Economic feasibility of low-impact retrofit strategies for enhancing energy efficiency in residential townhouses: a case study of Sharjah

Energy used in residential buildings accounts for more than 22% of total global energy consumption. Therefore, energy efficiency has become a crucial factor in design and planning processes. A courtyard can be considered one of the most important passive design strategies that contribute to reducing energy consumption. However, due to the spread of multi-story buildings all over the world, this significant strategy has been ignored, hence the emergence of the skycourt. Limited studies have investigated the influence of morphological indicators of skycourts on energy consumption and carbon emissions regarding a hot–humid climate, which presents a research gap. Thus, this research examines the effect of skycourts in reducing energy consumption through an applied study using the Design Builder simulation program for multi-story residential buildings in a hot–humid climate such as Port Said city. The results indicate that skycourt spaces contribute significantly to reducing air temperature by up to 3 °C in the hottest summers and contribute to reducing energy consumption by rates ranging between 8 and 10% annually and reducing carbon emissions. This reflects the role of the skycourt as one of the most important passive design strategies in the current era that can contribute to saving energy consumption in the building sector. Finally, a matrix is conducted to help select the appropriate replacement for the skycourt of multi-story residential buildings in hot–humid climates, which reflects the novelty of the research. The proposed investigations and matrix can contribute to providing well-being, sustainable communities, and overcoming climate change effects, hence reflecting sustainability and the Sustainable Development Goals (SDGs), especially goals three, eleven, and thirteen.

The purpose of this research was to demonstrate the application of energy simulation as an effective tool for specifying cost-effective residential retrofit packages that will reduce energy consumption by 30 %. Single-family homes in the hot–humid climate type of the Southeastern USA were used to demonstrate the application. US census data from both state and federal studies were used to create 12 computer simulation homes representing the most common characteristics of single-family houses specific to this area. Well-recognized energy efficiency measures (EEMs) were simulated to determine their cumulative energy reduction potential. Detailed cost estimates were created for cost-to-benefit analysis. For each of the 12 simulated homes, 4 packages of EEMs were created. The four packages provided home owners options for reducing their energy by 30 % along with the estimated up-front cost and simple payback periods. The simple payback period was used to determine how cost-effective a measure was. The packages are specific to a geographic area to provide a higher degree of confidence in the projected cost and energy savings. The study provides a generic methodology to create a similar 30 % energy reduction packages for other locations and a detailed description of a case study to serve as an example. The study also highlights the value that computer simulation models can have to develop energy efficiency packages cost-effectively and specific to home owner’s location and housing type.

The effect of building envelope on the thermal comfort and energy saving for high-rise buildings in hot–humid climate

There is a need for stakeholders in the construction sector to evaluate energy efficiency and renewable energy generation alternatives appliable to buildings at early design stages. In this regard, public and private organizations have developed tools to compare different options. It was observed that when the objective was to create nearly Zero Energy Buildings (nZEB), the number of tools was still scarce. With this aim, this work presents a new, free digital tool that can predict, among others, energy consumption, energy generation, emissions savings, and payback time. For this purpose, different alternatives applicable to the roof, such as phase change material (PCM), insulation, and reflective paint, as well as to window-to-wall ratios (WWR), with four different glass technologies, can be evaluated. Furthermore, four renewable energy systems were available for comparison: the solar thermal collector (ST), photovoltaic (PV), flat hybrid solar collector (PVT), and low-concentration parabolic solar collector (LCPVT). Our tool was developed based on the results of transient dynamic building simulations of both residential and non-residential building models located in the hot semi-arid conditions of Monterrey, Mexico. Among the results, the small impact of using only reflective paint, the need to combine PCM with insulating material to obtain the best energy savings, and the large impact on emissions savings when using an LCPVT stand out.

