Staying Cool in a Warming Climate: Temperature, Electricity and Air Conditioning in Saudi Arabia

Article Staying Cool in A Warming Climate: Temperature, Electricity and Air Conditioning in Saudi Arabia

Nicholas Howarth 1,*, Natalia Odnoletkova 2, Thamir Alshehri 1 , Abdullah Almadani 1 , Alessandro Lanza 1 and Tadeusz Patzek 2

1 King Abdullah Petroleum Studies and Research Centre (KAPSARC), P.O. Box 88550, Riyadh 11672, Saudi Arabia; [email protected] (T.A.); [email protected] (A.A.); [email protected] (A.L.) 2 Ali I. Al-Naimi Petroleum Engineering Research Center, King Abdullah University of Science and Technology (KAUST) 4700, Thuwal 23955-6900, Saudi Arabia; [email protected] (N.O.); [email protected] (T.P.) * Correspondence: [email protected]; Tel.: +966-54-845-7171

Received: 26 November 2019; Accepted: 28 December 2019; Published: 3 January 2020

Abstract: As global temperatures warm and populations and incomes rise, the demand for cooling will soar, creating a positive feedback loop between global warming and electricity-related carbon dioxide (CO2) emissions. This study explores the relationship between temperature, electricity, air conditioning (AC) and CO2 emissions, and the sustainability of cooling in the Kingdom of Saudi Arabia. With the highest share of AC in household electricity consumption in the world and its already very hot summers warming by 3 ◦C in many areas over the last 40 years, Saudi Arabia provides an important case study of how the cooling challenge can be managed. Data from the European Centre for Medium-Range Weather Forecasts (ECMWF ERA5) is used to illustrate local warming trends (1979–2018) and show the relationship between temperature and power generation within a typical year using hourly data (2011–2015). Using annual data (2010–2018), we then show that since 2016 the rapid growth in the Kingdom’s electricity demand for AC and its associated CO2 emissions have plateaued. This suggests energy eﬃciency measures, higher electricity prices and a shift from the use of oil towards gas in the power sector are having a positive eﬀect on energy sustainability. We identify key policies and technologies that will be important for the sustainable use of cooling in Saudi Arabia and beyond.

Keywords: climate change; adaptation; mitigation; energy eﬃciency; electricity pricing

1. Introduction According to the International Energy Agency (IEA), over the next three decades, the use of air conditioners (ACs) is set to soar, becoming one of the top drivers of global electricity demand [1]. Global energy demand from ACs is expected to triple from around 2000 terrawatt-hours (TWh) today to 6200 TWh by 2050, adding the equivalent electrical capacity of the United States (U.S.), European Union (EU) and Japan combined. Between 2015 and 2018 alone, AC consumption in the world’s most 20 prosperous nations increased by around 400 TWh [2]. The IEA has identified this growing demand for air conditioners as one of the most critical blind spots in today’s energy debate [1]. The U.S. National Oceanic and Atmospheric Administration (NOAA) recently reported that Earth’s average temperature in July 2019 was about 1 degree Celsius (◦C) above its twentieth-century average, making it the warmest month on record. The previous five years were also the five warmest on record. Every 1 ◦C rise in the Earth’s average temperature is estimated to increase AC electrical

Climate 2020, 8, 4; doi:10.3390/cli8010004 www.mdpi.com/journal/climate Climate 2020, 8, 4 2 of 25 consumption by around 15% [2]. In developing countries, this rate of growth is expected to be greater, as higher incomes allow more consumers to purchase AC units. The focus of the climate policy community is often on average global temperature changes, such as the 1.5 ◦C or 2 ◦C target, which can lead to an underappreciation of local warming trends, especially in summer. For example, The European Centre for Medium-Range Weather Forecasts’ (ECMWF’s) dataset shows that areas in the Middle East and North Africa (MENA) region have already experienced average warming greater than 2 ◦C for July. It also shows that, in the last 10 years, regions in Australia, Africa, Europe and the Americas have experienced average July temperatures of between 1 ◦C to 2 ◦C higher than those from 1880–1900 [3]. In the Middle East and many other regions, average summer temperatures are also rising faster than yearly averages, which may lead to an underappreciation of the maximum temperatures that may be experienced in hotter months. Local trends in temperature rises in the hottest months of the year are likely to be more meaningful when planning for weather extremes locally than global or even local yearly averages. This highlights the need for research that explores warming trends at the city or regional level and the implications this has for AC as an adaptation measure to maximum summer temperatures. Three main factors drive the use of AC and its impact on electricity consumption: the area and number of rooms in a dwelling to be cooled, the thermostat or temperature setting and the number of hours the AC is used. The amount of cooling demanded is thus a function of temperature, AC unit efficiency, and other factors such as size and type of dwelling and subjective perceptions of comfort. Families in Saudi Arabia tend to live in relatively large villas with many AC units. Studies suggest that around 73% of people in the Kingdom use their air conditioners between 10 and 24 h a day throughout the year, with most people leaving them on non-stop from May through to September to counter the extremely hot summer conditions [4,5]. This paper provides a case study of how Saudi Arabia is managing the twin demands of adaptation to a hot and warming climate while grappling with the increasing demand for electricity from AC units and their associated carbon dioxide (CO2) emissions. It also seeks to provide insight on how Saudi Arabia can improve the sustainability of its AC use. The paper uses the latest ECMWF ERA5 high-resolution dataset [6] to illustrate the climatic warming trend for Saudi Arabia over a 40 year period. The seasonal relationship between temperature and electrical generation within a typical year (2015) is then assessed using hourly electricity generation data provided by the Saudi Electricity Company (SEC). Next, annual data on the contribution of cooling to electricity demand is used to explore trends in electrical consumption. The electricity CO2 profile is then analyzed using fuel input data. This provides the basis for an assessment of the policies that have been introduced in the last few years to improve sustainability and control the historically fast growth of CO2 emissions from the power sector and AC demand. This paper is set out in three parts. The first covers the literature and basic characteristics of temperature, AC and the sustainability of electricity demand in Saudi Arabia. This includes a review of the key measures the Kingdom has recently taken to control its historically fast-growing electricity demand, focusing on AC energy efficiency, electricity price increases and fuel mix decarbonization. To our knowledge, this study provides one of the first assessments of electricity and AC trends since this reform program significantly gathered pace in 2016. The second section is an empirical analysis covering (1) climatic warming trends over the last 40 years; (2) the relationship between temperature and electricity generation within a typical year; (3) trends in the contribution of AC to electricity demand; and (4) shifts in the fuel mix of electricity demand and associated CO2 emissions. Our results suggest that AC energy efficiency, higher consumer electricity prices and fuel mix changes have contributed to a stabilization of the historically rapid growth in electricity demand and CO2 emissions. Indeed, this stabilization of emissions in the power sector helped contribute to the first major fall in total CO2 emissions in the Kingdom’s history in 2018 (Figures A1 and A2 in AppendixA). Climate 2020, 8, 4 3 of 25

In the ﬁnal section, we discuss our results in light of previous studies and summarize the key areas to improve the sustainability of cooling identiﬁed in the paper.

2. Review of Past Work on Temperature, Air Conditioning and Sustainability in Saudi Arabia

2.1. Temperature Characteristics of Saudi Arabia and the Need for Cooling Hasanean and Almazroui [7] describe the scientific knowledge relating to the climate and climate change in Saudi Arabia as being scattered, incomplete and limited, highlighting the need for research in this area. Literature on the Arabian peninsula describes a wide spectrum of conditions, including the snows of the Asir Province, the intense humidity of the Arabian Gulf, the monsoon rains of the Qara mountains in Dhofar [8–10], and the scorching heat of the Rub Al Khali, the largest continuous expanse of desert in the world. Irregular, heavy rainstorms happen only a few days a year, with 80% of precipitation occurring during the wet season (November to May) and focused only in some areas. For building and energy modelling purposes, several studies have classified regions in the Kingdom according to air temperature, relative humidity, wind speed and solar radiation. Between three to five distinct climatic zones have been identified, ranging from hot dry desert conditions to hot humid maritime areas and cooler mountain zones in the south [11–14]. While already very hot, studies suggest that the climate in Saudi Arabia is getting hotter and extreme temperature events are becoming more frequent [15]. For example, Almazroui et al. [16] reported an increase in temperature of 0.65 ◦C per decade. Alghamdi and Harrington [17] point out that 1338 heatwave events were recorded over a recent 35-year period. They define heatwave events as two consecutive days with daily maximum temperatures equal to or higher than the 90th percentile of the monthly maximum of the decade in question, and with a daily minimum equal or higher than the 85th percentile of the monthly minimum for the decade in question. Almazouri [18] found that the Hijaz region on the coast of the Red Sea would be affected by an increase in extreme rainfall events. Tarawneh and Chowdhury [19] assess temperature, rainfall and climate change trends using linear regression. They show the mean summer temperatures in most cities to be around 2.5 times higher in summer than in winter. Some areas in the southwest, where the seasonal difference is around 5 ◦C, are an exception. Using 30 years of data, they identify a warming trend for Riyadh for both summer and winter of 0.0583 ◦C per year and 0.0427 ◦C per year, respectively. Lelieveld et al. [20] suggest that by the end of the century the magnitude of warming in the Middle East and North Africa (MENA) region during the summer is expected to be about twice as much as during the winter. They also estimate that the Kingdom could expect an average temperature increase above 6 ◦C for the summer months by 2081–2100, relative to averages from 1986–2005. Saudi labour law already prohibits outdoor work between 12:00 a.m. and 15:00 p.m. from June to mid-September [21]. Temperatures may soon rise to the extent that it is unsafe to spend a significant amount of time outside an air-conditioned building during most summer days. Higher temperatures also are likely to lead to increases in water demand, with one study conducted for Phoenix, Arizona suggesting every 1 ◦C increase in temperature is associated with an increase in water demand of 6.7% [22]. Studies have also investigated the relationship between temperature and energy consumption in Saudi Arabia. Building on the work of Al-Hadhrami [23] and Indraganti and Boussaa [24], Atalla et al. [25] calculated a degree day dataset and suggested that around half of the Kingdom’s electricity consumption can be attributed to cooling demand. These studies used a degree-day methodology where the number of cooling (or heating) degree days refers to the number of degrees that a day’s average temperature is above (or below) a reference temperature (e.g., 18 ◦C). A general finding of these studies is that the energy consumed by buildings for heating and cooling follows a U-curve (Figure1). Climate 2020, 8, 4 4 of 25

Howarth et al. [26] conducted an international benchmarking of sectoral energy demand for Saudi Arabia based on per capita energy consumption (1980–2015). While per capita buildings electricity consumption (the dominant fuel source for air conditioning) is relatively high in Saudi Arabia, overall perClimate capita 2020, energy8, x FOR consumptionPEER REVIEW from buildings is roughly in line with other countries such as the4 of U.S. 25 and Canada once other fuels such as gas (used for heating) are factored in. They also found that per capitafound energythat per demand capita energy from buildings demand infrom Saudi buildings Arabia rosein Saudi at a fasterArabia rate rose than at a OECD faster countriesrate than duringOECD thecountries period during under consideration,the period under where consider it wasation, falling where or stable. it was falling or stable.

