The built environment is responsible for a substantial amount of energy use and greenhouse gas emissions. To improve energy efficiency and reduce environmental impacts, buildings can be renovated or replaced with more energy-efficient alternatives. Although new buildings often cause less environmental impacts from operating energy use, the higher material requirements cause additional environmental impacts. Housing corporations own more than 25% of residences in the Netherlands and need to decide between different energy efficiency improvement methods for their building stock. Therefore, the proposed thesis has the following research question: What are optimal building renovation or replacement solutions for housing corporations to improve energy efficiency and reduce environmental impacts in the context of the Dutch climate goals? Environmental impacts of materials and energy have been calculated according to the MPG+ method, which follows the life cycle assessment approach. The results show that extensively renovated porch flats and new buildings lead to similar amounts of environmental impacts if both use a collective heat pump and are insulated according to nearly-zero energy building standards. The comparison between the environmental impacts of extensive renovations and building replacement depends on the expected building life span after the intervention, the quantity of solar panels, and the use of sustainable materials. Renovations including lower energy efficiency levels or fossil energy sources cause more environmental impacts. The MPG+ method aligns with the Dutch policy context but lacks transparency, completeness, and data certainty. The alternative scenarios in this study are compared per square meter, so the overall environmental impacts may increase if the relative apartment size per resident is greater in the new building. Considering the Climate Agreement, the housing crisis, and many uncertainties, extensive renovations are recommended as a no-regret solution for housing corporations.