Parametric analysis of alternative energy conservation measures in an office building in hot and humid climate

This work aims to reduce the energy consumption of existing buildings through retrofitting and converting them into net zero energy buildings (NZEBs). Various retrofits for an existing academic building were modeled and analyzed using REVIT software. Energy consumption was reduced to approximately 34% through retrofits, and a Solar System of 41.6 kW was integrated to meet the reduced energy demand, consequently converting the building into an net zero energy building (NZEB). Furthermore, environmental and economic analyses were conducted, and the results show a reduction of 32.8 metric tons of CO2 emissions per year as a result of retrofitting the building, converting it into an net zero energy building. The building envelope retrofits and electrical appliances have a payback period of 2.96 and 2.62 years, respectively, whereas the proposed Solar System has a payback period of only 2.3 years. Moreover, the building was rated using the Leadership in Energy and Environmental Design (LEED) rating tool, and it qualifies for silver certification after retrofits and the integration of renewable energy sources (RES). The reduction in energy consumption and integration of renewable energy sources contribute to achieving Sustainable Development Goal (SDG) 7, and reduced CO2 emissions save climate variations, which leads to achieving Sustainable Development Goal 13.

Promoting and developing Zero Energy Buildings (ZEB) is crucial to achieving the goal of net-zero emissions. Zero Energy Buildings emphasize not only on buildings’ energy efficiency, but also on the transition of buildings’ energy consumption from nonrenewable energy to renewable energy. However, practically, since it is often impossible to achieve the “Zero” energy consumption in a strict sense, the concept of ZEB is implemented as Nearly Zero Energy Buildings (NZEB). Although adopting solar energy to achieve the goal of NZEB is currently one of the most feasible strategies, under what conditions the use solar energy for NZEB is technically feasible and how the building owners are motivated to invest in NZEB are still vague and challenging. As the solar power technology continues to advance and the environmental morality continues to rise in countries and societies, this study takes Taiwan as a case to study how feasible technically and behaviorally the NZEB is and what could be the main challenges.Through extensive literature review and expert interviews, we analyze and establish the standards for defining the NZEB in Taiwan. Then we categorize the building types and residential energy consumption scenarios in Taiwan and investigate different approaches to installing solar photovoltaic systems. In sum, the two main approaches to installing solar photovoltaic systems are the roof floor installation and the roof trellis installation. The types of buildings to be studied are the terrace houses, the five-story apartments, and the eight-story apartments. To simulate the net energy consumption, firstly, Ladybug Tools is used to simulate the annual power generation of each solar photovoltaic installation in different climatic regions in Taiwan. Secondly, the formula for calculating the photovoltaic power generation is proposed according to the simulation results. Lastly, we analyze whether each installation approach can meet the specifications of NZEB under different energy consumption scenarios and evaluate, accordingly, the technical feasibility of achieving the goal of NZEB.Based on the simulation, the roof trellis type is shown to generate the most power under the same construction area and to be the most feasible solar photovoltaic installation approach for the residential buildings to achieve NZEB.We also analyze the economic feasibility of different NZEB scenarios using NPV and IRR methods. It is shown that, except for the eight-story apartments in the northern Taiwan’s climatic region, the simulated NZEB scenarios are economically feasible. Among them, the NPVs of the roof trellis type are lower than other schemes, the investment costs are expected to be recovered in about 13 to 17 years, and the IRR is about 5 to 7% for terrace houses and five-story apartments. To conclude, based on the current/modern solar photovoltaic technologies, NZEB can be well achieved for the residential buildings if the housing owners choose to invest.Finally, whether the NZEB can be achieved depends on the house owners’ willingness to invest in NZEB, the main challenges of NZEB in Taiwan. We shall develop a consumer behavior model and form policy insights concerning NZEB.Acknowledgment: Grant number 111-2124-M-002-006 and Grant number 110-2221-E-002-

A review of net zero energy buildings in hot and humid climates: Experience learned from 34 case study buildings

Solar building architecture: edited by Bruce Anderson The MIT Press, Cambridge, MA, USA, 1990, 368pp, £35.95

