The current global energy resource balance relies heavily on oil, coal, and natural gas, all of which emit greenhouse gases and are non-renewable [1]. The building industry consumes approximately one-third of this energy, depending on the type and location of the building [2,3]. Therefore, the design of zero-energy buildings is an essential aspect of reducing energy consumption [4]. A zero-energy building (ZEB) generates sufficient renewable energy to meet or exceed its annual energy demand, to reduce the use of non-renewable energy in buildings [5,6]. ZEBs minimize their energy use by combining energy efficiency and renewable energy production. Furthermore, switching to ZEBs offers several long-term benefits, including a lower ecological footprint, increased resilience to energy shortages and natural calamities, and improved energy security [7,8].
Conserving energy through efficient building design is an indispensable design component and a fundamental priority in all NZB projects [9,10]. Optimizing the energy efficiency of buildings before installing a renewable energy system reduces the system’s overall size [11]. Energy simulation tools allow the design team to simulate zero-energy designs and determine energy efficiency measures [12]. Energy efficiency measures include design strategies and features that lower energy demand, such as high-efficiency building envelope, daylighting, solar shading, window and glazing selection, passive solar heating, and natural ventilation [13]. Once building loads are lowered, the remaining loads can be further reduced with high-performance equipment and systems, including energy-efficient appliances, lighting controls, highly efficient heating, ventilation, and air conditioning (HVAC) systems, and high-performance hot water heaters [14]. After considering efficiency measures, renewable energy systems can meet the remaining energy demands. Typical strategies for renewable energy systems include photovoltaics (PV) and solar water heaters [15,13,4].
Energy and environmental design guides and protocols, such as [16-20], provide information on the design and construction of buildings that consume either little or no energy at a cost equivalent to that of conventional buildings. These guides offer guidance for the design and implementation of zero-energy buildings in all climate zones. Designers and researchers pursuing zero energy in a variety of building types, can find helpful advice and suggestions on how to achieve their zero energy goals. Moreover, advanced innovative technologies are not always essential for zero-energy buildings. In fact, simplifying a building system increases the likelihood of the building being properly operated and implemented [17].
According to the Ministry of Energy and Mineral Resources, residential buildings are the second largest energy consumer in Jordan [21]. Therefore, offer an excellent opportunity for energy savings, as residential buildings’ energy consumption can be reduced by up to 70% through the design and implementation of low energy use intensity (EUI) [22]. Although the national energy code for buildings has been mandatory since 2009 [23], Jordan lacks a guide for achieving zero energy in residential buildings. For this reason, the development of zero-energy prototypes and measures in all climate zones of Jordan could pave the way for lower EUI and zero energy in the residential sector. The sector has a variety of housing types, mainly distributed in suburban and rural areas (about 78%), with the share of houses (DAR), apartments, and villas in suburban areas being 55%, 42%, and 2.4%, respectively, and in rural areas being 88.9%, 9.9%, and 1.2%, respectively [24]. Nonetheless, the climate in Jordan ranges from mixed to extremely hot, and the region is generally very arid. Summer temperatures are high, and about 75% of the rainfall occurs in the winter. The Jordanian climate is also affected by dry winds that cause large temperature fluctuations [25].
To promote zero-energy buildings and the built environment, it is common practice to design prototypes for acceptable building typologies. The design of prototypical buildings is typical for each geographic region and represents a major building type within that region [26,27]. Prior to the zero-energy design of these prototypes, statistical studies of current building designs must be conducted. Studies should focus on occupants’ needs and building energy performance. A prominent approach to achieving zero-energy design involves statistical building analysis, architectural prototyping, and then designing and selecting various energy-related systems [28].
The context of the above facts underlines the urgent need to promote zero energy in residential buildings. The main goal of developing zero-energy prototypes is to mitigate environmental and economic issues, caused by excessive energy consumption. This goal can be achieved through the design of representative zero-energy prototypes, that provide designers and owners with strategies and methods for achieving zero-energy savings goals. This study provides guidance for the design and construction of zero-energy residential buildings in all climate zones of Jordan, through specific recommendations that are appropriate for the region’s market, building characteristics, and climate zones.
