Green Building Rating Systems as Sustainability Assessment Tools: Case Study Analysis

Building performance and occupants’ comfort lie at the core of building design targets. Principles of green architecture and building physics are not given enough thought and consideration. In the best cases, some thought is given to such factors but without a scientific methodology, which takes into consideration appropriate climatic data and appropriate assessment tools. Most importantly, the interference of the environmentalist in architecture projects comes usually very late in the design processes. Facing these facts has driven most countries to adopt official strategies and policies to deal with building’s performance. The rating systems are among these initiatives. The author of this chapter adapts a detailed methodology to aid the integration of the principles of the green architecture in the early stages of design using rating systems. The Leadership in Energy and Environmental Design (LEED) 1 that was developed in the USA by the U.S. Green Building Council (USGBC) for Core and Shell has been employed as the main design target. This chapter presents a brief about the world green initiatives and discusses the results of applying the methodology of integrating the green architectural principles at the early stages of design processes—through precedent analysis.


Introduction
More than half of the world's population lives in cities; in 2050 the people living in urban areas are expected to increase up to 70% [1]. Cities are the major reasons of pollution; it produces 60% of carbon dioxide and greenhouse gas emissions, through using energy generations, industry, vehicles, and biomass use. Therefore, now climate change is challenging cities to reduce their impacts and adjust to changing condition [2]. Therefore, the increasing demand towards sustainability is pushing toward rapid changes in policies, laws, and regulations around the world regarding products and processes to encourage more sustainable projects [3]. Also, sustainability solves the local issues of communities in innovative progress, for implementing sustainability is different for every community, but they share common goals for a healthy environment, smart growth, and human well-being [4]. Consideration to sustainability principles in building industry is vital for natural environment and human being. Adopting passive strategies and measures that sustainability at the urban level to allow local and central governments to use data [10]. The climate positive development program (CPDP) addresses the challenges of rapid urbanization and climate change [11]. In addition, there is the United Nations Environment Program-Sustainable Building and Climate Initiative (UNEP-SBCI), which is a partnership of major public and private sector stakeholders in the building sector, working to promote sustainable building policies and practices worldwide [12]. The Passivhaus standard was developed in Germany in the early 1990s, and the first dwellings to be completed to the Passivhaus standard were constructed in Darmstadt in 1991 [13].
Rating systems assess the environmental impacts of buildings, constructions, infrastructure, urban-scale project, and community projects. The rating systems designed to assist projects to be more sustainable by providing frameworks with a set of criteria's that cover several aspects of a project's environmental impact [14]. Rating systems utilize the key performance indicators (KPI) to assure high quality of sustainability applications [14]. KPI are employed for building designers and decision-makers to measure the socioeconomic and environmental impacts on environment, infrastructure, waste system, regulations, pollutions, citizen's access to services, and more [15]. The significance of the sustainable design increased in the 1990s. The Building Research Establishment's Environmental Assessment Method (BREEAM) was the first green building rating system in the UK that addressed the required KPIs for better environmental performance of buildings. In 2000, the U.S. Green Building Council (USGBC) developed another rating system, which is the Leadership in Energy and Environmental Design (LEED). Others also responded to the growing interest and demand for sustainable design including additional rating systems that most of them were influenced by these early programs but are tailored to their own context with specific priorities. Other trails for rating systems intended to address broader issues of sustainability or evolving concepts such as social aspects, net zero energy, and living and restorative building concepts. It is estimated that there are nearly 600 green product certifications in the world with nearly 100 in use in the USA, and the numbers continue to grow [16]. Many other rating systems became a great evidence of adapting the sustainability principles in building industry [17,18]. The rating system is based on four major components [14].  • Categories: These form a specific set of items relating to the environmental performance considered during the assessment.
• Scoring system: This is a performance measurement system that cumulates the number of possible points or credits that can be earned by achieving a given level of performance in several analyzed aspects.
• Weighting system: This represents the relevance assigned to each specific category within the overall scoring system.
• Output: This aims at showing, in a direct and comprehensive manner, the results of the environmental performance obtained during the scoring phase. Figure 1 and Table 1 present the most common green rating systems all over the world chronologically. Table 1 summarizes the most important features of those rating systems, in terms of year of establishment, coverage, main categories for building rating, level of certifications, its development base, and main aim with the main link of the source.

