Earth-to-air Heat Exchanger Research Articles

Experimental study on ventilation using earth-to-air heat exchanger in Surabaya

The main problem related to thermal condition in Surabaya as a second-largest city in Indonesia is humid and hot. It is a typical condition of tropical climate. Ventilation in the hot day will bring warm and humid outdoor air into a room. It will increase the temperature of air in the room. One of some efforts to reduce the outdoor air temperature is using an earth to air heat exchanger (EAHE) to transfer heat from the air to the earth or ground. This paper will discuss about research done to study the effect of EAHE to a room temperature. The study used two model rooms which are similar and a model EAHE. One room called condition room will receive air flowing from the EAHE pipe and the other room is called the referent room. From the research, it is found that the air in condition room with EAHE is cooler in the daytime compared to the referent room. The temperature of the condition room with EAHE is more stable.

Techno‐economic analysis and energy performance of a geothermal earth‐to‐air heat exchanger (EAHE) system in residential buildings: A case study

AbstractNatural air ventilation in the hot‐dry regions plays a key role to decrease indoor air temperature in hot season, also to improve thermal comfort during the cold season. One of the most common ways to take advantage of natural ventilation is using wind catcher with an underground tunnel. In this method, the tower catches the airflow and directs it to the underground tunnel to decrease the air temperature by transferring heat to the ground, which is cooler in the summer and warmer in the winter. Earth‐to‐air heat exchanger (EAHE) is a modern form of wind catcher with underground tunnel. In this method, air after passing through buried pipes exchanges heat with the ground, and its temperature increases in the winter and decreases during the summer. This study analyzes the energy performance and cost‐effectiveness of earth‐to‐air heat exchanger to be utilized in a residential building in climate condition of the province of Kermanin Iran. In this regard, 9 different configurations of the EAHE are investigated to find the optimized EAHE. The system performance and cost‐effectiveness are studied in 3 different depths including 1, 2, and 3 m with 3 different pipe lengths including 25, 50, and 75 m. The results show that the EAHE is capable of reducing the inlet air temperature by 0.5‐9.9℃ in the summer and increasing it by 0.9‐11.2℃ in the winter. Furthermore, by integrating the EAHEs in a building design, one can reduce the total annual cooling load by 1.25%‐3.97% and for heating by 1.34%‐3.96%. The payback period of the system with a pipe length of 25 m is 16 years, but for the systems with pipe lengths of 50 and 75 m, this period reduces to almost 3 years.

Numerical Investigation of The Air Flow Rate Effect Performance of Earth to Air Heat Exchanger Used for Cooling of Poultry Houses

Usually, poultry houses are located in a remote area where there is no electricity, and where there is electricity, it is expensive, so resorting to these solutions is considered important solutions to save electrical energy and provide free cooling. The main part of generated energy is consumed by cooling and heating systems. One of the well-known approaches to implemented heating and cooling system is earth to air heat exchanger (EAHE) system. This system is effective passive heating and cooling systems which can be used with poultry houses and building. This research studies numerically the effect of mass flow rate on the overall performance of earth to air HE for poultry houses. Four parameters (mass flow rate, required rate, required cooling load and pipe lengths) are selected under environment of Nasiriyah city (a city located in the south of Iraq). The study is conducted using PVC material. The study has been done during summer season. The suggested numerical model has been tested and validated using existing approaches selected from literature review papers. This test shows good agreement with results of selected papers. Moreover, validation and simulation results showed that the required cooling load increased with increasing mass flow rate. Also, with the increasing length of pipe of EAHE, the inflow temperature compared to the space temperature is decreased. However, the overall performance factor of EAHEs decreases by the increase of length of pipe and mass flow rate. Which indicate the possibility of using the earth to air heat exchanger for cooling and heating poultry houses and reduce the use of electrical energy.

