Enhancing Urban Sustainability with Novel Vertical-Axis Wind Turbines: A Study on Residential Buildings in Çeşme

Abstract

This study investigates the integration of three types of vertical-axis wind turbines (VAWTs)—helical, IceWind, and a combined design—on residential buildings in Çeşme, Türkiye, a region with an average wind speed of 7 m/s. The research explores the potential of small-scale wind turbines in urban areas, providing sustainable solutions for renewable energy generation and reducing reliance on conventional energy sources. The turbines were designed and analyzed using SolidWorks and ANSYS Fluent, achieving power outputs of 350 W for the helical turbine, 430 W for the IceWind turbine, and 590 W for the combined turbine. A total of 42 turbines were mounted on a five-storey residential building model, and DesignBuilder software was utilized to simulate and evaluate the energy consumption. The baseline energy consumption of 172 kWh/m² annually was reduced by 18.45%, 22.93%, and 30.88% for the helical, IceWind, and combined turbines, respectively. Furthermore, the economic analysis showed payback periods of 12.89 years for the helical turbine, 10.60 years for the IceWind turbine, and 10.49 years for the combined turbine. These findings emphasize the viability of integrating VAWTs into urban buildings as an effective strategy for reducing energy consumption, lowering costs, and enhancing energy efficiency.

1. Introduction

The increasing urgency of environmental sustainability has driven significant interest in renewable energy and energy-efficient technologies within urban infrastructure. Vertical-axis wind turbines (VAWTs) have emerged as a promising solution to enhance energy efficiency in buildings, particularly within urban areas where spatial constraints and wind variability are major considerations. In contrast to traditional horizontal axis turbines, VAWTs are suitable for urban settings because they can capture wind from multiple directions, which is essential in city environments where wind patterns are disrupted by high-rise buildings [1].

Building energy consumption is a major contributor to global greenhouse gas emissions, with the construction sector accounting for about 36% of worldwide energy use and nearly 40% of energy-related carbon dioxide emissions [2]. Integrating renewable energy systems, such as VAWTs, into buildings aligns with global sustainability goals by reducing reliance on fossil fuels and decreasing carbon emissions [3]. For instance, the incorporation of VAWTs can significantly lower the energy demand from the grid, contributing to a more sustainable urban energy profile [4].

The economic viability of VAWTs is particularly noteworthy. Studies highlight that these systems generally require lower maintenance and have long lifespans, making them a cost-effective option for urban areas with limited space for renewable installations [5]. Additionally, supportive policies and incentives enhance the feasibility of deploying VAWTs. Government incentives, such as tax credits can offset initial installation costs, making renewable energy adoption more accessible for building owners [6].

Moreover, integrating VAWTs into urban structures addresses the critical need for sustainable building practices. As cities continue to grow, adopting technologies that lessen environmental impacts and enhance energy efficiency becomes increasingly essential [7]. Projects like the Bahrain World Trade Center, which integrates wind turbines into its design, demonstrate the effectiveness of incorporating renewable energy within architectural frameworks [8]. This approach not only addresses immediate energy demands but also aligns with long-term sustainability objectives by decreasing overall energy dependency [9,10].

Furthermore, advancements in VAWT technology have improved their efficiency and adaptability, making them more suitable for integration into existing buildings [11,12,13]. Innovative designs and materials have led to quieter operation and better performance at lower wind speeds, which are common in urban environments [14,15]. These developments enhance the practicality of VAWTs as a renewable energy solution for cities, contributing to global efforts to combat climate change [16,17,18,19].

Figure 1 presents a comprehensive projection of energy demand in the building sector from 2022 to 2050, focusing on energy sources and end uses under various scenarios. The data underscores the increasing importance of renewable energy, particularly in the Net Zero Emissions (NZE) scenario, where modern solid biomass, electricity from renewables, and other low-emission sources take precedence. By 2050, renewable energy sources will play a critical role in reducing dependence on fossil fuels and supporting global efforts to achieve carbon neutrality. Specifically, the shift toward renewables is evident in electricity demand for appliances and space cooling, emphasizing their central role in driving sustainability in the building sector.

The use of combined vertical-axis wind turbines (VAWTs) in urban and residential applications has emerged as a promising strategy for improving energy efficiency and sustainability. Researchers have explored innovative designs, advanced simulation techniques, and experimental approaches to optimize turbine performance and integrate them effectively into buildings. The following review discusses key studies that explore the potential of combined VAWTs and their impact on energy consumption in various settings.

