Experimental Comparative Study between Conventional and Green Parking Lots: Analysis of Subsurface Thermal Behavior under Warm and Dry Summer Conditions

Green infrastructure has a role to play in climate change adaptation strategies in cities. Alternative urban spaces should be designed considering new requirements in terms of urban microclimate and thermal comfort. Pervious pavements such as green parking lots can contribute to this goal through solar evaporative cooling. However, the cooling benefits of such systems remain under debate during dry and warm periods. The aim of this study was to compare experimentally the thermal behavior of different parking lot types (PLTs) with vegetated urban soil. Four parking lots were instrumented, with temperature probes buried at different depths. Underground temperatures were measured during summer 2019, and the hottest days of the period were analyzed. Results show that the less mineral used in the surface coating, the less it warms up. The temperature difference at the upper layer can reach 10 °C between mineral and non-mineral PLTs. PLTs can be grouped into three types: (i) high surface temperature during daytime and nighttime, important heat transfer toward the sublayers, and low time shift (asphalt system); (ii) high (resp. low) surface temperature during daytime (resp. nighttime), weak heat transfer toward the sublayers, and important time shift (paved stone system); and (iii) low surface temperature during daytime and nighttime, weak heat transfer toward the sublayers, and important time shift (vegetation and substrate system, wood chips system, vegetated urban soil). The results of this study underline that pervious pavements demonstrate thermal benefits under warm and dry summer conditions compared to conventional parking lot solutions. The results also indicate that the hygrothermal properties of urban materials are crucial for urban heat island mitigation

Integrating PCM into hollow brick walls: Toward energy conservation in Mediterranean regions

Nowadays, cooling demand in the building sector is increasing in cooling-dominant climates because of extreme heat waves reinforced by climate change. As the demand for thermal comfort in buildings continues to grow, energy consumption increases accordingly. The application of phase change materials (PCM) to building envelopes can improve thermal energy storage, thus they can be used to increase the thermal mass of buildings. This article shows the efficiency of using PCMs to mitigate building cooling demands in eight cities representing the Mediterranean region: Al Hoceima (Morocco), Malaga (Spain), Marseille (France), Taher (Algeria), Naples (Italy), Tripoli (Libya), Ankara (Turkey), and Port Said (Egypt). The energy performance of three types of building: single-family, collective housing and hotel housing, built with hollow bricks, with and without PCMs, is evaluated in these cities using a numerical model based on the apparent heat capacity. A wide range of PCM melting temperatures is studied (from 22 °C to 32 °C). The results confirm that climate profoundly influences the storage/release process of PCMs. Regardless of the building typology, energy savings can reach 56% in the North-East Mediterranean cities using a PCM with a 26 °C melting temperature, while no energy savings have been noted for the South-East cities. Finally, a correlation between the energy savings and the Cooling Degree Day is demonstrated, resulting in the recommendation of a PCM with a 26 °C median melting temperature in a given location

Development of a night-time radiative sky cooling production & storage system: A proposal for a robust sizing and potential estimation methodology

This paper proposes a sizing method to guide the design of water-circulating radiative sky cooling systems and water-based energy storage solutions. Following this method, the choice of operational flow rate in the radiative sky cooling (RSC) panels and the water storage is based on four indicators: sub-ambient temperature, cooling power density, minimum storage temperature and useful energy stored. The method is applied to the BaityKool Solar Decathlon Middle East (SDME) prototype in order to design a water-radiative sky cooling system with storage in the climatic conditions of Dubai. We developed passive strategies for the BaityKool prototype, including a multi-functional innovative exterior wall and a semi-indoor courtyard space, combined with active solutions (in particular a hydraulic radiative sky cooling system). The experimental campaign conducted on the RSC system over three successive nights in November (ambient air temperature between 22.7 and 31.4 °C) indicates an average cooling power of 30–45 W m−2 for a maximum sub-ambient temperature drop of 2.8 °C, and shows that great attention to the water pipes and storage insulation can lead to an increase in the thermal performance of radiative sky cooling systems

Choice of the Suitable Melting Temperature of Phase Change Material: Application on Solar Assisted Heat Pump

Thermal energy storage (TES) is a key issue in efficient energy systems applications. In this regard, phase-changing material (PCM) has been of interest as an active solution for efficient energy management, especially in the context of the building. This paper presents a thermal analysis on sensible and latent TES systems to investigate their thermal performance in the case of Solar Assisted Heat Pump (SAHP). The storage tank allows to store the heat produced via unglazed solar panels (Batisol®) and represents the heat source of the heat pump (HP). The objective of the study is firstly to define the suitable melting temperature of the PCM to be integrated in SAHP system, and then to compare its performance to the case of sensible storage. In order to improve the coefficient of performance (COP), the results indicate a melting temperature 15°C regardless to the volume storage. On the other hand, a melting temperature of 9°C is suitable to increase the solar coverage rate of SAHP system. Furthermore, the comparison with sensible storage shows an improvement in the COP when latent storage is used. In order to optimize the choice of melting temperature and the volume of the storage, future work will consist of conducting a multi-objective optimization study considering energy, economic and environmental criteria

