1. Introduction
In line with the environmental awareness and the need for global systems to measure its application in various sectors, the idea of the environmental assessment certificates had emerged to identify the environmental classification [1], [2]. In the building sector, an accelerated development in the environmental assessment field occurred recently, a number of environmental building rating systems were appeared to set the environmental principles and standards of green buildings, and a number of certificates were issued to classify the environmental efficiency in new and existing buildings. These systems helped the environmental commitment and building competition worldwide. A number of environmental building rating systems appeared all over the world, and the Building Research Establishment Environmental Assessment Method (BREEAM) in England was the first [1], [2], [3], which appeared in 1990 to assess the environmental performance of offices. Then, many other different systems appeared after [4], such as Leadership in Energy and Environmental Design (LEED) in the United States in 1998 (began its implementation in 2000), and Green Star in Australia in 2003 [4]. In Egypt, the Green Pyramid Rating System (GPRS) was put to use in 2011 for residential buildings [6]. Although the Comprehensive Assessment System for Building Environmental Efficiency (CASBEE) rating system appeared 14 years after BREEAM, it included unique characteristics and definitions, especially in the way of classifying buildings and getting their final score. It uses for that purpose an indicator called the Building Environmental Efficiency (BEE), which did not appear before. This indicator expresses a balanced relationship between the building and the environment. It uses an equation to ensure buildings balance as a consumer of resources and energy and producer of pollutants and waste, as shown in the next sections of the paper [5], [7].
One of the common ways to develop the current rating systems is benefiting from each other; many researches relied on comparing the rating systems to find the different advantages and disadvantages among them to be used in developing the other systems. There have been an enormous number of comparative studies among different rating systems that are currently in use. Some of these studies [1], [2], [3], [4] focused on the differences among the different rating systems to help improving them. Asdrubali et al. [1] compared between the environmental rating systems LEED and ITACA for two examined residential buildings located in Italy to prove the main features of both systems, and encourage the use of their advantages within each other, while Seinre et al. [2] compared some indicators and their levels from Estonian regulations against LEED and BREEAM requirements to help finding their shortcomings in these regions to improve them. Haapio and Viitaniemi [3] compared a number of environmental building rating systems and reviewed the differences among them. Roderick et al. [4] compared the building energy performance assessment between LEED, BREEAM and Green Star for a typical open-plan office building in Dubai, to highlight their differences effect out of their countries. Many other studies were carried out to study the differences between some building environmental rating systems to rectify their disadvantages, and make use of their advantages in improving each other.
Other studies mainly focused on improving some of the environmental rating systems according to their shortcomings; these studies [8], [9], [10] are some of them. Humbert et al. [8] evaluated the actual extent of the benefits and burdens of LEED, and identified the critical credits to develop a new scale, which was proposed to correct the miscorrelations of the LEED credits. Thilakaratne and Lew [9] analyzed the adaptation trends in LEED after comparing projects in the US and in Asia using simple statistical analysis methods, to show how the rating system should be more encompassing. Sergio Altomonte and Schiavon [10]argued that LEED needs to be improved in the occupant satisfaction requirements due to the difference in the mean satisfaction scores between LEED and non-LEED buildings.
When searching the most obvious comparative result between the BEE-scoring building environmental rating systems such as CASBEE and the point-scoring rating systems such as LEED, the use of BEE indicator occurs strongly to improve the second type systems to meet the various needs and remain at the highest level of evaluation-efficiency. In this regard, the researcher is seeking the feasibility of using the BEE indicator through the point-scoring rating systems to benefit from its advantages without exposing to some of the disadvantages that appeared with its usage in CASBEE.
2. Gradation in expressing the relationship between the buildings and the environment
The way to express the relationship between the building and the environment has been changing gradually over the time, which was reflected in the environmental assessment of buildings. It started from a stage that relied mainly on assessing the performance of the buildings, especially through the internal spaces. The assessment in that stage aimed to improve the living and users’ comfort, and did not take into consideration the environmental loads that the buildings emptied into the surroundings. While the second stage focused on the global environmental problems and led to establish the Environmental Impact Assessment (EIA) [11], [12], it took into consideration the building loads on the surrounding environment and emphasized on the global environment as an open system. Thus the second stage focused only on the environmental building loads, such as air pollutions, wind effects on urban areas, urban effects on daylight, and other negative impacts on the environment [11].
