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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.

Photoluminescent materials are advanced cutting-edge heat-rejecting materials capable of reemitting a part of the absorbed light through radiative/non-thermal recombination of excited electrons to their ground energy state. Photoluminescent materials have recently been developed and tested as advanced non-white heat-rejecting materials for urban heat mitigation application. Photoluminescent materials has shown promising cooling potential for urban heat mitigation application, but further developments should be made to achieve optimal photoluminescence cooling potential. In this paper, an advanced mathematical model is developed to explore the most efficient methods to enhance the photoluminescence cooling potential through estimation of contribution of non-radiative mechanisms. The non-radiative recombination mechanisms include: (1) Transmission loss and (2) Thermal losses including thermalization, quenching, and Stokes shift. The results on transmission and thermal loss mechanisms could be used for systems solely relying on photoluminescence cooling, while the thermal loss estimations can be helpful to minimize the non-radiative losses of both integrated photoluminescent-near infrared (NIR) reflective and stand-alone photoluminescent systems. As per our results, the transmission loss is higher than thermal loss in photoluminescent materials with an absorption edge wavelength (λAE) shorter than 794 nm and quantum yield (QY) of 50%. Our predictions show that thermalization loss overtakes quenching in photoluminescent materials with λAE longer than 834 nm and QY of 50%. The results also show that thermalization, quenching, and Stokes shift constitute around 56.8%, 35%, and 8.2% of the overall thermal loss. Results of this research can be used as a guide for the future research to enhance the photoluminescence cooling potential for urban heat mitigation application.

By 2030 Cyprus committed to reduce greenhouse gas emissions by 40% and increase renewables’ energy share by 19% according to the European engagements. Difficulties appear due to the continuous incr...

Urban overheating (UO) may interact with synoptic-scale weather conditions. The association between meteorological parameters and UO has already been a subject of considerable research, however, the impact of synoptic-scale weather conditions on UO magnitude, particularly in a coastal city that is also near the desert landmass (Sydney) has never been investigated before. The present research examines the influence of synoptic-scale weather conditions on UO magnitude in Sydney by utilizing the newly developed gridded weather typing classification (GWTC). The diurnal, and seasonal variations in suburban-urban temperature contrast (ΔT) in association with synoptic-scale weather conditions, and ΔT response to synoptic air-masses during extreme heat events are investigated in three zones of Sydney. Generally, an exacerbation in UO magnitude was reported at daytime over the years, whereas the nocturnal UO magnitude was alleviated over time. The humid warm (HW), and warm (W) air-masses were found primarily responsible for exacerbated daytime UO during extreme heat events and in all other seasons, raising the mean daily maximum ΔT to 8–10.5 °C in Western Sydney, and 5–6.5 °C in inner Sydney. The dry warm (DW), and W conditions were mainly responsible for urban cooling (UC) at nighttime, bringing down the mean daily minimum ΔT to − 7.5 to − 10 °C in Western Sydney, and − 6 to − 7.5 °C in inner Sydney. The appropriate mitigation technologies can be planned based on this study to alleviate the higher daytime temperatures in the Sydney suburbs.

The understanding of energy-related occupant behaviour and its better reproduction in building energy analysis has recently become a primary field of interest. The combination of computing ease and...

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.

Predicting the heating and cooling (HC) energy performance of a building is essential in the understanding and energy-efficient control of HC systems. The aims of this study were to develop and propose advanced and accurate energy prediction models using deep learning techniques. Also, to assess the importance and the significance of the relevant variables used in the models. The models were developed based on measured data collected in an educational building and were classified into different prediction time groups at 3-min, 15-min, 30-min, and 1-h time intervals. The inputs used in the models for the HC system and the EHP were selected through a variable selection process based on domain knowledge and correlation analysis. The results also indicate that the operational factors of the HC system had greater influence on the energy consumption than the indoor and outdoor temperatures. The performances of developed models indicate that a deep learning approach can be effectively applied to predict and understand the electric energy consumption of a HC system. Furthermore, the variable selection process and the important variables identified through it can be applied to energy prediction of HC systems in other buildings.

