Thermal performance of a supply-air window with triple heating glazing inserted in building envelope

Abstract

Nowadays, no one ignores that the building envelope plays a major role in terms of energy consumption and greenhouse gas production. Successive regulations have mainly resulted in a reinforcement of thermal insulation and an improvement of the airtightness of the envelopes. But this often results in poor estimations of consumption, condensation problems on the walls and poor air quality.
Our project consists in analyzing the contributions of a glazed, supply air and heating façade component that provides the ventilation, the heating of the building and the recovery of solar and fatal energy. It is based on a supply-air window of type "Paziaud" in which a heating glass has been inserted. A prototype has been installed on the façade of a building and has been extensively instrumented. Measurements of surface temperatures and air temperatures, pressure difference and velocity are completed in an original way by a fluxmetric instrumentation placed in the ventilated air gaps of the window and on the surfaces in contact with the interior and exterior environments.
This paper will allow us to share and discuss the first results obtained in this in-situ configuration. Our experimentation highlights the difficulties that arise in the interpretation of measurements in real sites, more or less disturbed during the day and at night by the variations of meteorological parameters. It is also a question of coming back to the definition of the performance indicators by comparing theoretical formulas and practical results. In particular, it is necessary to take a closer look at the definition of the outside temperature, which is involved in the expression of a surface transmission coefficient adapted to the component and to discuss an efficiency factor for the window which functions as an exchanger. It is also important to take into account the different heat sources (solar radiation, electricity and recovered waste heat), the heat convective exchanges coefficients that take place in the air gaps and the definition of performance indicators.