A review of the previous and current challenges of passive house retrofits

In order to reach the climate goals set by the Paris Agreement and similar such ambitions, energy consumption in the residential sector must be addressed. Space conditioning is responsible for the majority of the energy used, and has thus become a focal point for building energy codes and voluntary building standards. Passive House is one such standard. Their design philosophy is to build tight and ventilate right. By making highly insulated and airtight homes, there is very little heat loss, which subsequently reduces the energy consumption by up to 90%. The prime market for energy reduction ought to be existing buildings and historic buildings (older than 50 years). These buildings are the least energy efficient, and are projected to make up the majority of buildings in the future. Reducing the energy consumption in the existing building sector through deep energy retrofits is necessary for meeting the aforementioned climate goals. Despite their pivotal role in energy reduction, retrofits are still too few. Previous work has identified barriers to retrofitting as the lack of knowledge, the lack of regulation, and the financial challenges present with such a project. In order to understand how these problems evolved, case studies were collected and analyzed. It was found that lack of knowledge had shifted from technical problems regarding whether or not Passive House retrofits are feasible, to more nuanced research, such as the optimization of specific traits. Regulation has developed, with more codes and government support for energy conservation measures in general, but the retrofit market specifically could benefit from more specialized attention. The financial challenges are, have been, and will continue to plague retrofit projects. This problem is partially addressed through increasing knowledge and incentives, but it will never truly go away. The best solution is, in addition to increased affordability, that stakeholders begin to value the energy reduction thereby making the costs seem worth it. The overarching theme of the most recent research focuses on not doing just something, but doing the right thing. Optimization studies and holistic design approaches are starting to dominate the field, and financial analysis is no longer the dominating metric. What exactly the “right” solutions are will be a matter of research and debate for years to come.