Commercial and residential building is one of the four major final energy consumption and end-use sectors. In this sector, cooling loads represent an important part of the energy consumption, and therefore, they must be minimized, improving the energy efficiency of buildings. Ventilated façades are one of the most widely used passive elements that are integrated into buildings, precisely with the aim of reducing these loads. This reduction is due to the airflow induced in the air cavity by the buoyancy forces, when the solar radiation heats the outer layer of the façade. In the open joint ventilated facades (OJVF), ventilation is attained through the open joints between the panels composing the outer layer. Despite the steadily growing research in the characterization of this type of system, few studies combine the numerical modelling of OJVF with experimental results for the assessment of the airflow in the ventilated cavities. This paper experimentally validates a numerical simulation model of an OJVF. Firstly, the façade performance has been experimentally assessed in a laboratory model determining the temperatures in the panels and air gap and measuring the flow field at the gap using particle image velocimetry (PIV) techniques. Secondly, a numerical model has been developed using advanced Computational Fluid Dynamics (CFD) simulation tools. Finally, an experimental validation of the numerical model has been done. Experimental and numerical results are compared in different planes inside the ventilated cavity. The discrete ordinates (DO) radiation model and the k-ε renormalisation group (RNG) turbulence model better adjust the simulated results to the experimental ones.

An attached sunspace is a partially or fully glazed enclosure, usually located on the first floor, facing south (in the Northern Hemisphere) and adjacent to a conditioned room. Because of the length and orientation of the glazed area, the temperature in the sunspace is usually higher than outside the building. As a Trombe–Mitchel wall, the sunspace has a considerable mass that accumulates thermal energy, but in this case the thermal mass is located in the floor. This capacity to accumulate thermal energy confers the attached sunspace features beyond passive insulation. The sunspace studied in this paper is part of an experimental building located in the North of Spain that was built in the frame of the so-called ARFRISOL project. It consists of a south-facing glazed exterior wall with both clear glass and semi-transparent photovoltaic panels, an intermediate space with a thick layer of sand over a concrete floor, and a partially glazed interior wall. In this paper, a three-dimensional computational model has been implemented to analyse the thermal behaviour inside the sunspace. This analysis takes into account, among other factors, the effects of sun position, incident solar irradiation and temperature both inside and outside.

In the current context of environmental deterioration and rising energy costs, systems based on Stirling engines are interesting not only because of their proven efficiency and very low noise level, but also because of their ability to use renewable energies. Micro-CHP units based on Stirling engines fuelled by both solar energy and biomass can reduce CO₂ emissions on a household scale, but the second option avoids problems usually related to the intermittency of solar energy. This paper describes the geometry and experimental characterisation of a new non-tubular heater design that is potentially interesting for biomass applications, and its analysis by means of a CFD model. The CFD model provides valuable information, under engine operating conditions, on the temperature distributions in the walls and the working gas, as well as the pressure and velocity of the gas particles, which are operating variables that are almost impossible to measure in practice. The new heater can be coupled to the Stirling engine of a previously developed micro-CHP unit for solar energy conversion, which has another non-tubular heater. The heat transfer rates achieved with both non-tubular heaters are compared with each other and with the values of the SOLO V160 engine heater, which consists of a tube bundle. The results show that the micro-CHP Stirling unit would develop more indicated power with the biomass heater than with the solar heater, providing information for future improvements of the indicated efficiency.