Compatibility of global environmental assessment methods of buildings with an Egyptian energy code

Peer review under responsibility of Housing and Building National Research Center.

Abstract

Several environmental assessment methods of buildings had emerged over the world to set environmental classifications for buildings, such as the American method “Leadership in Energy and Environmental Design” (LEED) the most widespread one. Several countries decided to put their own assessment methods to catch up with the previous orientation, such as Egypt. The main goal of putting the Egyptian method was to impose the voluntary local energy efficiency codes. Through a local survey, it was clearly noted that many of the construction makers in Egypt do not even know the local method, and whom are interested in the environmental assessment of buildings seek to apply LEED rather than anything else. Therefore, several questions appear about the American method compatibility with the Egyptian energy codes – that contain the most exact characteristics and requirements and give the outmost credible energy efficiency results for buildings in Egypt-, and the possibility of finding another global method that gives closer results to those of the Egyptian codes, especially with the great variety of energy efficiency measurement approaches used among the different assessment methods. So, the researcher is trying to find the compatibility of using non-local assessment methods with the local energy efficiency codes. Thus, if the results are not compatible, the Egyptian government should take several steps to increase the local building sector awareness of the Egyptian method to benefit these codes, and it should begin to enforce it within the building permits after a proper guidance and feedback.

Keywords:

• LEED
• BREEAM
• Green Star
• GPRS
• Egyptian energy efficiency codes

Introduction

Many building makers in some countries prefer using the famous assessment methods for their buildings, even if they have their own local ones, without considering the used methods compatibility with the local characteristics and requirements, such as in Egypt. Standards and measurement approaches differ for different environmental assessment methods of buildings, even for the same assessed issues. For the energy efficiency, various standards are used among various environmental assessment methods, which lead to wonder about the suitability of using non-local assessment methods in Egypt to express buildings energy efficiency. This suitability can be studied according to the compatibility with the local Egyptian energy efficiency codes which resulted from a long and deep local experience in that field. Egypt had already put a local environmental method and used the local codes within, but unfortunately, this method is rarely used and known. Thus, the researcher planned to study the compatibility of the main energy efficiency items results of some famous assessment methods with the Egyptian energy codes, to find their possibility of replacing the released local method for that issue, and to give some recommendations for the government that may help ensuring energy efficiency of buildings within the required level and characteristics through the Egyptian building sector. This study was done using a simulation program.

Environmental assessment methods of buildings

Several environmental assessment methods of buildings had emerged all over the world. The Building Research Establishment Environmental Assessment Method (BREEAM) was the first of these methods, which released in 1990 from the Building Research Establishment (BRE) in the United Kingdom, then many others appeared [1]. The most well-known and widespread method is LEED, which appeared in 1998 from the US Green Building Council (USGBC) in the United States of America, and was applied in 2000 [2,3]. The Australian method, Green Star, was released from the Green Building Council of Australia (GBCA) in 2003 [4,5]. There are several clear differences among the different assessment methods due to the different practice, limitations, culture and potentials of each produced country. Some countries that did not put their own methods in an early stage decided to depend on some other earlier methods, whether by using them directly or by asking for a modified version of them to suit their characteristics. The modified versions differ only by adding or removing some assessing items besides changing the estimation weights and levels of the assessing fields and items requirements. LEED for example was used after some modifications in several countries such as Canada, India and the UAE. BREEAM also was modified to be used in Europe and the Gulf [1,3].

Energy efficiency assessment of buildings

Three famous environmental assessment methods of buildings, which are LEED, BREEAM and Green Star, are chosen to study the energy efficiency approaches used within, and the compatibility of their results with the Egyptian energy code results, Table 1 shows some reasons for choosing those methods. And then, the main items and measurement approaches in these methods were discussed.

Table 1 Reasons for selecting LEED, BREEAM and Green Star to identify their energy efficiency approaches used within Researcher using Refs. [1^{[2][3][4][5][6]}7].

LEED	• The most widespread (applied in many countries directly or after modifications) • The widest experience depending on the number of times used. It got a large base of experts across the world [1,3,6,7]
BREEAM	• The first environmental assessment method of buildings that many other methods benefited from • The second widespread method after LEED [1 –^[2]3]
Green Star	• Widely used in Australia and therefore have a considerable experience in assessing a range of different climatic areas • Australia includes a climate field that is similar to Egypt [4–^[5]6]

Some main Items used to assess energy efficiency of buildings

Each assessment method among LEED, BREEAM and Green Star put the greatest weight to assess the energy efficiency for each of them on different items, each of them with a different measurement approaches. These differences reflect the different countries’ interests. As the energy cost is considered the main interest in the US due its high load on the American society [1,7], while the amount of carbon dioxide emission resulting from buildings represent the most important problem related to energy consumption in the UK [8,9], and the greenhouse gas emission factors associated with energy consumption in Australia are very high in relative to other factors in similar countries [10,11]. Table 2 shows the main items in each previous methods used to reflect the energy efficiency within each of them.

Table 2 The main items in LEED, BREEAM and Green Star that are used to assess the energy efficiency of buildings Researcher using Refs. [4,12–^[13]14].

