indonesia. Four of these aspects include the right of land use, efficiency and energy conservation, water conservation, and health and comfort in the room. The application appears in the planning aspects of the design which utilizes the natural potential include the use of green roof , green walls , environmentally friendly materials , as well as planning refers to the Greenship benchmark..</em>

The Potential of Recycled Locally-Sourced Waste Materials for Green Roof Soil Mixtures

The increase in surface runoff has become a serious environmental problem and concern in Malaysia. Hence, promoting the use of green roofs in urban areas will potentially allow some storage area and time attenuation for any rainfall. Initial studies on a few substrate mixtures were done in order to find out the properties of green roof media. These included vermiculite (V), perlite (P) and peat moss (PM) together with locally-sourced waste materials such as empty fruit bunches (EFB) and wet diaper gel (D) which are expected to potentially retain more storm water runoff. A test on the substrate mixture properties and evaporation tests were conducted on seven types of soil mixtures. The results show that a basic substrate mixture of PVPM3,5,2 has a maximum water capacity of 50%. The modification and addition of diaper gel in DVPM1,3,2 and empty fruit bunch (EFB) in PEFBPM1,0.3,2 show an increment in both mixtures’ water holding capacity (54%). All the proposed mixtures have shown permeability values larger than 0.0005 cm/s. To investigate the maximum water storage availability, the evaporation tests show that both mixtures could provide 60 - 62 mm of water storage after 34 days without rainfall under ambient climatic condition (32 ̊ to 34 ̊) whereas under extreme heat temperatures (50 ̊), both mixtures took only 1 day to provide the same storage as the ambient condition. Therefore, this study has provided an initial understanding of the properties of the substrate mixture as well as the evaporation rate of the materials tested. This information can be used to demonstrate the relationship between soil characteristics and local climatic factors (temperature).

Sedum-dominated green-roofs in a semi-arid region increase CO2 concentrations during the dry season.

Green roofs are expected to absorb and store carbon in plants and soils and thereby reduce the high CO2 concentration levels in big cities. Sedum species, which are succulent perennials, are commonly used in extensive green roofs due to their shallow root system and ability to withstand long water deficiencies. Here we examined CO2 fixation and emission rates for Mediterranean Sedum sediforme on green-roof experimental plots. During late winter to early spring, we monitored CO2 concentrations inside transparent tents placed over 1m2 plots and followed gas exchange at the leaf level using a portable gas-exchange system. We found high rates of CO2 emission at daytime, which is when CO2 concentration in the city is the highest. Both plot- and leaf-scale measurements showed that these CO2 emissions were not fully compensated by the nighttime uptake. We conclude that although carbon sequestration may only be a secondary benefit of green roofs, for improving this ecosystem service, other plant species than Sedum should also be considered for use in green roofs, especially in Mediterranean and other semi-arid climates.

Thermal insulation and cost effectiveness of green-roof systems: An empirical study in Hong Kong

Hong Kong is a densely populated city with high density of skyscrapers and the population is typically concentrated on 30% of the land. The adoption of skyscrapers is therefore common to maximize its capacity. As a result, the need of open space and greenery in our built environment is thus often neglected. In recent years, many building professionals promote green-roof systems to increase green space. This paper investigates the effectiveness of using green-roof systems. Questionnaire surveys and interview discussions are conducted. It is found that the questionnaire respondents are interested in implementing green-roof systems and understanding their environmental, economical and social benefits. Three case studies are also conducted to show the effectiveness of green roofs thermal insulation. The results show that green roofs can reduce the inside temperature by up to 3.4 °C. However, the respondents were not willing to invest a large amount of money for green-roof systems. It is suggested that governments should take leading positions to promote green-roof systems. This paper can provide insights on the use of green roofs in Hong Kong and around the world focusing on cost effectiveness and thermal insulation effectiveness.

Retention capacity of extensive green roofs

AbstractClimate change causes a more frequent occurrence of extreme events. The result of these phenomena is the occurrence of floods and flooding, and periods of drought. Particularly unfavorable is intensive rainfall over the urban catchments. To prevent the negative consequences of these phenomena, unconventional solutions should be used. The use of green roofs in urban areas will serve the sustainable development of cities and the impact on local ecological changes. The study was performed at two green roof platforms 1.2×1.2×0.1 m each. An analysis was performed at different intensities given for precipitation. 20 min for the rain to stop was observed from 68 to 100% precipitation. The study was divided into two parts. The first part of the study has been performed in the dry period. In contrast, another round of tests was repeated in other conditions after rainfall. The amount of water at two experimental green roofs platforms before the test was 11.0 dm3. The research relates to the impact of green roofs on local hydrological changes. Development of technologies for green roofs had a positive impact on mitigating the effects of climate change associated with the occurrence of flooding the city.

An Insight into the Commercial Viability of Green Roofs in Australia

Construction industries around the world have, in recent history, become increasingly concerned with the sustainability of building practices. Inherently, the development of the built environment results in partial or complete destruction of the natural environment. Advanced European and North American countries have turned to green roofs as a means of sustainable development. Australia, on the other hand, has yet to fully realize the potential of green roof technology. In the first case, an extensive review of green roof literature was undertaken to establish the dominant perspectives and over-riding themes within the established body of international literature. The collection of primary data took the form of qualitative, semi-structured interviews with a range of construction practitioners and green roof experts; landscape architects, consultants and academics. The information gained from the interviews facilitated the primary aim of the paper; to critically analyse the state-of-practice in the Australian green roof industry. Green roofs, despite their proven sustainability benefits and their international success, have experienced a relatively sluggish uptake in the Australian construction industry. With this being said, the Australian green roof industry is considered to have promising potential for the future; should there be legislative changes made in its favour or greater education within the industry. To advance the local industry, it was found that government authorities are required to adapt policy settings to better encourage the use of green roofs, whilst industry bodies are required to host better, more targeted educational programs.