Case study analysis
In previous researches [56][57][58], the author of this chapter had set a detailed methodology to aid the integration of the principles of the sustainability in the early stages of design ( Figure 2). The outputs of these researches have been employed in several real-life building projects on the regional level. The current research Proposed detailed methodology to integrate the environmental assessment in the architectural design process [56].
presents one project as a case study analysis. The adopted methodology employs the environmental assessor "Leadership in Energy and Environmental Design" to measure the compatibility of the design with principles of sustainability. Also environmental software (Autodesk Ecotect, HTB2, and Weather Tool in addition to environmental tools such as psychometric chart, Mahoney tables, and Stereograph diagram and Solar Tool) have been used in order to analyze the context and quantify the effectiveness of proposed passive strategies and measures. By such, design proposals in the early stages of design (i.e., design concept, orientation of buildings, using passive strategies and techniques, facade designs and projections, colors of the buildings, opening size and design, etc.) could be quantified. LEED has 110 credits which cover all the different disciplines in building design and construction. However, the current application focuses on the related credits to the early stages of design which lie directly under the architect responsibility and can affect the total performance of the building.

Target identification
The adopted methodology employs the Leadership in Energy and Environment Design (LEED) 1 that was developed in USA by the U.S. Green Building Council for new construction as one of the most known environmental assessors in the market nowadays. The LEED tool aims to provide building stakeholders with a "report card" that indicates the health, efficiency, and comfort of the buildings. LEED recognizes the unique nature of the design and construction of ASHRAE Advanced Energy Design Guide [59] and addresses the specific needs of building spaces and occupant's health issues [60]. LEED is flexible to apply to all project types including healthcare facilities, schools, homes, and even the entire neighborhoods. LEED for Core and Shell can be used for projects where the developer controls the design and construction of the entire Core and Shell base building (e.g., mechanical, electrical, plumbing, and fire protection systems) but has no control over the design and construction of the tenant fit-out. Projects could include a commercial or medical office building, retail center, warehouse, or lab facility. It is designed to be complementary to LEED for commercial interiors and LEED for Retail: Commercial Interiors.
The allocation of points between credits is based on the potential environmental impacts and human benefits of each credit with respect to a set of impact categories. The impacts are defined as the environmental or human effect of the design, construction, operation, and maintenance of the building, such as greenhouse gas emissions, fossil fuel use, toxins and carcinogens, air and water pollutants, and indoor environmental conditions. A combination of approaches, including energy modeling, life cycle assessment, and transportation analysis, is used to quantify each type of impact. The resulting allocation of points among credits is called credit weighting [61]. These credit weightings are shown in Figure 3. LEED V4 are awarded according to the following scale in Table 2.
This work aimed at achieving the LEED Rating system (Core and Shell). Most of the LEED issues could be quantified by analyzing the design input data, while other issues such as Indoor Environmental Quality needs a quantification tool to be assessed. This methodology employs thermal comfort and energy efficiency as environmental design targets. The effectiveness of the proposed measures is determined according to its ability to passively achieve thermal comfort by using minimum amount of energy possible. This helps the designer to recognize successful LEED strategies and measurements for achieving credit category goals.
This work had set the guidelines for the architectural and engineering design of the GREENEDGE building based on analyzing the macroclimate for Cairo city and the microclimate data for the GREENEDGE site. This is done through using a specific scientific computer-based methodology developed by the author of the chapter through his research [6,7,[56][57][58][62][63][64][65][66][67] that mainly depends on a number of environmental design computer-based tools and especially the comprehensive environmental analysis and simulation tools. These tools are: • The analysis sustainable building design software (Autodesk Ecotect) • Climatic analysis software (Weather Tool) • Solar analysis software (Solar Tool) • Mahoney tables • Shadowing analysis (Stereograph diagram) • Synthesizing hourly climatic data (Meteonorm) The use of computer software allow the visualization of the unseen environmental attributes in a three-dimensional interface, allowing by such comprehensive understanding of the issues involved in the assessment process.  Table 2.

Project understanding and location
The New Cairo Business Hub (GREENEDGE) is located at plot 84, First sector, New Cairo City Center, that is directly overlooking the southern 90 road right beside BNP Paribas Headquarters (Figure 4). The building is designed to be a class (A) office building with total plot area of 33,000 m2 of office spaces for banks and multinational companies at one of the most developed business districts in Egypt with all required amenities and facilities at place and surrounded by Egypt's biggest banks, headquarters, as well as notable multinationals.

