Energy Sustainability in Built and Urban Environments

The quest for sustainable construction practices has been on the increase among relevant stakeholders including clients, sponsors, construction professionals, government agencies and other concerned regulatory bodies. This article examines the level of practice of sustainable development goals in the West African countries’ construction industry with an emphasis on the challenges, drivers and possible measures for improving its implementation and application. Various gaps and neglected issues in sustainable construction in the region were also reviewed to providing necessary information for the expansion of knowledge of relevant stakeholders and ensuring that construction projects are delivered to international standards.

Urban planning decisions related to the urban form, built density and neighbourhood location may affect the sustainability of neighbourhoods to an important extent. This chapter investigates the influence of urban planning on the financial and environmental impact of neighbourhoods. A number of schematic neighbourhood models with various layouts and built densities are analysed using an integrated life cycle approach, combining Life Cycle Costing (LCC) and Environmental Life Cycle Assessment (E-LCA). Furthermore, the influence of the neighbourhood location is assessed by comparing the impact of a rural and urban location. The results reveal substantial impact differences (up to 20–25%) between the neighbourhoods, showing the importance of good urban planning to decrease the financial and environmental impact of the built environment. The main reasons for these variations are the lower primary land use, lower energy use for heating and lower material use in high built-density neighbourhoods and compact buildings. Also, the neighbourhood location proved to be a key parameter to decrease the impact of user transport in neighbourhoods, with impact reductions up to 25–30% in an urban area.

Vietnam started to go for green rather late, officially in 2005 or 2006, shortly before Vietnam Green Building Council was established and the first legal documents paving the way for green building development to take root were drafted and then adopted. As the green building is a holistic concept and encompasses a wide range of specialisation, it seems that at the beginning, Vietnam chose energy—the most important component—to focus on before dealing with other measures in a comprehensive package of solutions. In terms of energy, most green, and energy-efficient buildings that Vietnam has constructed and been certified so far come from public and industrial building sector, such as schools, supermarkets, offices, showrooms and factories, while in housing which makes up the largest part of the country’s urban building market, this concept has not been properly developed, not only in quality but also in quantity. In order to provide more energy-efficient housing for the public and meet their very high demand, there are two options for architects—high-tech design and low-tech design—to propose in the local context. Furthermore, another possibility—combining the two tendencies—should be considered and discussed, because of its potential and flexibility in practice, as well as appropriateness in Vietnamese conditions.

The practice of energy efficiency to buildings requires a variety of interdisciplinary actions which are related to aspects of architecture and building services. To office buildings, it is more complicated for the fulfillment of energy efficiency and indoor comfort as such buildings’ designs are normally oriented in a way that creates mechanically air-conditioned spaces. In the context of Vietnam whose climate feature is classified as of humid tropical zone, the issue may become more serious and there is a need to look for new improvement in terms of architecture- and building service-related activities. The article provides an overview of actual situation of energy consumption and indoor conditions of office buildings in major cities of Vietnam, and, from the perspective of architectural and technical design, it gives ideas in aim of improving the energy efficiency and indoor comfort applied to the design concept of office buildings.

Improving the energy efficiency and sustainability in the urban sector plays a vital role in the energy transition. Hence, it is important to consider promising ways to design sustainable urban energy hubs linking neighborhoods into energy systems. Improving the efficiency and sustainability of urban energy infrastructure is a process with multiple steps. This chapter presents the workflow that is required to be followed in this process. A brief overview about the methods that can be used to consider urban climate, urban simulation, and energy system design are presented in this chapter highlighting the crosslinks among these topics. Finally, the chapter presents the research gaps and promising areas to conduct future research.

As buildings have a relatively long life span, it is important to consider climate change in energy performance modelling. Good quality weather data are needed to obtain accurate results. This chapter discusses widely used methods to predict future weather data (dynamical downscaling, stochastic weather generators and morphing) and provides an overview of available weather datasets (multi-year, typical years, extreme years and representative years) for building simulations. A Flemish office building is used for a comparative analysis of the estimated heating and cooling load making use of 1-year weather files (typical and extreme future climate conditions) derived from a recently developed convection-permitting climate model for Belgium. Climate models and weather generators are identified as the most preferred for the estimation of the average energy consumption and thermal comfort in average and extreme situations. Climate models have the advantage to better represent extreme weather events and climate differences due to territorial settings, while weather generators can generate multiple climate realizations. A combination of a typical year with an extreme cold and extreme warm year was found to result in an overall good representation of the energy need for heating and cooling in average and extreme weather conditions. Further, the influence of the methodological choices to extract 1-year weather files (typical or extreme years) from the 30-year climate data is highlighted as different results were obtained when different meteorological variables were considered for the creation of the 1-year files.