Couplage d'une PAC et d'un système de refroidissement d'eau par échanges radiatifs avec le ciel : modélisation et estimation de performances

National audienceL’étude concerne une modélisation sous COMSOL du couplage entre un système de production d’eau froide par Radiative Sky Cooling (RSC) et une Pompe À Chaleur (PAC) air/eau, et l’estimation de la performance de ce système couplé en vue assurer les besoins en climatisation d’un bâtiment tertiaire à Bordeaux. Ces panneaux RSC, permettent, par circulation d’eau en face arrière, de refroidir celle-ci par échanges radiatifs Grandes Longueurs d’Ondes (GLO) avec le ciel. Les besoins de ce bâtiment tertiaire ont été préalablement estimés à l’aide d’une Simulation Thermique Dynamique (STD) sous DesignBuilder. Le schéma du couplage suppose que le condenseur de la PAC soit immergé dans un Ballon de Stockage (BS) refroidit à l’aide de la production d’eau froide issue des panneaux RSC. L’objectif est ici de diminuer la température au niveau du condenseur par rapport à la température de l’air extérieur, dans le but de pouvoir améliorer la performance énergétique de la PAC. Les résultats obtenus sont comparés à 2 autres configurations de systèmes couplés : un échangeur air/eau classique venant remplacer les panneaux RSC, et, une PAC seule sans source d’eau froide (sans stockage ni production d’eau froide)

Couplage d'une PAC et d'un système de refroidissement d'eau par échanges radiatifs avec le ciel : modélisation et estimation de performances

L’étude concerne une modélisation sous COMSOL du couplage entre un système de production d’eau froide par Radiative Sky Cooling (RSC) et une Pompe À Chaleur (PAC) air/eau, et l’estimation de la performance de ce système couplé en vue assurer les besoins en climatisation d’un bâtiment tertiaire à Bordeaux. Ces panneaux RSC, permettent, par circulation d’eau en face arrière, de refroidir celle-ci par échanges radiatifs Grandes Longueurs d’Ondes (GLO) avec le ciel. Les besoins de ce bâtiment tertiaire ont été préalablement estimés à l’aide d’une Simulation Thermique Dynamique (STD) sous DesignBuilder. Le schéma du couplage suppose que le condenseur de la PAC soit immergé dans un Ballon de Stockage (BS) refroidit à l’aide de la production d’eau froide issue des panneaux RSC. L’objectif est ici de diminuer la température au niveau du condenseur par rapport à la température de l’air extérieur, dans le but de pouvoir améliorer la performance énergétique de la PAC. Les résultats obtenus sont comparés à 2 autres configurations de systèmes couplés : un échangeur air/eau classique venant remplacer les panneaux RSC, et, une PAC seule sans source d’eau froide (sans stockage ni production d’eau froide)

Energy savings potential by integrating Phase Change Material into hollow bricks: The case of Moroccan buildings

The building sector in Morocco represents 25% of the country's total energy consumption. The poor thermal performance of the building envelopes is one of the principal reasons for this consumption rate. In this study, the efficiency of integrating Phase Change Materials (PCM) into hollow bricks used in three typical housing types in the six climate zones in Morocco is investigated. The numerical model is based on the heat transfer equation and the apparent heat capacity formulation to model the phase change. A heat flux analysis is performed at the internal surface of the wall, giving a good understanding of the thermal behavior of hollow bricks with PCMs compared with hollow bricks with air. The results show that the heat flux density at the internal face of the wall is constant when the PCM is partially solid/liquid, and follows the outdoor conditions when the PCM is fully solid or fully liquid. Irrespective of the climate zone, the PCM with a 32 °C median melting temperature reduces the heat flux peak value in the hotel housing while the PCM with a 37 °C median melting temperature is better for the individual and collective housing. On the other hand, the PCM with a 27 °C median melting temperature is able to save up to 25% and 40% of energy consumption in the Saharan climate and oceanic climate, respectively. Keywords phase change materials, energy savings in buildings, cooling needs reduction, hollow bricks with PCM with a 27 °C median melting temperature is able to save up to 25% and 40% of energy consumption in the Saharan climate and oceanic climate, respectively