Modelling of Shaded and Unshaded Shallow-Ground Heat Pump System for a Residential Building Block in a Mediterranean Climate

M Bottarelli,C Yousif

doi:10.1088/1742-6596/796/1/012017

Abstract

Heat pumps may be coupled to shallow-ground geothermal fields and used for the purpose of space heating and cooling of buildings. However, quite often it is not possible to locate the geothermal field in cleared grounds, especially in cities where building density is high and land has a high premium. This leads to the possibility of burying the geothermal field under the basement of new building blocks, before construction of the building.In the present work, the shaded-unshaded arrangement is numerically studied by coupling the software DesignBuilder-EnergyPlus to assess the building’s energy requirement with the software FEFLOW to solve the heat transfer equation in porous media. Assuming a standard residential building block, the coupling between the two software is performed by assigning the thermal energy requirement for air conditioning, as calculated by EnergyPlus, to a flat-panel typology of ground heat exchanger simplified in a 2D FEFLOW’s domain.The results show that it is necessary to opt for a dual-source heat pump (air/geothermal) system to ensure that the ground is not frozen or over-heated at peak times and to improve the overall performance of the system.

Highlights

The dawn of the EU Energy Performance in Buildings Directive Recast 2010/31/EU has put new demands on new and renovated buildings to achieve zero net-energy buildings by 2021, while at the same time, one is witnessing greater importance being given to energy storage, which in this case is the underground thermal energy storage (UTES)
The situation could be completely different in urban areas, where multi-storey buildings are more common due to the high value of land and it would not be profitable for the developer to limit the number of storeys
The present paper reports the numerical analysis of a so-called dual-source heat pump (DSHP) in shaded and unshaded conditions, as a first step for future studies in urban cities

Summary

Introduction

The dawn of the EU Energy Performance in Buildings Directive Recast 2010/31/EU has put new demands on new and renovated buildings to achieve zero net-energy buildings by 2021, while at the same time, one is witnessing greater importance being given to energy storage, which in this case is the underground thermal energy storage (UTES). Ground-coupled heat pumps (GCHPs) are commonly depicted as energy efficient systems for air conditioning [1]. The most common system is the reversible air-source heat pump. Solar systems can satisfy the heating and cooling demands of single storey building blocks, which generally have relatively low energy demand and sufficient roof space area to install solar systems to counter-balance their energy consumption and bring them to near zero-energy status. The situation could be completely different in urban areas, where multi-storey buildings are more common due to the high value of land and it would not be profitable for the developer to limit the number of storeys. The available roof space and possibly part of the façade would not be sufficient to offset the total energy demand of the building, even when it is built with the highest energy efficiency standards

Methods

Results

Conclusion