Turhan and Saleh [20] examined the use of small-scale IceWind turbines to reduce building energy consumption. Integrating 40 three-blade turbines with a 112° arc angle into a building at Istanbul Airport, they achieved a 9.3% reduction in annual energy use through simulations. This study demonstrates the effectiveness of such turbines in urban settings and highlights their potential for enhancing energy efficiency in buildings. Saleh et al. [21] explored rebuilding energy-efficient buildings in Hatay, Türkiye, after the 2023 earthquake. They integrated vertical-axis wind turbines, PV panels, and green walls into a five-storey building, using simulations to measure energy savings. Results showed reductions of 18% with PV panels, 8.5% with wind turbines, and 4.1% with green walls, totaling 28.5% when combined, highlighting the potential of these strategies in sustainable reconstruction. Saleh et al. [22] also evaluated the energy-saving and economic viability of installing two types of small-scale VAWTs, the IceWind and Savonius turbines, on a residential building in Karaburun, Izmir. Through simulations, they found that 15 Savonius turbines achieved a 36% reduction in energy use, with a payback period of 8.93 years, offering superior efficiency compared to IceWind turbines, which provided a 22.5% reduction with a payback period of 14.57 years. This study demonstrates that Savonius turbines are a more cost-effective option for enhancing energy efficiency in urban residential buildings.

Chong et al. [23] developed a cross-axis wind turbine (CAWT) for building integration, capable of harnessing both horizontal and vertical winds. Tests showed the CAWT had significantly higher efficiency than a conventional VAWT, with a 266% increase in power coefficient at 100 mm height. This design improves wind energy capture for urban buildings. Issac et al. [24] developed a helical cross-axis wind turbine (HCAWT) combining helical and horizontal blades to harness multi-directional winds. CFD simulations showed a 186% improvement in power coefficient over a straight-bladed VAWT, with the HCAWT achieving a Cp of 0.43 at a 100 mm height, highlighting its efficiency and suitability for urban settings. Mohammed et al. [25] evaluated a rooftop-integrated hybrid VAWT combining Darrieus and Savonius rotors. Their findings showed a 63% increase in energy output and a 33% RPM boost compared to a standalone setup. Positioned 150 mm above a vaulted roof, the hybrid VAWT achieved a maximum power coefficient (Cp) of 0.182, highlighting the benefits of rooftop integration for urban wind energy.

Karadag and Yüksek [26] explored integrating wind turbines into tall buildings using CFD simulations to optimize turbine performance amid urban wind flows. Their study emphasized the role of interdisciplinary collaboration to enhance urban wind energy potential, showing that BIWTs can effectively contribute to sustainable energy in city environments. Han et al. [27] developed a 100 W helical-blade VAWT for low-noise urban use, targeting a wind speed of 9 m/s and 170 rpm. Their model predicted 108.34 W, while wind tunnel tests showed a 5.9% higher output at 114.7 W, confirming the design’s effectiveness for urban wind applications.

Kavade and Ghanegaonkar [28] examined a small-scale vertical-axis wind turbine (VAWT) with a variable pitch mechanism to boost efficiency. Testing showed a peak power coefficient (Cp) of 0.35 at a tip speed ratio of 2.5 and a wind speed of 10 m/s, demonstrating that variable pitching improves self-starting and performance, making VAWTs more suitable for residential energy use in windy areas. Ali et al. [29] evaluated six Darrieus VAWT models with different blade configurations to optimize performance at low wind speeds. Testing showed that the straight-bladed models with two blades performed best, achieving high power coefficients and self-starting at 3 m/s, making them suitable for low-wind environments.

Divakaran et al. [30] analyzed the impact of helix angles (60°, 90°, and 120°) on the performance of a helical vertical-axis wind turbine (VAWT) using 3D computational fluid dynamics (CFD) simulations. They found that a 60° helix angle provided the highest performance at moderate tip speed ratios (TSRs), while a 120° angle reduced shaft loading and improved stability. Their study also showed that increased helix angles caused faster dissipation of turbine wakes, minimizing interference effects. This research offers insights into optimizing helix angles for better aerodynamic performance and reduced mechanical stresses in VAWTs. Suresh et al. [31] analyzed aluminum airfoil profiles (NACA 0012 and NACA 0018) for helical VAWTs, using ANSYS Fluent v.2023 R1 to evaluate stability and performance under wind speeds up to 20 m/s. NACA 0012 showed superior lift-to-drag efficiency, supporting its use for energy-efficient turbines. The study confirmed that these aluminum blades maintain structural integrity, making them viable for urban wind applications.