Urban overheating, driven by global climate change and urban development, is a major contemporary challenge which substantially impacts urban livability and sustainability. Overheating represents a...

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.

Income, housing unit size, number of appliances owned and other components of socio-economic status (SES), are variables generally considered to influence residential energy use. Using structural equation modeling of SES indicators from the U.S. residential energy consumption survey (RECS), we provide evidence that SES, usually modeled as a latent construct with effect indicators, is better conceptualized as including at least some causal indicators. We studied the mediating effect of housing unit size and number of owned appliances on the relationship between SES, household size and residential energy consumption (REC). We found that household size was positively associated with REC, as a direct effect. SES had a strong impact on REC, while being mediated by housing unit size and number of appliances owned. In conclusion, research must take the latent nature of SES into account to uncover its total influence on REC.

Pervious pavements are efficient in the mitigation of urban heat island effects. Many studies have revealed the water availability of pervious paving materials dominates the evaporative cooling effect. However, the water retention capacity of these materials is affected by the water absorption capability, which has scarcely been investigated in relation to evaporation. Therefore, this study investigates the water absorption capability of pervious paving materials and its influence on evaporative cooling performance. We examine the water absorption capability of three similar-coloured materials, including sintered ceramic pervious brick (CB), pervious concrete brick (PB), and open-graded pervious concrete (PC), as well as their evaporative cooling performance under a steady-state hot-humid environment in a climatic wind tunnel. The results indicate that: (1) CB had the highest water absorption coefficient of 2.04 kg/m2·s0.5, which is approximately about 30 and 200 times higher than that of PB and PC, respectively; however, these materials had similar water retention capabilities, with a capillary moisture content of 110 ± 10 kg/m3, revealing that CB could hold more water in a very short time; and (2) CB and PB could effectively reduce the surface temperature by up to 20 °C and 12 °C with a cooling period of 16 h and 12 h, respectively. In comparison, PC demonstrated a weak cooling effect of 2 °C, which only lasted for 4 h. Overall, materials with a high water absorption capability can maintain hydraulic continuity balance for a long time, which is beneficial to enhancing evaporation and further lowering the surface temperature.

Construction materials play a crucial role in the thermal behaviour of the urban space as well as the building energy consumption and indoor environmental quality. Recently, there has been growing interest in optical construction materials/coatings as an effective method to minimise energy use, improve indoor and outdoor thermal comfort and fight urban overheating. Thermochromic materials as one of the advanced optical materials that change their optical properties/colour as a function of the ambient temperature can present lower/higher surface temperature than conventional materials during the warm/cold periods. Although pilot applications of thermochromic materials in the built environment shown a tremendous energy conservation potential, the serious optical degradation they exhibited, restricts seriously their use. Recent development in the field of thermochromic materials including quantum dots, plasmonics, photonic crystals, conjugated polymers, Schiff bases, liquid crystals, and nano optical filters for Leuco dyes present fascinating and impressive characteristics, enhance significantly the potential of thermochromic materials and opens new opportunities for the development and use of advanced cutting-edge optical materials. The present paper aims to offer a comprehensive overview of the recent developments on advanced thermochromic materials and on their energy conservation potential.

Pervious pavement system (PPS) is a suitable alternative technique for mitigating urban flooding and urban heat island (UHI) simultaneously. However, existing literature has revealed that PPSs cannot achieve the expected permeability and evaporation. To overcome this gap, this study presents an elaborate review of problems associated with PPSs and highlights its benefits to stormwater management and UHI mitigation. We determined key parameters of PPSs that could influence urban flooding and UHI mitigation, including hydrological properties, thermal physical properties, structure design, and clogging resistance. We identified the co-benefits approach of PPS towards performance synergism on stormwater management and UHI mitigation from quality controlled design and fabrication, periodic maintenance, and effective evaluation system based on practice environments. The results indicate that existing studies of PPSs primarily focus on permeability, while little emphasis is given to the evaporative cooling performance, leading to a biased development with a loss of test standards and regulations that cannot control the cooling potential of the system. The performance synergism of permeability and evaporative cooling in PPS should be studied further, while considering quality control of the materials and in-situ practice design. Parameter controls (with commonly used standards) during fabrication, periodic maintenance (during operation), and pre- and post-evaluation processes of PPSs should work collectively to achieve optimal benefits and reduced costs.