In Flanders, an obligatory software tool (EPR) is used to assess the energy performance of new buildings offering a simplified procedure to estimate the energy use for heating. This calculation approach is based on the principle of multiplying the building’s heating demand with standardised (sub)system efficiencies. In this paper, the accuracy of this simplified approach is assessed for a traditional, hydronic heating system in non-residential buildings. To do so, integrated dynamic simulations are performed in TRNSYS for a series of building design variants with varying insulation quality, thermal capacity, window-to-wall ratio and orientation. From the integrated simulations, monthly subsystem efficiencies are deduced. Results show that the efficiencies are significantly influenced by the part load ratio. As however losses of efficiencies are noticed only in periods of low heat demands, the overall effect on the annual use is limited. Energy assessment by the simplified method is within an error of <2.5 kWh/(m²·a) or <10%. Therefore, the simplified approach as currently applied in the EPR calculation tool in Flanders is concluded to be suited for the calculation of the final energy use. An evaluation of tabulated values for the overall system efficiencies used in this simplified method is however recommended.

Residential grid-connected microgrids (MG) comprising renewable generation and storing capability are constrained to grid-operator requirements which include, among others, a smooth and bounded grid power profile. These requirements attempt to mitigate a high unpredictability on the electrical power exchanged between the grid and the MG and affect the design of the MG Energy Management System (EMS). This chapter reviews several energy management strategies based on Fuzzy-Logic Controllers (FLC) designed in the last years to smooth the grid power profile of a residential grid-connected MG. Two MG power architectures are considered. Both include wind and PV solar renewable generation and non-controllable domestic electrical loads. The first architecture assumes a battery charger/inverter as the only controllable element whereas the second one also considers a thermal load as an additional controllable element. The chapter presents a fuzzy logic approach to design the control strategies of the microgrid EMS. The strategies are designed under two scenarios, the first one assuming that forecast of generation and consumption is not available and the second one using MG forecasted data. Simulation and experimental results are provided to highlight and compare the features of all the strategies in terms of their power profile smoothing capability.

Investors are becoming aware of the important role of renewable energy sources for mitigating global warming, which has encouraged them to invest in alternative energy mutual funds. However, the effectiveness of such financial instruments to mobilize private investments depends on the ability of managers to increase the investors’ wealth. For this reason, this paper examines the financial performance of alternative energy mutual funds compared to conventional and thematic market benchmarks in the Spanish market. To do so, we use a sample of 42 alternative energy mutual funds. Using these sample data, we implement a Carhart (1997) four-factor model. The results show that the use of a renewable energy index or conventional indexes affects fund performance. 19.05% of alternative energy mutual funds significantly exceed the renewable energy index, while 80.95% of alternative energy funds perform similarly to the market. There is no evidence of any effect of size or operating costs on the financial performance of funds.

The present chapter starts with an overview of some basic concepts concerning electrical power generation using wind turbines. Basic topics like the Betz limit and the importance of the power curve are explained. Harvesting energy is mainly a challenge due to the irregular behavior of the wind which explains the development of a large number of different wind turbine types. The dominance of three-bladed horizontal axis wind turbines is explained. The kinetic energy in the wind is used to drive the rotor, i.e., the translational motion of the wind is converted into a rotary movement of the rotor blades. Fluid mechanics are used to explain this conversion. Special attention goes to the drivetrain containing the generator which converts mechanical power into electrical power. The use of asynchronous generators, doubly fed induction generators, and synchronous generators are studied and compared. Finally, a number of technical challenges are considered. These challenges include the impact of the fluctuations of the power generation on the power balance of the electrical grid.