Method	LEED	BREEAM	Green Star
The main item used to express the energy efficiency	EA1: Optimize Energy Performance.	Ene1: Reduction of energy use and carbon emissions.	Ene-1: greenhouse gas emissions from the energy.
% of the total energy efficiency score	(18 points out of 33) 55%	((12 points out of 28) + 5 Innovation credits) 43%	(20 points out of 22) 91%
% of the overall score	33%	15%	22%

Main measurement approaches used to assess energy efficiency of buildings

Each previous method had chosen specific standards to define its energy efficiency baseline used to decide the assessed buildings energy efficiency levels [1,4,6,7,12,13]. Table 3 shows the different standards used in those methods and the different measurement approaches for each.

Table 3 General comparison of the measurement approaches used in LEED, BREEAM and Green Star methods [1,4,6,7,12,13].

Comparative aspects	LEED	BREEAM	Green Star
Used standards to define the baseline level	American Society of Heating, Refrigerating and Air-Conditioning Engineers/American National Standards Institute (ASHRAE/ANSI) Standards – Appendix G	UK National Calculation Methodology (NCM)	National Australian Built Environment Rating System (NABERS)
Measurement approaches	% of annual energy cost improvement, according to the Performance Rating Method (PRM)	CO2 emissions reduction, according to Energy Performance Certificate (EPC)	Expected Greenhouse gas emissions (kg CO2/m^2/year) according to The Australian Building Greenhouse Rating (ABGR)

Energy efficiency measurement approach used in LEED

LEED includes a Pre-request requirement which is achieving a “Minimum Energy Performance” and the EA1 item which is “Optimize Energy Performance”, the pre-request determines the baseline level of the energy performance, while EA1 item assesses the improvement over the minimum performance. The item is assessed using the data submitted by the project teams, as they should choose one of three options, one of them is using a simulation program to simulate the annual building energy to prove the proposed building improvement from the baseline (6% for new buildings or 4% for renovations for multi-residential buildings in 2014) according to the Performance Rating Method (PRM). The simulation program calculates the annual energy consumptions for the proposed building and base building (which compliant with section G in ASHRAE/ANSI standards) models, then decide the level of energy efficiency and its parallel score as set in LEED. For that item, there are number of achievement levels (ranging from 6% to 50% improvement for multi-residential buildings in 2014) and parallel scores ranging from (1 to 18 points) that vary over time and building type [12,14]. The following equation may be used to find the improvement in the energy efficiency according to LEED:$\%\text{of improvement}=100\times [1-(\text{Annual}\text{energy}\text{cost}\text{of}\text{Proposed}\text{Building}/\text{Average}\text{of}\text{annual}\text{energy}\text{cost}\text{of}\text{Baseline}\text{Buildings})]$

Energy efficiency measurement approach used in BREEAM

BREEAM includes Ene1 item which is “Reduction of energy use and carbon emissions” that depends on calculating the achieved Energy Performance Ratio (EPR) to compare it with the mentioned benchmarks in BREEAM, to award the corresponding scores. It can be assessed using an Energy calculator or calculations based on a proper simulation program. For residential buildings the simulation program is used to build models for the proposed building and the parallel Reference building (complying with the NCM part L1A for dwellings) to get the annual CO₂ emissions for both, then calculate the CO₂ reduction using NCM calculations [1,6,13]. This calculation includes several factors and rates, such as the Target Carbon Dioxide Emission Rate (TER), and the Dwelling Emission Rate (DER) (noting that for the non-residential buildings, this rate is called building Carbon Dioxide Emission Rate (BER)) which must be less than (TER), or TER/DER > 1, there are also the Reference Emission Rate (RER) and the Standard Emission Rate (SER), as SER = RER × improvement ratio. The improvement ratio depends on whether the building spaces are naturally or mechanically heated and ventilated [8,16]. The obtained score for Ene1 can be determined by comparing the resulted CO₂ emissions reduction with the CO₂ emissions index set in the Energy Performance Certificate (EPC). The EPC classifies energy efficiency in the buildings from A to G, where A represents the most efficient [6,13].

Energy efficiency measurement approach used in Green Star

Green Star includes the (Ene-) requirement that relates to pass a minimum greenhouse gas emissions resulted from the building operation, it also includes the Ene-1 item which is “Greenhouse gas emissions from the energy” that reflects the reduction in such emissions below the minimum previous requirement, this item is given its corresponding score depending on the resulted greenhouse gas emissions, the full score (20 points in 2014) represents a zero net greenhouse gas emissions [4,5]. The score of this item is determined using the current and last energy calculator version associated with the Green Star method and an appropriate simulation program. A base building is simulated according to NABERS to calculate the annual energy consumption (electricity (kWh/year) and gas (MJ/year)), the results are used in the calculator to achieve the predicted greenhouse gas emissions (kg CO₂ emissions/m²) according to the inserted Net Lettable Area (NLA) of the building (net area of the total floor area without the non-residential spaces), then Ene-1 item score appears automatically. Another way to determine the item’s score is using the ABGER Protocol to define the level of achievement and its parallel score [6,10,11]. This protocol provides an accredited assessment of the global warming intensity in residential buildings to get a classification on a scale from one to five. It uses Greenhouse gas emission factors that help to balance the differences among different Australian states [5,11,17].