From the previous, the first stage referred to the efficiency of internal spaces while the second stage referred to the efficiency of open spaces. The third stage started by issuing the environmental building rating systems. This stage merged the two previous stages together, but it lacked the connection between them. Most of these systems starting from BREEAM – excluding CASBEE and the rating systems depended on it – assessed both the performance of the internal building environment and the reduction in the external building load on the environment by using separated items [11], [12].
CASBEE differs from other rating systems in the way of assessing the relationship between the building and the environment. The evaluation of this system depends on the integration between improving the performance in the internal environment and reducing the negative impact of the building on the external environment. Therefore, the presence of CASBEE may be considered a beginning of a fourth stage in the relationship between the building and the environment. In this stage, the presence of a closed ecosystem had become necessary to determine the environmental abilities in the assessment when knowing that the capacity of the local and global environment had reached their maximum. Thus, a hypothetical enclosed space that defines the site boundaries is assumed in CASBEE to assess buildings environmentally, as shown in Fig. 1. The building load (L) can be defined as the negative impact on the external environment that extends over the enclosed space, while the environmental quality (Q) can be defined as improving the internal environment in the enclosed space. From the previous two definitions, the BEE indicator was presented in CASBEE to enable the integration of the assessment inside and outside the building site [12], [13], [14].
Figure 1. The relationship between the building and the environment in CASBEE based on a specific hypothetical enclosed space [13].3. The Building Environmental Efficiency (BEE)
The Environmental Efficiency (EE) can be defined as the value of products and service quality per unit environmental load. The efficiency is usually defined in terms of the amount of inputs and outputs; therefore, environmental efficiency is the: (benefit resulting)/(un-useful (inputs + outputs)). This definition can be expanded to define the Building Environmental Efficiency (BEE) which is used in CASBEE as an indicator for evaluation [15], [16]. The same idea can also be used on the urban level to assess the environmental performance, as the assumed – previously mentioned – enclosed space can be expanded to express any space, and it is easy to be applied at all levels [11].
Therefore, BEE helped CASBEE to calculate both improving the comfort of buildings’ users and reducing the negative impact on the environment, and created a holistic view of the ideal interaction between the building and the surrounding environment. BEE can be displayed according to the equation BEE = (Q)/(L) as set in CASBEE [12], [13], [14]. This equation proved to be efficient through the numerous assessed buildings used CASBEE. The equation reflects the balanced relation between the building and the environment requirements. The equation inputs are divided into two types, the first type is Qand the second is L. When applying the hypothetical enclosed space around the building, Q is defined as improving the quality of the environment within that space (describes the safety of the building to the user), and L is defined as the negative impact on the environment outside that space (describes the safety of the building to the planet) [15], [16], as shown in Fig. 2.
Figure 2. Definition of Q and L through a hypothetical boundary in CASBEE [12].In CASBEE, the Environmental Quality (Q) measures the following assessment fields: quality of the indoor environment, the building service quality and the quality of the surrounding site within the hypothesis space. On the other hand the Environmental Load (L) measures the following assessment fields: energy load on the environment, the resources and material loads, and the building environmental loads outside the enclosed space [11]. It is notable that the previous six assessment fields in CASBEE are divided totally between Q and L, as shown in Fig. 3. In CASBEE, BEE indicates the final environmental evaluation of buildings using a special graph to classify the buildings. The graph includes a number of straight lines, mostly starting from the origin point (0, 0) to different coordinates of various values of BEE. In that graph, the Q result should be put on the vertical axis (y-axis) and the L result should be put on the horizontal axis (L), and according to their junction the building classification is determined [12], [15], [16], as shown in Fig. 4. It is noted from the chart that, the more the increase in the Q value, the decrease in the L value leads to a more sustainable building. Thus, the efficient building is the one that represents the least environmental load and the highest environmental quality [17].
