From the Building to the Building Stock: Investigation of the Transformations of the Building Stock of the City of Athens for its Conversion into a Carbon Neutral City

Background: This paper examines the hierarchy of technologies for a sustainable mitigation of greenhouse gas emissions from the building sector in the City of Athens. The greenhouse gas inventory of the building stock of the city and its energy consumption is investigated, pinpointing to effective energy saving scenarios, in which available in the market technologies are examined for their efficiency, cost-effectiveness and sustainability. Methods: Criteria for selecting these technologies have derived from the United Nations Sustainable Development Goals. By using the Multi Attribute Utility Theory, these technologies are prioritised, taking into account the reduction of greenhouse gas emissions, energy savings, the payback period of the embodied energy of the technologies used for the energy upgrade of buildings, their impact on the heat island effect, the initial cost of the investment and its payback period. Through the dynamic hypothesis on greenhouse gas emissions from electricity generation, cost-benefit analysis highlights the actions that can significantly reduce greenhouse gas emissions with existing low-cost technologies, so that they are easily multipliable and practically applicable on the city’s building stock. Results: A feasible timetable for the measures for the energy upgrade of the building stock of the city of Athens, so that actions that offer considerable greenhouse gas emissions reductions at low costs are applied first, with short payback period and small initial investment. Actions focusing on HVAC systems have been found to meet these conditions. Conclusions: This research pinpoints to primary directions for financing strategies that can lead to the energy upgrade of the building stock, in order to meet the target for carbon neutrality of the city by 2050.