Summarization: Urban greenery is a natural solution to cool cities and provide comfort, clean air and significant social, health and economic benefits. This paper aims to present the latest progress on the field of greenery urban mitigation techniques including aspects related to the theoretical and experimental assessment of the greenery cooling potential, the impact on urban vegetation on energy, health and comfort and the acquired knowledge on the best integration of the various types of greenery in the urban frame. Also to present the recent knowledge on the impact of climate change on the cooling performance of urban vegetation and investigate and analyse possible technological solutions to face the impact of high ambient temperatures. Presented on

The present chapter aims to present and discuss the main challenges and opportunities in the Built Environment. The document analyses issues related to the impact of global and local climate change on the built environment, the challenges associated to the expected increase of the world population, social and technological issues related to energy poverty and future energy consumption. It also presents and discusses the major environmental problems in our cities and the expected energy and social problems related to the rapid urbanisation. The actual state of the art of the energy and environmental technologies for buildings and cities is presented. Futures priorities and ideas on the way to translate the current challenges into future opportunities are presented.

Variations in urban form lead to the development of distinctive intra-urban surface thermal patterns. Previous assessment of the relation between urban structure and satellite-based Land Surface Temperature (LST) has generally been limited to single-city cases. Here, examining 25 European cities (June&ndash, August 2017), we estimated the statistical association between surface parameters&mdash, the impervious fraction (&lambda, imp), the building fraction (&lambda, b), and the building height (H)&mdash, and the neighborhood scale (1000 &times, 1000 m) LST variations, as captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Correlation analysis, multiple linear regression, and spatial regression were used. As expected, &lambda, imp had a consistent positive influence on LSTs. In contrast, the relation of LST with &lambda, b and H was generally weaker or negative in the daytime, whereas at night it shifted to a robust positive effect. In particular, daytime LSTs of densely built, high-rise European districts tended to have lower values. This was especially the case for the city of Athens, Greece, where a more focused analysis was conducted, using further surface parameters and the Local Climate Zone (LCZ) scheme. For the urban core of the city, the canyon aspect ratio H/W had a statistically significant (p &lt, 0.01) negative relationship with LST by day (Spearman&rsquo, s rho = &minus, 0.68) and positive during nighttime (rho = 0.45). The prevailing intra-urban surface thermal variability in Athens was well reproduced by a 5-day numerical experiment using the meteorological Weather Research and Forecasting Model (WRF) model and a modified urban parameterization scheme. Although the simulation resulted in some systematic errors, the overall accuracy of the model was adequate, regarding the surface temperature (RMSE = 2.4 K) and the near-surface air temperature (RMSE = 1.7 K) estimations.

The effects of heat waves (HW) are more pronounced in urban areas than in rural areas due to the additive effect of the urban heat island (UHI) phenomenon. However, the synergies between UHI and HW are still an open scientific question and have only been quantified for a few metropolitan cities. In the current study, we explore the synergies between UHI and HW in Seoul city. We consider summertime data from two non-consecutive years (i.e., 2012 and 2016) and ten automatic weather stations. Our results show that UHI is more intense during HW periods than non-heat wave (NHW) periods (i.e., normal summer background conditions), with a maximum UHI difference of 3.30°C and 4.50°C, between HW and NHW periods, in 2012 and 2016 respectively. Our results also show substantial variations in the synergies between UHI and HW due to land use characteristics and synoptic weather conditions; the synergies were relatively more intense in densely built areas and under low wind speed conditions. Our results contribute to our understanding of thermal risks posed by HW in urban areas and, subsequently, the health risks on urban populations. Moreover, they are of significant importance to emergency relief providers as a resource allocation guideline, for instance, regarding which areas and time of the day to prioritize during HW periods in Seoul.