Figure 3. Main assessment fields in CASBEE divided between the Environmental Quality and Load sides and their presentation on a radar chart [12].
Figure 4. The chart used to determine BEE indicator and the building classification in CASBEE according to Q on the (y-axis) and L on the (x-axis) [13].4. Importance of including BEE in the environmental assessment of buildings
Most of the current environmental rating systems of buildings are point-scoring systems; they depend on gathering the items’ scores to get their final score. Each item in the point-scoring systems is assessed individually; thus, both the environmental quality performance (Q) and the building load reduction (L) are assessed separately, without assessing their relation or the percentage of their achievement. Each included item – whether reflecting (Q) or (L) – gets its own score, and then these scores are gathered to get the building final score, which is used to determine the building classification according to different limits by the different rating systems. Therefore, these systems lack a holistic way of integrating the environmental issues together to reflect the building environmental efficiency (Researcher using Refs. [7], [11], [14]). LEED, BREEAM, Green Star and GPRS are some of these systems. The point-scoring systems may create a misleading incentive away from the Green Architecture objectives, so one of their disadvantages is the possibility of ignoring any factor that does not appear directly in the listed items, which means affecting the ultimate goal of the assessment, and affecting its comprehensiveness unless putting all the required objectives in direct items [3], [5]. The way of getting the final result by gathering the items scores to get the final result means that there is a possibility of ignoring some assessment issues to achieve others, and the ability of ignoring one side of the BEE bases to focus on the other, while the building passes the assessment without considering such a problem.
On the other hand, the BEE-scoring systems (CASBEE and the rating systems based on it, such as China’s Green Building Assessment System (GBAS)) included more holistic objectives due to their reliance on the BEE indicator to express the building classification [7]. But, the used way of this indicator in those systems led to a difficulty of getting a separated items’ or fields’ scores when needed. This is considered a problem associated with these systems that should be treated as much as possible. This disadvantage appears when thinking of comparing buildings or studying their shortcomings on the level of any of these fields or items. So, although these systems have a holistic vision of achieving the green objectives in a unified indicator, they contain some undesirable cons [5], [15]. Table 1 shows general differences between the BEE-scoring rating systems and the point-scoring rating systems in regard to some assessment result aspects.
Table 1. Differences in some assessment result aspects between the different scoring environmental rating systems of buildings (Researcher using Refs. [7], [12], [14]).
| Comparison aspects | BEE-scoring rating systems (CASBEE) | Point-scoring rating systems (LEED) |
|---|---|---|
| Including BEE in the final building score | BEE indicator represents the final score | The assessment items’ scores are gathered to get the final score without pointing to (Q) or (L) |
| Possibility of separating the items results from the overall result | The item results cannot be known separately | Each item’s score is calculated separately, and the final result is calculated after |
From the previous, a question about the possibility of assessing the balance of the two BEE bases (Q and L) in the current building environmental rating systems appears, taking into consideration thinking of other ways to include BEE in the assessment that do not have the disadvantages appeared in the BEE-scoring rating systems.
5. A proposed way of determining the two bee bases in any rating system
Before proposing some ways to include the BEE indicator in the current point-scoring rating systems to improve their assessment efficiency, a proposed way should be put first to determine the BEE value that could be reached by using any of those systems, and the percentage of its bases in the assessment weights. Determining BEE and the percentage of its bases helps to ensure that the rating systems are balanced, and thus appropriate to be used before adding the next proposed ways to include BEE in the assessment; otherwise, they need to be modified first to be balanced between Q and L.
It is proposed in the research to determine the occurred BEE value that could be reached in any current rating system through number of steps. First, dividing all assessment items into one of the BEE bases according to their definitions – as previously mentioned –, items representing (Q) is improving indoor quality, while items representing (L) are reducing the environmental load. Second, the weights of each group of items are gathered to determine the overall (Q) and (L) weight values separately. Finally, the equation BEE = Q/L is used to examine the ability of achieving a balance between the previous two bases in the examined rating systems.