Gad et al. [32] tested various IceWind turbine designs, finding that the three-blade model achieved the highest torque and rotational speed in wind tunnel experiments at 6–14 m/s. This design showed optimal performance, comparable to Savonius turbines, and is suited for urban wind applications. Suffer and Saleh [33] examined IceWind VAWTs at two heights (250 mm and 125 mm) using CFD and wind tunnel tests. The 250 mm model performed better, achieving a power coefficient of 0.0688 and 610 RPM, indicating that taller turbines enhance energy capture for urban use.

Zheng et al. [34] examined the impact of blade numbers on drag-type VAWT performance, finding that power efficiency increased with more blades. The six-blade model achieved the highest efficiency at 26.82%, followed by the five-blade and three-blade models, highlighting that additional blades enhance stability and energy capture.

This study presents a novel combined-type VAWT that integrates both helical and IceWind rotor designs into a single unit to improve energy capture efficiency. Unlike previous studies, a complete simulation workflow covering 3D modeling, aerodynamic analysis, and building energy simulation is used to assess performance under the real climate conditions of Çeşme. By comparing the energy and financial outcomes of three turbine types on a residential building, the study provides practical insights for wind energy integration in urban environments.

2. Methods

This study focuses on the application of wind energy strategies through a detailed case study of a building located in Çeşme, Izmir, Türkiye. To begin, the energy performance of the building was analyzed in its original, unmodified state, providing a comprehensive baseline measurement of its fuel and electricity consumption. The research investigates three vertical-axis wind turbine (VAWT) strategies, each tailored to optimize energy generation under varying conditions. The first strategy involves the implementation of a helical three-blade VAWT, selected for its aerodynamic efficiency and compatibility with moderate wind speeds. The second strategy utilizes three IceWind blade turbines, valued for their compact design and suitability for urban applications. The third strategy integrates a combined VAWT system, merging attributes of both IceWind and helical type designs to enhance overall performance.

Figure 2 outlines the step-by-step process followed in this study, showcasing the approach to designing, simulating, and evaluating wind turbine systems. The workflow began with the system design phase, where SolidWorks v.2024 was used for creating 3D models of the turbines, and ANSYS Fluent v.2023 R1 was employed for conducting computational fluid dynamics (CFD) simulations. DesignBuilder software v7.3.1.003 was integrated to analyze the impact of the turbines on building energy performance. The next step involved location analysis and wind speed data collection, focusing on selecting a suitable site and gathering essential data to optimize the turbines’ performance. Three wind turbine designs—helical, IceWind, and combined-type—were included in the study, with their unique configurations evaluated in terms of aerodynamic behavior and energy savings potential. The data collected were utilized in the simulation phase, where CFD and energy modeling simulations were performed to assess the turbines’ performance and interaction with the building’s energy needs. This led to the energy evaluation phase, where the energy savings and efficiency improvements of the turbine designs were quantified. Finally, the findings were analyzed in the analysis and discussions phase, providing insights into the turbines’ overall performance, including their contribution to reducing energy consumption and their payback periods. This structured approach ensures a comprehensive evaluation of the proposed retrofitting strategy.

2.1. Climate and Location Analysis

Assessing the energy performance of these strategies, the economic viability of the proposed systems was examined by calculating the payback periods for each turbine type. Çeşme, a district in Izmir, was specifically selected as the study location due to its consistent and strong wind conditions, making it a prime candidate for wind energy exploration. Positioned at 38.42° N latitude and 27.14° E longitude, Izmir falls under the Mediterranean climate classification (Csa) as defined by the widely recognized Köppen–Geiger system [35]. This climate type, characterized by mild, windy winters and dry, hot summers, further supports the feasibility of wind energy installations in the region. Figure 3 shows the case study location of the analyzed building. According to the Global Wind Atlas [36], the location of Çeşme in İzmir is identified as an ideal site for wind energy applications due to its favorable wind conditions. The area experiences a strong local average wind speed of approximately 7 m/s, particularly in urban settings, making it suitable for integrating wind turbines into residential or commercial structures to optimize energy generation.