1.1 Previous Studies
Several previous studies have been conducted to investigate energy efficiency and zero energy in buildings, e.g., [29-40]. Zhihua Zhou [29] studied the operational performance of zero-energy buildings. The energy end-use of the buildings was simulated at the design stage using energy simulation software, and then PV systems were selected. The operating performance of occupied buildings revealed that the final energy consumption of actual buildings was much higher than the energy produced by PV systems. Nevertheless, the actual energy consumption of existing zero-energy buildings was studied in comparison with the simulated results during the design phase.
S.Deng and Attia [30,31] provided energy-oriented tools and procedures that incorporate meteorological parameters while providing useful support for promoting and evaluating zero-energy buildings. Energy modeling techniques were used to develop a benchmark that allows engineers to examine the energy performance of early design strategies. However, the methods were developed for use during the early design phase.
Albdour and Alalouch [34,35] investigated the possibilities of applying energy conservation standards to improve the energy consumption of residential buildings in Jordan and Oman. Measures based on building energy codes were proposed. The results were generated using energy simulation software and showed that the application of building energy codes had a large impact on annual energy end-use. A reduction of up to 48% was possible. However, the authors evaluated the impact of applying the building’s minimum energy requirements in warm and hot regions.
Zhijian Liu and Ludovico Danza [36,37] developed field measurement and evaluation methods for zero-energy buildings. The factors of indoor environment quality and energy use for HVAC systems were studied. The average energy usage for the HVAC systems was around 33 kWh/m2/y. Cooling and heating loads were reduced by up to 55% and 54%, respectively. In general, the NZBs offer acceptable thermal comfort and good indoor air quality with low energy use. Nonetheless, the studies focused on indoor air quality and HVAC system performance, omitting other systems such as lighting and water heating systems.
Siamak, Hoseinzadeh, and Lohwanitchai [38-40] studied buildings with zero-energy design systems, emphasizing the installed systems' economic viability. A typical residential building served as a baseline, and the energy efficiency and cost analysis were then analyzed based on qualitative and quantitative studies. The findings revealed no substantial distinctions between the actual cost of a zero-energy building and the cost of a conventional building. The research articles placed an emphasis on feasibility studies rather than the design process and efficiency measures.
There is a dearth of studies on the design of zero-energy buildings. Most studies, such as [29,30,34-40], focused on the theories, evaluation process, indoor air quality, thermal comfort, and cost estimation of zero-energy buildings. Previous researchers have largely overlooked the design of ZEBs suitable for different climates and owner preferences. The authors found no standardized studies that proposed zero-energy prototypes to promote energy efficiency in the residential sector. This problem can be solved by providing accurate designs and recommendations through building energy simulations.
The preceding discussion shows that there are still significant gaps in the design of zero-energy residential buildings based on specific building characteristics and weather conditions. As in many other countries, most new buildings in Jordan do not achieve the highest level of energy efficiency, mostly due to improper architectural design and/or the selection of energy-related systems. Therefore, there is a need to introduce residential buildings with zero energy design. Accordingly, the main aim of this work is to minimize the energy consumption of residential buildings and maximize the use of renewable energy. Two objectives were also established for this study: (1) to develop zero-energy prototypes in different climatic zones of Jordan, and (2) to introduce a design process to achieve zero-energy design in buildings. Then, two questions were raised:
-What architectural designs meet the needs of most Jordanians in the present and in the near future?
-To what extent can the design of zero-energy houses improve the overall energy consumption in different climates of Jordan?
Introducing zero-energy prototypes will increase awareness of energy efficiency. This study provides designers, builders, and owners with a unique guide on designing and constructing energy-efficient buildings. The added value of this work is not only that it addresses issues in Jordan, but also that the results can be applied to several neighboring countries with similar weather and building characteristics. In addition, it lays the foundation for a new Jordanian zero-energy design guide for residential buildings.