Green Roofs in the Tropics Conserve Energy

Background: Concrete buildings on Guam are exceptionally strong but also accumulate large amounts of heat. In the tropical environment of Guam, where 24 h average temperature ranges from 28 to 29°C year round, air conditioning is used every day and continuously. Concrete roofs are often painted light colors, which make them more reflective and accumulate less heat. They are also suitable for establishment of vegetation, which results in a large decrease in roof temperature and therefore decreases the need for cooling. Objective: The objective was to determine the magnitude of temperature reductions resulting from light color and from vegetation covering roof tops and to use this information to estimate energy savings. Method: Temperature was measured on the undersides of concrete model roofs in both sunny and rainy weather. Results: The temperatures on the undersides of light-colored concrete model roofs rose up to 3°C less in the course of the day than did those of dark-colored ones. The temperatures of "green" (vegetation-covered) model roofs rose up to 12°C less than did those of either of the bare concrete models. Conclusion: The differences were so large that use of green roofs on the tropical island of Guam, where most buildings are concrete and air-conditioning is needed year round, could cut a typical household's electric consumption in half.

Mitigation of heating of an urban building rooftop during hot summer by a hydroponic rice system

The use of green roofs is an important method for mitigating heating of urban rooftop environments. Our study aimed to demonstrate the mitigation of thermal effects on a hot rooftop during summer by a hydroponic system in which rice was grown. The system was installed on the top of a commercial building in the large city of Osaka, Japan; the roof was divided into two areas, one bare, the other covered by the hydroponic system. In both areas, we measured thermal factors, such as air temperature, rooftop surface temperature, and conductive heat flux; from the data we calculated three thermal mitigation indices. We also propose normalized types of mitigation indices. Mitigation effects on the thermal environment by the hydroponic system could be well estimated from ambient air temperature and solar radiation; the effects were better explained by solar radiation than by ambient air temperature. The results indicate that during the hot season, the system's mitigation effects on the thermal environment can be predicted from solar radiation level, and the normalized mitigation index is an appropriate index for estimating the cooling effect. Our results suggest that the hydroponic system might affect the energy flow in two ways: the proportions of sensible heat flux and latent heat flux are mainly affected by evaporative cooling and the portion of conductive heat flux is mainly affected by radiation shielding.

Tool to address green roof widespread implementation effect in flood characteristics for water management planning

Abstract. In the last decades, new approaches were adopted to manage stormwater as close to its source as possible through technologies and devices that preserve and recreate natural landscape features. Green Roofs (GR) are examples of these devices that are also incentivized by city's stormwater management plans. Several studies show that GR decreases on-site runoff from impervious surfaces, however, the analysis of the effect of widespread implementation of GR in the flood characteristics at the urban basin scale in subtropical areas are little discussed, mainly because of the absence of data. Thereby, this paper shows results related to the monitoring of an extensive modular GR under subtropical weather conditions, the development of a rainfall–runoff model based on the modified Curve Number (CN) and SCS Triangular Unit Hydrograph (TUH) methods and the analysis of large-scale impact of GR by modelling different basins. The model was calibrated against observed data and showed that GR absorbed almost all the smaller storms and reduced runoff even during the most intense rainfall. The overall CN was estimated in 83 (consistent with available literature) with the shape of hydrographs well reproduced. Large-scale modelling (in basins ranging from 0.03 ha to several square kilometers) showed that the widespread use of GRs reduced peak flows (volumes) around 57% (48%) at source and 38% (32%) at the basin scale. Thus, this research validated a tool for the assessment of structural management measures (specifically GR) to address changes in flood characteristics in the city's water management planning. From the application of this model it was concluded that even if the efficiency of GR decreases as the basin scale increase they still provide a good option to cope with urbanization impact.

Contrasting responses of urban and rural surface energy budgets to heat waves explain synergies between urban heat islands and heat waves

Heat waves (HWs) are projected to become more frequent and last longer over most land areas in the late 21st century, which raises serious public health concerns. Urban residents face higher health risks due to synergies between HWs and urban heat islands (UHIs) (i.e., UHIs are higher under HW conditions). However, the responses of urban and rural surface energy budgets to HWs are still largely unknown. This study analyzes observations from two flux towers in Beijing, China and reveals significant differences between the responses of urban and rural (cropland) ecosystems to HWs. It is found that UHIs increase significantly during HWs, especially during the nighttime, implying synergies between HWs and UHIs. Results indicate that the urban site receives more incoming shortwave radiation and longwave radiation due to HWs as compared to the rural site, resulting in a larger radiative energy input into the urban surface energy budget. Changes in turbulent heat fluxes also diverge strongly for the urban site and the rural site: latent heat fluxes increase more significantly at the rural site due to abundant available water, while sensible heat fluxes and possibly heat storage increase more at the urban site. These comparisons suggest that the contrasting responses of urban and rural surface energy budgets to HWs are responsible for the synergies between HWs and UHIs. As a result, urban mitigation and adaption strategies such as the use of green roofs and white roofs are needed in order to mitigate the impact of these synergies.