Introduction

In a given city, one of the major sectors that contributes to the environment’s pollution is residential buildings. Residential buildings are built-up constructions that are huge in terms of numbers and, as a result, energy consumption. According to Huovila [1], 30 to 40% of primary energy use and greenhouse gases (GHG) emissions worldwide have proven to be the responsibility of buildings. Later, according to Hammond et al. [2], the building sector contributed to 44.6% of all GHG emissions due to a 47.6% of all energy use in the U.S. Recently, it was found that in the U.S., only the construction sector (commercial, industrial, and residential) is responsible for 63% of the total energy consumption annually [3]; globally, things might be even worse. This shows the great growth of pollution graphs caused by the growing existing residential buildings sector.

Worldwide, numerous ways were sought to enable green buildings (or environmentally friendly buildings) to occur. Some have updated and enhanced their building codes to include requirements that will ensure greener building stock. While others had organizations, such as Green Building Councils (GBCs), which were formed to revolutionize the construction industry itself [4].

Literature review

This section will study the lost history of the most widely adopted green rating tools. The reason they are considered in this paper’s literature review is that their founding fathers had to think in the same way the author of this thesis have to think in order to study the green Egyptian market, understand its weaknesses, and suggest the best solutions that are practical enough to work with its residents. It is also worth noting that most of the data represented in this section is referenced to Rochelle Ade and Michael Rehm [5] who had to gather this data about BREEAM (Building Research Establishment Environmental Assessment Method) and LEED’s (leadership in energy and environmental design) histories through personal communications with their founding fathers.

BREEAM

BREEAM had suffered from some technical challenges and was developed internally, under a constraint timeframe. For example, it credited a large number of points for energy-efficient systems rather than final energy performance. This means that a naturally ventilated building could never achieve as many points as a worse performing but well-designed air-conditioned building. It has not been possible to locate an original list of credits for BREEAM for Offices v1 as there were no category or credit weightings [5].

As for the residential market, the BRE created a version of BREEAM for New Homes, launched in 1991. New Homes was claimed by Howard (one of the founding fathers) that it had failed twice before the residential rating tool (Eco Homes) got some adoption in the market [5]. The reason behind its failures was, according to Howard, due to its complexity and expensive demands for homebuilders to accept and adopt.

The ‘Founding Fathers’ have some conclusions about why the various BRE residential schemes have failed to gain much market attention. [6] stated that in order for adoption to occur, green building rating tools need to be cost-effective. The picture is even worse for the existing building market. Since the existing building market is 100 times larger than the new building market, it needs a much larger budget and marketing effort than GBCs can afford, concluded Howard [6].

LEED

After the launch of BREEAM, the United States Green Building Council (USGBC) developed the LEED rating tool [5]. However, unlike BRE, the USGBC is a non-profit, membership-based organization rooted in the building industry [4].

In the context of LEED building up, it is worth mentioning that LEED version 1 was a very simple rating tool that was composed of listed credits in alphabetical order and no weightings. As a remark, this rating tool was not called LEED. It was the Green Building Rating System.

By the year 2000, Version 2 of LEED had been launched, introducing a major change. LEED introduced weightings for its credits. Most credits in version 1 were only equivalent to 1 point, with only a few credits being given more energy efficiency. For LEED version 2, the USGBC conducted a weightings survey with the LEED Steering Committee.

For instance, LEED and BREEAM have gone through the same process of continuous renewal and improvement. Like BREEAM, Howard believes that the residential market is too large for LEED Homes to transform and will only succeed if mandated by government [5]. Howard further stated that any rating system needed to be easy to use and cost effective. In addition, having a clear value proposition for the building owners and tenants, who have different interests and concerns [5].

Methodology

The founding fathers of BREEAM and LEED stated that the main problem with applying green solutions is that they are:

  1. 1.

    Having high initial costs.

  2. 2.

    Complicated to apply. This happens in two ways:

  3. 1.

    No trained workers to apply the solutions.

  4. 2.

    Most solutions are case sensitive.

  5. 3.

    The existing market is too huge which is worsening the first two problems further.

In order to resolve the three problems mentioned above faced by the green market, a true average of the specifications for a typical Egyptian residential building is required. Consequently, a case study will be conducted on a hypothetical residential Egyptian building with features and energy consumptions gathered through a questionnaire, just like BREEAM and LEED did when they had to weight their credits. The questionnaire will also help gather information about the Egyptian residents’ tendency to turn their existing buildings green, as well as their current understanding of the term "green building". The study will introduce two methods of solution: the first is harvesting a more efficient energy resource and using equations to estimate the payback period required for the initial costs to be compensated. The second method is to develop ideas suggested by other studies with similar climates or goals in order to avoid the failure of reapplying the same solutions in different places. On that note, the suggested solution shall cover: windows orientation and window-to-wall ratio (WWR).