Figure 1.1.The The relationship relationship between between energy energy and climaticand climat conditions.ic conditions. Source: Source: Authors Authors based on based ASHRAE on climaticASHRAE design climatic conditions design 2017conditions [27–29 ].2017 Note: [27–29]. The average Note: temperatureThe average in temperature the hottest or in coldest the hottest months or arecoldest shown months alongside are annualshown coolingalongside and annual heating cooling degree daysand heating for each city.degree The days threshold for each comfort city. zoneThe

ofthreshold cooling comfort degree days zone (CDD) of cooling and heatingdegree days degree (CDD) days and (HDD) heating is 18 degree◦C. days (HDD) is 18 °C.

Research conductedconducted byby thethe IEAIEA [[1]1] suggests that in countries with over 3000 cooling degree days (CDD),(CDD), householdhousehold ownershipownership ofof airair conditionersconditioners risesrises toto virtuallyvirtually 100%100% onceonce thethe averageaverage perper capitacapita GDP of aroundaround $26,000$26,000 USDUSD inin 20152015 purchasingpurchasing powerpower parityparity (PPP)(PPP) termsterms isis achieved.achieved. InIn countriescountries such asas SaudiSaudi Arabia,Arabia, Brazil,Brazil, Egypt,Egypt, India,India, Thailand,Thailand, Indonesia and Venezuela, coolingcooling isis almostalmost essential for people to livelive andand workwork inin comfort.comfort. All major cities in SaudiSaudi ArabiaArabia havehave CDDsCDDs aboveabove 3000. According to the World Bank, in 2017, Saudi Arabia’s per capita gross domestic product (GDP) waswas USUS $54,000$54,000 inin 20152015 PPPPPP terms.terms. As such, it is perhaps unsurprising that the use of air conditioners inin SaudiSaudi ArabiaArabia isis amongamong thethe highesthighest inin thethe world.world. Enerdata [[2]2] describesdescribes Saudi ArabiaArabia as havinghaving thethe world’sworld’s highesthighest shareshare ofof airair conditioningconditioning inin household electricity, atat 70%.70%. This compares with 57% in the United Arab Emirates, 25% in the U.S., 20% in Malaysia, 18% inin India,India, 13%13% inin MexicoMexico andand 12%12% inin Egypt.Egypt. This suggests that when comparedcompared withwith otherother countriescountries withwith a similarsimilar climate in the samesame region, Saudi Arabia is at the extreme end of ACAC useuse andand raisesraises seriousserious questionsquestions regardingregarding sustainability.sustainability.

2.2. Sustainability and Electricity Demand Growth A well-established electricity sustainability challenge for Saudi Arabia has been identified on two main levels. Rapidly increasing AC demand has led to increasing amounts of oil being consumed domestically for power generation. This has been seen as a threat to oil export revenue and government spending for public services [30,31]. While not usually seen as the primary driver of policy, the latter relates to rising CO2 emissions associated with fast electricity demand growth [32–34]. In their report “Burning Oil to Keep Cool” Lahn and Stevens [35] suggest that, with stable oil production and rising domestic consumption, Saudi Arabia could switch to being an oil importer by

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2.2. Sustainability and Electricity Demand Growth A well-established electricity sustainability challenge for Saudi Arabia has been identified on two main levels. Rapidly increasing AC demand has led to increasing amounts of oil being consumed domestically for power generation. This has been seen as a threat to oil export revenue and government spending for public services [30,31]. While not usually seen as the primary driver of policy, the latter relates to rising CO2 emissions associated with fast electricity demand growth [32–34]. In their report “Burning Oil to Keep Cool” Lahn and Stevens [35] suggest that, with stable oil production and rising domestic consumption, Saudi Arabia could switch to being an oil importer by 2040 and face “intractable” fiscal deficits by 2022. In a similar vein, Abubakar and Aina [36] warned of oil demand growth reducing Saudi Arabia’s oil export capacity, possibly resulting in a shortage of funds to provide essential public services. Fattouh [37] used monthly data from the Joint Organisations Data Initiative (JODI) to highlight the summer swings in domestic oil demand due to AC use and the potential for this to influence global oil prices. The author describes how between 2003 and 2012 electricity sold increased by 78%, from 128,629 million kilowatt-hours (kWh) to 240,288 million kWh. During the same period, the peak load increased by 117% from 23.9 gigawatts (GW) to 52 GW. In 2012, the domestic consumption of oil rose from 1.682 million barrels per day in January to 2.619 million barrels per day in July due to the summer demand for AC. Fattouh goes on to describe the strategic decision to use oil or gas to fuel electricity and how a royal decree in 2006 stipulated that power plant capacity expansion should prioritize the use of crude oil. This saw the share of natural gas in the power sector fall from 52% in 2007 to around 39% in 2012. Other significant fuels used for power generation in 2012 were crude oil (35%), diesel (20%) and heavy fuel oil (HFO) (6%). Drawing on official Electricity & Cogeneration Regulatory Authority (ECRA) statistics, Farnoosh et al. [38] highlight that electricity consumption in Saudi Arabia grew at 8% in 2013, driven by population growth of around 2.3% per annum and the highly subsidized cost base of utilities. Algarni and Nutter [39] note how building new homes also increased the floor space requiring cooling and, hence, energy consumption. Exacerbating these energy consumption trends is the Kingdom’s old and poorly insulated building stock, with studies suggesting that around 70% of buildings are not insulated. Furthermore, there is a huge demand for air conditioning because of heat transmission through walls and roofs [5,40].

2.3. Energy Efficiency and Air Conditioning Krarti et al. [26] suggest that the biggest demand for electricity is from buildings, with 76% of total power demand; industrial use accounts for 19%. Residential users make up around 50% of total electricity demand, followed by commercial users (16%) and governmental offices (11%). The authors suggest that AC accounts for about 60% to 70% of total household electricity consumption, depending on the city. This contrasts with the study conducted by Proctor Engineering and AMAD [41] which suggested that AC accounts for around 46% of electricity consumption on average across the country. One possible reason for this difference is that [41] refers to residential AC consumption as a proportion of total electricity consumption, which includes commercial and industrial uses. Such differences are common in the literature and most likely relate to whether the proportion of AC is based on primary electricity generation or final electricity consumption and whether it incorporates commercial as well as residential AC use. Krarti et al. [26] suggest that combining more efficient air conditioners with improvements to insulation and air leakage could offer consumers energy savings of up to 50%. However, the authors highlight that householders are unlikely to make the necessary investments without stronger energy efficiency regulations and significant increases in electricity prices. The Saudi Energy Efficiency Center (SEEC) was established in 2010 and launched the Saudi Energy Efficiency Program (SEEP) in 2012. As an important part of its mandate, SEEC has strengthened Climate 2020, 8, 4 6 of 25 building code regulations for high- and low-rise buildings, introducing 14 insulation standards and standards for small and large AC units. Its enforcement of these standards means no new building can now be connected to the grid unless it complies with the building codes [42]. SEEC has also been steadily increasing the minimum energy efficiency rating (EER) standards of all major AC types (Figure2). Since 2007, the minimum EER for split type AC units has risen from 7.5 to 11.8, and the EER for window type units from 7.5 to 9.8. The current EER standard for commercial chillers is 9.7, and variable refrigerant flow (VRF) is 11.2 [42,43]. The government has also instituted a price discount scheme for the purchase of highly efficient split system AC units with EERs of 13.8 or higher. This program offers a 900 Saudi riyal (SAR) (US $240) rebate for each unit sold, up to a maximumClimate 2020, 8 of, xsix FOR units PEER per REVIEW household [41]. 6 of 25

Figure 2. Evolution of energy efficiency ratio (EER) Standards in Saudi Arabia. Source: Authors, based Figure 2. Evolution of energy efficiency ratio (EER) Standards in Saudi Arabia. Source: Authors, based on [42,43] and the Saudi Arabian Standards Organization (SASO). Note: T1 = 35 ◦C, T3 = 48 ◦C refers toon the[42,43] test conditionsand the Saudi at dry-bulb Arabian temperature.Standards Organization (SASO). Note: T1 = 35 °C, T3 = 48 °C refers to the test conditions at dry-bulb temperature. The IEA [1] reviewed EERs across selected countries and found large differences between the best availableThe IEA units [1] on reviewed the market EERs and across the EER selected for the countries average and unit found bought, large including differences in Saudi between Arabia. the Forbest example,available theunits minimum on the market standard and for the window EER for unitsthe average is thesecond-lowest unit bought, including ‘F’ rating in on Saudi a scale Arabia. from AFor to example, G. the minimum standard for window units is the second-lowest ‘F’ rating on a scale from A to TheG. Japan Refrigeration and AC Industry Association (JRACIA) provides an overview of world AC demandThe Japan by Refrigeration region, including and AC for Industry Saudi Arabia Associat (Figureion 3(JRACIA)). The relatively provides ine anffi overviewcient but of cheaper world upfrontAC demand cost windowby region, units including comprised for Saudi 63% ofArabia the residential (Figure 3). market The relatively in 2018, withinefficient 772,000 but units cheaper sold comparedupfront cost with window 455,000 units for thecomprised more effi 63%cient of split the resi systemdential units. market The numberin 2018, ofwith residential 772,000 units sold eachcompared year haswith also 455,000 been for declining, the more with efficient unit sales split fallingsystem by units. 28% The for number window of units residential and 22% units for splitsold systemeach year units has in also 2018. been declining, with unit sales falling by 28% for window units and 22% for split systemBy units way ofin comparison,2018. the JRACIA statistics [44] show that window AC sales constitute less than 1% of sales in China and Japan, 11% in the rest of Asia, 1% in Europe, 90% in the U.S., 41% across the Middle East and 5% in Australia.