Problem of using the local method that uses local codes

The Egyptian Green Building Council (EGBC) was established in 2007. It issued the Green Pyramid Rating System (GPRS) which is the Egyptian environmental assessment method of buildings. The first version was released in 2011. So, Egypt decided to track the hardest way to provide an environmental assessment for its buildings, it preferred to form its local method and not modifying another famous one to be used. Forming a local method helped to benefit from all other methods’ experiences in accordance with the Egyptian terms, besides focusing on the local circumstances, opportunities and limitations. It helped also to give a priority to its standards without being subjected to external influences [18–^[19]20], such as using the Egyptian energy efficiency codes to assess its item “Energy Efficiency Improvement” by demonstrating a further reductions in energy consumption from the Base case (using the same approach used in LEED).

According to a survey with several construction makers in Egypt, it was noted that about 80% of them do not know the existence of GPRS, and about 70% of who recognize it excluded using the GPRS against the LEED [Researcher using a questionnaire]. So, the Egyptian Council did not take in consider before releasing its issue of GPRS how it will rival other methods to be used in Egypt, how to spread it and attract builders and designers to use it. It seems that spreading LEED globally helped to attract the Egyptian building sector away from the local method without taking in consider the effect of local characteristics and circumstances, while logically, the Egyptian method is better to be used in Egypt because it uses local standards and codes that at an appropriate level of expressing the Egyptian requirements and based on a long and deep experience and studies. A question that needs an answer appears about if LEED or any other famous method can give a same or close result to the Egyptian method, and therefore no matter to be used instead of it. If the answer was negative, the building sector in Egypt should be alert of altering the environmental assessment of buildings from its main target into a commercial operation or fame objective.

The paper, therefore, is seeking to compare the results of one of the most important assessing fields among the Egyptian and some other famous environmental assessment method of buildings to find out: if there is another method that could replace the Egyptian method for assessing that field, if Egypt was wrong to produce its own method and it lost the time and effort for seeking an independence from other methods.

Energy efficiency results using different methods in Egypt

A simulation program which is Design-Builder was chosen for getting energy efficiency results for a building in Egypt, according to LEED, BREEAM and Green Star methods, as the program complies with these methods requirements [21]. The selected items for measuring their results among the chosen methods are the main ones associated with energy efficiency in each of them, the energy efficiency field was chosen to be studied in that paper due to the following:

•

Accuracy and credibility of energy efficiency assessment results of buildings in Egypt are considered of high importance, knowing that the traditional energy resources in Egypt are limited, and the high density energy technologies are still used in the Egyptian building sector and the associated industries. In general, the building sector is considered the highest in consuming electricity in Egypt, where the domestic and commercial buildings consume about 44% of the total consumed electrical energy [19–24].

•

Producing the Energy efficiency codes in Egypt was considered one of the most important steps toward improving building energy efficiency in Egypt. These codes helped Egypt to own its local reference for evaluating energy efficiency in an utmost credibility results depending on its local conditions, they were based on years of experience and studies according to all Egyptian climatic regions with their separated unique properties, but these codes are – similarly to those in other developing countries – voluntary and almost not applicable. Different countries, including the developed ones had chosen various ways to reach the transition from only developing their energy codes to apply them in buildings. The main real objective of creating the Egyptian Green Building Council and GPRS was to enforce using the Egyptian Energy codes in buildings [18,20,24], but unfortunately, the building sector in Egypt was not correctly oriented toward using the GPRS to achieve that, which is the main problem of this paper.

Proposed building models used for assessment

Three models that can form a local energy efficiency ruler in Egypt were used to find the relation between the energy efficiency results from non-local methods and the local energy requirements. These models are assumed from the researcher for the purpose of the research paper and were assumed to be for a residential building located in Cairo, with no renewable energy technology or lighting control used in the building, thus, the main energy efficiency focus was on the previously mentioned items for each method, which are EA1 in LEED, Ene1 in BREEAM and Ene-1 in Green Star. It was also assumed that the building did not use electrical devices with energy loads that exceed 10 W/m² of the space area, and all spaces were designed to be ventilated naturally.

First proposed building model

Represents: a good energy efficiency building in Egypt, where it exceeds the code requirements.

Surrounding environment characteristics: climatic and geographic data files of the Cairo region were downloaded from the program database (energy plus) to be used. According to the Egyptian Code the Cooling Degree day (CDD) was set at 25 °C, and the Heating Degree Day (HDD) was set at 18.3 °C. The thermal comfort limits were also identified as recommended for the hot, dry climate, ranging from 21.8 to 30 °C [Researcher using Ref. [24]].

Building formation: Building formation consists of four floors (ground and 3 floors) with a total 12.60 m high and an area of 312 m² (16 × 19.5) including an internal court, the internal clear height of each floor is 2.80 m, it consists of two apartments designed in accordance with the Egyptian building regulations and preferred spaces orientations. The building outline was designed to be a simple rectangle to avoid any self-shading, which means that the used external shading devices are only the affecting elements on the façades. Fig. 1 shows the horizontal plans designed for the building model.