Questionnaire results

Through the questionnaire results, a hypothetical case study could be extracted. It can be concluded that an average Egyptian home:

  • Has no solar panels already installed.

  • Is classified as an apartment and not a villa or other residential form.

  • Aims to set-point temperatures of 21.342 °C.

  • Turns on its air conditioners (AC) for 7.6525 h/day in summer and 0.9075 h/day in winter while it owns around 1.63 AC per home.

  • Turns on its air heaters in winter for 1.511 h/day while it owns around 0.606 ≈ 1 air heater.

  • Owns more electricity-based water heaters than gas-based in general.

  • Pays a monthly electricity bill of around 702.75 EGP.

However, the questionnaire’s main purpose is not only to create a hypothetical Egyptian home but also to read the typical Egyptian mindset as well as to test their information about green concepts and their tendencies towards their applications. The purpose of these goals is to help this study and future researchers inject green ideals into Egyptian society. In order to do that, the current Egyptian market and mindset should be investigated. Consequently, the current Egyptian mindset was found to:

  • Need to be more familiarized by the term “Green Building”.

  • Believe that they should contribute financially to the green cause.

  • Believe that the financial contribution in saving the environment is the responsibility of the government as well as individuals.

  • Would pay higher initial construction costs with low operational and maintenance costs (referred to as green building).

  • Not ready to indulge in the green cause given the financial chance. It was clear that the people of Egypt accepted the raw green concepts yet withdrawn when faced the actual difference between going green and staying conventional.

  • Not willing to wait for the actual required period of payback when it comes to constructing a green building.

  • Not willing to wait for the actual required period of payback when it comes to retrofitting their buildings into green; however, it was shown that they were encouraged to retrofit rather than to build green from the beginning.

  • Not comfortable with their monthly electricity bill, and it is affecting their consumption rate greatly.

  • Not affected by their water bill consumption-wise; even though half of the Egyptians find it too expensive.

Suggested solutions

In this section, two solutions will be discussed to be applied to the hypothetical Egyptian home drawn from the questionnaire results. The first solution is a retrofitting one. Solar panels are primarily chosen due to their popularity as a green solution in Egypt and around the world. The other solution is a renovation one. Windows orientation and WWR, are solutions that are theorized by the author to be relatively cheap, easy to apply, and can work on a large scale.

Solar panels

For the solar panels needed and according to the questionnaire results, an average electricity bill for a typical Egyptian home would be around 702 L.E. (22.76$); however, in order to avoid any errors, a design on a 750 L.E. (24.32$) bill will be taken instead. According to the Egyptian ministry of electricity, 1 kWh is sold for the residential sector for 1.28 L.E. (0.04$) As a result, a 750 L.E. bill would mean around 586 kWh (750 L.E./1.28) per month. However, the design will be calculated using 1200 kWh as the consumption rate instead. This is due to the fact that, usually, these buildings are prone to adding more devices and machines in the future, which will change the average energy usage. In addition, one of the main targets of installing solar panels is to profit from them. As a result, an on-grid system will be used to ensure selling any additional collected energy back to the government, shortening the payback period, dodging the use of storage batteries, which would have added tremendously to the initial costs, and enhancing the general performance of the system by eliminating any chances of electricity’s cutting off due to any solar panels’ system failure.

In order to calculate the needed number of panels, it is first necessary to choose the type of panel, multiply its output watts by the average number of working hours per day of the panel, multiply the result by 30 to get the number of watts made per month per one panel, divide that number by 1000 to change the unit from watts to kilowatt-hours, and finally divide our needed design kwh by the result.

  • Panels type chosen (550 W) * 5 (working hours per day. This number is standard by country/region) (Egypt’s working hours per day according to “Green Tech”. One of Egypt’s most prominent companies in the field) = 2750 watts/day per one panel

  • 2750 watts/day per one panel * 30 (days per month) = 82,500 watts/month per one panel ÷ 1000 (units change from watts to kilowatt) = 82.5 kWh per one panel.

  • 1200 kWh (target consumption rate) ÷ 82.5 kWh per one panel = 14.55 ≈ 15 panel.

One of the major problems faced while installing solar panels would be the space where they could be installed. To calculate the total size needed for the whole station, a kWh-to-meter relationship is usually introduced by the solar panel companies in order to speed up the calculation process of the needed installation space. According to Green Tech, each 1 kWh of the 550 W panel occupies around 10 m2 of space. Then:

  • 550 W * 15 Panels = 8250 W ÷ 1000 (units change to kWh) = 8.25 kWh.