Figure 3. Saudi Arabian AC demand by unit type (2016–2018) Source: Japan Refrigeration and AC Industry Association.

By way of comparison, the JRACIA statistics [44] show that window AC sales constitute less than 1% of sales in China and Japan, 11% in the rest of Asia, 1% in Europe, 90% in the U.S., 41% across the Middle East and 5% in Australia.

Climate 2020, 8, x FOR PEER REVIEW 6 of 25

Figure 2. Evolution of energy efficiency ratio (EER) Standards in Saudi Arabia. Source: Authors, based on [42,43] and the Saudi Arabian Standards Organization (SASO). Note: T1 = 35 °C, T3 = 48 °C refers to the test conditions at dry-bulb temperature.

The IEA [1] reviewed EERs across selected countries and found large differences between the best available units on the market and the EER for the average unit bought, including in Saudi Arabia. For example, the minimum standard for window units is the second-lowest ‘F’ rating on a scale from A to G. The Japan Refrigeration and AC Industry Association (JRACIA) provides an overview of world AC demand by region, including for Saudi Arabia (Figure 3). The relatively inefficient but cheaper upfront cost window units comprised 63% of the residential market in 2018, with 772,000 units sold compared with 455,000 for the more efficient split system units. The number of residential units sold each year has also been declining, with unit sales falling by 28% for window units and 22% for split Climate 2020, 8, 4 7 of 25 system units in 2018.

FigureFigure 3. SaudiSaudi Arabian Arabian AC AC demand by unit type (2016–2018)(2016–2018) Source: Japan Refrigeration and and AC IndustryIndustry Association. Association.

Proctor Engineering and AMAD [41] made several recommendations in their review of the By way of comparison, the JRACIA statistics [44] show that window AC sales constitute less potential for higher EER AC units. First, they recommended differential standards for AC units in than 1% of sales in China and Japan, 11% in the rest of Asia, 1% in Europe, 90% in the U.S., 41% across dry areas such as Riyadh, where little dehumidification is required, and evaporative cooling is more the Middle East and 5% in Australia. efficient than standard vapour compression units. Reducing the number of relatively inefficient and cheap window type AC units sold was another priority—a challenge, given a standard window unit is around half the cost of a split unit and is less complicated to install. Other recommendations included (i) providing incentives to local manufacturers to switch from producing window units and upgrade the efficiency of units produced; (ii) improving the enforcement of SASO minimum performance standards; (iii) equipping units with sensors which switch the unit off if no-one is in a room or dwelling; and (iv) using more field tests and ongoing monitoring studies to assess the actual performance of units in specific local temperature and humidity conditions. Another issue that has been identified is the uptake of inverter (variable speed drive) technology [43]. While more expensive than simple on-off type motor regulation systems, inverters (used in split systems) offer the possibility of the AC unit running at a lower intensity to maintain a level of thermal comfort and could offer energy savings of up to 30%. Adopting a seasonal energy efficiency rating (SEER) rather than a standard rating (EER) is seen as one way to promote inverter units as estimated energy savings are higher for inverter units on energy performance labels under the SEER. The potential for solar photovoltaic (PV) and solar thermal air conditioning has also received attention [45–50]. While the practical application is rare, it is an important area for research and deployment. This is particularly relevant in the context of the Kingdom’s plans to increase the share of renewable energy in its electricity grid. The King Abdulaziz City for Science and Technology (KACST) has a major focus on efficient air conditioning and sustainability [51]. In 2019 the King Abdullah University of Science and Technology (KAUST) launched a cooling initiative focusing on solar energy utilization as well as developing and testing highly efficient non-vapour compression air conditioners. King Fahd University of Petroleum and Minerals’ (KFUPM) Center of Excellence in Energy Efficiency also has a strong focus on cooling.

2.4. Energy Price Reform Policies Fattouh [37] provides a snapshot of the large energy subsidies which were in place in 2012, represented by the gap between the price paid by local power producers and the international prices paid for fuels. Reforms to remove subsidies from fuel inputs to electricity generation has seen prices for natural gas increase 66% from $0.75 per million British thermal units (MMBtu) in 2015 to $1.25 MMBtu in 2018. Diesel fuel prices increased 77% from $9.11 a barrel in 2015 to $16.15 a barrel in 2018. Climate 2020, 8, 4 8 of 25

Arab light crude increased 50% from $4.24 a barrel to $6.35 a barrel, and Arab heavy crude increased 65% from $2.67 a barrel in 2015 to $4.4 a barrel in 2018 [52]. The SEC increased tariﬀs in 2016 and 2018 (Figure4), passing on these higher fuel input costs to the consumer.Climate 2020, The8, x FOR winter PEER bill REVIEW for an indicative household has risen from around US $20 to US $70 per month8 of 25 (268%) and summer bills from around $250 USD to $450 USD per month (75%) (Figure5 and Figure A3 inClimate the Appendix2020, 8, x FORA). PEER REVIEW 8 of 25

Figure 4. Saudi Arabia’s 2016 and 2018 electricity price reforms. Source: Authors based on ECRA [53].

FigureFigure 4.4. SaudiSaudi Arabia’sArabia’s 20162016 andand 20182018 electricityelectricity priceprice reforms. reforms. Source:Source: AuthorsAuthors basedbasedon onECRA ECRA[ [53].53].

Figure 5.5. The eeffectffect ofof energyenergy priceprice reformsreforms onon energyenergy billsbills ofof aa typicaltypical villa.villa. Source:Source: AuthorsAuthors basedbased on SEC. Figure 5. The effect of energy price reforms on energy bills of a typical villa. Source: Authors based Toon helphelpSEC. ooffsetffset increased increased living living costs costs from from higher higher energy energy and and water water prices prices and and the introductionthe introduction of a 5%of a value-added 5% value-added tax (VAT) tax (VAT) (from (f Januaryrom January 2018), 2018), the Kingdom the Kingdom introduced introduced a system a system of means-tested of means- paymentstestedTo payments help through offset through itsincreased newly-established its livingnewly-established costs Citizensfrom higher Ci Accounttizens energy Account Program and water Program [54, 55prices]. The [54,55]. and monthly the The introduction paymentmonthly citizenspaymentof a 5% are value-addedcitizens eligible are for eligible tax is dependent (VAT) for is(f romdependent on income,January on financial 2018), income, the assets financialKingdom and the assets in numbertroduced and the of a family numbersystem dependents. ofof means-family dependents.testedAs payments of April 2019, through the total its numbernewly-established of Citizen Account Citizens Program Account accounts Program opened [54,55]. was The 3.76 monthly million, splitpayment betweenAs of citizens April accounts 2019,are eligible forthe entire total for households isnumber dependent of (61%)Citizen on in andcome, Account accounts financial Program for individualsassets accounts and the (39%). openednumber The was Programof family 3.76 hadmillion,dependents. made split 17 monthlybetween payments,accounts for amounting entire househol to 40 billionds (61%) SAR and ($10.7 accounts billion for USD). individuals (39%). The ProgramAs ofhad April made 2019, 17 monthly the total payments, number amountinof Citizeng Accountto 40 billion Program SAR ($10.7 accounts billion opened USD). was 3.76 million,The splitfigures between released accounts in April for 2019 entire also househol includedds an (61%) attribution and accounts of the payments for individuals for different (39%). cost The ofProgram living components. had made 17 From monthly the 40payments, billion SAR amountin distributed,g to 40 electricity billion SAR constituted ($10.7 billion 28%, USD). gasoline 25% and otherThe figures (including released VAT) in 47%, April meaning 2019 also 53% included of the anCitizen attribution Account of thepayments payments compensate for different energy cost priceof living reform. components. From the 40 billion SAR distributed, electricity constituted 28%, gasoline 25% and Theother highest (including income VAT) band 47%, to meaningqualify for 53% the of paym the Citizenents is 20,159Account SAR payments (US $5375) compensate per month, energy and theprice average reform. monthly payment has been 1000 SAR (US $267). It is also important to note that the paymentThe doeshighest not income go up or band down to qualifywith living for thecosts paym dueents to the is 20,159seasonalit SARy of(US electricity $5375) per bills. month, and the average monthly payment has been 1000 SAR (US $267). It is also important to note that the payment does not go up or down with living costs due to the seasonality of electricity bills.