Occupancy information is important to building facility managers in terms of building operation, predictive control, safety, as well as the indoor environment quality. Previous works have addressed different occupancy counting and estimation solutions in different buildings or spaces. In this study, we adopted a single system-single zone test bed using the existing university lecture rooms to install and compare four different occupancy counting methodologies: overhead video based occupancy counting system, pan-tilt-zoom camera face detection system, CO2-based physical model, and CO2-based statistical model. We attempt to address the occupancy counting challenge in educational building deployment scenario with large groups of people entering and leaving. Experiments have been conducted for three months with five-minute data reporting interval. The results show that the PTZ-camera based face recognition has the most stable and highest accuracy with an R2 of 0.972; followed by the CO2 based statistical model with an R2 of 0.938. Discussion and improvements on the methods are discussed. A final hybrid model is proposed by using the estimated occupancy by the PTZ face detection algorithm to train the CO2 model. This plug-and-play method overcomes the practical disadvantage of these two approaches, which also overcomes the main con of all of the methods that the modeling work is required before the technologies works.

This paper examines the extent to which different household socio-demographic and building characteristics contribute to high energy use in Social Housing. Using data from the sample created in the framework of the EU funded ICE-WISH project (social housing pilots in ten European countries, of around 25 dwellings each), an odds ratio analysis was performed to examine the effect of socio-demographic and building's structural determinants on high residential energy consumption. The analysis is performed separately for electricity use for lighting and appliances and for energy consumption for space and water heating. Results indicate that high electricity consumption in social housing is related to both socio-demographic characteristics of the occupants and characteristics of the buildings in which they live (OR = 5.6 for households with three occupants compared to single households and OR = 3 for households living in houses greater than 80 m2), whereas high energy consumption for space and water heating is only related to building characteristics (OR = 1.15 for households with three occupants compared to single households and OR = 4.77 for households living in houses greater than 80 m2). The outcomes of this paper call for future energy policy to intelligently incorporate traditional and behavior-based energy efficiency interventions for reducing residential energy consumption and CO2 emissions.

The continuously increasing urban temperature results to the well-known urban heat island phenomenon. Cool roofs and cool pavements are very promising mitigation techniques as they can be easily applied to new and existing buildings as well as urban spaces. In the present paper, the application of cool materials in the urban region of Acharnes municipality in Greece is described. Cool roofs in the form of ceiling tiles are installed on the rooftop of the municipality building while cool paving stones are used to replace conventional pavements. A series of monitoring activities are performed for the building and the urban region. Measurements of the outdoor meteorological conditions, the indoor thermal comfort of the case study building, the surface temperature of the roofs and pavements as well as thermal imaging are exploited for the analysis of the cool roofs and cool pavements’ performance. Thermal models using EnergyPlus and Envi-met are developed for the analysis of the cool roofs and cool pavements respectively. The overall study showed that the application of cool roofs results to 17% reduction in the annual cooling demand for the case study building while the surface temperature of the urban pavements is reduced by almost 10 K.

Associated with rapid urbanization and escalation of bushfire events, Sydney has experienced significant air quality degradation in the XXI century. In this study, we present a 15-year retrospective analysis on the influence of individual meteorological factors on major air pollutants (NO2, O3, PM10 and PM2.5) at 14 different sites in Greater Sydney and Illawarra. By applying a newly developed “zooming in” approach to long-term ground-based data, we disclose general, seasonal, daily and hourly patterns while increasing the level of spatial associativity. We provide evidence on the pivotal role played by urbanization, sprawling dynamics, global warming and bushfires on local meteorology and air pollution. We strike associations between temperature and O3, both as average trends and extremes, on account of increasing heat island effects. The role of wind in a coastal-basin environment, influenced by a vast desert biome inland, is investigated. A steady trend towards stagnation is outlined, boosted by enhanced urban roughness and intensified heat island circulation. Relative humidity is also crucial in the modulation between NO2 and O3. With a sharp tendency towards drier and hotter microclimates, NO2 levels dropped by approximately 50% over the years at all locations, while O3's median levels almost doubled in the last 10 years. Further, O3 and PMs shifted towards more frequent extreme events, strongly associated with the exacerbation of bushfire events. Such results suggest an urgent need to prioritize emission control, building air tightness improvement and urban heat mitigation, towards a future-proof governance in Sydney and similar regions in the world.