Fig. 1 Typical and ground floor plans designed for the proposed building models using the Design-Builder software [Researcher using Designbuilder software].

Thermal properties of the opaque parts in the building envelope: The selected overall thermal resistance values (R-values (m² °C/W)) for the opaque parts (ceilings, exposed floors and external walls above the soil level) were designed to comply with the chosen climatic region requirements as set in the Egyptian energy code tables. The ceiling = 5 m² °C/W, northern walls = 0.94 m² °C/W, eastern and western walls = 2.3 m² °C/W, southern walls = 1.38 m² °C/W. The interior court walls were treated similarly to the northern walls [Researcher using Ref. [24]]. Previous thermal resistance values were entered the program through the used building and heat insulating materials characteristics depending on the used cross-section dimensions.

External shading properties used for the openings: The Window Wall Ratios (WWR) were designed ranging from 10% to 20%, according to the natural lighting requirements in the Egyptian code. As a result of this ratio the used Solar Heat Gain Coefficient (SHGC) and the Shaded Glass Ratio (SGR) values were determined to exceed the requirements set in the Egyptian code depending on the opening direction as follow, the northern façades: SHGC and SGR are not required, the eastern and western façades: SHGC = 0.4, SGR = 80%, southern façades: SHGC = 0.64, SGR = 70%. The chosen glasses type were depended on the SHGC, and according to SGR values the extension louvers coefficients were determined from the code tables, therefore, horizontal louvers were designed for the southern façades with an extension coefficient = 0.8, and squared louvers for the western and eastern façades with extension coefficients for the east = 0.6 and for the west = 1.1 [Researcher using Ref. [24]]. Calculations were done according to the previous figures to determine louvers extension for each window according to its WWR, assuming that there are no horizontal or vertical distances between the used louvers and the shaded openings (as the louver extension = extension louvers coefficient × (opening width/opening height for vertical parts or opening width for horizontal parts + horizontal or vertical distance between the opening and the louvers)) [24].

Natural ventilation characteristics: These characteristics were chosen to exceed the minimum required in the Egyptian code, for living rooms = 5 L/S/person and for services (kitchens and bathrooms) = 7 L/S/person [Researcher using Ref. [24]].

Water heating system characteristics: LEED, BREEAM and Green Star determine that the used fuel for water heating should be gas, likewise the chosen fuel in the proposed model was gas to help the comparison process. The chosen system capacity was greater than 38 L storage, at 60 °C control degree. The determined heating efficiency was chosen to exceed the minimum required in the Egyptian code: 90%, while the acceptable efficiency = 85% [Researcher using Ref. [24]].

Natural lighting properties: Three adjacent building blocks were designed for the proposed building at a distance of 10 m from all sides except the North, to ensure that the obstacle angles would not exceed 70° as required in the Egyptian code [5]. The selected colors for all interior walls, the inner sides of the external walls and ceilings were light according to the Egyptian code requirements. Windows areas were designed to exceed the minimum required for the natural lighting, as the WWR was 15% of the service spaces and 20% of the living spaces. The selected glass type (single transparent with 3.2 mm thickness) was selected to achieve a light transmittance coefficient of 0.9 to exceed the required in the code (the minimum = 0.45) [Researcher using Ref. [24]]. The outer glasses frame was selected to be aluminum with thermal insulation. The thermal transmittance (U-value) of the used glasses and frames were identified from the Egyptian code tables.

Artificial lighting properties: fluorescent lamps were used in the model as recommended in the Egyptian code with the acceptable properties levels. The designed electrical lighting power density (W/m²⁾ complies with the global amounts in the code (bedrooms = 10, Living rooms and Receptions = 19, bathrooms = 14, Kitchens = 11, corridors and stairs = 13). The intensity of the lighting was also designed according to the average limit (Bedrooms = 75, guest rooms = 300, living rooms = 300, bathrooms = 150, kitchens = 200, corridors and stairs = 150) [Researcher using Ref. [24]].

Second proposed building model

Represents: an inefficient energy consumption building in Egypt, where it is beneath the Egyptian code requirements.

Surrounding environment characteristics: similar to the first proposed model.

Building formation: similar to the first proposed model in the interior and exterior form and the cooling zones distribution.

Thermal properties of the opaque parts in the building envelope: overall thermal resistance R-values were selected non-corresponded with the chosen climatic region requirements, as it was reduced below the minimum thermal resistance required, for western walls = 0.67 m² °C/W, eastern, southern and northern walls = 0.54 m² °C/W and for the roof = 0.97 m² °C/W [Researcher using Ref. [24]].

External shading properties used for the openings: all shading devices were canceled for that model. The WWR was chosen to be 45% for bed and living rooms, 30% for kitchens and bathrooms (the code requires that WWR do not exceed 30% for any façade except the northern, and the R-value of the openings (except the northern) shall not be less than 0.4 m² °C/W for the non-air-conditioned buildings) [5]. The used glass type for the openings did not verify the required as it exceeds the maximum value represented in the code, SHGC = 0.86. [Researcher using Ref. [24]].

