Thermal performance analysis of earth pipe cooling system for subtropical climate

Energy crisis is one of the major obstacles for human development. There are on-going researches to overcome this for a sustainable environment and economy. Passive air cooling system of earth pipe cooling is seen as a viable energy efficient technology for hot and humid subtropical climates. It can be an attractive economical alternative to conventional cooling since there are no compressors or any habitual mechanical unit. It utilizes earth’s near constant underground temperature to cool air for residential, agricultural or industrial uses. This paper reports the thermal performance of earth pipe cooling technology for a hot and humid subtropical climatic zone in Queensland, Australia. A series of pipes buried underground were used in order to increase the cooling performance of the system. To measure the thermal performance, a thermal model was developed for the earth pipe cooling system and simulated using ANSYS Fluent. Data were collected from two modelled rooms built from shipping containers and installed at Central Queensland University, Rockhampton, Australia. The impact of air temperature and velocity on room cooling performance has also been assessed. A significant temperature reduction is seen in this study, which will save energy cost for thermal cooling in buildings.

Performance assessment of earth pipe cooling system for low energy buildings in a subtropical climate

Energy consumption in heating and cooling around the world has been a major contributor to global warming. Hence, many studies have been aimed at finding new techniques to save and control energy through energy efficient measures. Most of this energy is used in residential, agricultural and commercial buildings. It is therefore important to adopt energy efficiency measures in these buildings through new technologies and novel building designs. These new building designs can be developed by employing various passive cooling systems. Earth pipe cooling is one of these which can assist to save energy without using any customary mechanical units. This paper investigates the earth pipe cooling performance in a hot humid subtropical climate of Rockhampton, Australia. A thermal model is developed using ANSYS Fluent for measuring its performance. Impacts of air velocity, air temperature, relative humidity and soil temperature on room cooling performance are also assessed. A temperature reduction of around 2 °C was found for the system. This temperature reduction contributed to an energy saving of a maximum of 866.54 kW (8.82%) per year for a 27.23 m3 room.

Numerical modeling of vertical earth pipe cooling system for hot and humid subtropical climate

Energy crisis is one of the major problems facing the progress of human society. There are several energy-efficient technologies that can be applied to save energy and make a sustainable environment. Passive air cooling of earth pipe cooling technology is one of them to reduce the energy consumption for hot and humid subtropical climates. The technology works with a long buried pipe with one end for intake air and the other end for providing air cooled by soil to the desired space such as residential, agricultural, or industrial buildings. It can be an attractive economical alternative to conventional cooling since there are no compressors or any customary mechanical unit. This chapter reports the performance of a vertical earth pipe cooling system for a hot and humid subtropical climatic zone in Queensland, Australia. A series of buried pipes were installed in vertical arrangement in order to increase earth pipe cooling performance. To measure the performance of the system, a numerical model was developed and simulated using the CFD software Fluent in ANSYS 15.0. Data were collected from two modeled rooms built from two shipping containers and installed at the Sustainable Precinct at Central Queensland University, Rockhampton, Australia. The impact of air temperature and velocity on room cooling performance has also been assessed. A temperature reduction of 1.82 °C was observed in the room connected to the vertical earth pipe cooling system, which will save the energy cost for thermal cooling in buildings.

Integrated model of horizontal earth pipe cooling system for a hot humid climate

Energy efficiency of a building has become a major requirement since the building sector produces 40%-50% of the global greenhouse gas emissions. This can be achieved by improving building’s performance through energy savings, by adopting energy efficient technologies and reducing CO2 emissions. There exist several technologies with less or no environmental impact that can be used to reduce energy consumption of the buildings. Earth pipe cooling system is one of them, which works with a long buried pipe with one end for intake air and the other end for providing air cooled by soil to the building. It is an approach for cooling a room in a passive process without using any habitual mechanical unit. The paper investigates the thermal performance of a horizontal earth pipe cooling system in a hot and humid subtropical climatic zone in Queensland, Australia. An integrated numerical model for the horizontal earth pipe cooling system and the room (or building) was developed using ANSYS Fluent to measure the thermal performance of the system. The impact of air temperature, soil temperature, air velocity and relative humidity on room cooling performance has also been assessed. As the soil temperature was below the outdoor minimum temperature during the peak warming hours of the day, it worked as an effective heat sink to cool the room. Both experimental and numerical results showed a temperature reduction of 1.11oC in the room utilizing horizontal earth pipe cooling system which will assist to save the energy cost in the buildings.

Parametric study on thermal performance of horizontal earth pipe cooling system in summer

Rational use of energy and its associated greenhouse gas emissions has become a key issue for a sustainable environment and economy. A substantial amount of energy is consumed by today's buildings which are accountable for about 40% of the global energy consumption. There are on-going researches in order to overcome these and find new techniques through energy efficient measures. Passive air cooling of earth pipe cooling technique is one of those which can save energy in buildings with no greenhouse gas emissions. The performance of the earth pipe cooling system is mainly affected by the parameters, namely air velocity, pipe length, pipe diameter, pipe material, and pipe depth. This paper investigates the impact of these parameters on thermal performance of the horizontal earth pipe cooling system in a hot humid subtropical climate at Rockhampton, Australia. For the parametric investigation, a thermal model was developed for the horizontal earth pipe cooling system using the simulation program, FLUENT 15.0. Results showed a significant effect for air velocity, pipe length, and pipe diameter on the earth pipe cooling performance, where the pipe length dominated the other parameters.

Evaluating rammed earth aalls: a case study

The following research has been undertaken as a response to the recent controversy regarding the suitability of rammed earth wall construction as an effective building envelope. Empirical (in-situ) measurements of temperature and heat flux are taken on the walls of an existing rammed earth building in New South Wales, Australia. An analysis is performed which examines the influence of walls, floor, ceiling and windows on the recorded temperatures within the building. It appears that diffuse sky radiation transmitted by the windows is an important factor in the summer heat load, and that night time cooling coupled with thermal mass has a valuable conditioning effect.

Validated model and study of a rammed earth wall building

A 2100 m² (GFA) two-storey rammed earth building was built on the Thurgoona campus of Charles Sturt University in 1999. The building is novel both in the use of materials and equipment for heating and cooling. The climate at Wodonga can be characterised as hot and dry, so the challenge of providing comfortable working conditions with minimal energy consumption is considerable. This paper describes a thermal model of one of the second-storey offices on the west-end of the building. The simulation software, TRNSYS, has been used to predict office temperatures and comparisons are made between these and measurements made over a typical week in summer. Reasonable agreement has been achieved under most conditions. The model has been used to investigate key building parameters and strategies, including night flushing, to improve the thermal comfort in the office.

Energy use and thermal comfort in a rammed earth office building

A two-storey rammed earth building was built on the Thurgoona Campus of Charles Sturt University in Albury-Wodonga, Australia, in 1999. The building is novel both in the use of materials and equipment for heating and cooling. The climate at Wodonga can be characterised as hot and dry, so the challenge of providing comfortable working conditions with minimal energy consumption is considerable. This paper describes an evaluation of the building in terms of measured thermal comfort and energy use. Measurements, confirmed by a staff questionnaire, found the building was too hot in summer and too cold in winter. Comparison with another office building in the same location found that the rammed earth building used more energy for heating. The thermal performance of three offices in the rammed earth building was investigated further using simulation to predict office temperatures. Comparisons were made with measurements made over typical weeks in summer and winter. The validated model has been used to investigate key building parameters and strategies to improve the thermal comfort and reduce energy consumption in the building. Simulations showed that improvements could be made by design and control strategy changes.