The Circular Economy in Affordable Housing to Reach Carbon Neutrality – Refurbishment and Greening

The dynamics taking place in the big cities of Europe and the world pose a series of challenges and unprecedented demands. On the one hand, the need for affordable housing has increased due to the growing population in cities like Milan and Vienna. On the other hand, phenomena related to climate change are affecting the livability of human settlements and requiring mitigation and environmental solutions, that should be combined with the necessary refurbishment of the existing housing stock. Most large cities worldwide have recently experienced the dramatic effects of the climate crisis. To meet the 1.5-degree pathway and the Paris goals, cities must reduce 55-60% of their net emissions by 2030. The cities of Vienna and Milan have been impacted by Urban Heat Islands (UHI) phenomena, which are particularly critical in densely populated residential districts. UHI challenges housing in several ways: new construction, as well as the operation of existing buildings significantly contribute to CO2 emissions. As one of the major causes of UHI, buildings therefore constitute a crucial field of action for mitigation and future reduction. Especially in densely built-up neighborhoods with few green spaces where larger households live with less income, the negative effects of hotter summers diminish residents’ quality of life. Modern tools of urban development and housing production after World War II have proven unable to face both challenges, leaving a huge stock of environmentally unsustainable post-war housing in heat vulnerable urban fabrics. However, even more contemporary standards applied to retrofitting have proven unable to sufficiently increase its environmental qualities. Since housing is an inertial object its transformation is hardly reversible, the consequences of today’s errors can last for decades. We urgently need innovation in the way we produce and transform the housing stock to provide more spaces for livability and sustainability. Especially the ecological aspects can no longer be relegated to certain “demonstration projects,” but have to be applied in every single project if the 1.5-degree goal is to be reached. This will be a daunting task for affordable housing production, which is already under economic pressure due to increased land and construction costs. The scarcity of resources and building materials resulting from the Covid-19 crisis have further raised the costs. In this context, design and regulation can play key roles. By following the cradle-to-cradle principles of a circular economy, a potential solution is offered. Architectural design based on a circular economy can combine affordable design solutions with environmental goals and integrate green concepts in new construction and renovation while achieving CO2 neutrality. Targeting the refurbishment of the existing building-stock provides a huge chance to achieve the ambitious 1.5-degree goals while improving the living situation of city dwellers. Greening concepts have been applied to facades and roofs of new buildings, but rarely to existing ones. Innovative and light-weight greening concepts present alternatives, while Nature-Based Solutions (NBS) for the design of open spaces can prove environmentally effective and cost-efficient. Building regulations often hinder both ecological refurbishment and architectural innovation. If redrafted according to circular economy principles, they could stimulate sustainable housing developments and the integration of green measures. Starting from these environmental, social and economic challenges and focusing on the cities of Vienna and Milan, the research will investigate opportunities for architecture and regulative innovation to improve green and environmental standards in housing production and renovation and, ultimately, to enable better and more livable housing experiences. The result shall be a guideline to apply the principles of circular economy to decrease housing costs and achieve the climate targets.