Natural ventilation characteristics: the natural ventilation was chosen to be 1 L/S/person for all building spaces, thus it was beneath the minimum required in the Egyptian code. [Researcher using Ref. [24]].

Water heating system characteristics: gas-heating system works with a capacity greater than 38 L storage and 50% efficiency which is beneath the minimum in the code. [Researcher using Ref. [24]].

Natural lighting properties: Three building blocks were designed next to the proposed building in exception with the northern façade, the blocks were put at a distance of 4 m that led to increase the obstacle angle above 70° and affected the natural lighting in the building spaces. The internal surfaces color of various spaces was chosen to be dark brown. [Researcher using Ref. [24]].

Artificial lighting properties: the characteristics of electrical lighting power density for all spaces = 20 W/m², and thus beyond the maximum values in the Egyptian code. [Researcher using Ref. [24]].

Third proposed building model

Represents: the minimum acceptable requirements in the Egyptian code.

Surrounding environment characteristics: similar to the first proposed model.

Building formation: similar to the first proposed model in the interior and exterior form and the cooling zones distribution.

Thermal properties of the opaque parts in the building envelope: overall thermal resistance R-values were selected to be the minimum requirements in accordance with the climatic region. For the ceiling = 2.7 m²m² °C/W, northern walls = 0.55 m² °C/W, eastern and western walls = 0.92 m² °C/W and the southern walls = 0.67 m² °C/W. The interior court walls were being treated similarly to the northern walls. Previous thermal resistance values were entered the program through the used building and heat insulating materials characteristics depending on the used cross-section dimensions [Researcher using Ref. [24]].

External shading properties used for the openings: similar to the first proposed model.

Natural ventilation characteristics: the selected natural ventilation characteristics in different spaces were the minimum required in the Egyptian Code, living and bedrooms = 3 L/S/person, kitchens and bathrooms = 14 L/S/person [Researcher using Ref. [24]].

Water heating system characteristics: gas-heating system works with a capacity greater than 38 L storage and the minimum accepted heating efficiency in the Egyptian code which is 85%, at a 60 °C control degree [Researcher using Ref. [24]].

Natural lighting properties: three building blocks were designed next to the proposed building at a distance of 8 m except the northern façade, to ensure that the obstacle angles were above 70° from all façades as required in the code. Light colors were chosen for the interior walls, the inner side of the external walls and the ceilings in accordance with the code. The WWR was set as the minimum required = 10% of the outer wall spaces of the services, and 15% of the living spaces [Researcher using Ref. [24]]. Glass type and outer frames were chosen similar to the first proposed building model.

Artificial lighting properties: the electric lighting power density was set similar to the first proposed building model, the lighting intensity was set in accordance to the minimum limit in the Egyptian code (Bedrooms = 50, guest rooms = 200, living rooms = 200, bathrooms = 100, kitchens = 100, corridors and stairs = 100) [Researcher using Ref. [24]].

Building models used for assessment comparison

In the following, the characteristics of the baseline building models of the previous three proposed building models for the EA1, Ene1, Ene-1 items included in the LEED, BREEAM and Green Star methods consecutively are represented.

Base buildings designed for the proposed models according to ASHRAE

Twelve models were designed in accordance with Appendix G in ANSI ASHRAE/IESNA Standards (the 2007 edition is the latest version for low-rise residential buildings), four for each proposed model with a different rotation angle (0°, 90°, 180°, 270°) [Researcher using Ref. [14,15,25]].

Surrounding environment characteristics: similar to the proposed models [25].

Building formation: similar to the proposed models taking in consider that the used glasses are on the same surface of the exterior walls and roof [Researcher using Ref. [25]].

Thermal properties of the opaque parts in the building envelope: According to the climatic classification of different countries in ASHRAE/ANSI Standards, which classifies Egypt within the “2a area” which represents the hot, dry climate. The maximum thermal transition values (U-values) of different components of the exterior building envelope were chosen to comply with the standards maximum values, where the U-value of the roof = 0.048 W/m² °C, for walls = 0.123 W/m² °C, for vertical openings = 0.75 W/m² °C and for floors = 0.87 W/m² °C. The minimum R-values can be inferred from the equation: R-value = 1/U-value, taking in consider not changing the different components thickness for the building models [Researcher using Ref. [25]].

External shading properties used for the openings: The glass type was chosen according to ASHRAE/ANSI Standards classification area that Egypt belong to, SHGC = 0.25 for vertical openings of all directions. Base Buildings should be designed without internal or external shading devices, therefore, the used louvers in the proposed models have been removed. Base Buildings are required to be designed according to the main directions (North-East–West-South), which was being already considered for all proposed models. For each proposed model four base buildings are designed according to 0°, 90°, 180°, 270° degrees, to avoid the effect of buildings self-shading, the average of these models results are then used in the calculations [Researcher using Ref. [25]].

Natural ventilation characteristics: should be similar to the proposed building models if they are not less than the minimum required rates, so the second proposed building model was adjusted to the minimum required ventilation properties for residential spaces in ASHRAE/ANSI Standards [Researcher using Ref. [25]].