  • 8.25 kWh * 10 (m2 per 1 kWh) = 82.5 m2 of space.

In which case most buildings will have good roof access in case of a villa while it will not be the case for other long residential buildings with multiple stories. Hence, a specialized field might be required depending on the number of stories included and that which will add to the total needed number of panels as well.

As per the needed weight, a 550 W panel is around 29 kg per panel. Multiplying that by the chosen number of panels (15 panels per a standard Egyptian home):

  • 29 kg * 15 = 435 kg per station.

The total price needed in order to buy, transport, and install this whole on-grid system, consisting of a total of 15 (550 W) panels, is around 142,105 LE (4607.8 $), according to Green Tech.

As shown in Table 1. The owner will be selling 940.83 L.E. (30.5$) per month while buying 337.536 L.E. (10.9$) In consequence, this system will profit:

  • 940.83–337.536 = 603.294 L.E. (19.5$) per month.

Table 1 Calculation of Egypt’s total consumptions and productions per month as well as bought and sold electricity while using solar panels
Full size table

In order to calculate the payback period, the total savings will need to be calculated. During the day, 322.3 kWh are consumed and offered by the system. Saving the owner from paying for these consumptions as a result. Converting these consumptions into the money they had saved:

  • 322.3 kWh * 1.28 L.E. (Egypt’s price per 1 kWh) = 412.544

  • L.E. ≈ 413 L.E. (13.39$) are saved monthly.

Adding the profit per month to the monthly savings:

  • 603.294 + 413 = 1016.3 L.E. (32.95$)

Multiplying that by 12 months in order to get the annual savings:

  • 1016 * 12 = 12,192 L.E./year. (395.33$)

Finally, the payback period shall be calculated by dividing the total system’s initial price by its annual profit:

  • 142,105 L.E. ÷ 12,192 = 11.66 years.

Since these calculations were based on the worst-case scenario, it is concluded that it would take no more than 12 years to payback for a whole solar system station in a typical Egyptian home. According to the questionnaire results, the number of Egyptians who would accept a payback period of 9 to 12 years was 9.8% of the total participants. While 11.6% accepted that it is okay to go beyond the 12 years. This shows that no more than 21.4% of Egyptians might get close to accepting the 12-year payback period as a retrofitting solution. In addition, most multi-story buildings in Egypt do not have enough spaces on their roofs or around them in order to support complete stations for every apartment. In addition, for every apartment to require 435 kg of weight, the existing roofs may not be able to sustain this new dead load as it was not in their initial design. Finally, it is concluded that the installation of solar panels as a green solution for typical Egyptian homes is not feasible in general but worth checking in case the client happens to be among the 21.4% and is able to have enough space that can carry the system.

It should be noted that these calculations were first calculated personally with the help of Eng. Raouf Mourad, a mechatronics engineer who is preparing his master’s degree in solar panels in Egypt. The results were later rechecked verbally with a Green Tech technician on December 21, 2022. Later on, other companies, like Solarizegypt and Onasolar, were contacted to further validate the results of this section, and it was found that most of those companies refused to make an offer for a system of 750 L.E. average monthly electricity bill while preserving their rights to showcase their company’s calculations. The reason stated was that such systems would be non-feasible to begin with. Other companies, like Solar Solutions, agreed to make an offer but for the system’s exact electricity bill of 750 L.E. in order to minimize the initial cost; however, according to their calculations, the same number of years to payback was needed and they required the same price offered by Green Tech despite the fact that their system was made up of only eight 550 W panels. On the other hand, Solar Solutions made its offer 5 months later than Green Tech’s.

Window-to-wall ratio and orientation

In buildings, energy performance highly depends on their building envelope, which is regularly broken by windows and doors since they have lower insulation levels in comparison to walls. For doors, suggested solutions are limited since they are strictly needed where they exist, but for windows things might be different. Window types have already been fetched out in many studies, but their numbers, sizes, and orientations have not. According to Lee et al. [7], windows are responsible for about 20–40% of energy loss, which is why it is important to tackle every aspect of them. In another study, a fully glazed façade placed in hot, arid areas was responsible for 45% of the building’s cooling load [7].

In a study made by Alghoul et al. [7] in Tripoli, Libya, which is a coastal city on the Mediterranean Sea, the cooling and heating energy consumptions of a typical office (4*4*4) m were tested. The author applied different Window-to-Wall Ratios (WWRs) (from 0 up to 0.9) on all cardinal and inter-cardinal directions in order to determine the best window orientation and ratio among the total of 16 cases (8 orientations tested for heating consumption and the same 8 for cooling consumption).