As previously mentioned, each of the six major fields in CASBEE represents one of the two BEE bases, so all the items in any of them are linked totally either to achieve Q or to reduce L, while it is proposed to link these two bases with the different existing fields’ items rather than the fields themselves. Therefore, there will be flexibility in calculating BEE without being exposed to the CASBEE fields’ names and structure, and flexibility in balancing the two BEE bases in the different rating systems with their different fields’ names and internal items currently and within their future versions, which means that, every field may include a number of items that are linked to achieve either Q or L or both of them with different percentages. Mostly, fields like those related to resources and materials will depend mainly on reducing L, fields like those related to the indoor environmental quality will depend mainly on achieving Q, and other fields that include a dual concern of Q and L such as those related to energy efficiency and water efficiency will have a calculated percentages of Q and Laccording to the included items weights, noting that different rating systems consist of different assessment fields and items. The overall percentage of achieving Q or reducing L can be gathered from the overall item groups of Q and L through all the assessing fields. Table 2 shows a comparison, between the proposed way to determine the two BEE bases and the one used in CASBEE, regarding the possibility of being determined at the detailed levels of the assessment components.
Table 2. A comparison between the proposed way and the CASBEE way in determining the two BEE bases at the detailed levels of the assessment components (Researcher using Refs. [12], [14], [15]).
| Comparison aspects | The proposed way | The CASBEE way |
|---|---|---|
| Possibility of distinguishing the two BEE bases at the detailed levels of the assessment components | Every detailed item can be expressed according to the BEE bases, and they are either helping to achieve Q, reducing L or both with a certain percentage between them | Each one of the main six fields – with all their items – is related to one of the two BEE bases, and they are either totally expressing achieving Q or reducing L |
| Possibility of determining BEE at the detailed levels | For the assessment fields, a BEE indicator can be calculated | BEE indicator can only rise at the end of the assessment, and cannot be calculated at any detailed level |
One of the rating systems that did not rely on the BEE indicator can be chosen as an example to determine its balance in assessing the two BEE bases in its current form; this rating system is the Egyptian system, the GPRS. The chosen version was that for the residential buildings in the pre-construction stage in 2011, which is the first and main version of the GPRS. To study the balance of the BEE bases, the included items in GPRS should be divided into two groups according to their relation to Q or L as previously mentioned. Table 3 shows the items related to achieve Q in the GPRS and their weights’ percentage to the overall weight. Table 4 shows the items related to reduce L in the GPRS and their weights’ percentage to the overall weight.
Table 3. Items related to achieve Q in each assessment field in GPRS and their weights’ percentage to the overall assessment weight (Researcher using Ref. [5]).
| Assessment Field | % of the overall weight | Items related to Q | % of the overall weight |
|---|---|---|---|
| Sustainable Site, Accessibility and Ecology | 15 | 0 | |
| Energy Efficiency | 25 | Energy Efficiency Improvement (5%) | 7.5 |
| Optimized balance of Energy and Performance (2%) | |||
| Operation and Maintenance (0.5%) | |||
| Water Efficiency | 30 | Indoor Water Efficiency Improvement (4.8%) | 15 |
| Outdoor Water Efficiency Improvement (5.4%) | |||
| Efficiency of Water-based Cooling (2.4%) | |||
| Water Feature Efficiency (2.4%) | |||
| Materials and Resources | 10 | 0 | |
| Indoor Environmental Quality | 10 | Optimized Ventilation (3.33%) | 10 |
| Controlling emissions from building materials (3.33%) | |||
| Controlling emissions from building materials (3.33%) | |||
| Thermal Comfort (1.3%) | |||
| Visual Comfort (1.3%) | |||
| Acoustic Comfort (0.67%) | |||
| Management | 10 | Providing access for lorries, plant and equipment (0.5%) | 3 |
| Providing a Building User Guide (1.5%) | |||
| Providing a Periodic Maintenance Schedule (1%) | |||
Table 4. Items related to reduce L in each assessment field in GPRS and their weights’ percentage to the overall assessment weight (Researcher using Ref. [5]).