Prevailing weather conditions and urban morphology are among the fundamental drivers of the radiative and turbulent exchange processes that inherently result in an urban heat island (UHI). The influence of such drivers varies with temporal changes and must be estimated using recent and sufficiently large meteorological and land-use datasets. We used the most recent in-situ temperature observations collected from a spatially extensive network of 54 automatic weather stations (AWS) gathered over a period of nine years to quantify the influence of wind speed, cloud coverage and land use characteristics on the magnitude of UHI in Seoul city. Through an analysis of variance and combined clustering techniques, we found increased UHI intensities (UHII) under low wind speeds, clear skies and densely built areas. Changes of 0.5 m/s in wind speeds and 1 octa in cloud coverage corresponded to 0.20 °C and 0.24 °C reductions in UHII, respectively. Also, statistically significant differences in peak diurnal UHII values of 1.2 °C were estimated between densely built and sparsely built areas. The obtained results shed light on the factors likely to influence UHI development in Seoul city, and fuel scientific discourse on the development of sustainable cities and effective policies for the management of the built environment.

The integration of microclimatic information and physical properties of the materials into urban design is essential for adequately addressing the challenges related to climate change and to adaptation of urban environment to new climatic loads. Especially, the thermal and optical properties of materials used in the urban fabric play a fundamental role in determining the microclimate and building's energy balance. The present research approach aims at analyzing the thermal characteristics of the materials and the surface temperature distribution using airborne multispectral imaging sensors mounted on Unmanned Aerial Vehicle (UAV). Aerial surveys and in-situ measurements have been carried out in April 2016 at the Municipality of Ymittos in Athens (Greece). The applied multi-sensory survey included high resolution imaging of the materials in the visible and near infrared (VIS/NIR) wavelength region and IR part of the spectrum. The images have been analysed to form maps of surface temperature distribution and of material properties. The derived thermal maps show the changes in surface temperatures of the urban materials during a diurnal heating cycle. In addition, ground measurements of VIS/NIR reflection and albedo from the survey area were obtained and an albedo map and a map of apparent thermal inertia were derived. Thermal scanning of the asphalt in the area, allowed the estimation of the state of decay due to weathering and traffic. The combined maps of surface temperature, albedo and apparent thermal inertia give new perspectives of the urban features and enhance the classification of fine urban material and the energy balance models.

As we are nowadays experiencing a transition period for the energy demand, there is a clear movement of the European energy market towards a new field of efficiency including reliable and smart systems that will upgrade the improvement of Europe's economic and environmental health. To this end smart systems introduce innovative applications with multiple and interdisciplinary characteristics: safe integration of additional renewables, distribution to the network, efficient delivery systems and monitoring control through demand response in order to achieve zero energy targets. The integration of smart technologies requires a holistic approach that takes into account all aspects of sustainability. The implementation of highly efficient smart buildings is feasible through the integration of smart metering, renewable systems acting as generators/storage and energy management. The holistic system supports and fulfils demand load management and distribution network of future grids.. Moreover, the benefits of effective thermal and electrical storage are underlined as a crucial factor of smart systems and smart buildings. This paper highlights the principles of integrated design procedure and links the process with smart building technologies. Energy efficiency methodologies and innovative techniques applied at building level are presented. To this context current EU policy framework, trends and perspectives concerning integrated design as a supportive tool for zero energy concept are also provided.