Macroclimate analysis
Cairo's climate is a desert climate, which remains mostly dry and arid yearround. The hot weather in Cairo means that the humidity can rise at times, particularly during winter (December to February). At this time precipitation is more likely, and temperatures drop to 13-19°C. Cairo weather in the summertime (May to August) sees temperatures of 45-47°C. The Cairo International Airport weather Station was chosen to most represent the location of new Cairo. The hourly climatic New Cairo location and the location of GREENEDGE building, after Google maps [68] and new Cairo City Council [69]. data file generated by the USDOE was used in this report. On analyzing the hourly climatic data using Weather Tool, Cairo climate is classified as an arid climate where precipitation rarely occurs. Cairo has a hot desert climate (Köppen climate classification: BWh). The climate is generally dry. The temperatures are hot or very hot in summer days and warm or mild in winter days, but warm in summer nights and cool in winter nights. The temperature varies greatly, especially in summer; it ranges from 7°C at night to 40°C during the day. While the winter temperature does not fluctuate as wildly, it can be as low as 0°C at night and as high as 18°C during the day. Cairo receives less than 25 mm of precipitation annually in most areas and almost never rains in summer. Air temperatures are being outside the comfort zone most of the year. Only during 4 months (March, April, September, and October), a good percentage of the total hours is found to be located in the comfort zone. The prevailing wind is coming from the north to northwest most of the year with average air temperature, while hot wind comes from the west-south direction during specific times of the year. Prevailing wind are coming from the north to northwest most of the year with average air temperature, while hot wind comes from the west-south direction during specific times of the year. Rainfall is rare in Cairo and does not exceed 25 mm/the whole year.
Passive solar heating, thermal mass effect, night purge ventilation, natural ventilation, direct evaporative cooling, and indirect evaporative cooling to enhance the environmental performance of the GREENEDGE in Cairo were tested using Weather Tool. The analysis revealed that while thermal mass and night purge ventilation can enhance the thermal performance during the whole year, almost only natural ventilation can enhance significantly the environmental performance of the building during the summer season. While indirect evaporative cooling can enhance the thermal performance slightly during the summer time, passive solar heating can also contribute to the thermal enhancement during winter time. Using Mahoney table, it revealed that it is essential to deal with such climate to use the following strategies: • Compact plans with interior courtyards In this section, the original design of GREENEDGE building ( Figure 5) will be explained, highlighting the problems, constrains, and potentials.
The GREENEDGE building in its base case was exposed to high incident solar radiation especially on its west and south facades that receive solar radiation every single day of the year with no any internal open spaces such as courtyards. This would affect negatively the building performance. Shaded open spaces are very preferable in the hot dry zones. They can reduce the daytime air and radiant temperatures inside the occupied space. The courtyard helps in maintaining cooled indoor temperatures. It provides a private internal open space that is visually and acoustically separated from the outside environment. The base case material for all the windows was single glazed that is not appropriate for such climate particularly for the west-south facades and high intensity of solar radiation.

Sustainable design enhancements
To deal with the current situation, several traditional and contemporary ideas have been adopted. The recommended ideas and solution could be classified under the recommended passive strategies that were raised from the climatic analysis using Weather Tool and Mahoney tables. This could be listed below.

Vegetation around the building
Maximizing the amount of vegetation inside and outside buildings affects positively the thermal performance of buildings. This could result in shading of the external surfaces of the building, shading the opened spaces, reducing and filtering the dust in the air, and elevating the humidity level [70]. However, vegetation in such climatic conditions could be expensive because of the limitation in the water supply for irrigation and by turn could be against the green architecture principles ( Figure 6). Specific types of trees and irrigation technology should be selected to best suit the climatic context.  Grass area has been avoided since it needs potable water for sprinkler irrigation system. According to the WHO guidelines for the use of treated wastewater for irrigation, gray water could not be used for adjacent area for man activity [71,72], also because gray water can affect negatively the sprinkler heads. Moreover, highefficiency drip irrigation systems can be 95% efficient, compared with 60-70% for sprinkler or spray irrigation systems [73]. Also, the use of native or adapted vegetation on the project site can assist project teams with earning more credits regarding sustainable sits.

Compact plans with interior courtyards that allow air circulation
A recommended northern courtyard with link between the courtyard and the backyard at the south orientation has been modified to the design. This can affect positively the thermal performance of the building. This link could be positioned at the first floors "called Takhtabush in vernacular architecture." This could be achieved by replacing the curtain glazing in this area to contemporary electronic Mashrabia (Figure 7).
This ensures a steady flow of air by convection [74]. Since the backyard is larger at the south orientation, and thus less shaded than the courtyard, air heats up more than in the courtyard. The heated air rising in the backyard draws cool air from the courtyard through the Takhtabush, creating a steady cool breeze.

7.2.3
Openings in the north and south walls, the exposed side of the human height of the wind, and interior wall openings Window height and details have been modified to be in two parts with different heights. Those of the north direction must be the same in height with the human being. Opposite ones must be in a higher position to enable the required crossventilation. This will give the occupants the controllability of opening the upper or the lower parts according to the weather condition.

