Indoor Environmental Quality in an Occupied Whole Life Straw Bale House in England, UK

In response to policy and legislative measures targeting the reduction of carbon dioxide emissions, building design has increasingly prioritised airtightness and energy efficiency. However, existing literature raises concerns that such designs may lead to issues such as overheating and inadequate ventilation. At the same time, some designers have turned to low-carbon construction materials such as straw bales, not only to minimise embodied carbon emissions but also to promote occupant health. Although straw bale buildings are known for their thermal efficiency, limited data are available on their indoor environmental quality (IEQ) during occupancy. This study presents a case study evaluating the environmental performance of an airtight, energy-efficient straw bale dwelling equipped with a decentralised ventilation system, located in southern England, UK. The research investigates whether the home maintains thermal comfort throughout the year, with a focus on both summer and winter seasons, along with an assessment of relative humidity and total volatile organic compounds (TVOCs). Data were collected over a 14-month period and evaluated against established IEQ benchmarks. Findings revealed no instances of overheating, even during a summer heatwave; however, elevated TVOC concentrations were recorded in summer compared to winter. Indoor temperature results also differed from those reported in previous studies on UK airtight homes, underscoring the need for broader research into the IEQ performance of dwellings constructed with natural materials to determine the extent to which sustainable building practices contribute to occupant comfort.