Ground corn-cob infill is evaluated as a low-cost wall retrofit strategy to improve thermal performance and assess building-level impact in rural dwellings in cold-climate China. Field measurements of indoor temperature and relative humidity were conducted in ten occupied households representing five household typologies during summer and winter. Median indoor temperatures were 29.8°C in summer and 5.5°C in winter, with only 1.3% of winter hours meeting the GB/T 18883-2022 comfort standard, indicating severe under-heating. The thermal transmittance of four wall configurations was determined using in-situ heat-flux measurements in accordance with ISO 9869-1. Ground corn-cob infill achieved the lowest U-value (0.981 W/(m²·K) under ΔT ≥ 10°C), representing a 46.6% reduction relative to an unfilled hollow-brick wall. Measured U-values were implemented in calibrated building performance simulation models to assess envelope-only retrofit scenarios. Under free-running conditions, none of the configurations met the national winter comfort standard. However, when evaluated against a locally derived comfort range (9.9–17.5°C), the addition of a corn-cob-infilled outer layer increased winter comfort duration by up to 197 hours in multi-generational households. No improvement in summer comfort was observed under sealed conditions due to reduced nocturnal heat dissipation. The results demonstrate that finely processed corn-cob infill can substantially reduce wall heat loss and improve winter thermal conditions in low-income rural housing. However, its effectiveness is seasonally dependent and requires integration with ventilation strategies to address summer performance. The proposed retrofit offers a scalable, low-cost solution for energy-poor rural contexts using locally available agricultural residues.
Yang et al. (Mon,) studied this question.