Evaluation of a diary-based questionnaire to capture the impacts of energy retrofits on occupant satisfaction, health and their connection to measured IEQ

• Occupant diary assessed IEQ satisfaction and health pre- and post-energy retrofits. • Post-retrofit improvements in IAQ satisfaction, thermal comfort, and respiratory health. • Diary and retrospective questionnaire methods yielded similar results. • Diary may better capture IEQ–health associations than retrospective questionnaire. Evaluating the effects of energy retrofits on occupant satisfaction with indoor environmental quality (IEQ) and health is essential to ensure sustainable living environments that support well-being. Therefore, it is important to identify effective methods to capture occupant experiences. This study evaluates a diary-based questionnaire to assess the effects of building energy retrofits on occupant satisfaction with IEQ and health, and their associations with measured IEQ, compared with a simultaneously administered retrospective questionnaire. Data were collected using 2-week diaries completed before and after energy retrofits by 271 residents of 212 apartments across 31 Finnish and 19 Lithuanian multifamily buildings. Retrofits included upgrades to insulation, heating, ventilation and/or windows. IEQ parameters including temperature and humidity, air change rate, and chemical and microbial agents were measured. The diary data indicated mostly positive changes in occupant satisfaction with indoor air quality, thermal conditions, and respiratory and eye symptoms, consistent with the questionnaire. Unlike the questionnaire, the diary data revealed associations between self-reported symptoms and measured IEQ, with fewer symptoms at lower indoor PM2.5 levels and higher air change rates. These associations did not explain post-retrofit health improvements. While both methods yielded similar results, suggesting that either may be suitable for assessing retrofit impacts, the diary may be more suitable for identifying underlying causes of health effects, possibly due to more specific questions or closer alignment with the IEQ measurement period.