Analysis of the Thermal Behavior of an Earthbag Building in Mediterranean Continental Climate: Monitoring and Simulation

Abstract

Nearly 30% of humanity lives in earthen dwellings. Earthbag is a sustainable, cheap, feasible and comfortable option for emergency housing. A comparative monitoring-simulation analysis of the hygrothermal behavior of an Earthbag dwelling in Mediterranean continental climate, designed under bioclimatic criteria, is presented. The dome shape Earthbag dwelling has a net floor area of 7.07 m 2 , a glass door facing south and two confronted windows in the east and west facades. A numerical model (EnergyPlus v8.8) was designed for comparison. Twenty-four hour cross ventilation, night cross ventilation, and no ventilation in free floating mode and a controlled indoor temperature were the tested scenarios. Comparisons between experimental data and simulation show a good match in temperature behavior for the scenarios studied. Reductions of 90% in summer and 88% in winter, in the interior thermal amplitude with respect to exterior temperatures are found. Position of the glazed openings was fundamental in the direct solar gains, contributing to the increase of temperature in 1.31 • C in winter and 1.37 • C in the equinox. Night ventilation in the summer period had a good performance as a passive system. Passive solar gains made a reduction of heating energy consumption of 2.3% in winter and 8.9% in equinox.

Thermal Monitoring and Simulation of Earthen Buildings. A Review

“…The thermal lag represents the time that elapses between the indoor air temperature maximum value and the outdoor maximum value. The decrement factor is defined as the reduction of the temperature range of both measures [13].…”

“…Rincón et al [13] present an experimental earthbag building located in Lleida (Spain); corresponding to a Mediterranean continental climate (BSk). The earthbag prototype has a dome shape of 3 m of diameter and a high of 3.3 m. The walls consist of different earthbag thicknesses-70 cm for the buttress, 35 cm for the wall and 28 cm for the roof-and an exterior lime mortar coating of 0.4 cm.…”

“…Moreover, the theoretical result for the decrement factor is 0.12, and the values obtained from the monitoring analysis are 0.12, 0.19 and 0.10, for winter, equinox and summer solstice, respectively. According to [13], night ventilation, from 8 p.m. to 8 a.m., takes advantage of the cooler temperatures at night to decrease the average temperature of the earthbag building, making it an appropriate passive strategy for cooling. In addition, a 24 h ventilation in summer was tested.…”

“…In addition, Ref. [13] assesses comfort conditions in the earthbag dwelling applying the ASHRAE Standard 55 Adaptive [25] comfort model during summer. The analysis resulted that most of the points are either within the comfort adaptive range or only a bit above the upper limit (0.5-3 • C) or slightly below the lower one (0.5 • C).…”

“…Rincón et al [13] used the EnergyPlus v.8.8 software to simulate the earthbag prototype monitored in Spain, mentioned in the previous section, in order to first validate the model and also to test different passive strategies to improve the thermal performance. The monitoring and simulation results showed a good match, discrepancies of 1 • C, in the temperature behaviour.…”