Building Eco-Informatics: Examining the Dynamics of Eco-Feedback Design and Peer Networks to Achieve Sustainable Reductions in Energy Consumption Rishee K. Jain The built environment accounts for a substantial portion of energy consumption in the United States and in many parts of the world. Due to concerns over rising energy costs and climate change, researchers and practitioners have started exploring the area of eco-informatics to link information from the human, natural and built environments. Specifically, they have begun exploring the use of normative eco-feedback systems to encourage energy efficient behavior and reduce building energy consumption. A normative eco-feedback system provides building occupants with information regarding their own energy consumption and the energy consumption of others in their peer network. While such eco-feedback systems have been observed to drive significant reductions in energy consumption, little is known about the specific system and peer network dynamics that are driving observed reductions. Without this deeper understanding, researchers run the risk of designing eco-feedback systems with low efficacy and may therefore fail to capitalize on potential energy savings. The central aim of this dissertation is to investigate the impact eco-feedback system design and peer network dynamics have on occupant energy consumption behavior. To enable both energy consumption and network data collection, I developed a web-based of an eco-feedback system prototype for an 69 unit residential building in New York City and utilized the system in three empirical experiments. The first experiment was designed to ascertain the effect eco-feedback interface design components have on energy consumption behavior. Analysis of time stamped interface usage and energy consumption data revealed evidence that providing users with incentives and information on their historical consumption levels encourages conservation behavior. Results also suggested that penalizing users for using more energy is not effective in driving energy reductions and instead discourages user engagement. To further understand the effect eco-feedback system design has on energy consumption behavior, a second experiment was conducted using an email-based eco-feedback system. The aim of this study was to examine the role feedback representation plays in encouraging reductions in energy consumption. Participants were broken into two different study groups; one group was provided with feedback in kWh, while a second group was provided with feedback in the equivalent trees required to offset emissions associated with their kWh energy usage. Results revealed that users who received feedback in the form of equivalent trees were more likely to reduce their consumption and had a less dramatic response-relapse effect to feedback emails than their counterparts who received feedback in kWh. The third experiment aimed to characterize the impact peer networks have on modifying energy consumption behavior. Specifically, the experiment was designed to determine if social influence drives energy savings in eco-feedback systems. Analysis of user interaction and energy consumption data was conducted by developing an algorithmic approach based on stochastic and social network test procedures. Social influence was found to impact energy consumption behavior and results indicated the potential of utilizing social influence and peer networks as a means to encourage energy conservation. Overall, the research in this dissertation provides insight into what design elements of an ecofeedback system encourage energy conservation and the impact social influence has on consumption behavior. Results from this research have widespread implications for researchers and policy makers as they strive to design effective policies and systems that will result in sustained energy savings and pave our transition to a less carbon intensive society.

BIM-based techno-economic assessment of energy retrofitting residential buildings in hot humid climate