2.2. Case Building and Energy Simulation Analysis

Weather data from the IZMIR-TUR IWEC database was utilized to enhance the accuracy and reliability of the simulation process. Two distinct scenarios were evaluated in this study: the first scenario involved simulating the baseline model, while the second scenario included simulations of three cases with different types of wind turbines: helical-type VAWTs in the first case, IceWind turbines in the second case, and hybrid-type turbines in the third case. The architectural design of the building, along with the corresponding model created in DesignBuilder v7.3.1.003, is presented in Figure 4 and Figure 5. These scenarios were modeled to provide a comparative analysis of the baseline energy consumption and the potential energy savings achieved through turbine implementation.

The baseline building model simulated in DesignBuilder v7.3.1.003 comprises a five-storey structure with a total area of 2120 m², distributed across 115 individual spaces. The thermal performance of various building envelope components is defined by their U-values. The external walls indicate a U-value of 0.317 W/m²K, while the internal walls have a significantly higher U-value of 1.923 W/m²K. For the roof, the thermal transmittance is calculated at 0.314 W/m²K, and the ground floor shows a U-value of 0.309 W/m²K. The glazing system incorporates reference materials with a U-value of 1.978 W/m²K.

The flat roof consists of multiple layers aimed at optimizing thermal insulation and structural integrity. These include a top layer of gravel, measuring 0.03 m thick and featuring a thermal conductivity of 2 W/mK, followed by a bitumen felt layer of 0.004 m thickness and 0.23 W/mK conductivity. A screed layer, 0.03 m thick with a conductivity of 0.41 W/mK, is included, along with an insulating layer of polyurethane foam at 0.08 m thickness and 0.028 W/mK conductivity. The composition is completed by a reinforced concrete layer of 0.18 m thickness, which has a thermal conductivity of 2.3 W/mK.

The ground floor similarly integrates layers to achieve effective thermal performance. These include a surface layer of carpet or textile flooring (0.015 m thick, 0.06 W/mK conductivity), a screed layer (0.05 m thick, 0.41 W/mK), a reinforced concrete slab (0.12 m thick, 2.3 W/mK conductivity), a polyurethane foam insulation layer (0.07 m thick, 0.028 W/mK), and a base layer of sand and gravel measuring 0.21 m in thickness and featuring a thermal conductivity of 2 W/mK.

The external walls incorporate a multi-layered construction method to enhance thermal resistance. The outermost layer consists of a cement–sand render, 0.015 m thick, with a thermal conductivity of 1 W/mK. Directly below this, a 0.08 m-thick expanded polystyrene (EPS) insulation layer is included, offering a thermal conductivity of 0.046 W/mK. This is followed by a medium-density concrete block with a thickness of 0.25 m and a conductivity of 0.51 W/mK. An additional layer of EPS insulation, measuring 0.03 m thick with the same thermal conductivity of 0.046 W/mK, is incorporated. The innermost layer is finished with gypsum insulating plaster, 0.015 m thick, which provides a thermal conductivity of 0.18 W/mK.

2.3. Retrofitting Strategies

Retrofitting buildings with renewable energy solutions, such as vertical-axis wind turbines (VAWTs), presents an effective strategy for reducing energy consumption and promoting sustainability. This study evaluates the performance of three distinct VAWT designs: helical-type, IceWind, and combined-type mounted on the rooftop of a building. Through computational fluid dynamics (CFD) simulations, the aerodynamic behavior, energy savings, and feasibility of these turbines are analyzed under realistic operating conditions.

The first case investigated a helical-type vertical-axis wind turbine (VAWT) featuring three blades and a rotor diameter of 1.515 m. The turbine’s rated power output is 350 W, making it suitable for small-scale energy generation applications. The computational domain for this simulation measures 9 m in length, 5 m in width, and 4 m in height. This domain size was carefully chosen to minimize boundary effects and ensure accurate simulation of aerodynamic behavior, with velocity inlet, pressure outlet, and no-slip wall boundaries placed at adequate distances from the turbine. The mesh used for this case comprises 777,032 nodes and 4,232,347 elements, balancing computational efficiency with the resolution required for precise flow analysis.

A static mesh configuration was employed to facilitate steady-state aerodynamic analysis, capturing critical flow features while maintaining computational feasibility. The Shear Stress Transport (SST) k-ω turbulence model was utilized to evaluate the turbine’s aerodynamic performance, given its reliability in predicting flow separation and aerodynamic behavior in VAWTs. Simulations were conducted at the rated wind speed of 13 m/s to emulate real-world operational conditions and predict power output and aerodynamic performance. Additionally, the analysis accounted for a local annual average wind speed of 7 m/s to provide a realistic assessment of the turbine’s energy-saving potential when installed on a building rooftop.