Water heating system characteristics: water heating efficiency values should be set similar to the proposed buildings if they are not less than the percentage included in ASHRAE/ANSI Standards tables, which is according to the used system type in the proposed building models = 80% [Researcher using Ref. [25]], therefore, it was adjusted for the second proposed building model to become 80% not 50%.

Natural lighting properties: base buildings should be designed without any external obstacles, so the surrounding buildings were removed. The WWR vales should be similar to the proposed building models when not exceeding 40% for each façade, 5% of the total flat roof area for ceiling windows [25]. Thus, the first and third models are not changed, the second building model was adjacent to reduce the building opening area until 40% for each façade. The base building models are required to have a roof albedo of 0.3 [25], so the roof finishing materials were changed to comply with that requirement, the old aged concrete with an albedo of 0.2–0.3 [Researcher using Ref. [18]] was chosen.

Artificial lighting properties: should be divided by the same division in the proposed building models with the same properties. The electric power for lighting was determined according to the minimum required density in ASHRAE/ANSI Standard, which are in the dining area = 22.8 W/m², stairs = 6.5 W/m², and other residential spaces = 10.86 W/m² [Researcher using Ref. [25]].

Reference buildings designed for the proposed models according to NCM

Three reference building models were designed according to NCM part L1A – which is used for new residential buildings -, each of them associated with a proposed building model (noting that the used regulations are related to the United Kingdom, as BREEAM does not include any suggested regulations for non-European countries unless asking and getting an international version from BRE) [13,16].

Surrounding environment characteristics: similar to the proposed models [16].

Building formation: similar to the proposed models with the same walls, roof and floors thickness.

Thermal properties of the opaque parts in the building envelope: U-values were consistent with those identified in NCM guide values, U-values for walls = 0.3 W/m² °C, for floors = 0.25 W/m² °C, for roof = 0.2 W/m² °C and for openings = 2 W/m² °C. Therefore, R-values can be calculated for different building parts [Researcher using Ref. [16]].

External shading properties used for the openings: Reference buildings should be designed without any internal or external shading devices [16]. Therefore, they were removed.

Natural ventilation characteristics: Total air permeability must not be less than 10 m³/(h × m²).

At 50 Pascal [16], it relies on the air changing rate (ach) at 50 Pa according to the building form, and for many purposes they may be considered similar [26]. In the F section in NCM – which relates to the ventilation requirements – the Air Change per hour should not be less than 4 ach for all residential spaces except bathrooms and kitchens, as the air should be directly thrown out of the building, and the total building ventilation rate should be 21 L/S (for the residential units of three bedrooms and four occupants). For all bathrooms and kitchens an external ventilation is required, whether the ventilation was continuous or intermittent, and the ventilation rate for kitchens should not be less than 13 L/S for continues ventilation and 30 for the intermittent, and the ventilation rate for the bathrooms should not be less than 8 L/S for continues ventilation and 15 for the intermittent. For the Reference building it is required to control moisture not to exceed 70% for more than two hours, 90% for more than an hour during any of the 12 h in summer, therefore, the point of return for controlling moisture was determined at 70% [Researcher using Ref. [27]].

Water heating system characteristics: Water heating system characteristics should be a gas-heating with a water heating efficiency not less than 90%, thus, the value in the second proposed building model was adjusted [Researcher using Ref. [16]].

Natural lighting properties: Natural lighting properties should be designed with the same shading effect of neighboring buildings and other geographical terrain in the proposed building models [16]. Openings area was calculated according to the way of opening. The area of sliding, outstanding or axial (that open with an angle of 30° or more) windows should be calculated as: the opening height × its width not less than 1/20 of the room floor space. For outstanding or axial windows that open with an angle less than 30° the area is calculated as: the opening height × its width not less than 1/10 of the room floor space. If the room has more than an operable window the area of all opened parts can be added to others to get the required ratio according to the largest opening angle in the room, and for external doors: the height × width for the opened parts should not be least than 1/20 of the floor area of the room [27]. In the proposed models it was considered that all the used windows are either sliding or axial with 30° opening angle, therefore, all openings area was designed to represent 1/20 of the floor area for different spaces. [Researcher].

Artificial lighting properties: Artificial lighting properties should be designed so the lighting areas are divided similarly to the proposed building models. The electrical lighting power density depends on the room activity and not less than the required for different activities [16].

Base buildings designed for the proposed models according to NABERS

Three base building models were designed according to the NABERS, each of them associated with a proposed building model.

Surrounding environment characteristics: similar to the proposed models [17].

Building formation: similar to the proposed models, considering that in case of non-availability of information about occupancy density, then 1/15 m² should be used, and the used devices loads are11 W/m² divided over different spaces [Researcher using Ref. [17]].

Thermal properties of the opaque parts in the building envelope: similar to proposed models [17].

External shading properties used for the openings: similar to the proposed models, noting that the movable shading devices should be designed movable in the base buildings [17].

Natural ventilation characteristics: similar to the proposed models [17].

Water heating system characteristics: similar to the proposed models considering that the need of water = 2 KW h/m² depending on the Net Lettable Area (NLA) of the building besides any loss in the system [Researcher using Ref. [17]].