The integration of microclimatic information and energy balance of the materials into urban design is essential for adequately addressing the challenges related to climate change and to adaptation of urban environment to new climatic loads. Several studies model the urban climate from multispectral satellite measurements. However, the remotely sensed measurements usually have a spatial resolution of several meters and are not suitable for determining microclimate effects in urban areas and on individual buildings. Moreover, they require consideration of the intervening atmosphere and the surface radiative properties that influence the emission and reflection of radiation within. The present research approach includes in-situ measurements and aerial surveys with VIS/NIR multispectral camera and IR camera mounted on a UAV. Analysis presented here, aims (1) to identify physical characterization of reflectance properties in a variety of urban settings in Athens, (2) to explore the response of vegetation, cool and conventional materials in the NIR region (3) to study climate parameters essential to the bio-climatic design in this urban cover (4) to elaborate observational studies for obtaining better validation of the surface effective parameters derived. The sensors on UAVs provide a unique perspective of urban features for revealing the complex mechanisms that lead to micro-climatic modifications and to quantify their relative contribution. The application of NIR images in building and urban scale analysis is innovative and reveals different properties of the surface of the objects.

The research activities described in this paper focus on the development and implementation of a comprehensive and cost-effective system for Net Zero Energy (NZE) settlements. The system is composed of innovative solutions for the building envelope, for building energy generation, and for energy management at the settlement level. The developed solutions will be implemented in 4 different demonstration projects throughout the EU, with varying climates and building types. The results of their implementation will be monitored, analyzed. The target is to achieve a reduction of operational energy usage to 0-20 kWh/m2 per year through a transition from single NZE buildings to NZE settlements, in which the energy loads and resources are optimally managed. In addition, investment costs will be at least 16% lower than current nZEB costs. In this paper, the methodology that was developed in order to optimize the energy, environmental and cost plans of the four case studies through the best integration and combination of the selected innovative energy technologies with excellent architectural and engineering design is described. In addition the evaluation of the four NZE settlements in terms of energy, environmental and cost performance is presented.

A 7 story social housing apartment building in Athens, Greece has been renovated following a holistic energy efficient retrofit process. The retrofit plan, resulting from tenant surveys, environmental parameters monitoring and extensive energy simulations, included commercially available technologies like insulation and energy efficient windows, innovative technologies like energy efficient lighting and smart coatings, passive techniques like night ventilation as well as RES, aiming to transform this inefficient building into a near zero energy one, achieving a reduction of the energy consumption and CO 2 emissions by 80% and significant improvement of thermal comfort conditions. An experimental campaign has been executed in order to measure and validate the energy savings and indoor comfort conditions before and after the retrofit. The results of this monitoring procedure are reported and analyzed. Measurements include air leakage and thermal imaging for determining leakage rate and heat loss through the building fabric, smart meters to record energy consumption and indoor and outdoor environmental measurements. The opinion of the occupants is taken into account through pre- and post-retrofit surveys.

With the rising focus on building energy big data analysis, there lacks a framework for raw data preprocessing to answer the question of how to handle the missing data in the raw data set. This study presents a methodology and framework for building energy consumption raw data forecasting. A case building is used to forecast the energy consumption by using deep recurrent neural networks. Four different methodologies to impute missing data in the raw data set are compared and implemented. The question of sensitivity of gap size and available data percentage on the imputation accuracy was tested. The cleaned data were then used for building energy forecasting. While the existing studies explored only the use of small recurrent networks of 2 layers and less, the question of whether a deep network of more than 2 layers would be performing better for building energy consumption forecasting should be explored. In addition, the problem of overfitting has been cited as a significant problem in using deep networks. In this study, the deep recurrent neural network is then used to explore the use of deeper networks and their regularization in the context of an energy load forecasting task. The results show a mean absolute error of 2.1 can be achieved through the 2*32 gated neural network model. In applying regularization methods to overcome model overfitting, the study found that weights regularization did indeed delay the onset of overfitting.