The second case focused on the IceWind turbine, which has a rotor diameter of 1.515 m and a rated power output of 430 W. The computational domain for this simulation is more compact, measuring 6 m in length, 3 m in width, and 3 m in height. This domain configuration is tailored to the IceWind turbine’s aerodynamic characteristics while maintaining sufficient space for accurate modeling of flow separation and wake dynamics. The mesh consists of 861,882 nodes and 4,790,485 elements, providing the resolution necessary to capture intricate flow features around the turbine.

As with the first case, the SST k-ω turbulence model was employed to ensure accurate predictions of aerodynamic performance, particularly in regions of flow separation. The turbine’s operation was analyzed at its rated wind speed of 13 m/s to evaluate its maximum energy capture efficiency. Additionally, simulations were conducted at an annual average wind speed of 7 m/s to assess its real-world applicability. These dual simulations provide a comprehensive evaluation of the IceWind turbine’s ability to reduce building energy consumption under varying wind conditions.

The third case explored a hybrid VAWT design that combines an inner IceWind rotor with semicircular blades and an outer Darrieus (helical) rotor. The IceWind rotor features a diameter of 0.7575 m and a height of 0.75 m, while the Darrieus rotor has a diameter of 1.05 m and a height of 1.52 m, resulting in a total swept area of 1.45 m². This dual-rotor configuration optimizes energy capture by combining the complementary aerodynamic strengths of the two designs.

The computational domain dimensions for this case are identical to those used in the first case, measuring 9 m in length, 5 m in width, and 4 m in height, ensuring a consistent setup for flow development and wake analysis. A high-resolution mesh with 965,768 nodes and 5,419,664 elements was implemented, capturing the complex aerodynamic interactions between the inner and outer rotors. The SST k-ω turbulence model was again employed to simulate the flow accurately, focusing on the interaction between the two blade systems. This case demonstrates the hybrid turbine’s capability to optimize aerodynamic performance and contribute significantly to reducing energy consumption in urban building retrofits.

The analysis of the three wind turbine cases is supported by detailed input parameters and computational setups.

Table 1. Input parameters of wind turbine.

Input Parameter		Input Parameter
Operation type	24/7	Cut out wind speed (m/s)	3.5
Rotor speed (rev/min)	177/159/191	Cut in wind speed (m/s)	25
Rotor diameter (m)	1.515/1.515/1.05	Maximum tip speed ratio	2/1.8/1.5
Number of blades	3/3/6	Maximum power coefficient	0.21/0.17/0.31
Rated power output (W)	350/430/590	Annual local average wind speed (m/s)	7
Rated wind speed (m/s)	13	Power control	Fixed speed variable pitch

summarizes the critical input parameters for each wind turbine, including rotor dimensions, rated power output, and operational characteristics, which serve as the foundation for the CFD simulations conducted in this study. Figure 6 illustrates the design of each turbine, modeled using SolidWorks v.2024, and their rooftop-mounted configuration on the building, ensuring optimal placement for efficient energy capture. Meanwhile, Figure 7 presents the computational domain dimensions and mesh quality for each case, detailing the boundary conditions, mesh density, and spatial configuration used to ensure accurate aerodynamic predictions.

2.4. Payback Period Analysis

The economic analysis of the wind turbine system was conducted to evaluate its feasibility and efficiency in reducing energy costs. Key factors considered include the total power output of the turbines, annual energy production, electricity savings, and associated costs such as initial investment and annual maintenance. Using these parameters, the net annual savings were calculated to determine the system’s payback period, which indicates the time required to recover the initial investment through energy cost savings. The following equations outline the methodology used for these calculations, providing a clear framework for assessing the financial performance of the system.

$${\mathrm{P}}_{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}}={\mathrm{P}}_{\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{b}\mathrm{i}\mathrm{n}\mathrm{e}}\times \mathrm{N}$$

(1)

$${\mathrm{E}}_{\mathrm{a}\mathrm{n}\mathrm{n}\mathrm{u}\mathrm{a}\mathrm{l}}={\displaystyle \frac{{\mathrm{P}}_{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}}\times \mathrm{H}}{1000}}$$