Natural lighting properties: Generally, similar to the proposed models, the external shading from adjacent buildings and deciduous trees must be simulated with different permeability over time [17]. So, the adjacent buildings in the proposed models were kept in the base building models.

Artificial lighting properties: Lighting loads should be designed to be 12 W/m². Night lighting must be simulated [17], but it was assumed there was no night lighting in the proposed models.

Results of the main energy efficiency items of global methods when used in Egypt

Table 4 represents the results of the simulated proposed and base building models which were used to identify the energy efficiency of the different proposed building models according to the chosen assessment methods (LEED, BREEAM and Green Star) [Researcher using the Design Builder simulation program].

Table 4 Simulation Results for the Proposed and Base Buildings Models [Researcher].

Model		Annual energy consumption		Emission of carbon dioxide (kg CO2 × 10^3)
		Electricity (MW h)	Gas (MW h)
First proposed building model (in compliance with the requirements of the Egyptian code)		199.42	57.77	147.87
Second proposed building model (non-compliance with the requirements of the Egyptian code)		278.33	67.11	203.74
Third proposed building model (minimum requirements of the Egyptian code)		204.23	65.29	152.6
Base building models according to ASHRAE requirements for the first proposed building model	Rotation angle 0°	195.62	45.79	142.93
	Rotation angle 90°	196.20	45.95	143.36
	Rotation angle 180°	197.12	45.31	143.86
	Rotation angle 270°	195.25	45.06	142.53
Base building models according to ASHRAE requirements for the second proposed building model	Rotation angle 0°	217.06	48.38	158.12
	Rotation angle 90°	217.32	48.63	158.35
	Rotation angle 180°	219.43	47.63	159.61
	Rotation angle 270°	218.20	47.08	158.65
Base building models according to ASHRAE requirements for the third proposed building model	Rotation angle 0°	204.16	46.30	148.88
	Rotation angle 90°	204.71	46.39	149.27
	Rotation angle 180°	204.97	45.87	149.35
	Rotation angle 270°	204.14	45.75	148.76
Reference building model according to NCM guide requirements for the first proposed building model		260.92	65.96	191.59
Reference building model according to NCM guide requirements for the second proposed building model		258.64	65.46	189.93
Reference building model according to NCM guide requirements for the third proposed building model		262.44	66.99	192.83
Base building model according to NABERS requirements for the first proposed building model		180.90	60.92	135.80
Base building model according to NABERS requirements for the second proposed building model		209.08	78.25	158.48
Base building model according to NABERS requirements for the third proposed building model		179.77	68.55	136.51

Each chosen environmental assessment method of buildings (LEED, BREEAM and Green Star) depends on different measurement approaches to reach their assessment results of energy efficiency main items, as discussed before. From the following table, the different energy efficiency assessment results according to these different methods were represented.

Assessment results for the proposed building models according to LEED

Each proposed model has a four base building models resulted due to their different rotation angles – to unify the self-shadow effect of the building -, the four base buildings results of each proposed model were averaged to be used in the calculations. The used calculations mainly calculate the annual energy cost for the proposed building operation in exchange of the base buildings by using the actual purchase rates of energy or average energy prices. The purchase price of electric power in Egypt is not a constant value, it changes through different energy consumption levels, where it is at a very low price for the first level while at a height price for the sixth level, it changes over time too, so there is a lack of a proper expression for the annual energy consumption cost in Egypt, especially when comparing two buildings with a close energy consumption, but a significant cost difference only because one of them moved from one purchase price level to another, and there is a difficulty to determine an average energy cost over the different consumption levels [28]. Therefore, the equation associated with the energy cost – which was previously mentioned in the paper – was excluded and the equation associated with the annual energy consumption was preferred, which is:

Improvement in energy efficiency percentage = 100 × (annual energy consumption of the base building – annual energy consumption of the proposed building)/annual energy consumption of the base building [6,12,15].

By applying the previous equation in Table 5, it was noted that all proposed building models have not been classified according to LEED for the EA1 item (zero points from maximum 18 points).

Table 5 Achieved scores for the three proposed buildings when applying the formula used to assess the EA1 item in LEED method [Researcher].

Proposed model	Results from applying the evaluation formula	Assessment score for EA1 item in LEED
First	241.57/(257.19–241.57) × 100 = (−6.5)% < 6%	0 points
Second	265.93/(345.44–265.93) × 100 = (−29.9) % < 6%	0 points
Third	250.57/(269.52–250.57) × 100 = (−7.5)% < 6%	0 points

Assessment results for the proposed building models according to BREEAM

The measurement approach used for assessing the main item of energy efficiency of buildings in BREEAM depends on comparing the annual CO₂ emission rate (in kilograms resulted from operating the building) among the proposed building models and their reference models (designed according to NCM – part L1A for residential buildings-) to get the ratio among them, then using that ratio through the carbon dioxide emission index taken from the energy performance certificate (EPC) to identify the proposed buildings energy efficiency, which classify buildings from A to G, where A represents a high-efficiency and G represent the least efficiency [22], The equation that is used to determine the energy efficiency according to EPC is as follows:

EPC Classification = 50 × (Dwelling Emission Rate (DER)/Standard Emission Rate (SER)).