"A Net Zero Energy Building (nZEB) is a residential or commercial building that consumes net zero energy over a set period of time, usually taken as one year. In short, for every unit of energy the building consumes over a year, it must generate a unit of energy to maintain an overall net balance. This is achieved by reducing the operational energy usage to a very low level through energy efficient design, and then providing renewable generation technologies on site to cater for the remaining energy demand. Energy use in all sectors of society is under scrutiny at present, largely due to the effects of climate change. In order to limit the release of carbon emissions and promote energy savings, the EU has set targets for Member States in relation to energy efficiency and renewable energy sources. As the residential building sector represents over a quarter of the energy usage within the Irish economy, the government has committed to improving building standards for new dwellings to enhance overall energy performance. While this will improve future energy trends within the sector, it is also necessary to improve the energy characteristics of current building stock which stands at almost 2 million housing units (based on 2011 figures). The research aims to establish the level of retrofit required to achieve net zero energy performance and investigate the effect of site location and terrain on the energy consumption and generation potential of a dwelling. In addition, the research examines the optimum phasing strategy for retrofitting a dwelling to achieve net zero energy performance and the economic viability of retrofitting dwellings to achieve this standard. To assess net zero energy performance for existing buildings in the Irish context, a bespoke software tool has been developed by the author for the purpose of analysing building energy performance in the pre- and post-retrofit condition. The Net Zero Energy Retrofit Calculator (NetZERO) is a Microsoft Excel based software program which estimates the existing energy consumption of a variety of dwelling types and assesses the level of retrofit required to achieve nZEB performance by implementing a range of energy efficiency upgrades and providing on site micro-generation. Overall energy usage is calculated by estimating the demand for space heating, hot water heating, lighting, auxiliary power and household appliances for the pre- and post-retrofit scenarios. The effect of dwelling occupancy and heating schedules is accounted for within the NetZERO calculations, together with the influence of local site climate. On-site generation is estimated using manufacturer data for a range of domestic wind turbines and solar PV arrays. The configuration of the overall micro-generation system can be amended based on user preference and site conditions. Using NetZERO, a total of four case studies are assessed to determine the potential of achieving nZEB performance for existing dwellings in Ireland. The selected case studies represent various combinations of dwelling type, site location and terrain, retrofit specification and micro-generation systems. Case study 1 examines a two-storey semidetached dwelling in an urban setting located in the Dublin region. Case study 2 consists of a one-story detached dwelling in a rural setting located in the Mid-West region. Case studies 3a and 3b comprise a one-story detached dwelling in the South-East region; with 3a representing a sub-urban setting and 3b representing a rural site. A net zero energy balance over one year is achieved for case studies 2, 3a and 3b while case study 1 does not achieve nZEB performance. The deep level energy efficiency retrofit applied to each dwelling is in accordance with S.R. 54:2014 Code of Practice for Energy Efficient Retrofit of Dwellings and yields energy savings of between 54% and 61%. The greatest potential for energy savings is associated with space heating which represents between 56% and 62% of the total energy consumption. The ability of each site to meet the residual energy demand using on-site generation varies according to site climate, location and terrain. For case studies 3a and 3b, a wind turbine provides a significant portion of the residual energy demand in combination with a solar PV array to achieve nZEB performance. For case study 2 a single wind turbine supplies the entire residual energy demand following a deep energy retrofit of the dwelling fabric and systems due to the high wind resource available on site. As case study 1 cannot facilitate the installation of a wind turbine due to poor wind resource and restricted site area, the dwelling does not achieve a net zero energy balance. Accordingly, the micro-generation system comprises a solar PV an'ay which only provides 24.5% of the residual energy demand. The export of excess electricity is important to the economic viability of a nZEB project as the export tariff gained offsets the capital investment over a shorter period. This is particularly evident for case study 2 where the calculated payback period is 15.7 years due to high levels of excess electricity at the site and the relatively low capital cost invested. The remaining sites which achieved nZEB performance have payback periods of 23.8 and 22.0 years respectively."

The use of variable frequency drive (VFD) is one of the main energy saving measures. In some industries and housing, and utilities of the energy savings when using VFD can reach 40% or more. Therefore, for optimization of operation modes of the main oil pipelines when using a VFD most attention is paid to energy criteria, the main of which is low power consumption. However, optimization of pumping units with a minimum of energy consumption reflects the efficiency of using the VFD only at a fixed number of VFD. When choosing the number of VFD for low power consumption may lead to increased frequency and consequently to increase the payback period. So the article with the optimization of main oil pipelines takes into account two criteria: the payback period and reducing energy consumption to VFD. The main factor, which allows achieving decrease in power consumption when using a VFD to exclude cyclic pumping is to increase the efficiency (efficiency) of pumps by reducing their speed. The article describes the method of calculating the reduction of energy consumption by increasing the efficiency of exploited oil. The methodology exception of cyclic transfer, when the use of VFD is aimed at reducing cyclical loading. So the first stage of estimation procedures is detection cyclic pumping and selection of the VFD to replace the cyclic pumping modes using a VFD. The application of the methodology on the example of two technological sections of trunk oil pipelines. operating now without the use of a VFD: the Reduction of power consumption is determined only by excluding cyclic pumping. It is shown that this by reducing energy consumption, the payback period for a VFD, even when using optimization calculations, is not less than 10 years. Therefore, to evaluate the effectiveness of the use of VFD when deciding about the appropriateness of the use of VFD it is necessary to consider not only the reduction of energy consumption, but other factors, such as the decline in the number of starts and reducing the cyclic loading of the pipeline internal pressure of the pumped product.

