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This paper describes a novel methodology for establishing the relative moisture performance of renders used to protect a novel walling system combining traditional dense cob with a low-density thermal cob. A new method of enhancing the thermal insulation of cob walls has been developed by an European Union (EU)-funded joint UK and French project called CobBauge. The external surface of traditional cob walls (comprising subsoil, fibre and water) is normally protected from driving rain by placing the walls on a short wall called a plinth, a pronounced eaves overhang and a breathable exterior render. As the low-density fibre and clay insulating layer in the CobBauge system differs from traditional cob, a method of establishing the moisture-related performance of a range of renders needed to be instituted to aid the materials selection process. A series of test panels were constructed with the thermal cob infill, faced by a number of render types. The panels were hung in an open position in a high exposure zone and the moisture content monitored using wood-block sensors, electrical resistivity and gravimetric measurements over a period of six months. The wood-block and electrical resistivity moisture measurements showed a good level of agreement with gravimetric measurements and showed a clear differentiation between the various render choices. [ABSTRACT FROM AUTHOR]

The population of developed nations spends a significant amount of time indoors, and the implications of poor indoor air quality (IAQ) on human health are substantial. Many premature deaths attributed to exposure to indoor air pollutants result from diseases exacerbated by poor indoor air. CO2, one of these pollutants, is the most prevalent and often serves as an indicator of IAQ. Indoor CO2 concentrations can be significantly higher than outdoor levels due to human respiration and activity. The primary objective of this research was to numerically investigate the indoor relative humidity and CO2 in cob buildings through the CobBauge prototype, particularly during the first months following the building delivery. Both in situ experimental studies and numerical predictions using an artificial neural network were conducted for this purpose. The study presented the use of a piecewise autoregressive exogenous model (PWARX) for indoor relative humidity (RH) and CO2 content in a building constructed with a double walling system consisting of cob and light earth. The model was validated using experimental data collected over a 27-day period, during which indoor RH and CO2 levels were measured alongside external conditions. The results indicate that the PWARX model accurately predicted RH levels and categorized them into distinct states based on moisture content within materials and external conditions. However, while the model accurately predicted indoor CO2 levels, it faced challenges in finely classifying them due to the complex interplay of factors influencing CO2 levels in indoor environments. [ABSTRACT FROM AUTHOR]

Soil‐based green infrastructure has the potential to improve building thermal performance and contribute to sustainable buildings. This study compares thermal conductivity response to soil moisture of three peat‐free artificial soils to evaluate their potential use within green roofs and living walls. Thermal conductivity was measured with changing soil moisture and density. All soils showed higher thermal conductivity measures with increases in soil moisture. The 'Biochar‐coconut coir compost' had the lowest thermal conductivity measures which displayed negligible response to density changes and exhibited the highest water holding capacity. When uncompacted, 'FabSoil' had low thermal conductivity measures, but when compacted, its measures were considerably higher. Results show the role of density on thermal performance will be soil type dependent. Overall, findings highlight the importance of considering substrate composition, density and suggest that peat‐free artificial soil substrates that contain biochar, have a higher percentage organic matter content and a finer particle texture are likely to result in lower thermal conductivity and higher soil water holding capacity. The results also showed that ThetaProbe measures (volumetric) had a high equivalence to actual soil moisture content (gravimetric), across different soil types and soil bulk densities. This finding supports the use of ThetaProbe measures as an effective method for monitoring soil moisture; with the potential for integration into irrigation control systems for green infrastructure. The findings of this paper offer the potential to improve building thermal performance by informing soil substrate choice, irrigation control and load bearing requirements in the design of green infrastructure. [ABSTRACT FROM AUTHOR]