Energy Conservation vs. Heritage Conservation: Evaluating Thermal Rehabilitation Scenarios by the Case Study of Terrassenhaussiedlung Graz

Both, energy conservation and heritage conservation are declared goals of the European Union and the Austrian government. In the case of historic landmark buildings, these ambitions conflict with and sometimes even exclude each other. At the same time the public interest of conservation often collides with the private interests of the owners and inhabitants. The present paper addresses these conflicts of interest by the case study of Terrassenhaussiedlung Graz - a late Modernist housing estate in Graz, Austria, and a rare example of Brutalism and Structuralism in this country. Three potential thermal rehabilitation scenarios are being proposed and further investigated: Interior insulation, exterior insulation and the replacement of non-structural elements. These strategies are evaluated and discussed in terms of their impact on energy efficiency, building physics, architectural appearance and their practicability. The paper shows a work in progress and seeks the discussion with the audience. It poses the question of how far energy conservation measures can go in a culturally valuable building complex and of how much heritage conservation is appropriate for a sustainable housing estate.