A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical and Economic Aspects: Turkey Case

*Arzuhan Burcu Gültekin and Abdullah Murat Eser* 

#### **Abstract**

 One of the biggest problems of twenty-first century is undoubtedly unrestrained increase of consumption. This increase has caused big environmental, economic, and energy crisis. At this point, the renewable resources have gained importance, although they could not reach a remarkable production level at the world scale. In this regard in this study, it is intended to highlight the importance of electricity generation from renewable energy resources in technical and economic perspectives, and create awareness among researchers, government authorities, local authorities, enterprisers, energy consultants, and public. Within the scope of this intention, the aim of this study is to comparatively evaluate the efficiency of electricity generation by solar, wind, and biomass energy in terms of technical and economic aspects. In this context, an evaluation method was developed, which contains technical and economic analyses. Solar, wind, and biomass energy that have high potential in Turkey, were evaluated comparatively according to the developed method. This comparison was focused in productivity of the resources in technical perspective and feasibility of the resources in economic perspective. Finally, the resource and electricity production potential of Turkey were mentioned, and the necessity of biomass energy was determined compared with the other resources.

**Keywords:** electricity, electricity production, electricity generation, solar energy, wind energy, biomass energy

#### **1. Introduction**

Basically, energy is the ability of doing work. As soon as the work is done, the energy will be converted to the power and the time dimension will be involved in calculations. About the electricity production and consumption, it is important to know distinction and units of the electric power and electrical energy. Watt is a unit of electric power and Wat-hour is a unit of electrical energy.

Energy resources are classified into two separate groups. The first one is primary energy resources, which exist in nature originally such as solar, wind, biomass, hydroelectric, and wave. This type of energy resources can be used directly or indirectly after converting into another energy form. The other type of energy, which is named as secondary energy resources, can be obtained as the result of

energy cycles, and they can be used as energy resources in this form. These energy resources are electrical energy, heat energy, mechanical energy, and so on [1].

The renewable energy is a definition that, in fact, refers to resources. It means that these resources can be renewed in nature sustainably. This feature of the renewable energy brings it eco-friendly and economically viable features, too. The energy cycle, yields, losses, transmission, and storage processes are related with the purpose and the location of the energy used, not with the type of resource. For example, the basic principles of generating electricity from nuclear, fossil, and biomass energy resources are the same and they are all given to the system without any separation until the load part. At this point, the important subject to be emphasized should be the cycle of energy.

Consumption takes part in much in the twenty-first century agenda. Consumption of the resources until the end means the system also consumes itself. While the system is consuming itself, at the same time the world, which is habitat of human, is also being consumed. The system produces consumption elements by consuming. Changing the consumption habits of the system can be achieved by not stopping the consumption, but by replacing the consumed resources. At this point of view, if the energy, which is the main element of production and work, could be put back after consuming, the system will change format within. Hereby, the electricity generation can be provided continuously, and the first step of the system change would be achieved. In this regard, the main questions of this study are how electricity can be generated continuously, which resources should be used, and which cycles should be preferred.

The renewable energy resources are not only solar, wind, and geothermal, at the same time there are biomass energy resources that do exist in nature. Biomass can be defined as total of live organism mass in an ecosystem and this mass has an energy, which is named as biomass energy. Biomass energy has many advantages over other energy types and these advantages could make this energy type be used for electricity generation efficiently instead of the other ones. Availability, continuity, and commonness are main advantages of biomass energy. This energy type has some disadvantages, such as process problems and transporting. Generating electricity from biomass energy does not contain high risk as nuclear energy, however it has nearly the same risk as solar and wind energy. The only method of generating electricity is not to use renewable resources, and it cannot be mentioned that the biomass energy is the only and the most efficient resource about generating electricity.

In this study, it is intended to create awareness for the importance of electricity generation from renewable energy resources in technical and economic perspectives, and to set light to researchers, government authorities, local authorities, enterprisers, energy consultants, and public. The aim of this study within the scope of this intention is to comparatively evaluate the efficiency of electricity generation by solar, wind, and biomass energy in terms of technical and economic aspects. In this context, an evaluation method was developed that contains technical and economic analyses in this study. Solar, wind, and biomass energy that have high potential in Turkey, were evaluated comparatively according to this method. This comparison focused in productivity of these resources in technical perspective, and feasibility of these resources in economic perspective.

