Phase change materials (PCMs) are materials that can store large amounts of heat during their phase transition from solid to liquid without a significant increase in temperature. While going from liquid to solid this heat is again released. As such, these materials can play an important role in future energy-efficient buildings. If applied in facades as part of a thermal buffer strategy, e.g., capturing and temporarily storing solar energy in so-called Trombe walls, the PCMs are exposed to high solar radiation intensities, which may easily lead to issues of overheating. This paper therefore investigates the melting process of PCM and arrives at potential solutions for countering this overheating phenomenon. This study uses the simulation program Comsol to investigate the heat transfer through, melting of and fluid flow inside a block of PCM (3 × 20 cm2) with a melting temperature of around 25 °C. The density, specific heat and dynamic viscosity of the PCM are modeled as a temperature dependent variable. The latent heat of the PCM is modeled as part of the specific heat. One side of the block of PCM is exposed to a heat flux of 300 W/m2. The simulations show that once part of the PCM has melted convection arises transporting heat from the bottom of the block to its top. As a result, the top heats up faster than the bottom speeding up the melting process there. Furthermore, in high columns of PCM a large temperature gradient may arise due to this phenomenon. Segmenting a large volume of PCM into smaller volumes in height limits this convection thereby reducing the temperature gradient along the height of the block. Moreover, using PCMs with different melting temperature along the height of a block of PCM allows for controlling the speed with which a certain part of the PCM block starts melting. Segmenting the block of PCM using PCMs with different melting temperature along its height was found to give the most promising results for minimizing this overheating effect. Selecting the optimal phase change temperatures however is critical in that case.@en

Over the last few years, reverberation times and sound pressure levels have been measured in many sports halls. Most of these halls, for instance those made from stony materials, perform as predicted. However, sports halls constructed with profiled perforated steel roof panels have an unexpected very low reverberation time in the 125 and 250 Hz octave bands. The aim of this study was to provide an explanation for this low-frequency anomaly. A 1:20 scale model of a sports hall was constructed and placed in a small anechoic chamber. The roof could be equipped with differing ceiling types: a flat non-absorbing ceiling, a flat absorbing ceiling, two different profiled non-absorbing ceilings and a profiled absorbing ceiling. With a spark sound source and a small microphone, the impulse-response of the scale model could be registered and analysed. Moreover, a Matlab model was constructed to simulate the acoustic behaviour of the sports hall. This model included the ‘ground effect’ of the roof surface, an effect typically not included in commercial ray-tracing programs. The measurements and the simulations showed that the high sound absorption values of a perforated panel roof structure at 125 and 250 Hz can be (partly) explained by its shape. The diffusing properties of the corrugated roof have an effect similar to sound absorption. Because the roof is the largest absorbing surface in a sports hall, this effect can have a significant effect on the low-frequency reverberation time.@en

Double Face 2.0 is a novel solar wall, joining a strong design identity and high technical performances. In response to the need for energy saving, new high-performance building elements are shape-optimised for passive climate design and to increase user engagement. Given a design concept, computational approaches help to optimise and to customise high-performance building elements for any environment. Double Face 2.0 has been developed by research through design involving designing, 3D modelling, robotic FDM printing, prototyping, experimenting, simulating, and simulation-based optimising. An adjustable, lightweight, translucent Trombe wall has been developed, using an insulator (aerogel) and heat storage (phase change material) encapsulated in optimised and customizable shapes. In winter, it captures, stores, and re-radiates heat from the sun (heating); in summer, it captures internal heat (cooling).@en

The Double Face 2.0 research project aims at developing a novel type of an adaptive translucent Trombe wall. The novelty of the proposed system is based on the integration of new lightweight and translucent materials, used both for latent heat storage and insulation, advanced computational design processes, used to identify the relationship between variations in geometry and their effect in terms of overall performance, as well as proposed fabrication methods based on Fused Deposition Modelling. Various concepts and geometric configurations are explored and improved via a computational design workflow. The exploration is deeply rooted in performance simulations manufacturing constraints and measurements of prototypes. The paper presents the workflow of the overall on-going research project, with specific emphasis on the incorporation of a omputational assessment and optimization process. Moreover, it presents the preliminary set of measurements and simulations for thermal performances, their results and related conclusions.@en

In order to reduce the energy demand of households, a new type of Trombe wall is being designed during a ‘research through design project’ called ‘Double Face 2.0’. A Trombe wall is a passive system that reduces the energy demand of a building. In winter, it captures the heat from the sun during the day and releases this heat into the building at night. In summer, it captures the heat from internal sources during the day and releases that heat at night towards outdoors. First simulations showed that our prototype of a lightweight, translucent, adjustable Trombe wall reduces the energy demand for heating of a typical Dutch household by 25-30%. Instead of stone-like materials, the new type of Trombe wall will consist of translucent materials: phase change material (pcm) and insulating aerogel. The insulation gives the opportunity to direct the thermal mass of the pcm. In this way, the system is adjustable for cooling and heating purposes. A selection of the design concepts is described in this paper, explaining the design choices and method of validation. Depending on the level of detail, different simulation software has been used. This paper describes the comparison and the experiences of using it.@en