(2)

$${\mathrm{S}}_{\mathrm{a}\mathrm{n}\mathrm{n}\mathrm{u}\mathrm{a}\mathrm{l}}={\mathrm{E}}_{\mathrm{a}\mathrm{n}\mathrm{n}\mathrm{u}\mathrm{a}\mathrm{l}}\times {\mathrm{C}}_{\mathrm{e}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{r}\mathrm{i}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{y}}$$

(3)

$${\mathrm{I}}_{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}}={\mathrm{C}}_{\mathrm{t}\mathrm{u}\mathrm{r}\mathrm{b}\mathrm{i}\mathrm{n}\mathrm{e}}\times \mathrm{N}$$

(4)

$${\mathrm{C}}_{\mathrm{m}\mathrm{a}\mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}}={\mathrm{C}}_{\mathrm{m}\mathrm{a}\mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e} \mathrm{p}\mathrm{e}\mathrm{r} \mathrm{t}\mathrm{u}\mathrm{r}\mathrm{b}\mathrm{i}\mathrm{n}\mathrm{e}}\times \mathrm{N}$$

(5)

$${\mathrm{S}}_{\mathrm{n}\mathrm{e}\mathrm{t}}={\mathrm{S}}_{\mathrm{a}\mathrm{n}\mathrm{n}\mathrm{u}\mathrm{a}\mathrm{l}}-{\mathrm{C}}_{\mathrm{m}\mathrm{a}\mathrm{i}\mathrm{n}\mathrm{t}\mathrm{e}\mathrm{n}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}}$$

(6)

$${\mathrm{T}}_{\mathrm{P}\mathrm{a}\mathrm{y}\mathrm{b}\mathrm{a}\mathrm{c}\mathrm{k}}={\displaystyle \frac{{\mathrm{I}}_{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l}}}{{\mathrm{S}}_{\mathrm{n}\mathrm{e}\mathrm{t}}}}$$

(7)

where

• $P_{turbine}:$ Power output of a single turbine (watts)
• $P_{total}:$ Total power output (watts)
• $N:$ Number of turbines
• $E_{annual}:$ Annual energy production (kWh/year)
• $C_{electricity}:$ Electricity price (USD/kWh)
• $C_{turbine}:$ Cost of a single turbine (USD)
• $C_{maintenance}:$ Maintenance cost per turbine (USD/year)
• $S_{annual}:$ Annual savings in electricity cost (USD/year)
• $T_{Payback}:$ Payback period (years)
• $I_{total}:$ Total initial investment (USD)
• $S_{net}:$ Net annual savings (USD/year)

3. Results and Discussion

The dynamic pressure distribution around the helical-type VAWT highlights critical aerodynamic behaviors essential to its performance. High dynamic pressure regions, observed near the leading edges of the blades, indicate effective wind energy capture as the airflow decelerates upon impact. In contrast, low-pressure wake zones downstream reflect energy extraction and flow separation. The asymmetry in the pressure field illustrates the influence of blade alignment and rotation relative to the incoming wind, directly affecting torque generation. Smooth gradients in the pressure distribution suggest minimal aerodynamic losses, enhancing overall efficiency. With a maximum dynamic pressure of approximately 267 Pa, the turbine effectively harnesses wind energy under the given conditions.

The IceWind turbine demonstrates unique aerodynamic characteristics in its dynamic pressure distribution. High-pressure zones, concentrated along the convex blade surfaces, result from airflow acceleration due to curvature and flow attachment. These regions, represented in red and yellow, demonstrate efficient energy capture. Downstream, elongated low-pressure zones in the wake, shown in blue, reflect effective energy extraction and momentum dissipation. The relatively symmetric pressure distribution highlights balanced aerodynamic performance. The turbine achieves a maximum dynamic pressure of approximately 186 Pa, showcasing its effectiveness in simulated conditions.

The combined-type VAWT exhibits a distinctive dynamic pressure distribution arising from the interaction of its dual blade designs. High-pressure regions near the leading edges of both blade sets indicate strong flow acceleration and efficient energy capture. The extended low-pressure wake, visible in blue, signifies enhanced energy extraction compared to single-blade designs. The asymmetry in pressure distribution results from the complex interaction between the Darrieus and IceWind components, optimizing aerodynamic performance. With a peak dynamic pressure of approximately 182 Pa, the turbine effectively maximizes energy conversion efficiency.