#### **2. Renewable energy resources**

Renewable energy is the energy, which is obtained from the existing energy flow in the ongoing natural processes. In general, the renewable energy resource is defined as being equal to the energy taken from the energy resource or renewing

#### *A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical… DOI: http://dx.doi.org/10.5772/intechopen.87836*

itself more quickly than the exhaustion rate of the resource [2]. Solar energy, wind energy, biomass energy, geothermal energy, and wave energy are the types of renewable energy resources. In this study, three kinds of energy types as solar, wind, and biomass were taken into account for comparison.

Electrical energy gains meaning after usage. However, this energy, which is used, must have a source, a certain cost, the manner of obtaining it, and positive or negative effects. While energy is being consumed, it is not known how it was produced and which processes were occurred, and by nature of consuming it is also not expected to be known. Regarding electricity generation, as desired in all areas, maximum efficiency, minimum loss, low cost, and sustainability of this situation are expected. As known, this situation can be provided with renewable energy resources.

Although the efficiency for electricity generation is at the forefront, the issue in front should be sustainability, as the existence of electricity is more important than the cheapness of electricity generation. If mankind is considered not to abandon electricity at any future stage of technology development, the first necessity of electricity generation would be sustainability. From the perspective of sustainability, renewable energy resources, which can be used generating electricity, are not limited. Renewable energy types can be diversified with the development of technology over time.

#### **2.1 Solar energy**

 Solar energy is known as the source of life. All kinds of living beings live with the existence of the sun. In this case, it is irrational to deny solar energy benefits for the technology. The solar energy is used for electricity generation with the help of photovoltaic panels. These panels behave as small power plants, when the sunlight reaches the surface of the panels. At that time, a little technical problem occurs with the obtained energy. This type of electricity has direct current and it must be converted to alternative current before used in network. Therefore, a few more types of equipment are required. In 2015, 0.3% of installed power belonged to solar energy in Turkey. When it came to 2016, 1.1% of the installed power of Turkey and in 2017 nearly 4.0% had been provided by solar power plants. Lastly, according to registered values, until the middle of 2018, 5.4% of the installed power had been belonged to solar energy. These values state for a graphic, which is sharply increasing after 2017 to today [3, 4].

#### **2.2 Wind energy**

 Wind energy is not like solar energy regarding the availability. In fact, wind can be seen in every season anywhere. However, when generating electricity from wind, continuous and high potential wind are required. This type of winds cannot be found everywhere. To evaluate the wind energy potential of a region, variety of scales can be used. In 2015, 6.2% of installed power had been provided by wind power plants in Turkey. As the advancing years are analyzed, in 2016 7.3% of the installed power of Turkey, and in 2017 nearly 7.8% had been provided by wind power plants. Lastly, until the middle of 2018, according to registered values, 7.7% of the installed power had been provided by wind power plants. These values mean that after 2016, electricity generation from wind maintain stable, when it is compared to installed power [3, 4].

#### **2.3 Biomass energy**

Biomass can be defined as the live mass formed as a result of photosynthesis. Plants can be calculated as biomass to the extent that they retain their biological

 properties after death. This definition is only about plants. In general, it can also be defined as the total mass of living organisms belonging to a species or a society of various species at a given time [5]. In 2015, less than 0.5% of the total installed power, and in 2016 less than 0.7% had been provided by biomass energy in Turkey. The ratios had been nearly the same in 2017 and 2018. Lastly, until the middle of 2018, according to registered values, 0.73% of the installed power was belonging to biomass energy. These values state that biomass energy and its benefits have not been understood in Turkey yet [3, 4].

#### **3. Comparative evaluation on the efficiency of electricity generation by solar, wind, and biomass energy in terms of technical and economic aspects**

Turkey's electricity generation capacity for 2017 was declared as 87,139 MWe, and generated electricity as 295.5 TWh. It is expected that, in 2023, Turkey's estimated electricity generation will be 385 TWh, and the electricity generation capacity is calculated as 113,531 MWe according to this capacity (**Table 1**) [6].

 About 34.14% coal, 29.53% natural gas, 20.08% hydro electrical, 10.81% wind energy, 2.59% solar energy, 1.83% geothermal, and 0.60% biomass energy were used to generate electricity in Turkey on the date of 04.08.2018 [3, 4]. In order to compare the efficiency of these energy resources, it is envisaged that a specific comparative evaluation method would be beneficial.