Climate 2020, 8, 4 9 of 25

The figures released in April 2019 also included an attribution of the payments for different cost of living components. From the 40 billion SAR distributed, electricity constituted 28%, gasoline 25% and other (including VAT) 47%, meaning 53% of the Citizen Account payments compensate energy price reform. Climate The2020,highest 8, x FOR incomePEER REVIEW band to qualify for the payments is 20,159 SAR (US $5375) per month, and9 of the25 average monthly payment has been 1000 SAR (US $267). It is also important to note that the payment doesProviding not go up monthly or down cash with payments living costs has due helped to the avoid seasonality the popular of electricity anger seen bills. in other parts of the worldProviding when implementing monthly cash similar payments reforms, has such helped as in avoid France the with popular the ‘gilets anger seenjaune’, in or other ‘yellow parts vests’ of the movement.world when However, implementing energy similar prices reforms,in Saudi Arabia such as are in Francestill low with compared the ‘gilets with jaune’, other orcountries, ‘yellow vests’and themovement. price reform However, process energy is ongoing. prices inFor Saudi example, Arabia average are still household low compared electricity with otherprices countries, in Australia and arethe around price reform US $0.2485 process per iskW ongoing.h, US $0.1289 For example, per kWh average in the U.S., household but only electricity US $0.048 pricesin Saudi in AustraliaArabia [56]. are aroundHigher US $0.2485electricity per prices kWh, in US Saudi $0.1289 Arabia, per kWhinitiate ind the by U.S., the start but onlyof the US energy $0.048 price in Saudi reform Arabia in 2016, [56 ]. representHigher a major electricity shift in prices the relationship in Saudi Arabia, between initiated the bystate the and start its of citizens the energy and pricehow reformthe country’s in 2016, naturalrepresent wealth a major is shared. shift in They the relationship also represent between an important the state natural and its citizensexperiment and regarding how the country’s energy pricesnatural and wealth energy is shared.use. After They briefly also representlaying out an our important materials natural and methods, experiment the regarding next sections energy present prices ourand empirical energy use. analysis After and briefly results, laying which out give our so materialsme insight and into methods, the impact the of next such sections policies. present our empirical analysis and results, which give some insight into the impact of such policies. 3. Materials and Methods 3. Materials and Methods 3.1. Data Sources 3.1. Data Sources To investigate the temperature change in Saudi Arabia, the ECMWF ERA5 dataset [6] has been used forTo investigatethe years 1970 the temperatureto 2018. ERA5 change is the inlatest Saudi and Arabia, fifth generation the ECMWF of ERA5global datasetclimate [6reanalysis] has been producedused for theby ECMWF. years 1970 The to 2018.greatest ERA5 advantages is the latest of this and dataset fifth generation include the of provision global climate of hourly reanalysis data andproduced fine spacial by ECMWF. resolution The (0.25 greatest degrees advantages latitude/longitude, of this dataset or what include is about the provision25 kilometres of hourly for Saudi data Arabia).and fine ERA5 spacial reanalysis resolution can (0.25 thus degrees be used latitude to track/longitude, atmospheric or what conditions is about 25at kilometrescity levels forand Saudi has foundArabia). practical ERA5 reanalysisapplication can in thusvarious beused climate to track change-related atmospheric studies conditions such atas city one levels conducted and has for found the BBCpractical [3]. application in various climate change-related studies such as one conducted for the BBC [3]. TheThe dataset dataset provides provides atmospheric, atmospheric, land-surface land-surface and and sea-state sea-state parameters. parameters. This This study study uses uses the the airair temperature temperature at at 2 2m m above above the the surface surface of of land, land, sea sea or or in-land in-land water. water. Temperature Temperature trends trends were were obtainedobtained by by plotting plotting a a linear rate ofof changechange overover the the sample sample period period for for geographical geographical coordinates coordinates of keyof keycities. cities. The The linear linear trend trend was was fitted fitted to yearly to yearly mean me temperaturesan temperatures (the (the mean mean of monthly of monthly means means of daily of dailytemperature temperature means). means). A trend A trend for summer for summer temperature temperature changes changes was obtainedwas obtained in the in same the same way, whereway, wheresample sample data included data included mean mean summer summer temperatures temperatures for each for year each from year 1979from to 1979 2018. to 2018. TheThe SEC SEC power power generation generation data data divides divides the the Kingdo Kingdomm into into four four regions, regions, with with the the majority majority of of generationgeneration in in the the Western, Western, Centra Centrall and and Eastern Eastern regions regions (Figure (Figure 66).).

FigureFigure 6. 6. PowerPower operation operation areas areas of of Saudi Saudi Arabia Arabia [57]. [57]. Source: Source: SEC. SEC.

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Hourly electricity data was available for 2011–2015, except for 2012. Electricity data includes demand from all sources, the main groupings being buildings and industrial uses. SEC is the largest provider of electricity in the Kingdom, with a share of 66% of Saudi Arabia’s total electricity capacity [57]. The SEC data excludes some independent electricity power generation produced by some large industrial users, such as cement plants and refineries. The SEC data also relates to the total amount of primary generation before transmission, distribution and other losses. For example, according to Enerdata [56] in 2018 the total primary electricity generation was 351 TWh while total final electricity consumption was 285 TWh, implying losses of 19%. The main portal for our annual energy data is Enerdata [56,58] downloaded as of September 2019. This sources primary information from the IEA [59] and national sources including the Saudi Arabian Monetary Agency (SAMA) and the Saudi Energy Efficiency Center (SEEC) and is updated regularly as new information is released to inform the most recent year of estimates. One important distinction between the hourly SEC data and Enerdata’s annual data for residential and commercial energy consumption [58] is that the later is based on final electricity consumption after transmission and distribution losses. Final consumption data has an advantage over the hourly primary SEC generation data by being able to distinguish electricity use by each sector (buildings and industry). Within the buildings sector the use of electricity it is disaggregated into residential users and commercial (services) users. For example, in 2018 total final electricity consumption of 285 TWh comprised of 41 TWh used for industry (14%), 144 TWh used for residential buildings (51%) and 100 TWh used for the services sector (35%). This suggests around 86% of the total final electrical demand comes from buildings. Enerdata then further disaggregates buildings electricity consumption according to end use (cooling, lighting, hot water, cooking, etc.) using information supplied by SEEC. For example, in 2018 the total electricity demand from cooling for the residential and services sectors was 101 TWh and 70 TWh respectively constituting around 70 of the total electrical demand for each sector. Annual data on electricity fuel inputs and CO2 emissions from electricity were obtained from [56]. The two main fuel inputs are natural gas and oil-based liquid fuels. Oil-based fuels include crude oil, heavy fuel oil, diesel as well as some other oil products. While the dynamics of these individual fuels can be assessed using monthly data from the Joint Oil Data Initiative (JODI) it was beyond the scope of this paper to evaluate these trends. This would be a useful exercise for future research on the Kingdom’s changing CO2 emissions.

3.2. Analytical Approach

The capital, Riyadh [24.75◦ N 46.75◦ E] was chosen as a representative location for temperature evaluation in the Central region, as the majority of the Central region population is concentrated in this city. Temperatures for each of the rest of the regions were identified by averaging temperatures in their respective key cities. The temperature in the Eastern region was determined by the average across Dammam [26.50◦ N 50.00◦ E] and Dhahran [26.25◦ N 50.00◦ E]. The temperature in the Western region was determined by the average across Jeddah [21.50◦ N 39.25◦ E] and Mecca [21.50◦ N 39.75◦ E]. The Southern region temperature was estimated as the average across Al Baha [20.00◦ N 41.50◦ E], Abha [18.25◦ N 42.50◦ E], Khamis Mushait [18.25◦ N 42.75◦ E], Najran [17.50◦ N 44.25◦ E] and Jazan [17.00◦ N 42.75◦ E]. National temperature changes were obtained by averaging the temperature data points from ERA5 on a latitude/longitude grid inside the boundaries of the Kingdom. We took into account latitude cosine correction, as the distance between each degree of latitude decreases as the distance from the equator increases. This accounts for the fact that points further from the equator should be assigned less weight when calculating countries’ average weather values. We used hourly data from the ECMWF ERA5 dataset and paired it with the SEC’s hourly electricity generation data to perform correlation analysis between temperature and power. We performed the correlation analysis for each individual year using a Pearson correlation test in Matlab including 8760 paired data points in each year and selected 2015 (the most recent) for illustrative purposes. While Climate 2020, 8, 4 11 of 25 total generation increased on average by 6% per year from 2011 to 2015, the correlation coefficients between temperature and power generation were relatively stable (Table A1 in AppendixA). We then used OLS regression to obtain an estimate of the amount of power generation added for each 1 ◦C increase in temperature throughout the year in each region. We conducted the OLS analysis for each year individually and again selected 2015 for illustrative purposes (for detailed regression results see Table A2 in AppendixA). The relationship between hourly temperature and hourly power generation was highly significant in all regions with all p values very close to zero. In the summary Climate 2020, 8, x FOR PEER REVIEW 11 of 25 table in the appendix we have shown the relevant t-statistic values. These indicate that the trend of linear regression is significant for all the tests at a 99.99% confidence level. While the strength of the strength of the relationship means a simple linear functional form provides a robust general result, relationship means a simple linear functional form provides a robust general result, further research further research could explore the evidence of nonlinearity especially in the Eastern and Central could explore the evidence of nonlinearity especially in the Eastern and Central regions. It should regions. It should also be noted that the 𝛽 values describing the level of power generation added also be noted that the βˆ values describing the level of power generation added due to temperature due to temperature change are higher in each subsequent year from 2011 to 2015 reflecting the change are higher in each subsequent year from 2011 to 2015 reflecting the increase in overall power increase in overall power generation over this period. generation over this period. To assess post-2016 trends in electricity consumption and the impact of energy price reform, To assess post-2016 trends in electricity consumption and the impact of energy price reform, energy efficiency and fuel switching policies we employed descriptive statistical analysis of annual energy efficiency and fuel switching policies we employed descriptive statistical analysis of annual final electricity consumption in the residential and commercial sectors, the fuel mix from primary final electricity consumption in the residential and commercial sectors, the fuel mix from primary electrical generation and the associated CO2 emissions from 2010 to 2018. electrical generation and the associated CO2 emissions from 2010 to 2018. 4. Results 4. Results

4.1.4.1. LocalLocal WarmingWarming TrendsTrends (1979–2018) (1979–2018) TheThe ECMWFECMWF ERA5ERA5 datasetdataset isis consistentconsistent withwith previousprevious studiesstudies onon temperaturetemperature characteristicscharacteristics ofof thethe Arabian Arabian Peninsula. Peninsula. Figure Figure7 and7 and Table Table1 describe 1 describe the the monthly monthly mean mean of daily of daily temperature temperature means means for Januaryfor January and Julyand 2015,July and2015, the and key the temperature key temperature characteristics characteristics in each of in the each four of electricity the four generation electricity regions.generation We regions. chose 2015 We chose as the 2015 representative as the representative year as this year is theas this most is recentthe most year recent for the year detailed for the electricitydetailed electricity data from data the SEC.from the SEC. In 2015, January temperatures ranged between 15 °C to 20 °C, while July temperatures were In 2015, January temperatures ranged between 15 ◦C to 20 ◦C, while July temperatures were within a 30 °C to 40 °C range. About half of all territory in Saudi Arabia, predominantly in the east, within a 30 ◦C to 40 ◦C range. About half of all territory in Saudi Arabia, predominantly in the experienced summer highs of 45 °C in 2015. Only in very few locations in the south-west and north- east, experienced summer highs of 45 ◦C in 2015. Only in very few locations in the south-west and west did average temperatures in the summer months stay below 30 °C. north-west did average temperatures in the summer months stay below 30 ◦C.