Globally, the building sector is a major consumer of primary energy sources and a significant contributor to greenhouse gas emissions. As a result of modernization of civilizations coupled with urbanization and increasing living standards, the building sector’s contribution to energy consumption and greenhouses gases emissions are expected to increase further. In hot and humid regions, designing energy-efficient and thermally comfortable houses and buildings with high-quality indoor air is a challenge. Most of the research and developments in this sector are performed in advanced and industrialized countries; the majority of which are in temperate regions of the world. With globalization, some concepts and ideas that have been developed for temperate regions could be reengineered to suit hot and humid regions. However, raw concepts, ideas, and technologies still need to be refined for effective application in hot and humid regions, as these regions have different ways of life, cultures, traditions, and economic standards than industrialized regions. As awareness of the advantages of the energy-efficient and environmentally friendly houses and buildings has grown in hot and humid regions, more research and development efforts have been supported by government and nongovernment organizations in these regions. Hence, the building and operational technologies of houses and buildings in hot and humid regions are expected to become more refined as research, developments, and applications of modern architecture and building sciences become more prevalent in these regions.

In the pursuit of ever more efficient built environments, able to resiliently respond to the many implications of climate change, near room-temperature caloric cooling could be a game changer from multiple standpoints. In this paper, perspectives and challenges of successful implementation of elastocaloric devices in the built environment are explored by contrasting the current readiness level with the envisaged potentiality. Material-level and device-level criticalities are identified and potential solutions are discussed. The roadmap towards an informed and efficient use of this environmentally friendly technology is eventually proposed aiming at an increase of building’s energy efficiency, but also at counteracting the urban heat island effect.

Summary A primary contributor to urban overheating is the urban heat island (UHI) formed due to increased urbanization. The adverse effects of UHI on building energy use are substantial and well documented. However, such effects are typically demonstrated through numerical simulations which are susceptible to modeling uncertainties and lack of validation resulting in a pressing research gap. Here, for the first time, we conduct a large-scale assessment to demonstrate the devastating impact of UHI on building energy consumption using real building energy use data. We find empirical evidence correlating UHI with building energy use; changes in average UHI intensity of 0.5 K correspond to an increase in monthly cooling energy consumption in a range of 0.17 kWh/m2–1.84 kWh/m2. The study validates theoretical evidence on the impact of UHI on building energy and proposes a highly innovative methodology to assess the impact of overheating on the energy balance of cities., Graphical abstract, Highlights • Real energy data used to study the effect of local climates on building energy use. • Cooling energy rises between 0.17 and 1.84 kWh/m2 due to 0.5 K urban overheating. • Heating energy drops between 0.06 and 1.19 kWh/m2 due to 0.5 K urban overheating. • Urban overheating effects are more exacerbated during the cooling period., Energy policy ; Engineering ; Energy engineering ; Energy Systems

Cooling of buildings currently represents a considerable fraction of the total energy consumption in the world. Global and local climate change in combination with the projected population increase and economic development is expected to increase tremendously the future cooling energy demand of buildings and make it the dominant energy component. The present paper aims to present and discuss the details of the framework which defines the present and future cooling energy consumption of the building sector. The more recent quantitative and qualitative data concerning the penetration of air conditioning around the world are presented and analyzed. The main technological, economic, environmental and social drivers that determine the market penetration of air conditioning are identified and their impact is investigated. The potential future evolution of the main parameters that define the cooling energy consumption and in particular climate change, the population increase, income growth, potential technological improvements and the main socioeconomic drivers are investigated and existing forecasts are presented. Proposed methodologies to predict the future cooling energy consumption of the building sector are reported and discussed, while existing estimates and predictions regarding the future cooling energy consumption of individual buildings as well as of the total building sector are documented, evaluated and analyzed. Based on the explored inputs and forecasts, a model to predict the future cooling energy consumption of both the residential and commercial sector is developed. Three scenarios based on low, average and high future development, compared to the current development, are created and the range of the expected cooling energy demand in 2050 is predicted under various boundary assumptions. It is calculated that the average cooling energy demand of the residential and commercial buildings in 2050, will increase up to 750% and 275% respectively.