#### **3.1 Evaluation method**

 An evaluation method was developed in this study in order to comparatively evaluate the efficiency of electricity generation by solar, wind, and biomass energy in terms of technical and economic aspects. In this context, the method contains technical and economic analyses. Solar, wind, and biomass energy potential of Turkey were evaluated comparatively according to the developed method. Objective, practical, internationally valid data, as well as Turkey specific daily values, were used in the comparison. The comparison was focused in productivity of the resources in technical perspective, and feasibility of the resources in economic perspective.

The evaluation method proposes two different approaches. The first approach, which can be defined as *"capacity coverage ratio"*, measures the ratio of the resource's generation capacity to the country's electricity generation capacity. The second approach that can be defined as *"full capacity production ratio"* measures how much of the capacity of the resource will be sufficient for the whole production of the country.

The first approach is related to the production capacity of Turkey. It is aimed to determine the production capacity percentage in case all the resources were used for generating electricity. Electricity generation capacity of the solar power plants varies directly with the surface area of the photovoltaic panels. Accordingly, in the second approach, it was assumed that the criterion for electricity generation from


**Table 1.** 

*Turkey's electricity generation capacity electricity generation over years [6].* 

*A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

solar energy is the land area. Wind energy was found to be insufficient, therefore it was not taken into account in the second approach. Besides, electricity generation from biomass power plant is directly related to raw materials, for this reason, the resources are considered as the criterion of capacity of biomass power plant. The results of the both approaches were evaluated at the conclusion section of the study with technical and economic results.

#### **3.2 Assumptions for comparative evaluation**

In this section, efficiency, capacity, capacity coverage ratio, and full capacity production ratio were compared for three resource types. For comparison, assumptions for evaluation of solar energy, wind energy, and biomass energy, which constitutes the base of this study, were developed (**Table 2**). In this context of assumptions, rates of daily, monthly and annual electricity production, and revenues from electricity generation are determined [7].

*3.2.1 Comparative evaluation of solar, wind, and biomass energy in terms of technical aspects* 

#### *3.2.1.1 Evaluation of solar energy in terms of technical aspects*

 In this section, the PVGIS software data of The European Commission's "Institute of Energy and Transportation (IET)" website were used. This website shares and provides instant, accurate, and valid data without international access restrictions [8].

For the solar analysis, five different points were selected at the south of Konya city and monthly solar radiation data for these points were collected from PVGIS. Selected five points were Beyşehir Karahisar, Çumra Türkmencamili, Ereğli Kutören, Seydişehir Akören, and Karaman Dinek, respectively.

Radiation time, which expresses hours suitable for generating electricity from solar energy, was an important data set for solar power plants at the first stage of the solar analysis. At the second stage, the significant issue is the capacity factor, which was calculated as "6.97/24 = 0.2904 (29.04%)" by the formula of *radiation time*/*24 hours* (**Table 3**).

Sum of the daily values for each day of every month was calculated, and noted as the value of the related month. Factors affecting the output performance of the solar panels can be classified in three categories. The first factor is the efficiency of the solar panels (71.56%), which is about the working mechanism of the panels. The efficiency was calculated as "715.59/1000 = 0.7156" by the formula of *production*/*production capacity* (**Table 3**). The second factor, which is about energy type (29.04%), is the capacity factor as above mentioned. The last factor, which depends on every issue about solar power plants, is the performance of the solar panels. This performance was unpredictable in this study, and it was assumed as 90.00% [2].

All calculations were made for 1000 kWh solar power plants. All error and loss values were reflected in the results (**Table 3**).

According to **Table 3**, 1000 kWe or 1 MWe capacity solar power plant produces 1,599,906.98 kWh (approximately 1.6 GWh average) electrical energy per year.

#### *3.2.1.2 Evaluation of wind energy in terms of technical aspects*

In Turkey, it is estimated that there is at least 5000 MW electricity potential in regions with a minimum wind speed of at least 7.0 m/s. Besides, a minimum of 48,000 MW electricity potential is estimated in regions with a minimum wind


#### **Table 2.**

*Developed assumptions for comparative evaluation.* 

speed of at least 8.5 m/s. In this case, wind potential can be calculated as 12 billion kWh per year. However, 12 billion kWh potential annual means 4.06% of all demand of Turkey's 2017. Same value corresponds 3.12% of all Turkey's 2023 demand [2, 9].