Numerical Research and Parametric Study on the Thermal Performance of a Vertical Earth-to-Air Heat Exchanger System

The earth-to-air heat exchanger (EAHE) system, as a clean and efficient shallow geothermal energy application technology, has obvious effects in reducing the energy consumption of passive low-energy buildings. The traditional horizontal EAHE system is difficult to apply and popularize due to its large occupation, unfavorable shallow soil temperature, and difficulty in timely centralized discharge of condensed water. This paper proposes a new type of vertical earth-to-air heat exchanger (VEAHE) system. The VEAHE system has a number of advantages such as smaller occupation, efficient geothermal energy utilization, and centralized discharge of condensed water. In order to evaluate the influence of different parameters on the thermal performance of the VEAHE system, a mathematical model of the VEAHE system was developed. And, the data calculated by the model highly tallied with the experimental data. The results showed that laying thermal insulation layers at the outlet of risers will effectively restrain the interference of downcomers to risers. It is advisable to set thickness and length of the insulation layer at 30 mm and 3 m. Considering the compromise between thermal performance and construction costs of the VEAHE system, the length of the ducts at 30–50 m and the diameter at 150–250 mm are recommended. The air supply volume of a single shaft can reach 500–1200 m3/h as the air velocity reaches 3–7 m/s.

Heating performance of the PVC earth­air tubular heat exchanger applied to a greenhouse in the coastal area of west Syria: An experimental study

Earth­to­air heat exchanger (EAHE) system is a geothermal environmental technique able to reduce the energy consumption and their costs for heating/cooling, by using the undisturbed temperature of the ground for conditioning of air. This study aims to use a tubular heat exchanger to heat an agricultural greenhouse in the Baniyas area in a simple, more economical, and environmentally friendly way. In addition, to assess the length, diameter, and flow velocity parameters that affect the efficiency of the heat exchanger. Tests were carried out in a Mediterranean climate at Tartous Governorate in the coastal area of west Syria. The exchanger pipes of 20 m length were buried at 1 m deep. The diameters used are 10.16 and 15.24 cm for each studied exchanger with two velocities 1.5 and 2 m/s. Two exchangers were set up along a plastic greenhouse. Tests were performed through a month starting from 1 December 2020. The results showed a significant effect of the parameters on both exchangers heating performance. During the heating period, soil temperature was between 18 and 19 °C and inlet air temperature average was between 11 and 12 °C. An increase in the length of the tube to 20 m caused an increase in the heating performance to 56% and 36.28% for 10.16 cm and 15.24 cm diameter, respectively. Therefore, the smaller diameter tube was better, in addition, decreasing airflow velocity during the pipe from 2 to 1.5 m/s caused an increase in temperature from 5.5 to 6.99 °C.

The Readiness Investigation of The Ground Soil Temperature for Underground Heat Exchange Systems Installation in Hot Climates

This present article investigates the possibility of the use of ground soil of hot climates for the investiture of it for cooling and heating aims by using it as an underground heat exchange. The study region is Al-Najaf city, 168.83 km south of Baghdad the capital of Iraq. This heat exchange represents one of the sustainable energy types which depends on the difference between the ambient air and ground soil temperature, which can lead to reducing the exhaustion of fossil fuels. To measure the soil temperatures during all the months of the year, A hole drilled to a depth of 5 meters, seven thermocouples has been installed at each depth (0.5, 1, 2, 3, 4, and 5 m), and at the ground surface. The new experiment result of variation of the soil temperature with depth and during the year has been compared and evaluated in order to estimate the possibility of using Earth to Air Heat Exchanger (EAHE) for heating or cooling purposes along the year. The result shows that the average temperature difference between the ground surface and ground soil temperature during the months increasing as the underground depth increases. The results have let it a perfect referral for the priorities of the use that location at equal to or more than 3 m depth for cooling during summer months (the temperature differences reach to 16.17 oC) rather than heating during winter months (the temperature differences reach to 10.76 oC). The less than 3 m depths can use it for precooling and preheating purposes because it is directly affected by the ambient temperature, which reduces the possibility of using it in a better way. The most significant results were the important negative temperature variances for testing location that becomes an emboldening factor in designing and researching other factors for the build clean, cheap, and efficient ground source heat exchange systems.

Potential Applicability of Earth to Air Heat Exchanger for Cooling in a Colombian Tropical Weather

Buildings exhibit a high energy consumption compared with other economic sectors. While percentages vary from country to country, buildings are responsible for approximately 40% of the global energy demand. Most of this is consumed for achieving human thermal comfort. In Colombia, the government promotes policies for the adoption of efficient energy strategies in this sector. The earth to air heat exchanger (EAHE) can be used to reduce the cooling load of a building. Therefore, this study aims to evaluate the energy savings that can be obtained by installing an EAHE in a tropical climate in Colombia. To do so, a mathematical model is implemented in TRNSYS (Transient System Simulation Tool) to predict the thermal performance and the cooling capacity of the EAHE. The system is modeled as a function of pipe length, diameter, material, thickness and air mass flow. Moreover, soil, local atmospheric conditions and building features are taken into account. It is found that the air leaves the EAHE at temperatures between 20.9 °C and 24.1 °C, which are approximately 3 °C below ambient temperature. Furthermore, the economic feasibility of the project is verified. Thereby, it is demonstrated that the EAHE can be a competitive alternative to current HVAC systems.

Numerical modelling of a building integrated earth-to-air heat exchanger

This paper investigates an innovative earth-to-air heat exchanger (EAHE), namely the geothermal foundation Fondatherm®. This system solves numerous technical problems inherent to a traditional EAHE. However, an accurate understanding of its thermal behavior is crucial to ensure the best energy gain and its economic viability. This current paper focuses on a numerical study of the ventilated foundation. A time-dependent three-dimensional finite volume numerical model is developed. This model considers coupled heat and moisture transfers as well as complex boundary conditions such as the weather, the building and the water table simultaneous influences. A matric-head based system of equations is used to represent the heat, vapor and liquid transfers within the soil. It is combined to a capillary pressure-based formulation of the heat and vapor balance equation for the concrete foundation. Furthermore, a numerical method built on a switching from a potential- to a flux-based system of equations is proposed. It is added to a variable time-step method of resolution and allow to handle the greatest hygric loads variations at the ground surface. The numerical code is successfully validated against analytical solutions for simple cases, and against experimental and in situ measurements.

Coupled heat and moisture transfer model to evaluate earth-to-air heat exchangers exposed to harmonically fluctuating thermal environments

The heat and moisture transfer process of an earth-to-air heat exchangers (EAHE) determines its ability to cool/heat an indoor environment. In humid climates, the moisture content of the EAHE inlet air is relatively high and exhibits a different fluctuation behavior than the air dry bulb temperature. In this study, a mathematical model was accordingly developed to evaluate the coupled heat and moisture transfer in an EAHE. Two prerequisites were considered by the model: the inlet was exposed to both harmonically fluctuating outdoor air temperature and moisture content, and the surface of the EAHE was directly formed by the surrounding material and always saturated due to water infiltration from this material. Based on the harmonic analytical method and a numerical approach, solutions for the amplitude dampening and phase-shifting of air temperature and moisture content were obtained. The model was validated using the results of well-regulated experiments, which indicated that phase-shifting and amplitude dampening of both air temperature and moisture content fluctuations occur in an EAHE. The coupled heat and moisture transfer between the humid air and the wet EAHE walls was found to intensify the phase shift but considerably attenuates the air enthalpy fluctuation amplitude. Then, application examples were analyzed corresponding to typical humid and dry cities-Chongqing and Beijing, respectively. The results showed the normalized fluctuation amplitude of the outlet air enthalpy for the Chongqing and Beijing environments decreased by 56.7 % and 61.1 %, respectively, indicating that moisture transfer considerably influences the air enthalpy fluctuation at the EAHE outlet.

Multivariant optimization and sensitivity analysis of an experimental vertical earth-to-air heat exchanger system integrating phase change material with Taguchi method

Shallow subterranean ventilation of earth-to-air heat exchanger (EAHE) system can improve renewable utilisation, decrease CO2 emission and promote carbon-neutral transition. However, the conventional EAHE system has drawbacks, e.g., large occupied land area, low energy-usage efficiency, small falling gradient for buried pipe and fluctuated outlet air temperature. This study proposes a vertical EAHE integrated with annular PCM with advantages, including less occupied floor space, higher energy efficiency, better centralised discharge of air condensate water and more stable outlet air temperature. An experimental test-rig was established for online testing and the real-time monitored data was for modelling calibration to characterise the sophisticated heat transfer in phase change process. Afterwards, multivariant analysis on thermo-physical PCM parameters was conducted on cooling capacity and outlet air temperature fluctuation. A dimensionality reduction approach from redundant experiments was adopted for multivariant optimization and sensitivity analysis. Results show that PCM fusion temperature and latent heat of PCM dominate the cooling capacity with percentage contribution of 37.61% and 28.91%, respectively. PCM thickness and melting temperature dominate the temperature fluctuation with percentage contribution of 31.27% and 26.18%, respectively. This study provides benchmark and guidelines on PCM thermo-physical parameters’ selection with an efficient dimensionality reduction approach, paving path for application of the vertical EAHE integrated with PCMs in buildings.

Forced and natural ventilation of a room with a combined solar chimney and Earth - to - Air Heat Exchanger system

In this study, a passive ventilation and cooling technique which is widely used in sustainable building designs was investigated by a numerical simulation based on computational fluid dynamics (CFD). A system of a solar chimney (SC) and an Earth-to-Air Heat Exchanger (EAHE) is able to ensure thermal comfort in a house by generating an air flow which is induced by the thermal effect. The solar chimney drew ambient air (at 35°C) through the inlet of EAHE; the air flow was cooled by a lower temperature of the underground pipes (at 20°C) before circulating inside the house and leaving through the outlet of the solar chimney. Both the openings of the system were exposed to the atmosphere, and the atmospheric pressure was set at the inlet of the EAHE pipe and the outlet of the solar chimney. The performance of this ventilation and cooling system was analyzed under effects of design parameters, including the gap of the chimney, the diameter and length of the EAHE pipe as well as the solar heat flux applied on the wall of the air channel of the chimney. The results of the assessed parameters, such as temperature inside the house, show that the indoor temperature was reduced to 25°C and 26°C, respectively for the forced ventilation case of 0.2 m/s and natural ventilation case in the configuration with the EAHE pipe length of 11m. The coupled solar chimney and EAHE system can achieve the thermal comfort conditions for both cases of natural and forced ventilation.

Parametric study on the thermal performance of phase change material-assisted earth-to-air heat exchanger

As a passive technology, the earth-to-air heat exchanger (EAHE) can be used to reduce energy consumption within a building. This paper presents a novel design for an EAHE system assisted by a phase-change material (PCM). To study the thermal performance of the newly proposed PCM-assisted EAHE (PCM-EAHE) system, a transient three-dimensional model has been built in FLUENT. A range of validated numerical models is established and utilized to investigate the effects of design and operation parameters (i.e., phase-change temperature, PCM container diameter, pipe length, pipe diameter and air velocity) on the thermal performance of the system. The results indicated that the phase-change temperature should be consistent with the time-average ambient air temperature. Furthermore, the polynomial regression models for predicting the outlet air temperature with high accuracy are obtained using statistical product and service solutions (SPSS). The optimal air velocity levels for enhancing the heat transfer performance are 4.5 m/s and 6.8 m/s during the charging and discharging processes, respectively. Therefore, it is recommended to apply the PCM-EAHE system to new and existing buildings.

Impact of the environmental conditions on the efficiency of earth-to-air heat exchangers under various configurations

In the present paper, the impact of local climatic conditions on the efficiency of earth-to-air heat exchangers (EAHEs) is investigated by experiments. Four cases of EAHEs were considered: (1) a simple EAHE, (2) an EAHE with solar protection at the upper parts, (3) an EAHE with a chimney effect at the outlet, and (4) an EAHE with a fan at the inlet. The values of air temperature and relative humidity at the inlet, as well as at the outlet of the exchanger, were determined. For Cases 1 and 2, the lowest value of ΔT was -9 °C. However, the highest values were 11.9 and 12.5 °C for Cases 1 and 2, respectively. For Cases 3 and 4, the values of ΔT were equal to 7 and 12.5 °C, respectively. For the hygrometry and in Case 1, the difference in the relative humidity (ΔRH) has been increased by 13% and then decreased by 30%. Case 2 provided an increase in ΔRH by 47%. However, an increase of ΔRH by 43% followed by a decrease by 47% was observed in Case 4. Finally, Case 4 yielded a drying tendency and a stable decrease in ΔRH by 30% during almost all day. The use of a fan allowed the most significant control and reducing the impact of external climatic conditions.

Performance analysis of domed roof integrated with earth-to-air heat exchanger system to meet thermal comfort conditions in buildings

In the present study, an integrated cooling system consisting an earth-to-air heat exchanger (EAHE) and a domed roof is investigated numerically to meet the thermal comfort conditions and supply the cooling demand for a building. Simulation of airflow in the EAHE and a test room with the domed roof is performed with ANSYS FLUENT software three-dimensionally, and the thermal behavior of the system is modeled with the code developed in MATLAB software. Furthermore, for verifying the numerical results of EAHE modeling, an experimental study is conducted. The impact of both geometric and environmental parameters on the system performance is also investigated. The obtained results reveal that the system is capable of providing thermal comfort conditions, according to adaptive thermal comfort standard (ATCS), for the test room with a maximum cooling demand of about 1000 W alone and without consuming electric energy by using three pipes with a length of 35 m and a diameter of 0.4 m. The application of the proposed system instead of the split inverter air conditioner and the evaporative cooler to provide a similar cooling load can reduce the electrical energy consumption up to 0.360 kW h, and 0.200 kW h, respectively. In addition, the environmental analysis indicates that the utilization of this system instead of the split inverter air conditioner and evaporative air cooler with similar capacities leads to respective 361.89 kg and 216.06 kg reduction in CO2 emissions for summer months. Finally, the application of the proposed integrated system for a two-story building with domed roof is evaluated. The results show the ability of the system to provide thermal comfort for the two-story building with a maximum cooling demand of approximately 300 W for each floor using two pipes with a length of 35 m and a diameter of 0.4 m.

Numerical modelling of parameters of the operational parameters of an earth-to-air heat exchanger for geothermal ventilation

The aim of this work is to develop a numerical model of the year-round operation of an earth-to-air heat exchanger (EAHE) with a circular cross-sectional shape with further its validation based on the obtained experimental data. We consider that these studies can form the basis for the development of methods for calculating and designing geothermal ventilation systems for climate conditions of Ukraine. The analysis of literature sources showed that now there are quite a lot of studies devoted to the issues of geothermal ventilation. The results of such heat exchanger modeling with various geometric data and which operate in their authentic soils under various hydraulic regimes and that are located at different depths are widely presented. However, these studies do not allow obtaining generalized patterns of heat transfer during the operation of the heat exchangers and the influence of the geometric parameters of the heat exchanger on the operation of the geothermal ventilation system as a whole. Much attention is paid to the issues of modelling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. To conduct experimental research on the operation of the geothermal ventilation system at the Institute of Engineering Thermophysics of the National Academy of Sciences of Ukraine an experimental stand was created. This stand is designed to study thermophysical processes during the operation of a geothermal ventilation system elements. The results of these studies are the basis for the development of a method for determining the optimal diameter of the earth-to-air heat exchanger under operating conditions for soil in Kyiv, Ukraine.

The Optimization of the Thermal Performances of an Earth to Air Heat Exchanger for an Air Conditioning System: A Numerical Study

The aim of this paper is to research the parameters that optimize the thermal performances of a horizontal single-duct Earth to Air Heat eXchanger (EAHX). In this analysis, the EAHX is intended to be installed in the city of Naples (Italy). The study is conducted by varying the most crucial parameters influencing the heat exchange between the air flowing in the duct and the ground. The effect of the geometrical characteristics of the duct (pipe length, diameter, burial depth), and the thermal and flow parameter of humid air (inlet temperature and velocity) has been studied in order to optimize the operation of this geothermal system. The results reveal that the thermal performance increases with length until the saturation distance is reached. Moreover, if the pipe is designed with smaller diameters and slower air flows, if other conditions remain equal, the outlet temperatures come closer to the ground temperature. The combination that optimizes the performance of the system, carried out by forcing the EAHX with the design conditions for cooling and heating, is: D = 0.1 m s−1; v = 1.5 m s−1; L = 50 m. This solution could also be extended to horizontal multi-tube EAHX systems.

Field experiments on the effects of an earth-to-air heat exchanger on the indoor thermal environment in summer and winter for a typical hot-summer and cold-winter region

An earth-to-air heat exchanger (EAHE) is a shallow geothermal energy utilization technology, which can significantly reduce the building energy consumption. This study aims to investigate the effects of an EAHE on the indoor thermal environment in hot-summer and cold-winter regions. A full-scale experiment was conducted for a continuous 24 h period using two identical buildings (with and without an EAHE) exposed to the same outdoor conditions on typical summer and winter days. Experimental results show that the EAHE provides an average outdoor air temperature reduction of 9.12 °C under cooling conditions and increase of 5.53 °C under heating conditions. Moreover, the average outdoor air relative humidity increases by 46.89% and decreases by 27.41% in the cooling and heating conditions, respectively; the corresponding average EAHE coefficients of performance (COP) are 7.03 and 4.26, respectively. Compared to that of the building without EAHE, the average indoor air temperature of the building with EAHE decreases by 5.9 °C in summer and increases by 4.29 °C in winter, and the average walls’ internal surface temperature decreases by approximately 6 °C and increases by approximately 5.8 °C. Moreover, the EAHE system reduces the average building cooling and heating loads by 55.4 and 40.43 W/m2, respectively.

Contribution of Low Enthalpy Geothermal Energy in the Retrofit of a Single-Family House: A Comparison between Two Technologies

In recent years, the European Union has developed a sustainable, competitive, safe, and “decarbonised” energy approach. To achieve this objective, especially in highly urbanized contexts, there is a need to drastically improve the energy behavior of buildings and related energy systems. For this purpose, the aim of this paper is to analyse two very promising technologies that exploit the geothermal energy of the ground: the Earth-to-Air Heat eXchanger (EAHX) and the Ground Source Heat Pump (GSHP). These two systems are used as an energy retrofit strategy for the air conditioning system in an existing single-family house, located in Naples (south Italy). The building and the related systems are dynamically simulated using the DesignBuilder software. The results show energy savings of these two systems (compared to a traditional solution with an air-to-water heat pump) between 13% and 28%, with a total yearly primary energy consumption of about 80 kWh/m2 for the case with EAHX and around 67 kWh/m2 for the case with GSHP.

A novel solar-geothermal system integrated with earth–to–air heat exchanger and solar air heater with phase change material—numerical modelling, experimental calibration and parametrical analysis

In order to compensate drawbacks of traditional earth–to–air heat exchanger (EAHE) system, such as the unstable outlet air temperature, the overheating and the limited operation period, a novel coupled system systematically integrating an EAHE and a solar air heater (SAH) with phase change material (PCM), was proposed in this study. The complementary between geothermal and solar energy is exploited and served for building energy savings. On-site experimental testing and enthalpy-based numerical modelling using the control volume method were conducted for thermal and energy performances prediction. Systematic and parametrical analyses have been conducted using the developed mathematical model to investigate the effects of critical parameters on the thermal and energy performances. Our findings illustrate that the implementation of PCM can effectively stabilize the outlet air temperature for nearly 4.5 h and prolong the working period to 24 h. Due to the heat transfer enhancement, the increase of the airflow rate can significantly increase the system heating capacity, whereas the outlet air temperature is decreased with a maximum magnitude of 5.3 °C. Furthermore, the diurnal thermal performance of the system is highly dependent on the phase change temperature, whereas the time-duration of the effective operation is highly dependent on the PCM latent heat. Moreover, the system nocturnal thermal behavior can be improved with the increase of the PCM thermal conductivity, whereas a saturated improvement can be noticed when the PCM thermal conductivity is 1.0 W/(m·K). This study proposes a complementary geothermal and solar energy system, together with phase change material for the performance stability improvement, which are important for the promotion of green buildings with energy-efficient utilization of geothermal and solar energy.

Utilization of Earth-to-Air Heat Exchanger to Pre-Cool/Heat Ventilation Air and Its Annual Energy Performance Evaluation: A Case Study

An earth-to-air heat exchanger (EAHE) system utilizes the low-grade thermal energy of underground soil to warm up and cool down the flowing air within an underground buried pipe. Integrating the EAHE system with building ventilation can reduce the energy demand for conditioning ventilation air. The main purposes of this paper are to estimate the year-round energy-saving potential of the EAHE-assisted building ventilation system and provide its design guidelines in a hot-summer and cold-winter climate. A steady-state heat transfer model was proposed to calculate the outlet air temperature of an EAHE and further identify its ability to preheat and precool ventilation air. Influences of depth, length, and diameter of a buried pipe on the year-round thermal performance of the EAHE system were evaluated. The results show that considering the compromise between thermal performance and construction costs of the EAHE system, a depth of 5 m and a length of 80 m are recommended. The EAHE system can provide a mean daily cooling and heating capacity of 19.6 kWh and 19.3 kWh, respectively. Moreover, the utilization of the EAHE system can reduce by 16.0% and 50.1% the energy demand for cooling and heating ventilation air throughout the whole year.