Human beings have caused an adverse effective on the stability of Earth. Many activities that human practice and different process that have been derived to sustain the standards of living have proven that they are unsustainable. This results to the idea of green revolution that has taken the world by storm. Many substitutes have being developed that includes cars, energy generation and the design type of buildings that people live. In buildings, the use of plants on top of the roofs that people live as resulted to the idea of green roof.
Research Question Develop modern buildings in an environmental “green” way with the application of green roof design. Purpose of Study The aim of the green roof system is to ensure that the environment is preserved and aesthetic values are added to the concerned buildings. Conversely, such roofs should be safe and user friendly. Introduction of green roof technology will also feature the nature of the different buildings that are still modern and their impact in general.
This means that if the process should succeed it should achieve a balance between the principal cost, public safety, operation and maintenance cost, environmental friendly and public convenience should be meet. Other objectives include: Reduce the energy that is used by such buildings Reduce the water run – off from the said roofs Increase the lifespan of the building Eliminate the issue of roof leak that is common in modern buildings Provide a foundation that concerns the measurements and research on the impacts of green roof buildings. Be an example to in leading practices that relate to sustainability
Library Research Master plans that contain details of various roof styles were studied before preparation of this proposal. The general criteria that are practically applicable in designing green roof were given high priority and are followed in this research. In addition, the benefits of such plans were checked out with the help of completed buildings that contain the green roof technology. Green Roof Technology A green roof is a type of roof of a given building that is partially or completely covered with soil and vegetation – growing medium, which is planted on a membrane, which is waterproof.
In addition, there is the presence of drainage, irrigation and root barrier (Patrick 90, Douglas 76). There are two types of green roofing: Extensive and intensive. Extensive roofs are usually light in weight and are not designed for use by human e. g. walking and are installed in steeper roofs when compared to the intensive system. They are able to hold plants in containers and the soil depths start at 2 – 3 inches, and support those plants with low water requirements. Intensive roofs are heavier with soil depth that starts at 6 – 8 inches.
It is appropriate for human use e. g. walking on it. Benefits of Green roofing The extensive and damaging causes that are related to the global warming and human activities have developed various ideas, the idea of environmental concerns should be applied in different fields, and buildings are not spared (McDonald 154). This means that the building should be “green”. When this method is employed, pollution will greatly be reduced and beautification of the buildings that are within the congested city could create a homey atmosphere (Peter 67).
In addition, the introduction of such technology to the rooftops will create an appreciation of nature by the users and they will be able to acknowledge nature and the environment in general. When population is taken care of, the living standards will be improved since hazards that are caused by pollution will be reduced. This shows that general population healthy factors will be taken into considerations. Other benefits include: Reduce effects of heating and cooling due to its thermal resistance. Increase the life of roof span Reduce the effects of storm water run off
Growing of horticulture is possible They can also reduce the effect of urban heat island. Standards and Codes E2400 – 06 Standard Guide for Selection, Installation, and Maintenance of Plants for Roofs E2399 – 05 Standard Test Method for Maximum media De4nsity for Dead Load Analysis of Green Roof Systems E2398 – 05 Standard Test Method for Water Capture and Media Retention of Geocomposite Drain Layers for Green Roof System E2397 – 05 Standard Practice for Determination of Dead Loads and Live Loads associated with Green Roof Systems
E2396 – 05 Standard Test Method for Saturated Water Permeability of Granular Drainage Media for Green Roof Systems Time Scale and Research Planning. Research through Jun 30 2. Correspondence through July 3 3. Review correspondence received finish July 8 4. Write preliminary draft finish July 12 5. Produce graphics finish July 14 6. Finalize preliminary draft finish July 15 7. Deliver preliminary draft on July 16 at 8:00 AM Methodology Feasibility The initial and most important step in trying to retrofit is determination of feasibility.