#### *3.2.1.3 Evaluation of biomass energy in terms of technical aspects*

 The population of Turkey as of 2017 was 79,814,871. The waste amount of this population and the energy values of these wastes, which were published by Turkish Republic General Directorate of Renewable Energy, are presented in **Table 4**. In case of meeting all necessary conditions, electricity generation from these resources


*A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Table 3.**

*Electricity generation of a solar power plant [2, 8].* 

 is possible with various efficiency levels. In this section, evaluation was made with the total energy in a general framework without any resource separation.

According to **Table 4**, total energy equivalent of waste in 2017 was 44,228,796 TOE per year. 1 TOE equals to 11,627 kWh electrical energy, when appropriate conditions are provided [10], which means 44,228,795 × 11,627 = 514,248,199,465 k Wh of electrical energy. Thus, if the mentioned amounts of wastes had been used, 514.25 TWh of electrical energy could have been generated in 2017. Furthermore, the electricity generated would be equal to 1.74 times that of Turkey's 2017 electricity production.

 As for the efficiency matter, it would be at least 30% even if the most primitive system (boiler—steam turbine system) is used to generate electricity from biomass. If it is considered that working period is 8760 hours per year, the minimum electricity production of Turkey would be 154,274,459,800 kWh in 2017. Besides, the generated electricity would be equal to 52% of the Turkey's 2017 electrical energy production [10].

 From the view of "full capacity production ratio", Turkey's land area is nearly 783,562 km2 and 2017 electricity generation of Turkey was 295.5 TWh (295,500 GWh). In this study, it is assumed that 20,000 m<sup>2</sup> land area is


#### **Table 4.**

*Biomass resource (waste) potential of Turkey [2].* 

#### *ISBS 2019 - 4th International Sustainable Buildings Symposium*

sufficient to generate 1.6 GWh electrical energy annual (**Table 3**). In this case, 295,500/1.6 = 184,688 power plants or 184,688 × 20,000 m<sup>2</sup> land area is required. It means 3693.76 km2 land area corresponds only 0.47% of Turkey's land area. As for 2023 production of Turkey, it corresponds 0.61% of Turkey's land area.

In **Table 5**, output capacities were illustrated for each energy type with electrical power values (kWe), and percentage values. Generated electrical energy (kWh) and average income (USD) were also illustrated in the table concurrently. These values constitute a perspective for each energy type at first step. Annual


#### **Table 5.**

*Technical and economic values of each type of plants [2, 6–9, 11].* 

*A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical… DOI: http://dx.doi.org/10.5772/intechopen.87836* 

electricity production of biomass energy power plant was nearly three times of the other types of power plants. Moreover, wind energy had better performance than solar energy in electricity production. When the subject was annual income, the ranking changed. However, all these data does not make everything clear, since investment and annual costs of the biomass energy plants are much more than the others. Consequently, the necessity of making a financial evaluation was appeared. Data related to capacity, production, sufficiency, and cost of each power plant are presented in **Table 5**.

#### *3.2.2 Comparative evaluation of solar, wind, and biomass energy in terms of economic aspects*

In terms of economic aspect, it is not possible to carry out operations on behalf of efficiency analysis without using the cost and income values. Therefore, appropriate studies were carried out by using valid economic values in this section. Additionally, valid interest rates and USD LIBOR values are used for all financial calculations via the necessary financial data given in **Table 6**.

 In the economic evaluation, it is accepted that three methods as "internal rate of return (IRR), modified internal rate of return (MIRR), and discounted payback period" should be used as economic analysis method [14]. In the first method, capital's rate of return can be evaluated according to "Weighted Average Capital Cost (WACC)." This means, the investment is profitable, when IRR is greater than WACC and it can be applicable under the conditions mentioned. This method can be used for the project's feasibility itself. In the second method, in addition to the previous method, roughly, capital replacement cost is considered. This method can be used for comparative evaluation of the power plants. In the last method, different from the others, discounted payback period was calculated in order to determine how many years it will take for capital to come back. Time value of money was considered in this method.

Three investment scenarios were created and IRR, MIRR, and payback period values were separately calculated for each investment scenarios. The following three investment scenarios were considered in the financial evaluation:

Scenario 1. 100% equity capital.

Scenario 2. 90% equity capital and 10% debt.

Scenario 3. 50% equity capital and 50% debt.


