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Refrigerants in vapor-compression systems have a global warming potential thousands of times that of carbon dioxide, yet their spread on the market is unrivalled. Elastocaloric systems, based on solid state cooling, feature among the most promising alternatives. In this paper, an elastocaloric device for air ventilation (ECV) composed by parallel and serial connection of multiple shape memory alloy (SMA) films, is investigated via volume-based finite difference simulation in MATLAB and dynamic building simulation in TRNSYS considering eight cities across the globe. The models assume experimentally demonstrated thermal parameters for the elastocaloric phase transformation around room temperature and a single-storey reference building. The ECV operates according to an optimized, energy-saving logic that includes load partialization and recirculation. Parametric analyses suggest that moderate terminal velocities (∼2 m/s) and a climate-specific design aimed at maximizing the use of the ECV device at nominal cooling capacity are key to reach building cooling needs reductions up to 70% in the considered scenarios. Partialization results in enhanced energy flexibility and conservation, whereas recirculation extends the ECV usability to extreme heat conditions. In absolute terms, the ECV works best under hot climates (e.g. Cairo, Dubai, Brisbane), with monthly cooling load reductions about 2/3-fold compared to cold locations (e.g. Milan, Hobart). The performance is extremely sensitive to the ventilation rate. Thermal zones requiring 1 to 2 air changes per hour are best suited. These findings provide initial insight into design criteria, opportunities and limitations on the use of elastocaloric devices for building ventilation to guide future experimental verification.

Application of fluorescent materials has proven to be an effective method for urban overheating mitigation due to their unique ability to re-emit a portion of the absorbed solar irradiation through photoluminescence (PL) effect. Herein, we introduced the idea of using quantum dots (QDs) as tunable fluorescent materials with potentially higher cooling capacity than their bulk counterparts and proposed a novel algorithm to model their thermo-optic behaviour under the sunlight. Our proposed method represents a major step forward in the understanding of the heat-rejection mechanism through PL effect and optimization of QDs fluorescent properties for urban overheating mitigation. Since it’s complicated to distinguish surface temperature reduction caused by reflection from that of PL effect, our developed algorithm could be used as a reliable tool for precise estimation of the PL effect contribution to heat dissipation.

Building sector is one of the primary culprits of environmental deterioration and energy consumption. Green building (GB) can be an effective solution to these challenges and has been prioritised by many nations, while the quality of most GBs was still low. Therefore, this paper aims to examine the application of GB techniques. In specific, an empirical study was conducted among 106 GBs in China. Results indicate that both water-saving and site planning categories received the highest achievements, followed by indoor environmental quality and energy-saving, and the material-saving and innovation categories were the most difficult to achieve. The items in site planning, energy-saving and indoor environmental quality clusters that depended more on design techniques could be realised evenly, while the water-saving and material-saving clusters that relied more on materials and equipment witnessed two extremes: one approaching to 100% and one close to zero. There could be an increase in technique achievement from low-quality GBs to high-quality GBs. Nevertheless, the achievements of many items were extremely in both one-star, and two- and three-star groups. Some even witnessed the reduction from the low-quality GBs to the high-quality GBs. A further investigation indicated that the unavailability of GB technique checklist, the impact of economic cost, low technological operability and the unavailability of GB products constrained the GB technique application. The combining impacts of them could further lower the GB technique application. To unlock these barriers, efforts should be made from the perspective of (1) revision and localisation of GB standard, (2) extensive technical support, (3) government regulations and support, and (4) the co-benefits: integration with other programmes. Overall, this paper is of value to improve GB technique application and facilitate the transitions towards higher quality GB agenda.

Pervious pavement has been regarded as an effective technique for both water storm management and overheating prevention. However, compared with its widely recognized permeability capability, its solar evaporative cooling performance remains under debate after post-occupancy evaluation; thus, it is essential to predict the solar evaporative cooling ability before practical use. Hygrothermal properties (i.e., albedo, water absorption, and water retention properties) are key factors that affect the solar evaporative cooling effect of pervious materials and could be extracted as predictive indicators. However, an approach for assessing the water absorption and retention properties has not been well studied. Therefore, this study aimed at characterizing a feasible method for testing water absorption and retention properties of pervious materials as well as the influence of albedo on the solar evaporative cooling performance. Five widely used pervious materials were selected as research subjects, and three hydrological test methods, including the integral immersion test, partial immersion test, and rainfall simulation test, were conducted for comparing the feasibility of measuring water absorption and retention properties. Furthermore, the solar evaporative cooling performance of pervious materials with high and low albedo was also investigated. The results reveal that the partial immersion test has the highest accuracy for evaluating the water absorption and retention properties of pervious materials. Although the high albedo could weaken the evaporation rate, pervious materials with high albedo could also achieve better solar evaporative cooling performance. The results of this study support the proper selection of pervious materials to alleviate urban overheating.