For instance, the author claims that the increase in WWR is important to reduce heating energy consumption for north, northeast, and northwest orientations. This makes sense in terms of WWR, as windows act as a weak point in the building’s envelope that lets in sunlight and filters all the other soothing factors out, like wind, so the more windows there are, the warmer it feels inside the building. For window orientation, it is expected that the best orientations for windows to feel warmer would be east and west (facing the sun); however, according to what is shown in this study, south has consumed zero heating energy for almost all ratios. It can be concluded that since “south” is the only orientation away from the blowing winds coming from the Mediterranean Sea in the north, it had recorded the most heated side in the building despite having the sun mostly in the eastern and western parts of the building. Figure 1 shows these results and finalizes its results by saying that having windows installed in the southern part of the building in a coastal area where the sea is located at the north is the best orientation there is, giving no eye to the number of windows needed or WWRs. Make note that the best side in this example was south for heat savings and not east or west for the sole reason of having high winds coming from the northern Mediterranean Sea.

Fig. 1
figure 1

Annual heating consumption for different WWR and orientations. Al Ghoul et al. [7]. P. 5, Fig. 4

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As for Egypt’s main target, cooling energy consumption, the higher the WWR, the more cooling energy is required for all orientations. The author concluded that the increase in cooling load or consumption is related to the increase in direct solar load in addition to long-wave radiation from inside to outside. In general, according to the results shown in Fig. 2, windows in the southern orientation have shown the highest cooling energy consumption for all WWR, while windows in the northern orientation showed the best results with the least cooling energy in comparison. For the window ratios, a change in WWR from 0.1 to 0.9 for southwest orientation will increase the annual cooling energy from 52 to 210 kWh/m2. In other words, the load was quadrupled for south and southwest orientations, tripled for northeast and northwest, and increased by nearly 3.7 times for east and west orientations.

Fig. 2
figure 2

Annual cooling consumption for different WWR and orientations. Al Ghoul et al. [7]. P. 6, Fig. 5

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For the case in hand, it seems that the south could score the worst while the north scored the best results in cooling, while it is quite the opposite when it comes to heating. This proves that for a certain building, it has to be determined whether the general weather is tending to be cold or hot, and then windows have to be installed in the best orientation accordingly. As for the number of windows needed, again, it seems like the true answer to this question depends on whether cooling or heating is the actual target of placing the windows. In case the building needs to be cooled most of the time, as per this study’s needs, then perhaps having a WWR of 0.3/0.4 or less would be the best answer. While it will not make such a difference in the case of heating consumption as shown in Fig. 1 it is fair to note that these orientations might differ depending on the case studied. This is why the worst orientation for this case study happened to be south instead of east and west despite having Libya in a hot climate, which means avoiding the sun’s path would be the correct orientation; however, in this case, a Mediterranean Sea existed in the north, which changed the whole case for the orientations part and also proved that winds have a greater impact on heating and cooling the building than the sun does.

Conclusion

To sum up this paper’s solutions, it is clear from the questionnaire that one of the Egyptian people’s main problems is the high difference in the initial costs between going green and staying conventional. Therefore, cheap solutions are more than welcome in the field. The study’s first solution was to change the power source itself into a more economical one. Solar panels were the first solution introduced in the study but proved to be not as feasible as expected on a large scale. Due to their high initial costs and low purchase price per 1 kWh, solar panels had long payback periods, which made them a non-feasible solution for the Egyptians, according to the questionnaire provided.

Window-to-wall ratio, or WWR, and window orientation were handled altogether by one study that took place in the neighboring country of Libya. According to the mentioned study, if there is any wind, it has proven to have the upper hand when it comes to window orientation and not the sun. As for the WWR, the study found that the fewer the number of windows, the better the cooling energy consumption needed. Applying both solutions to Egypt, these case study results can be taken wholly as due to the fact that Libya falls under very close coordinates to Egypt’s. As a result, perfect window orientations would be towards the sea or high wind movements, as is common practice; however, the fewer the windows, the better the cooling energy consumption.

Recommendations

Due to the findings of this study, some recommendations are suggested for future researchers:

  • Solar panels in Egypt need to have better purchasing deals in order to be financially viable. According to the feasible study made in this paper, the problem of applying solar panels is mainly caused by the huge price of the solar panels offered by the companies versus the cheap purchasing price offered by the government for the electricity generated by the panels. Perhaps a better plan should be advised to resolve this issue.

  • According to the findings of the questionnaire, Egyptians seem to lean more towards paying in installments than in cash for the green cause. Researchers should test this methodology of resolution in the Egyptian market and question its feasibility.

  • Advising a plan to resolve the conflict of applying too many green solutions, which may affect the economy negatively since the old power sources are highly invested in and will stay in action. Perhaps it is too early to think about this issue, but a protective plan is always superior to a corrective one.