Knowing that SER for buildings that are heated and ventilated naturally = Reference Emission Rate (RER) × 0.765 [8,29].

By applying the previous equation, it was noted from Table 6 that all proposed building models have been classified according to BREEAM for the Ene1 item (one or two points from maximum 12 points [13]).

Table 6 Achieved scores for the three proposed buildings when applying the formula used to assess the Ene1 item in BREEAM method [Researcher].

Proposed model	Results from applying the evaluation formula	Assessment score for Ene1 item in BREEAM
First	50.44	2 points
Second	54.4	1 point
Third	51.7	2 points

Assessment results for the proposed building models according to Green Star

The measurement approach used for the main item of energy efficiency of buildings in Green Star depends on designing a base building model according to NABERS, then simulate it to identify its total annual electricity and gas consumptions to use them through the energy calculator, noting that other data are required in the calculator such as the Net Lettable Area and the building region [29]. The calculator calculates the expected greenhouse gas emission by multiplying the obtained energy consumption by the greenhouse gas emission factors, according to the project’s site, and it should be noted that these factors vary among different regions and energy types [5,10]. The energy calculator compares each emission area unit of the proposed building with the standard emission for this unit, each 5% of emission reduction award points until 20 points when it reaches 100% reduction. There is a table in Green Star to classify the energy efficiency according to the calculator results to identify the awarded scores [4,5]. It should be noted that the used factors are Australian National Greenhouse Accounts (NGA) [10], therefore, the use of these figures over the world may give inaccurate results, therefore, the Egyptian factors were used in the calculator calculations which are 0.5 kg CO²-e/kWh for electricity, and 0.61 kg CO²-e/kWh for gas [22,23].

Knowing that the (NLA) of the building = 1200 (300 × 4) m², Table 7 shows the results of applying the energy calculator for all proposed building models, noting that the first and third proposed buildings were classified according to the Green Star method for the Ene-1 item. They achieved three and one point consecutively from maximum 20 points in that version of Green Star.

Table 7 Achieved scores for the three proposed buildings when using the energy calculator to assess the Ene-1 item in the Green Star method [Researcher].

Proposed model	Greenhouse gas emissions (kg CO^2-e/m^2/annual)			Assessment score for Ene-1 item in Green Star
	From the total annual electric consumption	From the total annual gas consumption	Total
First	71	10.5	81.5	3 points
Second	82	30.7	112.7	0 points
Third	70.5	26.9	97.4	1 point

Conclusion, results and recommendations

Three proposed buildings were presented in the research paper to express an energy efficiency ruler according to the Egyptian energy code, as each of them reflects a status of compliance, non-compliance and minimum requirements of the code. These buildings were used to study how close are the energy efficiency results when using one of the famous assessment methods in Egypt (LEED, BREEAM and Green Star) with the Egyptian code requirements – that represents the utmost suitable requirements for the Egyptian buildings among different climatic zones –. For the LEED method (that depends mainly on an item that measures the % of annual energy cost improvement, according to the Performance Rating Method (PRM) through a relation between the proposed building model and its base buildings that designed according to ASHRAE/ANSI Standards) the three proposed buildings were not classified even with the existence of a classified regions with different properties to suit different countries. For the BREEAM method (that depends mainly on an item that measures the CO₂ emissions reduction, according to Energy Performance Certificate (EPC) through a relation between the proposed building model and its reference building designed according to NCM requirements) the three proposed buildings were succeeded to pass the minimum limit. For the Green Star method (that depends mainly on an item that measures the expected greenhouse gas emissions (kg CO₂/m²/year) by using an energy calculator for a base building that is designed according to NABERS requirements) the non-compliance proposed building was not classified, while the others were classified, and the proposed building with the minimum requirements was given 1 point score, noting that the greenhouse gas emission factors used in the calculations were the Egyptian values. Therefore, LEED and BREEAM methods were not compatible with the intended assessment of the energy efficiency requirements in Egypt, while Green Star was the most compatible, then it can be preferred to be used until the Egyptian method GPRS can rival other methods.

Using a method that already depends on the Egyptian codes which is GPRS logically helps the most credible and accurate results for that field. From previous, the following can be concluded the following:

•	The assessment results of the famous assessment methods of buildings do not necessarily reflect the proper evaluation results when used out of their producing countries, thus, they may lose their main environmental purpose and be used only as a commercial tool.

•	The recent spread of LEED in the Egyptian building sector must be reduced in exchange with the Egyptian method, and when it is a must to use a non-local method, Green Star is the most suitable one to express the energy efficiency according to the Egyptian requirements.

Therefore,

•	The Egyptian government is recommended to put a series of stimulating ways to encourage the use of the Egyptian assessment method of buildings until imposing it within the building permits after obtaining an appropriate guidance and feedback.

•	The Egyptian Green Building Council is recommended to raise the awareness of the Egyptian assessment method of buildings to help its presence in the Egyptian market and competitive with other methods.

•	The Egyptian Green Building Council is recommended to provide rapidly specialized assessors whom are trained on using the Egyptian assessment method of buildings.

Conflict of interest

None declared.

Notes

Peer review under responsibility of Housing and Building National Research Center.