Information that concerns the building and structure should be analyzed so that to ascertain if the project is successful. An example is the load bearing capacity of the building in question. Various people who have knowledge that concerns the different buildings were contacted and discussions were also held. In addition, various blue prints and documents that relates to the modern buildings were analyzed. After this analyzes the team decided that project was good and decided to proceed with the project. Lightest green roof was decided to be implemented e.
g. extrusive. When the project was on path, data that concerned water runoff was gathered and analyzed in effect with the green roof design. Water Budget The aim of doing a water budget on green roof is to be able to know the behavior of roof during events of waterfall. The water budget will be able to measure the amount of rainfall that can be used by the growing plants. The runoff water that will remain after reaching the storage capacity will be measured, and it can predict the performance during different rainfall events.
For the purpose of design the maximum amount of runoff from the green roof will be know and the right of drainage will be developed. After considering all this factors, a water budget was prepared in order to quantify the benefits of storm water management, and analyze the nature and performance of roof during different storm events. The method that was employed was simple mass balance. Usually the first step is to define the control volume. For our research, all layers that consist of green roof design were analyzed: water retention layer, plants, drainage layer and the growing media (Patrick 133).
When this method is employed – mass balance, its give birth to the following equation: ?S = P – E – Q Where; (all measurements are in inches) ?S is the change in storage P is precipitation E stands for evaporation, and Q is the runoff Such equation was applied in our case with information’s and data from National Weather Service and additional information’s on daily precipitation, hourly precipitation and daily evaporation were used. The data that was obtained was for the past 30 years (1977 – 2007).
Lastly, in the water budget methodology was the analysis of the information that we were provided with. We analyzed rainfall events between the months of April to October and the average for 30 year monthly for run off was obtained. Roof Design After doing a thorough research at the library, on line, and obtaining information’s from professionals that concerns green roofs, we concluded that there were a lot of information’s that pertain to green roofing from the internet. The design criteria that the green roof would be contingent upon included:
Water proofing membrane Capacity of bearing structure Soil media Drainage Irrigation or storage of water Plants Cost Benefit Most common cost savings that are related to green roof is the ability of adding an extra layer of insulation, which results in reflecting sun’s away from the roof. To be able to determine the benefits that are related to heating and cooling costs, it will depend on the amount of heat that is transferred through the roof. There are different forces that related to heat transfer: convention, conduction, and radiation.
Radiation is common in summer due to heat flux from the beam solar irradiance and diffuse solar irradiance. Therefore, the small amount that the roof reflects the greater the fraction that the roof will absorb while the energy from the skies and clouds are dependent to weather conditions. Convectional heat is primary caused by the effects of wind current. In addition, it is dependant on the difference between the temperature that is outside, the temperature of the roof and heat transfer coefficient. Conduction is related to conventional heat and is dependant on the thermal conductivities and thickness.
The three heat transfers (convection, conduction, and radiation) are brought together to obtain the general heat transfer from the following equation (Kibbe 45). Q total = q rad + q cond + q rad When Q is positive, heat energy is entering the building while when Q is negative, heat is leaving the building. Cost analysis part is obtained from determining the cost of counteracting the heat gain or loss. Data Collection Data was obtained form the National Climatic Data Center that concerns the radiation, convectional, and conduction heat.
The information that calls on radiant beam was collected on monthly averages while the indoor temperature, wind speed, and sky radiation were based on yearly average. The data that pertains to the internal nature are usually constant. These are the green roofs and conventional properties, and usually are constant. These properties are emissivity, absorptivity, layer thickness and thermal conductivities can be easily be found from literature. Existing data that contains the cost of air conditioning were obtained from the market. Assumptions
The information that is missing is that of the temperature that is of green roofs and conventional. From literature the maximum temperature change that is of ambient air for black roof with maximum sun and negligible wind is 50 degrees Celsius (Douglas 56). In this case, the maximum temperature increase is 16 degrees Celsius. The value of temperature change is calculated with the help of Cool Roofing Database. This value is halved for conservative estimate from the actual temperature, hence, results in lower, cost saving and conservative estimate. Other assumptions are in the speed of the wind.
Due to the assumption that the heat is adiabatic, this is a poor assumption because heat can enter or exit through the external walls and windows. While for the issue of air conditioning, the assumptions that were made were that the efficiency was 100%. The same principles were used for those cases that involve heating. Calculations Radiant beam was calculated by removing a percentage of the maximum possible energy in respect to the month percentage of possible daily sunlight, and the average of the daily hours of sunlight. Through the assumptions, the roof temperature was determined by the use of ambient air temperature change.
