Effects of energy retrofits on the indoor microbiota in Northern European apartmentsOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked how building energy retrofits change the microbes living in indoor air. Researchers sampled settled dust from apartments before and after retrofits, which mostly upgraded insulation, heating, ventilation, and windows. They used amplicon sequencing to characterize fungal and bacterial communities. Analyses paired pre versus post samples using mixed models and ANCOM differential abundance testing, adjusting for confounding factors.
Who was studied?
The study covered 193 apartments in 40 apartment buildings in two Northern European countries, Finland and Lithuania. The units were sampled before and after energy retrofit work. The subject was the indoor microbiota in airborne settled dust, not human participants or animals. The authors describe this as the first dedicated multi-country study of how energy retrofits affect indoor microbiota.
What were the most important findings?
Energy retrofits produced significant, country-dependent shifts in the relative abundances of individual bacterial and fungal taxa. The direction of change differed between Finland and Lithuania. In Finnish buildings, the proportion of human-sourced bacteria was smaller after retrofits than before. Outdoor temperature and ventilation type influenced both bacterial and fungal composition indoors, consistent with prior work. These environmental factors acted alongside the retrofit changes.
What are the greatest implications of this study?
The findings show that energy-saving building upgrades can measurably alter the indoor microbial environment, and that effects depend on national context and building factors. This matters because indoor microbes relate to occupant exposure and possibly health. The authors frame the work as a foundation for future research rather than a health verdict. Because health outcomes were not measured, the practical health relevance of these microbiome shifts remains to be determined.