The phenomenon of heat island increases the urban temperature and the energy demand for cooling, as well as worsens the comfort and environmental conditions in the urban environment. In order for the consequences of the phenomenon to be counterbalanced, important mitigation techniques have been proposed. The pavements cover a very high percentage of the urban surface and contribute to a significant degree to heat island’s growth in cities and towns. The use of cool pavements achieves significant decrease in the surface temperature as well as in the flow of sensible heat towards the atmosphere. Therefore, it seems to be one of the most important proposed areas of mitigation as far as the aforementioned phenomenon is concerned. This assignment deals with the development and experimental testing of a new technique for the mitigation of the urban heat island, this of the corporation of photovoltaics in pavements. The objective of this assignment is to evaluate their contribution in the mitigation of the phenomenon. The experimental procedure was divided in two time periods: the one took place during the summer–autumn 2012 and the second during the summer 2013. The measurements were done on a daily basis in different weather conditions. In addition, the results were checked by a theoretical mathematical model. The whole measuring campaign indicated that lower temperatures were measured on the PV pavement than those measured on the other two materials (soil, asphalt). The numerical predictions are compared with the experimental data where similar results are found. In order for the contribution of these pavements to the improvement of urban microclimate to be measured, a simulation of an appropriate model took place. More specifically, the model Envimet 3.1 was applied in one particular area of Athens with and without the (incorporation) of the photovoltaic pavement. The outcome of the aforementioned experiment proved that the incorporation of the photovoltaic pavement can achieve a surface temperature decrease of 5 K as well as a decrease in the ambient temperature of almost 1 K.

The present paper discusses issues related to the three major problems of the built environment in Europe and in particular, the energy consumption of buildings, the energy poverty and the local climate change. The article introduces the idea of a zero concept world where the global impact of the three specific sectors will be diminished. The paper analyses the actual status of each sector and identifies the main problems. It discusses and sets a road map to satisfy this objective, involving future quantitative and qualitative targets for the three considered sectors while it investigates the major technological, economic and social forces and policies that have to be employed in order to minimize the energy consumption of buildings, eradicate the energy poverty and mitigate the local climate change. The links, synergies and impacts between them are analysed in a comprehensive way and the interrelated nature and characteristics of the three sectors is highlighted. The mechanisms to transform the actual problems into opportunities and appropriate drivers for future development are identified and analysed. A road map involving a full estimation of the necessary investments to fulfil the defined targets is presented. The major medium and long term benefits for the society, including the impact on the economy, employment, the environment and health are fully quantified and analysed. (C) 2016 Elsevier Ltd. All rights reserved.

A new expression for the integral transmission of atmospheric water vapor has been developed. This expression is based on the latest known water vapor spectral absorption data, on a new vertical atmospheric profile and finally, on the Neckel and Labs model (1981; 1984), incorporating the most recent corrections of the extraterrestrial solar spectrum. The proposed expression can be easily used by solar radiation models in order to predict the beam, diffuse, and global solar radiation, especially in regions where the vertical atmospheric profile is similar to that in Athens.

Results from a recently completed study of 95 solar greenhouses from around the world, representing the state-of-the-art in this field, are presented and are classified. Relevant technical information on the utilised heating systems using alternative energy sources are identified and the existing applications are grouped according to the characteristics of the implemented type of technology. Five categories of passive solar greenhouses are reviewed, according to the characteristics of the heat storage system, namely, water, latent heat material, rock bed, buried pipes, and some other type of systems. Available information on the performance of each system is also included. The suitability of the technologies for each climatic zone and type of cultivation is estimated and evaluated. This up-to-date information on the state of the art in this field can be of great importance to potential users for the successful development of future applications.