(a) (b)

FigureFigure 7. 7.Monthly Monthly mean mean of dailyof daily temperature temperature means means in Saudi in Saudi Arabia Arabia (2015). (2015). (a) January (a) January (b) July ( Source:b) July AuthorsSource: Authors based on based ECMWF on ECMWF ERA5. ERA5.

Compared to the previous and following years, 2015 was neither hot nor cold, with annual and summer temperature means close to 2012–2018 averages (Table 1). This also makes 2015 a good year to use for illustration.

Table 1. Temperature characteristics of the most populated areas in each region for 2015 (°C).

Mean Maximum Minimum Location East 27.4 44.7 6.6 Dammam, Dhahran average Central 27.4 45.5 2.2 Riyadh West 29.8 43.5 14.3 Jeddah, Mecca average

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Table 1. Temperature characteristics of the most populated areas in each region for 2015 (◦C).

Mean Maximum Minimum Location East 27.4 44.7 6.6 Dammam, Dhahran average Central 27.4 45.5 2.2 Riyadh West 29.8 43.5 14.3 Jeddah, Mecca average Average across Al Baha, Abha, South 24.4 36.2 9.8 Climate 2020, 8, x FOR PEER REVIEW Khamis Mushait, Najran and Jazan 12 of 25 Source: Authors based on ECMWF ERA5 [6]. Average across Al Baha, Abha, Khamis Mushait, South 24.4 36.2 9.8 Compared to the previous and following years, 2015 was neitherNajran hotand nor Jazan cold, with annual and summer temperature means closeSource: to 2012–2018Authors based averages on ECMWF (Table ERA51). This [6]. also makes 2015 a good year to use for illustration. FiguresFigures 8 andand9 9 use use historical historical datadata fromfrom the the ECMWF ECMWF ERA5ERA5 datasetdataset toto show show thethe temperature temperature changeschanges across across the the Arabian Arabian Peninsula Peninsula and and the the surro surroundingunding regions regions for for the the 40 40 years years from from 1979–2018. 1979–2018. On average, Saudi Arabia has warmed by about 1.9 °C since 1979, which equates to around 0.471 °C On average, Saudi Arabia has warmed by about 1.9 ◦C since 1979, which equates to around 0.471 ◦C per decade or 0.047 °C per year. Mean summer temperatures increased at faster rates for most of the per decade or 0.047 ◦C per year. Mean summer temperatures increased at faster rates for most of the country. If only summer months are considered, the warming is 2.2 °C degrees on average across the country. If only summer months are considered, the warming is 2.2 ◦C degrees on average across the whole country, or 0.557 °C per decade and 0.056 °C per year. whole country, or 0.557 ◦C per decade and 0.056 ◦C per year.

(a) (b)

FigureFigure 8. 8. TemperatureTemperature change change from from 1979 1979 to to 2018. 2018. ( (aa)) whole whole year year ( (bb)) summer summer only. only. Authors Authors based based on on ECMWFECMWF ERA5 ERA5 Dataset. Dataset.

TheThe coastal areasareas warm warm less less compared compared with with inland inland areas areas with with the Red the Sea Red providing Sea providing better thermal better thermalregulation regulation compared compared with the with Persian the Persian Gulf. ForGulf. example, For example, in general, in general, Jeddah Jeddah remains remains cooler cooler than thanDammam. Dammam. The northernThe northern parts ofparts the Kingdomof the Kingdo are experiencingm are experiencing the most the intense most warming, intense warming, especially especiallyduring summer. during summer. For example, For exam in Sakakaple, in (in Sakaka the north-west (in the north-west of the country), of the country), the average the average summer summertemperature temperature has increased has increased by 3.3 degrees by 3.3 sincedegrees 1979. since The 1979. capital, The Riyadhcapital, hasRiyadh also seenhas also dramatic seen dramatictemperature temperature rises, of aroundrises, of 2.3 around◦C and 2.3 2.8 °C◦C and for whole2.8 °C yearsfor whole and summeryears and months, summer respectively months, respectively(Figure9). Warming(Figure 9). is Warming most limited is most in thelimited northwest, in the northwest, southwest southwest and southeast and southeast of the country. of the country.For example, For example, the Neom the project, Neom aiming project, to aiming be a new to be ‘city a new of the ‘city future’ of the on future’ the border on the with border Egypt with and EgyptJordan, and is inJordan, one of is these in one zones. of these zones.

(a) (b)

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Average across Al Baha, Abha, Khamis Mushait, South 24.4 36.2 9.8 Najran and Jazan Source: Authors based on ECMWF ERA5 [6].

Figures 8 and 9 use historical data from the ECMWF ERA5 dataset to show the temperature changes across the Arabian Peninsula and the surrounding regions for the 40 years from 1979–2018. On average, Saudi Arabia has warmed by about 1.9 °C since 1979, which equates to around 0.471 °C per decade or 0.047 °C per year. Mean summer temperatures increased at faster rates for most of the country. If only summer months are considered, the warming is 2.2 °C degrees on average across the whole country, or 0.557 °C per decade and 0.056 °C per year.

(a) (b)

Figure 8. Temperature change from 1979 to 2018. (a) whole year (b) summer only. Authors based on ECMWF ERA5 Dataset.

The coastal areas warm less compared with inland areas with the Red Sea providing better thermal regulation compared with the Persian Gulf. For example, in general, Jeddah remains cooler than Dammam. The northern parts of the Kingdom are experiencing the most intense warming, especially during summer. For example, in Sakaka (in the north-west of the country), the average summer temperature has increased by 3.3 degrees since 1979. The capital, Riyadh has also seen dramatic temperature rises, of around 2.3 °C and 2.8 °C for whole years and summer months, Climaterespectively2020, 8, 4 (Figure 9). Warming is most limited in the northwest, southwest and southeast of the13 of 25 country. For example, the Neom project, aiming to be a new ‘city of the future’ on the border with Egypt and Jordan, is in one of these zones.

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Figure 9. Linear warming trend for (a) Riyadh [24.75° N 39.25° E] (b) Jeddah [21.50° N 39.25° E] (c) Figure 9. Linear warming(c) trend for (a) Riyadh [24.75◦ N 39.25◦ E] (b) Jeddah(d) [21.50◦ N 39.25◦ E] Dammam [26.50° N 50.00° E] and (d) Sakaka [30.00° N 40.25° E] over the past 40 years based on (c) Dammam [26.50◦ N 50.00◦ E] and (d) Sakaka [30.00° ◦ N 40.25° ◦ E] over the past° 40 years° based on averageFigure 9. yearly Linear temperature. warming trend Source: for (Authorsa) Riyadh based [24.75 on ECMWFN 39.25 ERA5E] (b) Dataset.Jeddah [21.50 N 39.25 E] (c) averageDammam yearly [26.50 temperature.° N 50.00° Source: E] and Authors(d) Sakaka based [30.00 on° N ECMWF 40.25° E] ERA5 over the Dataset. past 40 years based on 4.2. Intra-Year4.2. Intra-Yearaverage Seasonality yearly Seasonality temperature. of Electricityof Electricity Source: Generation Generation Authors based on ECMWF ERA5 Dataset. Driven by the extreme shift between winter and summer temperatures within a year and the Driven4.2. Intra-Year by the Seasonality extreme of shift Electricity between Generation winter and summer temperatures within a year and the demand for cooling, daily electricity generation in August or July may be almost two times higher demand for cooling, daily electricity generation in August or July may be almost two times higher than Drivenin December by the or extreme January shift (Figure between 10). Inwinter 2015, an duringd summer specific temperatures summer days, within power a year generation and the thanreacheddemand in December around for cooling, or 60 JanuaryGW, daily while electricity (Figure during 10 generationthe). winter In 2015, itin was duringAugust as low or speciﬁc asJuly 23 mayGW. summer be almost days, two power times higher generation reachedthan around in December 60 GW, or whileJanuary during (Figure the 10). winter In 2015, it wasduring as lowspecific as 23 summer GW. days, power generation reached around 60 GW, while during the winter it was as low as 23 GW.

(a) (b)

Figure 10. (a) Average(a )daily power generation (load) in each operation region(b) (b) Daily power generation (load) curve averaged for each month. Source: Authors based on 2015 data from Saudi FigureElectricityFigure 10. 10.(a )Company ( Averagea) Average (SEC) daily daily Note: power power Does generation generationnot include (load) (load)transmission in in each each and operation operation distribution region region losses. (b) (Dailyb) Daily power power generationgeneration (load) (load) curve curve averaged averaged for for each each month.month. Source: Source: Authors Authors based based on on2015 2015 data data from from Saudi Saudi Electricity Company (SEC) Note: Does not include transmission and distribution losses. ElectricityIt is also Company important (SEC) to note Note: that Does variations not include in the transmission daily power and load distribution curve profile losses. are the highest during summer, especially in July and August, where the difference between peak and off-peak hours reachesIt is 13 also GW. important In summer, to note this that accounts variations for inapproximately the daily power 20% load of curvethe SEC’s profile total are capacity. the highest In contrast,during summer, during winterespecially in 2015, in July the and difference August, betweenwhere the peak difference and off-peak between power peak production and off-peak did hours not exceedreaches 9 13 GW GW. and In in summer, some days this was accounts less than for 5approximately GW. Such high 20% daily of variationthe SEC’s in total the loadcapacity. profile In providescontrast, duringa rationale winter for loadin 2015, smoothing the difference technologies between such peak as andchilled off-peak water poweror ice storageproduction and districtdid not coolingexceed 9to GW help and level in peak some loads, days especiallywas less thanfor commercial 5 GW. Such buildings. high daily variation in the load profile providesThe scatterplotsa rationale for of loadhourly smoothing power generation technologies and such hourly as chilled temperature water or for ice thestorage four andregions district of Saudicooling Arabia to help are level shown peak in loads, Figure especially 11 using for data commercial from 1 January buildings. to 31 December 2015. As expected, temperatureThe scatterplots and electricity of hourly generated power are generation strongly positivelyand hourly correlated temperature in every for the region. four Acrossregions the of year,Saudi the Arabia strongest are shown correlation in Figure exists 11 in using the Eastdataern, from Central 1 January and toWestern 31 December regions, 2015. where As 91%,expected, 86% andtemperature 85% of andthe changeelectricity in generatedelectricity are generation strongly positivelyis associated correlated with temperature in every region. variation. Across The the year, the strongest correlation exists in the Eastern, Central and Western regions, where 91%, 86% and 85% of the change in electricity generation is associated with temperature variation. The

