Assessing renovation interventions towards ''Energy plus'' buildings through parametric exploration--- the case of glazed buffer spaces

Starting from an entry in the recent German Energy Plus Renovation competition (EPA --- EnergyPlus im Altbau 2012), the paper presents the design tools used to assess the project's energy consumption at competition stage. It further elaborates on the potential of such tools to support design decisions in allowing the consistent exploration of the influence on performance of a particular design component. The EPA competition asked participants to elaborate a renovation concept for a social housing building and to transform it into an “Energy Plus” building, a building producing more energy averaged over the year than its own consumption. To achieve such energy standards, focus is put in design components contributing to performance as well as  architectural value. The paper focuses on glazed buffer space additions on the facade providing energy gains in winter, reducing insulation needs on the existing facade and increasing usable space in summer. By combining an open source parametric scripting engine in interaction with EnergyPlus, a full multi-zone thermal model including airflow network is easily defined, refined and transformed by  the designers themselves. The use of such tools at the competition stage demonstrates the ability to support early design decision making. It allows to determine the parameters that constitute a functioning buffer space both in terms of usage and thermal efficiency. The parametric scripting approach allows an order of magnitude in simulation runs supporting broader exploration of the design space without sacrificing modeling accuracy. This research is part of a general effort in developing, in parallel, a set of design tools and a catalogue of design components addressing the energy spending of the existing building fabric, with the prospect to apply it to new projects.