#### **Table 6.**

*Financial data and assumptions for comparative evaluation [7, 12, 13].* 


#### **Table 7.**

*Results of financial evaluation.* 

 The evaluation results were obtained after using the above-mentioned three methods and making the necessary financial calculations. The related results were presented in **Table 7**.

#### **4. Conclusions**

As a result of comparative evaluation of solar, wind, and biomass energy in terms of economic aspects, financially the most efficient resource was determined as solar energy. In terms of biomass and wind energy, it was observed that biomass was close to solar energy and wind energy had the lowest performance.

 From the view of "capacity coverage ratio," biomass resources were determined as sufficient to provide 52.21% of Turkey's installed capacity as of 2017. It was also observed that biomass resources are sufficient to provide 40.07% of Turkey's estimated installed power as of 2023. Besides, it can be stated that solar energy potential is sufficient to provide all demand of Turkey's 2017 and 2023. Wind energy was determined to provide only 4.06% of Turkey's installed capacity as of 2017. It was also observed that wind energy could provide only 4.06% of Turkey's installed capacity as of 2017, and can provide only 3.12% of the demand as of 2023.

At this point, it is important to say that, the lifetime of solar power plants and biomass power plants were assumed as 25 years in order to make more effective comparison. Solar power plants are guaranteed for 25 years by producers and distributors; however, the lifetime of biomass power plants are in general more than 25 years (nearly 40–50 years). Actually, lifetime expectancy for biomass power plants is estimated to occur more than the assumption of this study. The estimated expectancy would increase cashflows, IRR, and MIRR percentage values in favor

#### *A Comparative Evaluation of Solar, Wind, and Biomass Energy in Terms of Technical… DOI: http://dx.doi.org/10.5772/intechopen.87836*

of biomass power plants. Therefore, this increase could ensure the biomass power plants be preferable instead of solar power plants for Turkey.

It was ascertained that, in first and second scenarios of IRR and MIRR methods, biomass power plants were more effective than the others in terms of economic aspects. IRR was calculated as 15.04% and MIRR as 6.90% when focused on the results of scenario 2. In this case, the above-mentioned values gained meaning when the discounted payback period was calculated as 5 years and 4 months.

 From economic perspective, although solar and wind power plants do not need raw materials to produce energy, they remained behind the biomass energy. The point to note in this case is that solar and wind energy are both environmentally friendly and they do not have the cost of raw materials. In spite the fact that biomass power plants require raw materials, and more expenditure than solar and wind power plants, it remained superior to the others in terms of technical and economic aspects. This case, which stems from the productivity of biomass, can be converted into an advantage for electricity generation in Turkey. As there are many kinds and big amounts of biomass resources in Turkey (see **Table 4**), it is possible to generate electricity at various efficiency levels from these resources.

 The resources used by biomass energy to generate electricity are the waste of people or nature. When they are not used to generate electricity or anything else, it is a fact that they will remain idle in nature. Likewise, when they are not recycled, they will disrupt the ecosystem and will cost a lot to be stored or transported. In this case, it will be extremely productive to re-use these wastes that have negative impacts on humanity and consumption through completely natural methods.

In this context, it is of great importance for the government, related sectors, the investors, and the researchers to consider the contribution of biomass power plants to the environment and the economy. Moreover, it is essential to accelerate biomass power plant investments in Turkey for achieving energy efficiency in terms of technical and economic aspects.

#### **Author details**

Arzuhan Burcu Gültekin\* and Abdullah Murat Eser Department of Real Estate Development and Management, Ankara University, Ankara, Turkey

\*Address all correspondence to: arzuhanburcu@yahoo.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Koç E, Şenel MC. The state of energy in world and Turkey. Engineer and Machine. 2013;**639**(54):32-44

[2] General Directorate of Renewable Energy. Republic of Turkey Ministry of Energy and Natural Resources [Internet]. 2019. Available from: http://www.yegm.gov.tr/anasayfa.aspx [Accessed: January 5, 2019] (in Turkish)

[3] Turkey's Electricity Distribution Corporation (TEDC, TEDAŞ) [Internet]. 2019. Available from: http:// www.tedas.gov.tr/#!tedas\_anasayfa [Accessed: January 5, 2019] (in Turkish)

[4] The Chamber of Electrical Engineers (UCTEA, EMO) [Internet]. 2019. Available from: http://www.emo.org. tr/ekler/34427e6be0fae4a\_ek.pdf [Accessed: January 7, 2019] (in Turkish)