It is commonly known that buildings in hot climate contribute to a huge amount of electricity consumption mainly due to air conditioning needs. Many countries around the world are aiming to convert buildings to net zero energy buildings (NZEB). However, buildings in hot climates require varieties of active and passive measures to adapt the concepts behind NZEB. This work attempts to resolve the challenges associated with shifting school buildings to NZEB in hot arid climates. It presents an energy performance analysis that is focused on two scenarios for new and retrofitted schools. Building thermal simulation is used to assess the implications of several energy conservation measures, and different scenarios are suggested to utilize up to 80% of roof’s area for the installation of Photovoltaics (PV), and on-site wind turbines. The implemented energy conservation measures show a reduction in annual energy consumption by 35% and 21% for new and retrofitted schools respectively. Discounted payback period is used to estimate the economic feasibility of the suggested scenarios. It is found that NZEB is technically feasible at highest roof area PV installations with respective discounted paybacks of 3.55 and 5.54 years for the new and retrofitted schools. However, adding wind-turbines can delay the breakeven year of investments needed to achieve NZEB. The estimated savings in net present value (NPV) are 3273 and 4284 thousand US dollars for the retrofitted and new schools respectively, and each school’s roof can generate 40.63 GWh in 25 years and avoid 29.23 kilotons of CO2.

Additive manufacturing (AM) provides the ability to produce complex, fully functional, multi-material parts directly from its three-dimensional models, resulting in reduction of prototyping lead time and costs. In the literature it can be seen that various techniques have been developed to improve productivity of AM processes by focusing on reducing time and cost, and improving quality during part production. Despite these advantages of AM, it is characterized by high energy consumption that can decrease its sustainable benefits. Moreover, there is limited work in the literature that addresses productivity improvement in terms of energy consumption. This study addresses this shortcoming by introducing a framework for minimizing energy consumption during the production process. A novel optimization-based framework for part decomposition is presented that results in energy savings for AM processes thereby addressing an important research gap for decreasing energy consumption in manufacturing processes. The framework integrates a Genetic Algorithm (GA) based optimization approach to determine the optimal decomposition of a part into sub-parts and their corresponding orientation. This approach thus aims to achieve a reduction in energy consumption by reducing the energy required for both the build and assembly phases of production. In this study, the framework targets a reduction in energy consumption by at least 10% compared to the original, undecomposed part by decomposing a part into sub-parts and optimizing their orientation. The study thoroughly discusses the application of this framework to the Selective Laser Sintering (SLS) process, detailing the procedure from the initial calculation of energy consumption for a given part orientation to the iterative process of generating and evaluating decomposed parts. This decomposition process continues until the framework achieves the target energy consumption reduction, demonstrating the framework’s adaptability to different AM processes and energy savings goals. The effectiveness of the framework is validated by applying it to four diverse test cases, including both simple geometric objects and complex shapes like the Stanford Bunny. For each test case, the target of 10% reduction in energy consumption due to decomposition is exceeded which demonstrates the potential of this framework to improve the energy efficiency of AM processes. These results demonstrate the utility of this framework as a practical tool for designers and manufacturers aiming to optimize energy use in AM thereby supporting the ongoing efforts on sustainable manufacturing practices. This research thus focuses on energy consumption reduction through intelligent part design and orientation thereby mitigating the environmental impacts of AM. Additionally, by filling the gap in existing literature regarding energy savings in the design phase of an AM process, this work lays the foundation for further innovations in sustainable manufacturing. In future the framework’s application to other AM processes will be assessed, its impact on other production properties will be investigated, and energy savings from the assembly process will be quantified for a more comprehensive understanding of its utility.