The static pressure distribution around the helical-type VAWT reveals intricate aerodynamic interactions between the airflow and the turbine blades. High-pressure regions near the leading edges result from airflow deceleration upon impact, causing a significant increase in static pressure. Conversely, low-pressure zones on the trailing edges and within the wake, depicted in blue and green, reflect flow acceleration and separation. This pressure differential across the blade surfaces is critical for generating lift and torque. The uniform gradient in pressure contours indicates balanced aerodynamic loading, contributing to stable turbine operation. The maximum static pressure of approximately 67.4 Pa underscores the efficiency of this design under the simulated conditions.

The static pressure distribution of the IceWind turbine highlights its aerodynamic efficiency. High-pressure regions near the leading edges, shown in red, result from airflow deceleration against the curved blade surfaces, enabling effective energy capture and torque generation. Low-pressure zones in the wake, depicted in blue and green, result from flow acceleration and separation, emphasizing energy extraction. The relatively symmetric distribution ensures balanced aerodynamic loading and steady performance. A maximum static pressure of approximately 76.8 Pa demonstrates the turbine’s strong capability to operate effectively in simulated conditions.

The static pressure distribution for the combined-type VAWT reflects the aerodynamic synergy of its dual blade designs. High-pressure zones near the leading edges of both blade types, depicted in red, indicate effective deceleration of airflow and energy capture. Low-pressure regions, shown in green and blue along the trailing edges and wake, signify efficient energy extraction and flow separation. The asymmetric pressure distribution highlights the interplay between the Darrieus and IceWind components, optimizing lift and torque generation. With a maximum static pressure of approximately 73.9 Pa, the combined-type VAWT efficiently harnesses wind energy under simulated conditions.

The velocity magnitude and pathline distributions for the helical-type VAWT demonstrate the aerodynamic efficiency of its blade design. High-velocity regions, shown in green and yellow, concentrate along the blade surfaces and wake, indicating accelerated airflow driven by rotational motion. Low-velocity zones, depicted in blue, are observed near the trailing edges and wake, reflecting energy extraction and flow separation. Smooth velocity transitions and consistent pathlines across the blade span highlight the turbine’s ability to maintain stable aerodynamic performance with minimal turbulence. A maximum velocity magnitude of approximately 20.1 m/s reflects the helical design’s effectiveness in converting wind energy under simulated conditions.

The velocity magnitude distributions for the IceWind turbine highlight its aerodynamic performance in both 2D and 3D visualizations. In the 3D pathlines view, high-velocity regions, concentrated near the blade tips and wake, result from the rotational motion of the turbine. Surrounding the blade surfaces and downstream wake regions, low-velocity zones in blue indicate energy extraction and flow separation. The 2D visualization complements this by showcasing wake development and gradual airflow velocity reduction downstream, emphasizing efficient energy capture. The turbine achieves a maximum velocity magnitude of approximately 16.5 m/s, effectively harnessing wind energy while maintaining smooth aerodynamic behavior.

The velocity magnitude distributions for the combined-type VAWT reveal the aerodynamic synergy of its dual blade designs. High-velocity regions, shown in green and yellow, concentrate along the blade surfaces and wake, demonstrating accelerated airflow due to the combined effects of the Darrieus and IceWind components. Low-velocity zones in blue, near the trailing edges and areas of flow separation, reflect effective energy extraction. The 2D visualization emphasizes the wake’s extension downstream, with reduced airflow velocity highlighting the turbine’s energy conversion efficiency. The maximum velocity magnitude of approximately 17.0 m/s underscores the combined design’s ability to maintain stable and efficient performance under simulated conditions.

Figure 8 below compares the dynamic pressure, static pressure, and velocity magnitude distributions for the helical-type, IceWind, and combined-type wind turbine cases.

Figure 9 and

Table 2. Simulation results for all cases.