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It is also important to note that variations in the daily power load curve profile are the highest during summer, especially in July and August, where the difference between peak and off-peak hours reaches 13 GW. In summer, this accounts for approximately 20% of the SEC’s total capacity. In contrast, during winter in 2015, the difference between peak and off-peak power production did not exceed 9 GW and in some days was less than 5 GW. Such high daily variation in the load profile provides a rationale for load smoothing technologies such as chilled water or ice storage and district cooling to help level peak loads, especially for commercial buildings. The scatterplots of hourly power generation and hourly temperature for the four regions of Saudi Arabia are shown in Figure 11 using data from 1 January to 31 December 2015. As expected, temperature and electricity generated are strongly positively correlated in every region. Across the year, the strongest correlation exists in the Eastern, Central and Western regions, where 91%, 86% and Climate85% of 2020 the, 8 change, x FOR PEER in electricity REVIEW generation is associated with temperature variation. The correlation14 of 25 coefficient is lower in the cooler southern region, where temperature changes are associated with correlationaround 70% coefficient of the variation is lower of power in the generation. cooler southern region, where temperature changes are associated with around 70% of the variation of power generation.

(a) (b)

FigureFigure 11. 11. AverageAverage hourly hourly temperatures temperatures in in and and hourly hourly power power generation generation in in ( (aa)) Eastern Eastern ( (bb)) Central Central ( (cc)) WesternWestern ( d) Southern regions (2015). Source: Source: Authors Authors based based on on data data from from SEC SEC and and ECMWF ECMWF ERA5 ERA5 DatasetDataset for for 2015. 2015.

TheThe βˆ𝛽values values for for the the ordinary ordinary linear linear regressions regressions for each for region each with region temperature with temperature as an explanatory as an explanatoryvariable give variable an indication give an of theindication increase of in the electricity increase generation in electricity associated generation with eachassociated 1 ◦C of with warming, each 1as °C each of warming, region transitions as each region from wintertransitions to summer. from winter These to aresummer. 267 MW These for theare Eastern267 MW region, for the 334Eastern MW region, 334 MW for the Central region, 489 MW for the Western region and 87 MW for the Southern region in 2015. This increase represents around 2.0% of average power generation in the Eastern region, 2.9% in the Central, 4.6% in the Western and 2.4% in the Southern region. The Western region adds the most electricity for each degree of temperature increase suggesting a higher intensity of AC use relative to the rest of the country. Overall, approximately 1.177 GW is added nationally for every 1 °C increase in temperature from winter to summer. Figure 11 also distinguishes each season, with autumn and spring exhibiting the strongest link between temperature and power generation. A likely reason for this is that people manage their AC loads more actively during these months, depending on the temperature. The lower correlation coefficient for summer is likely because, once temperatures reach a certain level, people leave their air conditioning on continuously—the variation in electricity demand is related to external temperatures and thermostat settings. This provides a rationale for ‘smart’ ACs with networked connectivity to help consumers manage AC usage more actively in hot months, especially when they are not in their dwelling or a particular room.

Climate 2020, 8, 4 15 of 25 for the Central region, 489 MW for the Western region and 87 MW for the Southern region in 2015. This increase represents around 2.0% of average power generation in the Eastern region, 2.9% in the Central, 4.6% in the Western and 2.4% in the Southern region. The Western region adds the most electricity for each degree of temperature increase suggesting a higher intensity of AC use relative to the rest of the country. Overall, approximately 1.177 GW is added nationally for every 1 ◦C increase in temperature from winter to summer. ClimateFigure 2020, 8, 11x FOR also PEER distinguishes REVIEW each season, with autumn and spring exhibiting the strongest15 of link 25 between temperature and power generation. A likely reason for this is that people manage their AC loadsIn winter, more we actively see lower during correlation these months, coefficients depending, especially on the temperature.in the dry Central The lower region, correlation where variationscoefficient in for temperature summer is likelyand power because, generation once temperatures are essentially reach unrelated. a certain level,This is people not the leave case their for the air coastalconditioning regions on where continuously—the temperature variation variation still in electricity accounts demandfor between is related 34% and to external 75% of the temperatures change in electricityand thermostat generation. settings. The This lower provides correlation a rationale coeffici forents ‘smart’ may also ACs be with due networkedto the use of connectivity AC units for to heatinghelp consumers as temperatures manage fall AC below usage 18 more °C. actively in hot months, especially when they are not in their dwellingThe orCentral a particular and Eastern room. regions show evidence of a non-linear relationship between temperatureIn winter, and we power see lowergeneration, correlation with power coeffi cients,generation especially relatively in theless dryresponsive Central to region, temperature where untilvariations temperatures in temperature of around and power22 °C generationare reached. are This essentially contrasts unrelated. with the This Western is not theand case Southern for the regions,coastal regionswhere wherepower temperature generation variationgenerally still increases accounts linearly. for between This 34%could and be 75% due of to the the change higher in proportionelectricity generation.of industrial The electricity lower correlation demand coein ffithecients Eastern may alsoand beCentral due to regions, the use ofwhich AC units is less for influencedheating as temperaturesby temperature. fall below 18 ◦C. The Central and Eastern regions show evidence of a non-linear relationship between temperature 4.3.and Share power of AC generation, in Total Elec withtricity power Demand generation from Buildings relatively less responsive to temperature until temperaturesFigures 12 of and around 13 show 22 ◦C total are reached. electrical This consumption contrasts with in TWh the Western for buildings and Southern in the residential regions, where and servicespower generation sectors (panel generally a) and increases their respective linearly. year This-on-year could be percentage due to the changes higher proportion (panel b). In of 2018 industrial total electricityelectricity consumption demand in the in Eastern buildings and was Central around regions, 244 TWh, which with is less residential influenced uses by accounting temperature. for 144 TWh (59%) and services (the commercial sector) 100 TWh (41%). In 2018, air conditioning consumed 4.3. Share of AC in Total Electricity Demand from Buildings 101 TWh in the residential sector and 70 TWh in the services sector. During the period under analysis, the shareFigures of air 12 conditioningand 13 show in total total electrical final electric consumptionity demand in TWh from for buildings buildings was in relatively the residential stable and at 70%services for both sectors the (panel residential a) and and their commercial respective sectors. year-on-year percentage changes (panel b). In 2018 total electricityBetween consumption 2010 and in2015 buildings annual wasgrowth around in elec 244tricity TWh, withdemand residential in the usesresidential accounting sector for was 144 approximatelyTWh (59%) and 6% services on average, (the commercial and 11% for sector) the serv 100ices TWh sector. (41%). From In 2018, 2016 air there conditioning was a distinct consumed shift toward101 TWh lower in the rates residential of growth. sector For and example, 70 TWh in in 2016 the services residential sector. electricity During demand the period fell under by 1.7% analysis, and registeredthe share ofno air significant conditioning change in totalin 2017 final and electricity 2018. Commercial demand from demand buildings increased was by relatively 1% and stable0.5% in at 201670% and for both 2017, the respectively residential and and regist commercialered no sectors. significant change in 2018.

(a) (b)

FigureFigure 12. 12. ResidentialResidential electricity electricity consum consumptionption and and air air conditioning conditioning ( (aa)) absolute absolute ( (bb)) percentage percentage change change year-on-year.year-on-year. Source: Source: Authors Authors based based on on Enerdata. Enerdata.

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Climate 2020, 8, x FOR PEER REVIEW 16 of 25

(a) (b)

FigureFigure 13. 13. ServicesServices electricity electricity consumpt consumptionion and and air air conditioning conditioning ( (aa)) absolute absolute ( (bb)) percentage percentage change change year-on-year.year-on-year. Source: Source: Authors Authors based based on on Enerdata. Enerdata.

4.4. ElectricityBetween Fuel 2010 Mix and and 2015 CO2 annualEmissions growth in electricity demand in the residential sector was approximately 6% on average, and 11% for the services sector. From 2016 there was a distinct shift In 2018, total electricity production was 351 TWh, comprised of 145 TWh generated from oil- toward lower rates of growth.(a) For example, in 2016 residential electricity(b demand) fell by 1.7% and based products and 206 TWh from natural gas (Figure 14). In 2013, gas replaced oil as the primary registered no signiﬁcant change in 2017 and 2018. Commercial demand increased by 1% and 0.5% in fuel inputFigure for 13. electricity Services electricity production consumpt and increasedion and air to conditioning59% of the fuel (a) absolute mix in 2018. (b) percentage Oil has about change a 25% 2016 and 2017, respectively and registered no signiﬁcant change in 2018. higheryear-on-year. CO2 intensity Source: than Authors gas, with based 20 on kg Enerdata. per gigajoule for oil compared with 15.3 kg for gas. This

2 shift4.4. Electricityin the fuel Fuel mix Mix from and oil CO to2 Emissionsgas has consequently had a significant bearing on CO emissions associated4.4. Electricity with Fuel power Mix generationand CO2 Emissions [60]. In 2018, total electricity production was 351 TWh, comprised of 145 TWh generated from oil-based In 2018, total electricity production was 351 TWh, comprised of 145 TWh generated from oil- products and 206 TWh from natural gas (Figure 14). In 2013, gas replaced oil as the primary fuel input based products and 206 TWh from natural gas (Figure 14). In 2013, gas replaced oil as the primary for electricity production and increased to 59% of the fuel mix in 2018. Oil has about a 25% higher CO fuel input for electricity production and increased to 59% of the fuel mix in 2018. Oil has about a 25%2 intensity than gas, with 20 kg per gigajoule for oil compared with 15.3 kg for gas. This shift in the higher CO2 intensity than gas, with 20 kg per gigajoule for oil compared with 15.3 kg for gas. This fuel mix from oil to gas has consequently had a signiﬁcant bearing on CO2 emissions associated with shift in the fuel mix from oil to gas has consequently had a significant bearing on CO2 emissions power generation [60]. associated with power generation [60].