[5] Topal M, Arslan IE. Biomass energy and Turkey. In: VII National Clean Energy Symposium UTES'; 17-19 December 2008; İstanbul, Turkey (in Turkish). 2008

[6] Republic of Turkey Ministry of Energy and Natural Resources. [Internet]. 2018. Available from: http:// www.enerji.gov.tr/tr-TR/Sayfalar/ Elektrik [Accessed: November 2, 2018] (in Turkish)

[7] Erkeç M. Unlicensed electricity generation in Turkey and legal regulations about renewable energy. In: 6. Energy Efficiency, Quality Symposium and Exhibition; 5 June 2015; Sakarya, Turkey: Sakarya University (in Turkish). 2015

[8] PVGIS. Photovoltaic Geographical Information System, Institute for Energy and Transport (IET) [Internet]. 2019. Available from: http://re.jrc. ec.europa.eu/pvgis/ [Accessed: January 5, 2019] (in Turkish)

[9] Yılmaz M. The energy potential of Turkey and its importance of renewable energy sources in terms of electricity production. Ankara University Journal of Ecology. 2012;**4**(2):33-54 (in Turkish)

[10] Özcan M, Öztürk S, Yıldırım M, Kılıç L. Electricity energy potential of different biomass sources based on different production technologies. In: ELECO' 2012, Electrical-Electronics and Computer Engineering Symposium; 29 November-1 December 2012; Bursa, Turkey (in Turkish). 2012

[11] Mutlular Biomass Power Plant [Internet]. 2018. Available from: http:// midseff.com/tr/factsheets\_tr/mutlular. pdf [Accessed: November 2, 2018] (in Turkish)

[12] Republic of Turkey Ministry of Energy and Natural Resources [Internet]. 2019. Available from: https://www.tcmb.gov.tr/wps/wcm/ connect/TR/TCMB+TR/Main+Menu/ Temel+Faaliyetler/Para+Politikasi/ [Accessed: January 5, 2019] (in Turkish)

[13] Central Bank of the Republic of Turkey (TCMB) [Internet]. 2019. Available from: https://www.tcmb.gov. tr/wps/wcm/connect/TR/TCMB+TR/ Main+Menu/Temel+Faaliyetler/ Para+Politikasi/ [Accessed: January 5, 2019] (in Turkish)

[14] Gedik T, Akyüz KC, Akyüz İ. Preparation and evaluation of the investment projects (analyzing the methods of internal return and net present value). ZKÜ Bartın Journal of Faculty of Forest. 2005;**7**(7):51-61 (in Turkish)

#### **Chapter 54**

## Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel

*John O. Onyango and Nea Maloo* 

#### **Abstract**

 An interest in energy consumption in building and associated carbon dioxide emission has been increasing. The hospitality industry consumes vast amounts of energy even during periods when buildings are not occupied, and it was estimated that almost a quarter of total energy is used for cooling during hot season, while almost two-thirds of total energy demand is for space heating in the winter. The demand and use profile varies depending on climatic location. The openings such as door and windows are a source of unregulated energy loses and the design and detailing affects this. This chapter reports on the analysis of results of experimental work and numerical simulation of a typical mid-chain hotel in cold climate of midwest USA, and compares it with measured data from sample rooms. It reveals that the design of the window seal, reveals, location of curtain within the space affects the performance of the space cooling device, and comfort of occupants. It suggests that the hotel industry could save vast amounts of energy costs in addition to reducing the carbon emission and raising corporate profiles with expensive retrofitting.

**Keywords:** energy consumptions, cooling, hotels, window design, sustainability

#### **1. Introduction**

On average, there were 4.8-million guests each night staying in hotel rooms in 2015 [1]. Hotel rooms are enclosed spaces that create adequate comfortable thermal microclimate achieved mostly through use of HVAC systems. The most important factors for comfort in rooms are temperature of the room air, surfaces of surrounding walls, windows, and heating surfaces. Studies of energy consumption profiles of hospitality industry reveal that on average, hotel guest room reveal that they account for 40–80% of total energy use, but for those that cater for high-end guest, the consumption is 50–70 kW and for the luxurious guest rooms more than 80 kW per day [2].

