Towards determining the effect of shallow depth horizontal ground loop clearance on the heat loss of a single family residential dwelling

Felix Chen

doi:10.32920/ryerson.14639094

Abstract

Using solar energy stored in the ground to preheat incoming fresh ventilation air with ground loops is a renewable energy system which is becoming more frequently used in new residential developments. The purpose of this research was to examine the effect of ground loop to foundation wall clearance on building heat loss. Additionally, the thermal properties of the soil were examined to determine their impact on the ground loop’s effect on heat loss. A simulation based research approach was conducted using HEAT3, which is a three-dimensional transient heat transfer software. This study found that ground loop clearance had a larger impact on building heat loss for areas with low thermal conductivity soils than for areas with high thermal conductivity soils. On average, ground loop clearances of 10cm, 50cm, 100cm, and 200cm resulted in increased building heat losses of 20%-83%, 19%-55%, 16%-35%, and 12%-15% respectively.

Highlights

Using solar energy stored in the ground to preheat incoming fresh ventilation air with ground loops is a renewable energy system which is becoming more frequently used in new residential developments
The results showed that the temperature difference between the reference average ground temperature and the horizontal ground heat exchanger (HGHE) area was 2.22 ± 1.23 °C for the linear HGHE
For a low thermal conductivity soil, the building heat loss percent increase from a ground loop at a 10cm clearance versus a ground loop at a 200cm clearance decreases from 356% to 61%, which is a difference of 295%

Summary

Introduction

Using solar energy stored in the ground to preheat incoming fresh ventilation air with ground loops is a renewable energy system which is becoming more frequently used in new residential developments. The ground loop can be installed in nearly any typical building excavation at various stages of construction since its clearance from foundation walls has traditionally been in the order of 1 m to 2 m. It can be placed under slabs, beside footings, and in other trenches dug for utilities or drainage. A typical system consists of plastic piping, isolation valves, manifold headers, a fluid to air heat exchanger, a fluid circulator, a freeze protected fluid such as a refrigerant, expansion tank, air separator, and other closed-loop system components

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