Smart Building Technologies for BIPV-Based Low-Carbon Energy Retrofitting: A Critical Review

The significant share of the building sector in global final energy consumption and subsequent CO2 emissions makes this sector a pivotal element in decarbonization pathways through energy retrofitting strategies. However, integrating effective solutions such as smart building technologies and building-integrated photovoltaic (BIPV) systems into energy retrofitting projects faces critical challenges, including fragmented evidence-based knowledge, discrepancies in assessment methods, and the complexity of coordinating multiple systems. This critical review synthesizes the fragmented body of literature to present a comprehensive framework for implementing smart building technologies in BIPV-driven energy retrofitting, using a structured PRISMA-based protocol, multiple technological taxonomies, and statistical analysis. The study presents three major novel contributions to this field: (i) a retrofit-depth classification of smart building technologies and further categories aligned with intervention intensity; (ii) a retrofit phase-based key performance indicator (KPI) framework; and (iii) a performance-priority decision matrix linking performance levels to technological measures across four primary performance goals: carbon emission reduction, cost optimization, grid flexibility and renewable self-sufficiency. Statistical analysis reveals a notable imbalance in the existing research landscape where physical interventions, such as system replacements and renewable system integration, dominate the literature, while the application of digital monitoring and control systems and social/readiness KPIs are significantly underrepresented. The findings further demonstrate that integrated technological solutions are more frequently associated with higher performance improvement. This study and proposed performance-priority decision matrix further provide evidence-based practical guides for researchers, practitioners, and policymakers to implement and promote effective and climate-focused smart building retrofitting strategies.