Model Name	Energy Consumption (kWh/m2)	Energy Saving %	Payback Period (Years)
Baseline model	172	-	-
Case 1	140.27	18.45	12.89
Cass 2	132.56	22.93	10.60
Case 3	118.89	30.88	10.49

below provide a comprehensive comparison of the energy savings and payback periods for the three wind turbine types relative to the baseline model. The baseline, with an annual energy consumption of 172 kWh/m², is listed in the table as the reference point, with no energy savings. Case 1, representing the helical-type VAWTs, achieves an energy reduction to 140.27 kWh/m², equivalent to an 18.45% saving, but it has the longest payback period of 12.89 years. Case 2, featuring the IceWind turbine, performs better, lowering energy consumption to 132.56 kWh/m² and achieving a 22.93% energy saving, with a slightly improved payback period of 10.60 years. Case 3, which utilizes the combined-type VAWTs, delivers the best results, reducing energy consumption to 118.89 kWh/m², corresponding to a 30.88% energy saving and the shortest payback period of 10.49 years. The figure visually presents these differences, showing the combined-type turbine’s superior performance in both energy efficiency and economic viability.

The economic analysis of the turbines revealed distinct differences in their initial costs, maintenance expenses, and overall payback periods. Across all cases, the local electricity price of USD 0.07 per kWh and an annual maintenance cost of USD 75 per turbine were considered in the calculations.

The helical turbine, with an initial cost of USD 1800 per unit, had the lowest upfront investment but required the longest payback period of 12.89 years. This extended payback period is attributed to its moderate energy-saving performance of 18.45%, which limits annual financial returns.

The IceWind turbine, priced at USD 2000 per unit, achieved a payback period of 10.60 years. Its higher energy-saving capacity of 22.93% offset the slightly higher initial investment, making it a more favorable option compared to the helical turbine.

The combined-type turbine, with an initial cost of USD 3000 per unit, achieved the shortest payback period of 10.49 years. Its superior energy-saving performance of 30.88% effectively compensated for the higher upfront cost, making it the most cost-effective solution over time. These results emphasize the role of initial costs, maintenance expenses, and energy-saving potential in determining the economic viability of VAWTs for residential applications.

Integrating these turbines into the case building reduced annual energy consumption from 172 kWh/m² to as low as 118.89 kWh/m², contributing to sustainability goals. Economic analysis confirms the feasibility of such systems, with payback periods aligning with expectations for renewable energy technologies. The average wind speed of 7 m/s in Çeşme provided favorable conditions, but urban wind variability must be considered for effective implementation. This study demonstrates that VAWTs can be a practical solution for urban energy challenges. The superior results of the combined-type turbine point to the benefits of hybrid configurations, and future research could explore additional optimizations in blade design and integration with other renewable energy systems for broader applications.

The study includes mesh size, element count, domain dimensions, and turbulence modeling to ensure simulation reliability. However, mesh sensitivity analysis and experimental validation were not included, as the main objective was to obtain power output for integration into building-scale energy and economic analysis. The authors recognize the value of these steps for aerodynamic studies and will consider them in future work to strengthen the simulation accuracy.

4. Conclusions

This study explores the integration of vertical-axis wind turbines (VAWTs) into urban residential buildings as a sustainable approach to reducing energy consumption and achieving economic feasibility. Leveraging Çeşme’s favorable wind conditions, the research demonstrates the potential of small-scale turbines to contribute to urban energy demands. The findings emphasize the importance of selecting and optimizing turbine designs to maximize energy efficiency while ensuring an economically viable payback period.

• The helical turbine, while functional, achieved the lowest energy savings of 18.45% and the longest payback period of 12.89 years. Its design offers stability and moderate performance, making it a suitable option for applications with limited spatial or financial constraints. However, the turbine’s lower efficiency suggests the need for further aerodynamic refinements to enhance its performance in urban wind conditions.
• The IceWind turbine demonstrated better results, with an energy saving of 22.93% and a payback period of 10.60 years. Its compact and efficient design makes it well-suited for urban areas with consistent wind patterns. Despite its promising performance, there is room for improvement in optimizing its aerodynamic features to further enhance energy capture and reduce costs.
• The combined-type turbine outperformed the other designs, achieving the highest energy savings of 30.88% and the shortest payback period of 10.49 years. By combining the strengths of Darrieus and IceWind designs, this hybrid configuration proved to be the most effective in capturing wind energy and reducing aerodynamic losses. Its success highlights the potential of hybrid turbine systems in urban building retrofits, offering a robust solution for energy efficiency.

These findings emphasize the practicality of integrating 42 VAWTs into residential buildings and provide a pathway for advancing urban energy sustainability through innovative turbine designs.

These results demonstrate the practical advantage of integrating the combined-type VAWT into residential buildings using real wind conditions. The study uniquely links CFD-based power predictions with whole-building energy analysis and economic evaluation, providing a comprehensive approach that has not been widely addressed in previous literature.