In many applications, only a reduced percentage (industrial processes 30–40%, internal combustion engines ICE 25%, photovoltaic systems PV 15%, etc.) of the primary energy is converted into useful energy. Increased energy efficiency can be realized through better performance of the involved devices, but also through the recovery of the energy losses. Partial recovery of the losses (mainly heat) may be done using mechanical means (turbines, Stirling generators, solar collectors), but still, the heat wasted to environment remains important. In this context, the thermoelectric generators (TEG) based on (novel) thermoelectric materials may offer a good alternative for heat recovery, since TEGs are static devices that in principle do not require maintenance and may work even in harsh environments, like, e.g., space, extreme cold, etc. Besides, TEGs can be used together with PV systems in hybrid installations to harvest more energy from the solar radiation. Up to date, expensive (due to complex manufacturing and scarcity of used materials) and not so efficient (due to low figure of merit ZT < 1 and inefficient MPPT techniques) TEGs have not been applied at large scale for low-grade heat recovery and for (solar) energy harvesting in smart buildings. However, in recent years, many research and development activities around TE-materials are going on worldwide and there is more pressure to increase the energy efficiency of many heat wasting processes and of (solar) energy harvesting in smart buildings. Potential of existent, commercially available TEGs and of emerging TEGs is investigated taking into account their properties, their past and emerging usage related to industrial and residential waste heat recovery and (solar) energy harvesting.

Renewable energy resources are susceptible to intermittent power supply, and their standalone operation has prime importance for steady power supply. Solar energy resources have high global availability and potential among all energy sources. Most of areas with high solar energy potential have either dry hot or tropical climate. A major portion of primary energy supply for such area is utilized in their cooling energy needs. In this chapter, a sustainable approach for cooling needs has been proposed using solar energy-based highly efficient concentrated photovoltaic (CPV). A combined cooling system, based upon mechanical vapour compression (MVC), and adsorption chillers have been considered. The MVC chiller utilizes the produced electricity by the third -generation multi-junction solar cells (MJCs). However, adsorption chiller is operated with thermal energy recovered from the cooling of CPV system, which also increases the system efficiency as high as 71%. To handle intermittency, hydrogen production is used primary energy storage system, along with the hot water storage. The complete system configuration is then optimized for standalone operation with optimum components size and minimum cost, using micro-genetic algorithm according to proposed optimization strategy.

We describe an economical, novel method for implementing a hydrogen fuel clean energy cycle based on the chemical reaction between salinated (sea) or desalinated (fresh) water (H₂O) and sodium (Na) metal that produces hydrogen (H₂) fuel and sodium hydroxide (NaOH) byproduct. The sodium hydroxide (NaOH) is reprocessed in a solar powered electrolytic Na metal production plant that can result in excess production of chlorine (Cl₂) from sodium chloride (NaCl) in sea salt mixed with NaOH, used to effect freezing point lowering of seawater reactant for hydrogen generation at reduced temperatures. The novel method and molten salt electrolytic cell enable natural separation of NaCl from NaOH, thereby limiting excess Cl₂ production. The recovered NaCl can be used to produce concentrated brine solution from seawater for hydrogen generation in cold climates, or can be converted to sodium carbonate (Na₂CO₃) via the Solvay process for electrolytic production of Na metal without Cl₂ generation.

The economic development has serious impact on the nexus between water, energy, and environment. This impact is even more severe in Non-Organization for Economic Cooperation and Development (non-OECD) countries due to improper resource management. It is predicted that energy demand will increase by more than 71% in non-OECD as compared to 18% in developed countries by 2040. In Gulf Cooperation Council countries, water and power sector consume almost half of primary energy produced. In the past, many studies were focused on renewable energies based on desalination processes to accommodate fivefold increase in demand by 2050 but they were not commercialized due to intermittent nature of renewable energy such as solar and wind. We proposed highly efficient energy storage material, magnesium oxide (MgO), system integrated with innovative hybrid desalination cycle for future sustainable water supplies. The condensation of Mg(OH)₂ dehydration vapor during day operation with concentrated solar energy and exothermic hydration of MgO at night can produce 24 h thermal energy without any interruption. It was showed that Mg(OH)₂ dehydration vapor condensation produces 120 °C and MgO hydration exothermic reaction produces 140 °C heat during day and night operation, respectively, corresponding to energy storage of 81 kJ/mol and 41 kJ/mol. The produced energy can be utilized to operate desalination cycle to reduce CO₂ emission and to achieve COP21 goal. The proposed hybrid desalination cycle is successfully demonstrated by pilot experiments at KAUST. It was showed that MgO + MEDAD cycle can achieve performance over UPR = 200, one of the highest reported ever.