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From field to wall: On-site ground corn-cob infill for low-cost passive thermal-comfort retrofits in rural cold-climate China

Lookup NU author(s): Di Yang, Professor Neveen Hamza, Professor Rose GilroyORCiD

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).

Abstract

© 2026 The AuthorsGround 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 18,883–2022 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 h 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.

Publication metadata

Author(s): Yang D, Hamza N, Gilroy R

Publication type: Article

Publication status: Published

Journal: Building and Environment

Year: 2026

Volume: 302

Online publication date: 01/06/2026

Acceptance date: 30/05/2026

Date deposited: 15/06/2026

ISSN (print): 0360-1323

ISSN (electronic): 1873-684X

Publisher: Elsevier Ltd

URL: https://doi.org/10.1016/j.buildenv.2026.114825

DOI: 10.1016/j.buildenv.2026.114825

Data Access Statement: Data will be made available on request

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