(a) (b)

Figure 14. Fuel inputs to electrical generation (a) absolute (b) percentage change year on year (2000– 2018). Source: Authors based on Enerdata.

Figure 15 shows that CO2 emissions from power generation fell by 4% in 2013 and 5.9% in 2016. In 2017, emissions from the power sector rose by 2.9%, while in 2018 emissions from power were stable. One of the major (driversa) of these changes has been the shift in the (useb) of oil in the fuel mix. Shifts in the use of natural gas resulted in relatively small changes in emissions. Another factor behind Figure 14. 14. FuelFuel inputs inputs to toelectrical electrical generation generation (a) absolute (a) absolute (b) percentage (b) percentage change change year on year year on (2000– year the fall(2000–2018).2018). in emissions Source: Source: Authors may Authorsbe based that onnew based Enerdata. combined-cycl on Enerdata. e gas power plants are significantly more efficient than the older simple cycle oil plants they replace. The increased use of gas in more efficient power plantsFigure has helped 15 shows stabilize that CO emissions2 emissionsemissions in from fromthe powepower powerr sector,generation generation alongside fell fell by by 4%slowing 4% in in 2013 2013 electricity and and 5.9% 5.9% demand in in 2016. 2016. growthIn 2017,2017, as emissionsemissions a result of from from higher the the powerprices power sectorand sector increased rose rose by 2.9%,by AC 2.9%, energy while while in efficiency. 2018 in 2018 emissions emissions from powerfrom power were stable.were Onestable. of One the major of the drivers major drivers of these of changes these changes has been has the been shift the in theshift use in ofthe oil use in theof oil fuel in mix.the fuel Shifts mix. in theShifts use in of the natural use of gasnatural resulted gas resulted in relatively in relatively small changes small changes in emissions. in emissions. Another Another factor behind factor behind the fall inthe emissions fall in emissions may be may that be new that combined-cycle new combined-cycl gas powere gas power plants plants are significantly are significantly more more efficient efficient than thethan older the older simple simple cycle cycle oil plants oil plants they replace. they replace. The increased The increased use of use gas of in gas more in emorefficient efficient power power plants plants has helped stabilize emissions in the power sector, alongside slowing electricity demand growth as a result of higher prices and increased AC energy efficiency.

Climate 2020, 8, 4 17 of 25 has helped stabilize emissions in the power sector, alongside slowing electricity demand growth as a resultClimate of2020 higher, 8, x FOR prices PEER and REVIEW increased AC energy eﬃciency. 17 of 25

(a) (b)

Figure 15.15. ElectricityElectricity sectorsector CO CO2 2emissions emissions (a )(a absolute) absolute (b )( percentageb) percentage change change year year on year on (2010–2018).year (2010– Source:2018). Source: Authors Authors based onbased Enerdata. on Enerdata.

5. Discussion of Results in Light of Previous Studies Existing literature on electricity, temperaturetemperature and the sustainabilitysustainability of cooling in Saudi Arabia are spread over severalseveral methodologicalmethodological or disciplinarydisciplinary ﬁelds.fields. While some interdisciplinary research has been undertaken, notably the IEA’s work on coolingcooling [[1],1], few academicacademic studies have taken an interdisciplinary approach. The The sustainability sustainability of of cooling cooling encompasses temperature change andand techno-economic studies of energy use. Accordingly, Accordingly, we feel such anan interdisciplinaryinterdisciplinary approach is important toto fully understand and manage the sustai sustainabilitynability challenge of cooling. We have organized the discussion of our results in this section as they relate to methodological or thematic groupings in the literature. We concludeconclude byby summarizingsummarizing thethe keykey insightsinsights ofof thethe paper.paper.

5.1. Physical Science of Temperature Change in Saudi Arabia 5.1. Physical Science of Temperature Change in Saudi Arabia The analysis of temperature change from 1979–2018 using the ECMWF ERA 5 datadata conductedconducted in thisthis paperpaper suggestssuggests average warming across the country of 1.9 ◦°CC over 40 years, or 0.475 ◦°CC per decade and 0.0475 ◦°CC per year. Mean summer temperatures rose faster: by 2.2 °C◦C over 40 years, or 0.55 ◦°CC per decade and 0.055 ◦°CC per year. The fastest rate of warming was in the summer in the northern central part of thethe country,country, includingincluding citiescities suchsuch asas SakakaSakaka ((+3.3+3.3 ◦°C)C) and RiyadhRiyadh ((+2.8+2.8 °C).◦C). Coastal areas, particularly on the Red Sea and in the region of Neom in in the the north north west west of of the the country, country, showed moremore moderate moderate warming warming (below (below 2 ◦ C),2 °C), as did as thedid sparsely the sparsely populated populated south eastsouth of theeast country of the borderingcountry bordering Oman. This Oman. distribution, This distribution, rate of temperature rate of temperature change and thechange faster and rate ofthe warming faster rate in theof summerwarming season in the issummer consistent season with is the consistent findings ofwith other the studies, findings which of other identified studies, annual which warming identified in theannual range warming of 0.0583 in◦ Cthe to range 0.125 ◦ ofC for0.0583 summer °C to and 0.125 0.0427 °C for◦C tosummer 0.0662 ◦andC for 0.0427 winter, °C depending to 0.0662 on°C thefor locationwinter, depending [19,61]. on the location [19,61]. Considering thatthat averageaverage globalglobal warmingwarming sincesince 18801880 hashas beenbeen aboutabout 11 ◦°CC[ [62,63],62,63], a 2 ◦°CC warming on average over the last 40 years in Saudi Arabia is high, placing the country in a global hotspot of localized warming.warming. This view is supported by a global application of the ECMWF data, which shows that Saudi Arabia has experienced some of the most significantsignificant warming trends on the planet over recent decades [[3].3]. When interpretinginterpreting this this result, result, it isit importantis important to keepto keep two two issues issues in mind. in mind. First, two-thirdsFirst, two-thirds of global of warmingglobal warming since 1880 since has 1880 occurred has occurred in the in past the fourpast decades,four decades, encompassed encompassed by our by study.our study. Second, Second, the temperaturethe temperature change change on land on exceeds land exceeds that of thethat oceans, of the which oceans, means which the averagemeans the global average temperature global changetemperature is lower change if the is surface lower areaif the of surface the oceans areais of included. the oceans By is comparison, included. By the comparison, land temperature the land in thetemperature Northern in Hemisphere the Northern has Hemisphere warmed by has around warmed 1.25 by◦ aroundC over the1.25 past °C over 40 years, the past based 40 years, on a linearbased trendon a linear in yearly trend average in yearly temperature average temperature data from NASA data from GISS NASA [62,63 ].GISS [62,63]. Our results make a contribution to the field by providing an assessment of local warming trends for Saudi Arabia as a whole and for key cities in different regions. This provides valuable information for utility managers and city planners responsible for infrastructure decisions that can help local populations adapt to changing climatic conditions. It also provides policymakers involved in climate discussions with a clear indication of the direction and magnitude of past temperature changes in

Climate 2020, 8, 4 18 of 25

Our results make a contribution to the field by providing an assessment of local warming trends for Saudi Arabia as a whole and for key cities in different regions. This provides valuable information for utility managers and city planners responsible for infrastructure decisions that can help local populations adapt to changing climatic conditions. It also provides policymakers involved in climate discussions with a clear indication of the direction and magnitude of past temperature changes in Saudi Arabia, and what the implications may be of trends continuing or intensifying. For example, one study has suggested that, if past trends continued, the MENA region could experience another 6 ◦C of warming in the summer months this century [20]. Such work highlights the need for adaptation strategies and increased awareness of how climate change affects Saudi Arabia.

5.2. Energy Economics and the Relationship between Temperature and Electricity Consumption This study provides a detailed assessment of the relationship between electricity generation and temperature in each of the four SEC generation regions of the Kingdom in each season of the year using hourly data. For the country as a whole, ordinary least squares (OLS) regression suggests for every 1 ◦C of warming, approximately 1.177 GW of power generation was brought on line in the seasonal transition from winter to summer. In 2015, average winter and summer loads were 28.27 GW and 49.75 GW, respectively. To check the OLS result, we can take the average winter temperature of 16 ◦C and the average summer temperature of 32 ◦C, with a differential of 19 ◦C, and compare it to the difference between average winter and summer generation. This implies around 1.13 GW is added for each additional 1 ◦C of temperature rise within the year. This is consistent with our OLS result. The result is also consistent with past work that suggested average winter electricity generation is roughly double average summer levels to handle the increased AC load [23–25]. In this context, the results of our study provide a more recent and detailed analysis. While it was beyond the scope of this study to conduct a more in-depth econometric analysis, future work could incorporate multiple years (subject to data availability) and include other variables such as humidity. Seasonal dummy variables could also be used to filter the analysis following similar approaches in studies on other countries [64–66]. Alternative functional forms such as log-linear could also be explored, given the evidence of non-linearity between temperature and electricity generation in some regions. An index approach involving cooling degree-days and humidity could also be taken as an alternative to using temperature as the main explanatory variable.

