ENHANCING OCCUPANT HEALTH THROUGH RESIDENTIAL RETROFITS: A COMPREHENSIVE REVIEW OF INDOOR ENVIRONMENTAL QUALITY

Residential retrofits are central to decarbonisation but risk unintended health impacts via indoor environmental quality (IEQ).This systematic review of 29 studies (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023)(2024) employs the IEQ-Compass framework to evaluate retrofits across thermal comfort (THER), indoor air quality (IAQ), lighting (VIS), and acoustics (ACOU).While retrofits significantly reduce energy demand, they introduce critical trade-offs: airtightness traps radon and Volatile Organic Compounds (VOCs), while insulation increases overheating risks for vulnerable groups.Smart technologies, such as Internet of Things (IoT) ventilation and hygrothermal modelling, stabilise humidity (<35% RH) and particulate matter, though regional disparities persist.For instance, passive insulation in rural China mitigates energy povertyrelated hypertension, while adaptive solar Heating, Ventilation, and Air Conditioning (HVAC) systems optimise thermal stability (20-25C) in temperate climates.However, gaps remain in acoustic standards and equitable design, exacerbated by engineering-centric databases underrepresenting health outcomes.The IEQ-Compass's uniform domain weighting overlooks climate-specific priorities, such as shading in tropical zones.Policy recommendations advocate embedding health metrics-IAQ thresholds, overheating resilience-into global building codes to align with Sustainable Development Goals (SDGs).Future research must integrate longitudinal health tracking, occupant behaviour dynamics, and multi-disciplinary approaches to bridge energy efficiency with well-being.By harmonising building science and public health, this review calls for occupant-centric retrofits that prioritise IEQ alongside decarbonisation, ensuring equitable health co-benefits.