Literature review on research on indoor thermal conditions have been carried out using finite elements to study the characteristics of laminar and turbulent air flows, two-dimensional numerical prediction, and computational fluid dynamics (CFD) among others methods [3–5]. ASHRAE 55 Thermal Comfort using PMV with acceptability rate of 80 recommends that indoor operative temperatures should be in the range of 23.3 and 30.3°C at relative humidity of 80% [6]. It has been shown that a 1–4°C thermostatic setback results in a reduction in energy

demand response savings of 5–12% [7]. For cold climates, energy the reduction per °C which is 5.4% of total annual [8]. Hotel facilities present abundant opportunities for energy savings. In 2007, there were over 25,000 hotels in the United States, that annually spend an average of \$2196 on energy costs per room that amounts to about 6% of the total annual hotel operating cost [9].

Most budget level hotels such as Quality Inn, Super-8, Wyndham, Fairfield Suites all use window-based packaged terminal air conditioner (PTAC) for heating and cooling (**Figures 1** and **2**). However, these types of units do not have great demand response, thermostatic systems (**Figure 3**) is an example of a packaged terminal air conditioning that has capacity of 0.6 tons or 7000 BTU of cooling and 3 kW electrical heater (12.2 EER, 230 V) heating. They are typically installed through the wall below the window and even though they are installed close to bed location, the room may appear comfortable, however at what cost to the environment? It was estimated that hotels emit an equivalent of 10 tons of CO2 per bedroom per year [10].

 The use of PTAC units in hotels is common because of their low initial costs and simplicity of the systems. The design and location of PTAC units within the wall

**Figure 1.**  *External view of super 8 in South Bend, IN [11].* 

**Figure 2.**  *External view of quality inn & Suites in South Bend, IN [12].* 

*Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 3.**  *Typical packaged terminal air conditioner (PTAC) [13].* 

results in inefficiencies dues to factors that could lead to excessive energy consumption, typically left running in unoccupied rooms, unless a good energy management systems is in place. This is unlikely as hotels tend to keep rooms cool, so room service personnel would always turn them on if they found them off.

#### **2. Methodology**

The objectives of this study were firstly, to understand the thermal environment in typical hotel bedroom, secondly to look at the impact of the location and design of window-based PTAC on the thermal environment and energy consumption, and finally to suggest simple design retrofits to reduce energy consumption and impacts of the various retrofits strategies. The hotel room is similar in size and configuration to illustrations in **Figures 4** and **5**. The work discussed here involved logging of energy use recording of the PTAC window unit over 24-hour period with the curtains as designed and repeated with the curtains placed tight along the window. It was undertaken using a three-channel PicoLog CM3 data logger with accuracy within ±1% and uses industry-standard clamps and was connected to Mac OS via

**Figure 4.**  *Typical guest room.* 

**Figure 5.**  *Typical guest room plan [14].* 

USB (**Figure 6**). The clamp on data loggers measure the AC circuit currents and voltage in a non-invasive manner without breaking the circuit being measured. Data were acquired using the PicoLog 6 data logging software. The electrical consumption data from the HVAC circuit was captured every 5 minutes for 24 hours period which were then used to obtain the averages values of the voltages and currents, that is related to mean square root voltage as given in equation (1). The voltages were calculated using the mean square root (RMS) of the logged periodic voltage then used to calculate the electrical consumption in kilowatts (kW) with the current data.

$$Vrms = 1.11\text{ V}\,\text{ave}\tag{1}$$

where *Vrms* is theroot mean square value of the AC voltage; *Vave* is the logged average AC voltage.

**Figure 6.**  *PicoLog CM3 data logger [15].* 

*Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 7.**  *Air quality CO2 + RH/T data logger [16].* 

In addition, IEQ data were recorded using air quality 1% CO2 + RH/T environmental data logger at the following locations: air exit of the PTAC, at 36″ above the floor near the bed head and at thermostat location (5′-0″). Data were acquired from the logger and viewed using GasLab® software (**Figure 7**).

#### **3. Results and discussion**

 **Figures 8** and **10** are thermal images of the room close to the window where the PTAC is located. It can be noticed that in **Figure 8**, the curtains have not sacked in air being discharged from the PTAC unit and the temperature distribution is fairly uniform. However, **Figures 9** and **10** reveal the effect of discharged air being sacked into the window curtains, thereby affecting the thermal environment of the room. It can be noted that the budge in the curtain has a lower temperature hue than in same area in **Figure 8**, indicating cooler air being trapped and thereby affecting the distribution and overall thermal environment of the room. This not only results in inefficiency in use through trapped cool or warm air in fairly well insulated curtains, but also in temperatures being higher for same thermostat settings. As a result, the room occupants would respond by either changing the thermostatic setting or the PTAC units needing to continue working harder to try and meet the comfort setting of the occupant.