5.3. Studies on the Sustainability of Cooling in Saudi Arabia Most existing literature on the sustainability of electricity consumption in Saudi Arabia predates the significant energy price reforms that began in 2016 [35,36]. Commencing in 2016, significant energy price reforms have been complemented by the intensification of AC energy efficiency standards, stronger building regulations and enforcement, and consumer rebates for high-efficiency AC units. To our knowledge, this study provides one of the first assessments of electricity and AC trends since such measures came into effect. It also fills a gap in the literature by providing a focused analysis of the contribution of ACs to electricity demand in buildings in Saudi Arabia, the country with the highest share of AC use in household electricity consumption globally [2]. Our analysis shows that, between 2010 and 2015, growth in electricity consumption ranged between 4–10% per annum in the residential sector and by 2–18% per annum in the commercial sector. Since 2016, there has been a significant break in this trend, with residential electrical consumption falling in 2016 and showing no growth in 2017 and 2018. Commercial electricity consumption stabilized and grew at less than 1% in each year between 2016 and 2018, having fallen from even higher growth rates than residential consumption. Studies on the sustainability of electricity and cooling in Saudi Arabia have primarily focused on the amount of oil used domestically in power generation and the implications of this for oil exports [32–35]. While CO2 mitigation is seen as a co-benefit, few studies have explicitly analyzed CO2 emissions. Wogan et al. [67] is a notable exception and provides a forward-looking assessment of Climate 2020, 8, 4 19 of 25

power sector pathways to meet Saudi Arabia’s 130,000 million tonnes of CO2 (MtCO2) commitment under the Paris Agreement. While the authors do not consider AC or energy efficiency explicitly, they model a range of renewable energy, nuclear, carbon intensity and energy-price reform policy options through to 2030. The authors conclude that increasing the costs of fuel inputs would be the most effective pathway for reducing CO2 emissions, a process now underway. Our results fill a gap in the literature by providing a more detailed view of the electricity-related CO2 emissions and their drivers in the fuel mix based on historical information (2010–2018). Power sector emissions are highly sensitive to the quantities of oil products used in the generation mix, and any policy or activity that reduces the use of oil products, especially in summer, will have a significant impact on emissions. For example, in July 2013 around one million barrels per day of oil products were added to the electricity generation mix compared with January [37]. Updating this monthly analysis using data from JODI would be a useful extension to the analysis in this paper and a topic for further research. While the use of oil products fell relative to gas from 2010–2018, in absolute terms electricity generation from oil has remained constant at around 150 TWh. Future research can explore the barriers and opportunities for decommissioning old, inefficient oil-based generation capacity and substituting this with gas or renewable energy. The latter is likely to be especially important in the Western region, where gas infrastructure is limited.

6. Conclusions This paper provides an overview of climatic conditions in Saudi Arabia and analyzes temperature changes from 1979 to 2018. According to the ECMWF data, Saudi Arabia is in a global hotspot of localized warming, with average summer temperatures in some cities having risen by over 3 ◦C and by 2.8 ◦C in the capital, Riyadh during this 40-year period. Considering global average warming of 1 ◦C since 1880 and the potential for this to rise to 2 ◦C or more, the future for local summer temperatures in Saudi Arabia should be an important concern for policymakers. For example, such information is relevant for climate change adaptation strategies and can inform the development of mega projects currently underway, such as Neom, a new city to be located in the milder north west of the country, less exposed to the warming climate. That Saudi Arabia’s extreme summer temperatures are associated with large increases in electricity demand to power the country’s AC units is an expected result. What is perhaps surprising is that the share of household electricity consumption devoted to AC is so far above that of other countries with similar climatic conditions, such as the United Arab Emirates (UAE). While cultural factors such as larger living spaces and subjective perceptions of comfort may play a role in influencing this, it nevertheless highlights the potential for improvements to be made to the Kingdom’s building stock and its use of AC. Based on our review of past studies and informed by our empirical analysis, Table2 summarizes some of the main areas that could contribute to a more sustainable future for cooling in the Kingdom. Progress in reducing the CO2 intensity of the power sector, higher consumer prices, stronger AC standards, building codes and public awareness around responsible energy use have all helped put Saudi Arabia’s cooling needs onto a more sustainable path. With increasing temperatures, a growing population and an increasing area of floor space in need of cooling, Saudi Arabia represents an important case study at the extreme end of AC use. This paper fills a gap in the existing literature by drawing attention to the challenge of sustainable cooling and presenting solutions for Saudi Arabia and beyond. Climate 2020, 8, 4 20 of 25

Table 2. Summary of key areas for sustainable cooling in Saudi Arabia.

Reform Area Action Increase electricity prices. Average household Continued electricity price reform electricity prices are still ~37% of electricity prices in the U.S. and 19% of those in Australia Substitute towards gas and renewable energy and Reduce the carbon intensity of the electricity fuel mix away from more carbon intensive crude oil, HFO and diesel in electricity generation. Strengthen minimum standards and close the gap AC standards, building codes and public awareness between the average AC EER purchased and the best available EER. Apply the latest cooling and building envelopes in Urban planning, new cities and mega the design of new cities such as Neom, the Red Sea housing projects Project, and large-scale public housing developments in Riyadh. Expand district cooling. Use times of surplus District cooling and storage of cool water or ice generation capacity to chill water or ice to balance the extreme intraday swing in electricity demand. Stop sales of window AC units that are cheaper to buy and install but less efficient than split systems. Phase out and replace existing window AC units Introduce a ‘cash for clunkers’ AC program. Window units are no longer sold in many countries. Saudi Arabia has agreed to phasedown hydrofluorocarbon usage in AC units by 2028 under Phase out of HFC AC units the United Nations Kigali Amendment to the Montreal Protocol. Differential AC standards for humid versus Use the more efficient evaporative AC in dry areas dry climates such as Riyadh. Realize up to 30% energy savings with greater use of Adopt a seasonal energy efficiency rating (SEER) inverter technology or variable speed drives. Increase funding or create prizes for innovative high-efficiency AC units, and strengthen local Innovation, research and development programs manufacturing capabilities away from window units towards solar thermal and PV AC systems. Equip AC units with digital sensors that can switch SASO standards for sensors and ‘smart’ AC systems off or turn down the unit if no one is present in a room or dwelling. Collect information on the actual use and Field tests or living lab to evaluate AC performance performance of ACs in local Saudi Arabian conditions. Source: Authors, based on a literature review.

Author Contributions: N.H., paper conceptualization, literature review, writing—original draft preparation, review and editing, formal analysis—AC efficiency, annual electricity consumption, AC and CO2. N.O., data curation—ECMWF ER5 temperature and SEC electricity generation, methodology—temperature and power generation correlation, formal analysis—temperature characteristics, temperature and power correlation; writing—original draft preparation and review. T.A., data curation SEC generation, data analysis and visualization—electricity prices and household bills, writing—review and editing. A.A., investigation—household electricity and AC energy consumption. A.L., data curation and validation, methodology; formal analysis—annual electricity, AC and CO2. T.P., supervision of N.O. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Acknowledgments: The original idea for this article came from a workshop organized by Rory Jordan at KAUST on the future of cooling. The authors would like to thank the KAPSARC Data Portal team for making hourly SEC data available for the analysis. The authors would also like to thank Wardana Saputra for his help in organizing Matlab code to analyze and sort the ERA5 dataset. Chay Allen, Senior Editor at KAPSARC, also provided helpful suggestions on the text. Two anonymous reviewers provided valuable reactions and suggestions to improve the article for which we are grateful. Conflicts of Interest: The authors declare no conflicts of interest. Climate 2020, 8, x FOR PEER REVIEW 21 of 25 ClimateClimate 20202020,, 88,, x 4 FOR PEER REVIEW 2121 of of 25 25

ClimateAppendix 2020, 8A, x FOR PEER REVIEW 21 of 25 Appendix A Appendix A Appendix A

Figure A1. Total CO2 emissions for Saudi Arabia and annual percentage change (2010-2018). Source: Figure A1. Total CO2 emissions for Saudi Arabia and annual percentage change (2010-2018). Source: [56]. [56]. Figure A1.A1. TotalCOTotal CO22emissions emissions for for Saudi Saudi Arabia Arabia and and annual annual percentage percentage change change (2010-2018). (2010-2018). Source: Source: [56]. [56].

Figure A2.A2. Sectoral annual percentage change in COCO2 emissions (2011–2018) Source: [[56].56]. Figure A2. Sectoral annual percentage change in CO22 emissions (2011–2018) Source: [56].

Figure A2. Sectoral annual percentage change in CO2 emissions (2011–2018) Source: [56].

Figure A3.Figure Monthly A3. Monthly electrical electrical consum consumptionption for an indicative for an indicative household. household. Source: Source:SEC. SEC. Figure A3. Monthly electrical consumption for an indicative household. Source: SEC. Figure A3. Monthly electrical consum ption for an indicative household. Source: SEC.

Climate 2020, 8, 4 22 of 25

Table A1. Hourly temperature-power correlation coeﬃcients.

2011 2013 2014 2015

Mean annual temperature across KSA, ◦C 23.6 23.6 24.0 24.4 Mean summer temperature across KSA, ◦C 31.8 31.1 31.4 32.0 Eastern operation region Total SEC electricity production, TWh 86.7714 94.74 110.14 117.17 Total 0.874 0.883 0.905 0.905 Winter 0.139 0.104 0.411 0.341 Spring 0.807 0.819 0.839 0.857 Summer 0.609 0.601 0.564 0.590 Autumn 0.828 0.848 0.863 0.872 Central operation region Total SEC electricity production, TWh 74.6136 84.19 92.74 100.44 Total 0.845 0.834 0.861 0.856 Winter 0.045 0.052 0.069 0.054 − − − Spring 0.829 0.786 0.820 0.833 Summer 0.737 0.737 0.739 0.748 Autumn 0.796 0.816 0.844 0.874 Western operation region Total SEC electricity production, TWh 73.556 83.45 87.51 92.88 Total 0.815 0.823 0.841 0.853 Winter 0.603 0.684 0.658 0.698 Spring 0.720 0.739 0.761 0.741 Summer 0.610 0.586 0.633 0.611 Autumn 0.768 0.706 0.770 0.771 Southern operation region Total SEC electricity production, TWh 22.347 27.23 29.46 31.82 Total 0.700 0.713 0.724 0.698 Winter 0.042 0.150 0.146 0.135 Spring 0.552 0.571 0.558 0.514 Summer 0.370 0.484 0.425 0.412 Autumn 0.601 0.602 0.549 0.551

Table A2. Details of OLS regression analysis.

2011 2013 2014 2015 Eastern operation region βˆ 0.174 0.239 0.254 0.267 tStat 168.36 175.94 199.06 198.96 Central operation region βˆ 0.234 0.290 0.301 0.334 tStat 147.56 141.23 158.22 154.98 Western operation region βˆ 0.354 0.417 0.455 0.489 tStat 131.5 135.67 145.68 152.96 Southern operation region βˆ 0.064 0.075 0.086 0.087 tStat 91.729 95.217 98.306 91.229

Dependent variable: hourly power generation (GW); Explanatory variable: hourly temperature (◦C); Degrees of freedom (df): 8758 for each test of each year. Climate 2020, 8, 4 23 of 25

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