A procedure to measure the in-situ hygrothermal behavior of unstabilised rammed earth walls

The conducted research examines the thermal behaviour of the rammed earth walls, which is the basic structural and fa?ade element of traditional Vojvodina house. The traditional rammed earth house represents an important part of the total building stock of Vojvodina. Earth is a locally available, cheap, natural, environmentally friendly building material and has been used extensively for traditional family houses in Vojvodina. It has ecological and ?green? characteristics, which can be assessed as very high quality, and they are of significant importance in the context of sustainable development and striving to reduce energy consumption today. The research examines thermal behaviour of rammed earth wall, including theoretical analysis of: the heat transfer coefficient, U, the thermal resistance, R, and thermal conductivity, ?. One of the basic elements of thermal behaviour, the thermal mass, has been analyzed both theoretically and by measuring in situ. The in situ measurements were conducted on the traditional house in Vojvodina by measuring inside and outside surface wall and air temperature in summer. Analyses of rammed earth wall thermal performances have shown that the wall has low thermal conductivity, high heat capacity and significant thermal mass effect which is the key element enabling thermal stability. The research indicates rather good thermal properties of the rammed earth walls. Potential of rammed earth wall in Vojvodina should be an issue of further analysis, although the possibility of improvement of existing facilities to meet current standards in terms of energy efficiency should be considered.

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Evaluation of the Thermal Comfort and Energy Demand in a Building with Rammed Earth Walls in Spain: Influence of the Use of In Situ Measured Thermal Conductivity and Estimated Values

Buildings ◽

10.3390/buildings11120635 ◽

2021 ◽

Vol 11 (12) ◽

pp. 635

Author(s):

Miguel Ángel Mellado Mascaraque ◽

Francisco Javier Castilla Pascual ◽

Víctor Pérez Andreu ◽

Guillermo Adrián Gosalbo Guenot

Keyword(s):

Thermal Conductivity ◽

Thermal Comfort ◽

Energy Demand ◽

Winter Period ◽

Rammed Earth ◽

Thermal Mass ◽

Nominal Data ◽

K Value ◽

Earth Walls

This paper describes the influence of thermal parameters—conductivity, transmittance, and thermal mass—in the estimation of comfort and energy demand of a building with rammed earth walls, and consequently, the compliance with standards. It is known that nominal design data does not match in situ measured values, especially in traditionally constructed buildings. We have therefore monitored a room in a building with rammed earth walls, designed a computerised model, and compared four different alternatives where we have changed the value for the thermal conductivity (in situ vs. estimated) and the consideration of thermal mass. When we then analyse the compliance with the Spanish energy saving code, using measured values would result in lower differences with the standards’ limits and even comply with the global thermal transmittance (K-value) requirement. This would mean a more realistic approach to the restoration of traditional buildings leading to the use of thinner and more suitable insulation and retrofitting systems, encouraging the use of rammed earth in new buildings, and therefore reducing the carbon footprint due to materials used in construction. Results show that the building model that uses in situ values and considers thermal mass (S1) is closer to reality when assessing thermal comfort. Finally, using nominal data would result in requiring 43% more energy in the selected winter period and 102% more energy in the selected summer period to keep the same comfort conditions as in the alternative where measured values are used.

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Design Optimisation Strategies for Solid Rammed Earth Walls in Mediterranean Climates

Energies ◽

10.3390/en14020325 ◽

2021 ◽

Vol 14 (2) ◽

pp. 325

Author(s):

Giada Giuffrida ◽

Maurizio Detommaso ◽

Francesco Nocera ◽

Rosa Caponetto

Keyword(s):

Energy Demand ◽

Construction Material ◽

Base Material ◽

Energy Performance ◽

Embodied Energy ◽

Rammed Earth ◽

Earth Construction ◽

Material Choice ◽

Earth Walls ◽

Raw Earth

The renewed attention paid to raw earth construction in recent decades is linked to its undoubted sustainability, cost-effectiveness, and low embodied energy. In Italy, the use of raw earth as a construction material is limited by the lack of a technical reference standard and is penalised by the current energy legislation for its massive behaviour. Research experiences, especially transoceanic, on highly performative contemporary buildings made with natural materials show that raw earth can be used, together with different types of reinforcements, to create safe, earthquake-resistant, and thermally efficient buildings. On the basis of experimental data of an innovative fibre-reinforced rammed earth material, energy analyses are developed on a rammed earth building designed for a Mediterranean climate. The paper focuses on the influences that different design solutions, inspired by traditional bioclimatic strategies, and various optimised wall constructions have in the improvement of the energy performance of the abovementioned building. These considerations are furthermore compared with different design criteria aiming at minimising embodied carbon in base material choice, costs, and discomfort hours. Results have shown the effectiveness of using the combination of massive rammed earth walls, night cross ventilation, and overhangs for the reduction of energy demand for space cooling and the improvement of wellbeing. Finally, the parametric analysis of thermal insulation has highlighted the economic, environmental, and thermophysical optimal solutions for the rammed earth envelope.

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