 The thermostat of the PTAC unit was set to 74° F, however, the IAQ data for room at the unit, at bed head, and at back wall at 5′-0″ were 75.2° F, 78% RH; 72.1° F, 81% RH; and 76.4° F, 71% RH, respectively. The average temperature and humidity values for the room were 74.6° F and 76.7%. **Tables 1** and **2** are extracted from measured data that show that the hourly energy consumption for the PTAC unit at one of the sampled hotel room is 13.63 kW. The consumption if the window is designed to include either a longer window sill that would stop air being sucked into the curtains, the consumption is 12.82 kW.

The above results were snap short of the data, however over longer period of 24-hours, they were 327.12 and 307.92 kW, respectively, if the system was running

**Figure 8.**  *Thermal image of room + window.* 

**Figure 9.**  *View of window with air sucked in.* 

*Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Figure 10.**

*Thermal image of window with air sucked in.* 


#### **Table 1.**

*Hourly energy consumption (kW).* 

 over that period. The reality is that, it runs intermittently and sometimes overridden by the user, in our case, we turned it off during the day when we were away, hence the number is representative of a period of 12 hours very close to what literature review indicates.

The equivalent to energy reduction was therefore between 5.9 and 6.21%, if a simple scheme that would keep the curtains from sucking in air being emitted from the PTAC unit was installed as was done at the Microtel by Wyndham Hotels in South Bend (**Figure 11**) and as proposed by authors (**Figure 12**).

One could potentially resolve the issue by mounting the PTAC unit a little forward by say 4″ into the room; another strategy would be to fix the unit at a


#### **Table 2.**

*Hourly energy consumption (kW).* 

**Figure 11.**  *Double queen room with modified window sill [17].* 

lower position leaving a space between the top of PTAC unit and the window sill which should also be extended to block air from being sacked into the curtains (**Figure 12**).

The first option is limited by the depth of the unit (11-1/4″) which fits a typical wall construction. In the second strategy, which is an easy design option may result in some air being trapped in the curtain, but definitely an improvement to the original design. **Figures 12** and **13** illustrates strategies 3 that involves extending the window sill without changing position of the PTAC unit. Even though it results in air not being sacked into the curtain, it will, however impact the distribution of air through the room and affect the thermal comfort and introduce drafts and vertical temperature differentials between the feet and the head locations. Strategy 4 is optimum solution that involves both lowering the location of PTAC unit and extending the window sill. It will result in better temperature distribution as well as ensuring air is not sacked into the curtains. The authors acknowledge the limitation of the study did not include testing the energy reduction using the various strategies and will be looking at this over next 12 months using CFD modeling and analysis in IESVE as well physically testing them in hotels here in South Bend Indiana, USA.

*Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **Figure 12.**

*Sketches of Modified Location of PTAC [18].* 

**Figure 13.**  *Sketches of Modification to Window Sill [19].* 

#### **4. Conclusion**

 Literature review indicated that the high-end guest rooms consumed between 50 and 70 kW per day [2] and that the reduction noticed using modified design was between 5.9 and 6.2% translating to energy savings of approximately 3 kW daily. The impact across the many rooms in the 25,000 hotels is enormous and perhaps it is high time hotel industries consider their commitment to sustainability through energy consumption by simple upgrades to their window sill design.

#### **Acknowledgements**

 This work would not be possible without support of the funds provided by the Dean School of Architecture at University of Notre Dame & Dean College of Architecture and Engineering, Howard University.

#### **Conflict of interest**

We neither have to our best knowledge any conflict of interest in work presented in this chapter, nor do we promote any particular proprietary product or processes.

#### **Author details**

John O. Onyango1 \* and Nea Maloo2

1 School of Architecture, University of Notre Dame, Indiana, USA

2 College of Engineering and Architecture, Howard University, Washington, D.C., USA

\*Address all correspondence to: jonyang1@nd.edu

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Analysis of Impact of Window Design Detail on Energy Demand Profile of Typical Hotel DOI: http://dx.doi.org/10.5772/intechopen.87836* 

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[18] Onyango JO. Sketch of Modified Location of PTAC; 2019

[19] Onyango JO. Sketch of Modification to Window Sill; 2019

#### **Chapter 55**