Heavy construction for strong thermal inertia for walls and roofs: Time lag more than 8 hours
In the hot dry climate, high heat resistance and high heat capacity of the envelope elements are necessary. High resistance minimizes the conductive heat flow into the building mass during the daytime. Actually, this would reduce the rate of cooling the building mass during nighttime, but it could be overcome by employing night purge ventilation strategy and new techniques of sunscreen which allow air movement [70,75]. High thermal mass has been achieved traditionally by thick walls that are made of heavy materials such as stone, brick, adobe, and mud. To achieve this with the glazing wall, it has been modified to be double-tinted glazing. A U-value of 1.0 W/m 2 K has been used for the external facades. A canopy was added to the southern facade in the form of glazed sunscreen. Shading devices have been designed for the west facade to avoid the very hot solar rays of the afternoon. Firstly, a plan of blocking the solar rays of the summer season from 1:00 pm to 5:00 pm was achieved by 2.4 m depth shading device, which would not be accepted by the architectural consultant and the city council regulations. Therefore, the time range has been minimized to be between 1:00 pm and 3:00 pm and combined between the vertical and horizontal shading devices to minimize the depth of the devices to be 1.0 m (Figure 8). The same shading devices have been applied to the east facade for esthetic reasons.

Shaded roof
It also recommended to shade part of the roof, particularly the service area, with a pergola that can used for the photovoltaic cells to generate green power ( Figure 9).

Daylight and lighting views
To provide the building occupants with a connection to the outdoors, through the introduction of daylight and views into the regularly occupied areas of the building (Figure 10), it has been recommended to achieve a direct line of sight to the outdoor environment via vision glazing between 30 inches (75 cm) and 90 inches (225 cm) (Figure 11) above the finish floor for building occupants in 90% of all regularly occupied areas [73]. The floor area of the typical floor plan has been simulated using Autodesk Ecotect, and the daylight has been calculated on a height of 30 in (75 cm) above the floor. An interval of 5 foot (150 cm) has been employed in the analysis grid in the two directions X and Y. The first results did not satisfy the credit condition with the windows at sill height of 90 cm. Therefore, the height of the sill height was changed to be 30 in (75 cm).
By calculating the nodes of more than 25 fc (269.1 lux), the calculation showed that 472 out of 568 nodes are more than 25 fc and less than 500 fc. The percentage of area under the acceptable condition of the credit = 472/568 = 83.09% which is more than the required level by LEED (83.09% > 75%) ( Figure 12).

Simulation results analysis
Using Autodesk Ecotect, the base case and the modified case have been modeled and simulated. The thermal performance of the third floor has been utilized for the  comparison purpose. The same specifications of the zone in terms of air velocity, number of occupants, latent heat, operation hours, occupant activity and cloth, etc. were given for the two case scenarios. The passive heat gain breakdown of the building has been calculated for both the base case of the GREENEDGE building   Passive heat gain breakdown of the proposed case (done by the author using Autodesk Ecotect). and the after modifications. Figures 13 and 14 and show that the passive heat gain breakdown for the proposed case after modification was almost half the passive heat gain breakdown of the base case.

Conclusion
Although the GREENEDGE building is a mechanical-ventilated building (active ventilation), passive strategies and measures were followed to minimize the required energy for cooling and heating loads during the different seasons. The total hours of the years during energy consumption has been reduced by 12% after energy modeling analysis. The design recommendations could be summarized as follows: 1. Maximizing the amount of vegetation inside and outside buildings and using drip irrigation system to minimize the water consumption.
2. Having a northern courtyard with link between the courtyard and the external environment (the Takhtabush).
3. Shading part of the roof, particularly the service area, with a pergola that can be used for the photovoltaic cells to generate green power with the solar reflective index (SRI) not more than 29.
4. Placing vertical and horizontal shading devices on the west/east facades to block the solar radiation during the noontime of the day. 5. Windows has been modified to include two parts (lower and upper parts) that can give the occupants the controllability of opening the upper or the lower parts according to the weather condition. Those of the north direction must be the same in height with the human being. Opposite ones must be in a higher position to enable the required cross-ventilation.
6. Heavy construction for strong thermal inertia for walls and roofs: time lag more than 8 hours. To achieve this with the glazing wall, a doubled glazing with a U-value of 1.0 W/m 2 K has been used at the south and west facades.

7.
A canopy has been added to the south facade in the form of Mashrabia, shading devices, or glazed screen.
The GREENEDGE building imitating the LEED goal for a golden certificate is packed with good design potentials which can lead for such project to be one of the first office buildings in Egypt to be certified with a Golden certification using the newly announced LEED for Core and Shell. It is worth mentioning here that the building has been achieved a Preliminary Platinum Certificate.