For the overall heat transfer coefficient, the conduction term was obtained from the existing roofs and a sample of a green roof. The example green roof was similar to the proposed and was used because there was lack of appropriate knowledge that concerns the thermal conductivities. With the help of equations that relates to convective, radiant and conduction transfers were then used to calculate the total value of heat energy. Cost Analysis The amount of saving are calculated based on the difference of energy in the heating and air conditioning between the green roofs and the existing roofs.
Internal rate of return (IRR) were used as the financial devices to analyze the capital cost versus cost savings. In addition, it included factors such as maintenance cost, life span of the roof and the increase in the electricity cost. It is estimated that the lifespan of a green roof is 40 years while the conventional roof is 20 years. Participants In this case, the respondents are derived from different field of specialty and profession. People who are involved in general architecture, air conditioning and environmental were called upon in this research.
There wide knowledge that concerns different fields was employed in developing the proposal to the state that it is in. In additional, the Local council was contacted to explain the issues that stand on the codes and standards of building up a green roof. Results and Discussions Water budget The idea of urban storm water management is important in achieving of sustainability. The result of rapid runoff that is associated with the roofs and other surfaces can exacerbate flooding and an increase of erosion and may result in overflows of sewer.
Green roofs are developing at a greater rate because they can manage and sustain storm water. The purpose of water budgeting is to quantify the amount of water that is reduce because of presence of green roof (McDonald 120). Three scenarios that concern the green roof were analyzed: present roof, green roof with one inch of growing media and two inches of media. The media that contain a growth of one inch of growing media retain small amounts of water when compared to the two inches type. The green roof achieves more in reduction of runoff in the period of fall and spring. Water Quality
From the current research it has been shown that the green roofs improves the quality of storm water runoff. The green roofs have the ability of filtering contaminants from rainwater that has flowed on the roof surface. Other plants can work on the pollutants, which are then degraded. Improvement of water quality is another aspect that relates to the sustainability of green roofs (McGlynn 23). Plant Survivability Some species of plants like the sedum are preferred in situations of shallow green roofing. This is because it can withstand extended drought conditions, tolerant to cold temperatures and has a high growth index.
Sedum can survive drought period of up to 28 days and therefore, needs a single watering period within this time. Plants that are supposed to be used in the green roof project should be able to withstand different temperatures (Peter 89). Heat Transfer The main difference between the different methods that concerns with climate is the absorptivity. It is evident that most heat transfer is due to radiation and majority in heat loss is due to convection. When the method of green technology is employed, it exhibits different results since some roofs are designed to regulate heat.
Feasibility Through the research that was carried out it was evident that the project will be successful if implemented. The roofs of buildings that have been developed can easily take in the aspect of green roof (Kibbe 34). Roof capacity of certain buildings cannot withstand the weight that is associated with the green roof. This makes other buildings to increase the amount of weight handling capacity. Project Management To make the process be successful there are various managerial, and business oriented skills to be employed.
Issues like risks management, project scope and other various factors that contribute to this project should be analyzed. Resources are required to make the proposal successful and this includes financial funding (Kibbe 56 – 57). The estimate of cost and the resources that are required to complete the project is given in the following table: Issues that relate to risk should be analyzed with methods such SWOT, brainstorming, and root cause analysis. Ethical and legal factors should be brought into consideration in each step that the project is undertaken including issues like contracts (Douglas 90).
Conclusion Many buildings owners and architectures are turning there focus to the technology of green roofs due to garden like improvement, insulation, longetivity of the roof and aesthetic improvement. The success of any green roof design is the nature and the type of plants, soil, climate and the taste of the developers. The weight carrying capacity of different roofs calls for different type of green roof design: intensive or extensive. The amount of water that is present also calls into focus various adjustment to the project.
This means that more rain will result in development of better drainage system compared to when irrigation is administered. The amount of water that will be used for irrigation will be maintained to the minimal level to manage the environment. Management that enables the successful completion of the project should be analyzed from different perspective. All people who are concerned in the development of the project should collectively accomplish the project. The management should check issues that relates to the development of the project like risks, project scope and ethical and legal factors.
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