| Assessment Field | % of the overall weight | Items related to L | % of the overall weight |
|---|---|---|---|
| Sustainable Site, Accessibility and Ecology | 15 | Desert area development (1.5%) | 0 |
| Informal area redevelopment (1.5%) | |||
| Brownfield site redevelopment (1.5%) | |||
| Compatibility with National Development Plan (1.5%) | |||
| Transport infrastructure connection (1.5%) | |||
| Catering for remote sites (1.5%) | |||
| Alternative methods of transport (1.5%) | |||
| Protection of habitat (1.5%) | |||
| Respect for sites of historic or cultural interest (1.5%) | |||
| Minimizing Pollution during construction (1.5%) | |||
| Energy Efficiency | 25 | Passive External Heat Gain/loss Reduction (3.5%) | 7.5 |
| Energy Efficient Appliances (1.5%) | |||
| Vertical Transportation Systems (1.5%) | |||
| Peak Load Reduction (3%) | |||
| Renewable Energy Sources (5%) | |||
| Environmental Impact (2%) | |||
| Energy and Carbon Inventories (1%) | |||
| Water Efficiency | 30 | Water Leakage Detection (3.6%) | 15 |
| Efficient water use during construction (1.8%) | |||
| Waste water management (7.2%) | |||
| Sanitary Used Pip (2.4%) | |||
| Materials and Resources | 10 | Regionally procured materials (1.5%) | 0 |
| Materials fabricated on site (0.5%) | |||
| Use of readily renewable materials (1.5%) | |||
| Use of salvaged materials (1.5%) | |||
| Use of recycled materials (2%) | |||
| Use of lightweight materials (0.5%) | |||
| Use of higher durability materials (0.5%) | |||
| Use of prefabricated elements (1.5%) | |||
| Life Cycle Cost (LCC) analysis of materials in the project (0.5%) | |||
| Indoor Environmental Quality | 10 | 10 | |
| Management | 10 | Providing Containers for site materials waste (1%) | 3 |
| Control of emissions and pollutants (1%) | |||
| Providing Employing waste recycling workers on site (0.5%) | |||
| Providing Identified and separated storage areas (1%) | |||
| Project Waste Management Plan (0.5%) | |||
| Engaging a company specialized in recycling (1%) | |||
| Protecting water sources from pollution (1%) | |||
| Waste from mixing equipment (1%) | |||
From the two previous tables, when gathering the weights of the items associated with achieving Q, they reach 35.5% of the overall assessment weight while the weights of the items associated with reducing L reach 64.5%. Therefore, the two bases of the Building Environmental Efficiency (BEE) are unbalanced in that version of GPRS, which means that using it in its current form in the assessment may lead to have a passed building without including an acceptable balanced level of Q and L.
It is noted that even in the case of finding an acceptable balance of Q and L in any current point-scoring rating system, there is no obligatory requirements in these systems to guarantee achieving that balance in the assessed buildings, which means that there is a need for considering some new features in the rating systems to increase their credibility in expressing a right relation between the building and the environment by using the BEE indicator when assessing the buildings, which are proposed in the following section.
Advantages resulting from determining the two BEE bases in the current rating systems:
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Ability of expressing the building relationship with the environment using the BEE indicator that is the best current expression for that relation.
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Presence of a governor relationship when changing the items’ weights in any new version to keep the balance between Q and L, in spite of the different variables and concerns affecting these weights.
6. Proposed ways to include BEE in the environmental assessment of buildings
There are three proposed ways to include BEE in the environmental assessment of buildings. The first way depends on connecting the success of the building by achieving a minimum level of BEE (minimum balanced level of achieving Qversus reducing L). The second way depends on connecting the assessment pre-requests and other important items (that have high weights) by achieving both Q improvement and L reduction together. The third way depends on rewarding buildings that achieve ideal BEE relations. The last way depends on the possibility of expressing the final building score using the BEE indicator when needed. The four proposed ways are presented as follows: