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In the present study, the real-world performance of a ground-to-air heat exchanger (GAHE) was analyzed in the Polish climate which is characterized by warm summers and cold winters. The heat exchanger’s performance was monitored over a period of three years (2017 to 2019), and real-world conditions were compared with a Typical Meteorological Year (TMY). The aim of the study was to assess the exchanger’s energy-efficiency potential in various ventilation scenarios in a single-family home under variable real-world conditions, rather than to simply determine its heating and cooling capacity. The analyzed single-family home was a modern, single-story building with a usable floor area of 115 m2. The building’s thermal insulation and airtightness met stringent energy-efficiency standards. Energy consumption in a building equipped with a natural ventilation system was compared with three other scenarios: ventilation coupled with a GAHE, mechanical ventilation with heat recovery and a high-efficiency heat exchanger (HE), and mechanical ventilation with heat recovery coupled with a GAHE. Sensible heating and cooling loads were calculated based on standard ISO 13790:2008, and latent heating and cooling loads were also included in the energy balance. During the year, the GAHE generated around 257.6 W of heating energy per hour and 124.7 W of cooling energy per hour. Presented results can be used to select the optimal HVAC system scenarios for engineering projects as well as private investors.

Greenhouse agriculture in humid tropical regions faces significant challenges due to excessive heat and humidity, which compromise crop productivity and necessitate energy-efficient cooling solutions. This study evaluates the performance of a ground-to-air heat exchanger (GAHE) for greenhouse cooling under the humid tropical climate of Ibadan, Nigeria. The GAHE system, comprising underground PVC pipes at 1 m and 2 m depths, was designed. Experimental trials measured inlet and outlet temperatures over 35 days, revealing that the 2 m depth achieved a mean cooling of 2.99 ± 1.01 °C, with maximum reductions of 4.45 °C. In contrast, the 1 m depth provided negligible cooling (0.06 ± 0.43°C) and occasionally increased air temperature due to soil heat absorption. Results demonstrate that deeper installation leverages stable subsurface temperatures, mitigating daytime thermal fluctuations and solar influence. The findings align with prior studies emphasising depth-dependent efficiency and validate GAHE’s potential as a low-energy cooling strategy in tropical greenhouses. This study concludes that GAHE systems installed at 2 m depth offer a sustainable and practical solution for greenhouse temperature control in humid tropics.

Natural 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. 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.

This work proposes a new device for air treatment with dehumidification and water recovery/storage, with possible mitigation of indoor environmental conditions. The system is based on Peltier cells coupled with a horizontal earth-to-air heat exchanger, it is proposed as an easy-to-implement alternative to the heat pumps and air handling units currently used on the market, in terms of cost, ease of installation, and maintenance. The process provides the water collection from the cooling of warm-humid air through a process that leads to condensation and water vapor separation. The airflow generated by a fan splits into two dual flows that lap the two surfaces of the Peltier cells, one flow laps the cold surfaces undergoing sensible, latent cooling with dehumidification; the other flow laps the hot surfaces and heats up. The airflow undergoes thermal pre-treatment through the underground horizontal geothermal pipe that precedes the Peltier cells. In the water storage tank, which also works as a mixing chamber, the two air streams are mixed to regulate the outlet temperature. The system can be stand-alone if equipped with a photovoltaic panel and a micro wind turbine, able to be used in places where electricity is absent. The system, with different configurations, is modeled in the African city Kigali, in Rwanda.

In this study, a new design for energy recovery from the return air has been introduced to improve the air handling unit (AHU) performance through the energetic analysis. The main objective is defined as the reduction in cooling and heating coils energy demand. In the novel AHU, the coldness from the exhaust air is transferred to the fresh air through the primary heat exchanger to reduce the cooling coil energy usage, while in the secondary heat exchanger, the warmness from the return air is recovered to the outlet cold air of the cooling coil to reduce the heating coil energy usage. Results showed that using air-to-air heat exchanger in hot and dry climate regions, the total energy consumption decreased up to 26.38%, which in turn increased the first law efficiency up to 35.84%, while in hot and humid climate these figures are 13.11% and 10.57%, respectively. It is concluded that the effect of using the air-to-air heat exchangers in hot and dry climate has priority over the hot and humid one.

The energetic analysis of an air handling unit (AHU) combined with an enthalpy air-to-air heat exchanger has been studied to improve the first law thermodynamic efficiency. The energy balance equations for enthalpy air-to-air heat exchanger, conditioned space, heating coil, cooling coil and mixing box have been performed and solved based on a program developed in Engineering Equation Solver. The results showed that using an enthalpy air-to-air heat exchanger leads to energy recovery which in turn decreased the total required AHU power. The effect of using an enthalpy air-to-air heat exchanger on recovered energy in hot and humid ambient is more than the cold and dry one. Using the enthalpy air-to-air heat exchanger, the cooling coil load decreases by 28.27%, which in turn increases the first law efficiency by 32.8%.

In this study, the exergy analysis of an AHU equipped with a heat and exergy recovery unit was investigated. The equations obtained from energy and exergy balance were solved based on a program developed in engineering equation solver. Through the air-to-air heat exchanger, the energy is transferred from the fresh air to the exhaust one but the exergy is transferred from the exhaust air to the fresh one. Therefore, the cooling coil power consumption and irreversibility were reduced. The efficacy of installing an air-to-air heat exchanger is dependent on the temperature and relative humidity of the ambient. Based on the results, at the lowest ambient temperature and relative humidity, the power consumption is reduced by 10.8%, while in the highest ambient temperature and relative humidity, this figure was 33%. Under ambient conditions with low temperatures and high relative humidity, installation of heat recovery unit reduced the irreversibility by 5.18%, while in the highest temperature and lowest relative humidity this figure was 12.8%.

Purpose This study aims to simulate the flow and heat transfer through an air handling unit to reduce its energy consumption by a novel creative idea of using an air-to-air heat exchanger. Design/methodology/approach To do this, both first and second laws of thermodynamics energy and exergy balance equations were solved numerically by an appropriate developed computer code. Findings Using the air-to-air heat exchanger in dry conditions decreases the cooling coil load by 0.9 per cent, whereas the reduction for humid conditions is 27 per cent. Similarly, using air-to-air heat exchanger leads to an increase in the first law of efficiency in dry and humid conditions by 0.9 per cent and 36.8 per cent, respectively. Originality/value The second law of efficiency increases by 1.55 per cent and 2.77 per cent in dry and humid conditions, respectively. In other words, the effect of using an air-to-air heat exchanger in humid conditions is more than that in dry conditions.

A large part of the total energy consumption in buildings in the Kingdom of Saudi Arabia (K.S.A.), is devoted to air cooling. This leads to high electricity costs for residents and a high amount of equivalent CO2 emissions. The work presented in this paper aims at evaluating and applying shallow geothermal energy for cooling and heating to reduce cost and environmental issues in the Kingdom. The system is based on the earth-air heat exchanger (EAHE) equipped with an air circulation fan. In this study, six cities have been selected; Madinah city, where our university is located, and five other cities representing five different climatic zones. A new parameter called “geothermal percentage” is proposed to calculate the ratio of geothermal energy to the cooling/heating total load. It has been shown that the proposed system covers part of the cooling load and the total heating needs for almost all the country’s territory. However, both heating and cooling needs can be fulfilled by the EAHE for few cities such as Guriiat and Khamis, characterized by a moderate climate.

The article analyzes a ground-to-air heat exchanger (GAHE) for a mechanical ventilation system in a building. The heat exchanger’s performance was evaluated in northeastern Poland between May and August of 2016, 2017, and 2018. In spring and summer, the GAHE can be theoretically used to precool air for HVAC systems. The aim of the study was to compare the real-world performance of GAHE with its theoretical performance determined based on the distribution of ground temperature and the temperature at the GAHE outlet modeled in compliance with Standard PN-EN 16798-5 1:2017-07. The modeled values differed considerably from real-world data in May and June, but the model demonstrated satisfactory data fit in July and August. In all years, the modeled average monthly air temperature at the GAHE outlet was 8.3 °C below real-world values in May, but the above difference was only 1.1 °C in August. The developed mathematical model is simple and easy to use, and it can be deployed already in the preliminary design stage. It does not require expensive software or expert skills. However, this study revealed that the model has several limitations. The observed discrepancies should be taken into account when modeling the performance of a GAHE.