Abstract
<title>Abstract</title> <p>It critically examines the economic feasibility of European building renewable energy deployment, comparing monetary performance variation by technology, region, and policy context, differences in economic outcomes defying assumptions of worldwide viability for renewable energy. Solar photovoltaic systems have superior residential performance with IRRs of more than 15% in well-designed structures, but system size makes a dramatic difference in returns with well-sized installations delivering five times the Net Present Value of conservative practices. Heat pump technologies have high COP ratings of as much as 3.65, but performance is extremely varied in European climate regions in a way that is not adequately explored in current literature. Support mechanisms by government are found to be crucial, with hybrid schemes that draw on various instruments performing better than single-policy mechanisms, but institutional capacity also becomes as important as incentives. Regional analysis reveals long-standing adoption differences between western/northern and southern/eastern European nations that go beyond policy design to the effectiveness of governance. The review identifies critical methodological deficiencies including excessive dependence on simulated data, geographic representation bias, and inconsistent economic evaluation approaches reducing practical application of research findings. Evidence has been confirmed for the economic viability of renewable energy under certain conditions but necessitating context-specific as opposed to generic performance assumptions for successful investment and policy-making choices.</p>