Design choices and thermal simulations of a new test cell facility

The paper presents a new test cell facility, named Box Office and under development at the Ecole Spéciale des Travaux Publics (ESTP Paris) for the analysis and characterization of the thermo-physical properties of building envelope components under real climate conditions. The facility will allow to obtain reliable estimates of thermal performance indicators of transparent and opaque building elements. Particular care has been taken in the design phase in order to minimize or to monitor all sources of uncertainty, such as (i) conductive heat losses through the test cell envelope, (ii) time lag of response to transient outdoor conditions, (iii) levels of airtightness and of resistance to vapour or water penetration. Highly variable solar conditions can seriously affect both the correct functioning of outdoor test facilities and the indoor climate conditions in the cell. For this reason, the thermal behaviour of the Box Office was simulated in Matlab environment, implementing a lumped-parameter model, and results are used for refining the design choices and selecting the most promising operative conditions and control strategies. The output of test cell experiments will be beneficial to various target groups, such as designers and manufacturers (to boost the research and development of new products), research centres (to fully understand and model the physical phenomena occurring in a controlled space facing real outdoor conditions) and potential clients, who ask for economically affordable solutions guaranteeing high levels of Indoor Environmental Quality

Modélisation et simulation d'une cellule test en plein air pour l'évaluation énergétique des composants d’enveloppe

The article presents the thermal modelling and simulation work that will constitute the basis for the design of an outdoor test cell. The facility aims at characterizing the thermo-physical properties of transparent and opaque envelope components under real weather conditions, and to study the impact of different air-conditioning configurations on the indoor thermal comfort and indoor air quality. The response delay of the calorimetric measure is particularly critical when trying to achieve a good quality of measurement in rapidly-varying weather conditions. For this reason, the thermal behaviour of the test cell has been described, by means of a lumped parameter model, to simulate a range of operating conditions. The results are used to evaluate the thermal inertia of different solutions, refine the design choices and the most promising control strategies. The article presents the thermal models used to compare the test cell to a traditional installation in terms of calorimetric accuracy under transient external conditions

Conception of a new test cell facility for characterizing building envelope components

Outdoor test cells have been extensively used for analyzing the thermo-physical properties of building envelope components under real climate conditions. The paper presents a new test cell facility, under development at the Ecole Spéciale des Travaux Publics, du Bâtiment et de l'Industrie (ESTP Paris) within the framework of a collaboration between the end-use Efficiency Research Group of Politecnico di Milano and ESTP. The facility will allow to obtain reliable estimates of thermal performance indicators of transparent and opaque building elements. A particular care has been taken in the design phase in order to minimize or to accurately evaluate all sources of uncertainty, such as (i) conductive heat losses through the test cell envelope, (ii) time lag of response to transient solar conditions, (iii) levels of airtightness and of resistance to vapour or water penetration.

Indoor climate assessment of a classroom with mechanical ventilation and operable windows

Ventilation air may be provided in buildings by means of natural or mechanical strategies. When a HVAC system is installed, thermal comfort and indoor air quality (IAQ) may be controlled with higher precision. However, especially between the 70s and the 90s, mechanical ventilation systems have been installed on formerly naturally ventilated buildings without providing any control for natural ventilation. The two ventilation systems are therefore overlapping, without any energy or comfort oriented control strategy, and the occupants are operating windows without any consistent understanding of IAQ and comfort conditions, neither of energy consumption. It may both lead to a substantial energy waste and to low indoor climate conditions. A typical university classroom with exhaust mechanical ventilation and operable windows without switching control has been assessed, in order to understand how occupant behaviour and different ventilation scenarios may influence indoor climate conditions

Ventilation rates and thermal comfort assessment in a naturally ventilated classroom

Ventilation systems are meant (i) to guarantee good indoor air quality (IAQ) by providing and distributing fresh air to the occupied/breathing zone and (ii) to dilute and remove pollutants emitted by indoor sources. On the other hand, inadequate ventilation rates can induce discomfort issues and excessive energy consumption. This study focuses on the performance assessment of natural ventilation strategies in university classrooms, which are characterized by a high occupancy level and the necessity to provide high levels of comfort to perform intellectual work. The high occupancy level creates challenging conditions both in terms of internal gains and CO2 concentration. This paper presents an experimental performance assessment of four natural ventilation strategies applied to a university classroom: single side ventilation, cross ventilation, stack ventilation with and without window supply. Each strategy is evaluated in terms of thermal comfort and air change rate measurements. Thermal comfort assessment were performed during occupancy period (physical parameter measurements and questionnaires) whereas air change rate measurements, based on tracer gas techniques, were performed during unoccupied periods

Numerical assessment of mechanical ventilation filtration

The improvements in living standards and air-conditioning have widely been applied, however, the health effects of indoor air pollution have been increasing, especially in the last three years with the coronavirus. To get clean air through the building, filtration is one of the most efficient strategies to optimize indoor air quality. In this regard, a comparative study was done in a classroom at ENTPE laboratory to emphasize filtration’s importance and to test the efficiency of analyzed type PM10_50. The results highlighted allows us to see the impact of control strategy on the efficiency of filtration (air conditions and ventilation systems performances). The numerical feedback has also been analyzed and the results allowed us to find an efficient filter and draw recommendations for their use

Evaluation of Post Processing Analysis to determine Optimal Thermo-Optical Properties for Adaptive Glazing Systems with Quick Adaptation Speed

Adaptive envelope technologies are considered as ones of the most promising for reducing the energy use in buildings. Nonetheless, their real-world implementation is low, because of fragmented researches and limited capabilities of current BPS (building performance simulation) tools in evaluating properly their behaviour at a time-scale consistent with the highly dynamic drivers effecting the adaptation mechanism. The aim of this research is to investigate the effectiveness of simplified methods to determine optimal thermo-optical properties for adaptive glazing systems able to modulate two parameters, g-value (or SGHC) and τvis, with quick adaptation speed (5 minutes), using inverse approach and post processing analysis. This type of study is meant to provide a useful tool in early design phase for choosing the best fitted adaptive technology and for the development of new adaptive glazing technologies, since it identifies the requirements to be satisfied by means of the best suited technological solutions