This paper reports on the research-driven design process of an innovative thermal mass concept: Convective Concrete. The goal is to improve building energy efficiency and comfort levels by addressing some of the shortcomings of conventional building slabs with high thermal storage capacity. Such heavyweight constructions tend to have a slow response time and do not make effective use of the available thermal mass. Convective Concrete explores new ways of making more intelligent use of thermal mass in buildings. To accomplish this on-demand charging of thermal mass, a network of ducts and fans is embedded in the concrete wall element. This is done by developing customized formwork elements in combination with advanced concrete mixtures. To achieve an efficient airflow rate, the embedded lost formwork and the concrete itself function like a lung. The convection takes place with separate pipes on both sides of the concrete’s core to increase the charge/discharge of the thermal storage process. The first stage of the research, described in this paper, is to simulate the Convective Concrete at the component level, whereupon a mock-up is tested in a climate test set-up. The paper concludes with describing planned activities for turning this concept into a real building product.@en

Thermal mass is usually positively associated with energy efficiency and thermal comfort in buildings. However, the slow response of heavyweight constructions is not beneficial at all times, as these dynamic effects may actually also increase heating and cooling energy demand during intermittent operation or can cause unwanted discomfort. This study investigates the potential of energy simulations to support the exploration-driven development of two innovative responsive building elements: “Spong3D” and “Convective Concrete”. Both use fluid flow (Spong3D: water, Convective Concrete: air) inside the construction to reduce building energy demand by exploiting the use of natural energy sinks and sources in the ambient environment, aiming to make more intelligent use of thermal mass. During the development of these concepts, different simulation tools were used alongside experiments for e.g. materials selection, climate analysis, comfort prediction and risk assessment. By presenting the results from a series of simulation studies and by reflecting on their application, this paper shows how computational building performance analyses can play a useful role in ill-defined R&D processes.@en