Annual Energy Demand Research Articles

Incorporating PCMs and thermal insulation into building walls and their competition in building energy consumption reduction

To diminish the 30 % share of buildings in final energy consumption, in this study, phase change material (PCM) and insulation are incorporated into the walls of the building. The primary goal is to determine whether insulation or PCM is more effective in reducing heat exchange through walls. Defining the parameters of the indoor setpoint (7 cases), the type of material (9 cases of PCM and one thermal insulation), the thickness of PCM or insulation (2 cases), and their location (3 cases: L1, L2, and L3), energy consumption (output parameter) was investigated in 420 cases. Because the geographic location of the building has a significant effect on energy consumption, in four different climate regions (ASHRAE index: 3B, 2B, 4B, and 4B), the competition between PCM and insulation in reducing energy consumption was investigated running 1680 cases. In the first climate zone, a layer of PCMs (3 cm thickness) with a melting range of 22–25 °C must installed at the L2 location to achieve the 61.8 % reduction in annual energy demand. If the thickness reaches 6 cm, the optimal material (PCM) should be installed at L3. If the indoor temperature is set higher than 27 °C, insulation should be installed instead of PCM. In the second and third zones, in all cases, it is better to install insulation than PCM. In the fourth zone, at a thickness of 3 cm, PCM can compete with insulation, but at a thickness of 6 cm, insulation is almost a better option. Numerical results affirm that in 71.4 % of cases, thermal insulation is superior to PCM. Genarally it is not recommended to install insulation/PCM in layers close to the building interior.

Multiple machine learning models for predicting annual energy consumption and demand of office buildings in subtropical monsoon climate

Multiple machine learning models for predicting annual energy consumption and demand of office buildings in subtropical monsoon climate

Analysis of Electricity Supply and Demand Balance in Residential Microgrids Integrated with Micro-CAES in Northern Portugal

As global energy demand continues to rise, integrating renewable energy sources (RES) into power systems has become increasingly important. However, the intermittent nature of RES, such as solar and wind, presents challenges for maintaining a stable energy supply. To address this issue, energy storage systems are essential. One promising technology is micro-compressed air energy storage (micro-CAES), which stores excess energy as compressed air and releases it when needed to balance supply and demand. This study investigates the integration of micro-CAES with RES in a 19-home microgrid in northern Portugal. The research aims to evaluate the effectiveness of a microgrid configuration that includes 100 kW of solar PV, 70 kW of wind power, and a 50 kWh micro-CAES system. Using real-world data on electricity consumption and local renewable potential, a simulation is conducted to assess the performance of this system. The findings reveal that this configuration can supply up to 68.8% of the annual energy demand, significantly reducing reliance on the external grid and enhancing the system’s resilience. These results highlight the potential of micro-CAES to improve the efficiency and sustainability of small-scale renewable energy systems, demonstrating its value as a key component in future energy solutions.

Towards sustainable living in high radiation cold climates: A two-phase genetic algorithm approach for residential building optimization

The High Radiation Cold (HRC) region's unique climatic conditions, characterized by high solar radiation and low air temperatures, present distinct challenges for optimizing building climate responsiveness. In this study, residential building design is bifurcated into two phases: building geometry (Phase I) and envelope design (Phase II). In Phase II, we propose a heterogeneous vertical envelope (HVE) design to suit HRC climates. This research framework establishes multiple objectives: energy efficiency, indoor comfort, and economy. It aims to identify a balanced and sustainable design by optimizing various parameters and materials using a Multi-Objective Genetic Algorithms（MOGA). The results indicate enhanced building adaptability in HAV climates through MOGA. The optimal solution in phase I results in an annual heating load of 59.12 W/m2, 33.38 % annual indoor visual comfort hours and the adaptive model predicts 35.59 % annual comfort hours. Incorporating phase II optimization, the total annual energy demand is reduced by 34.42 % with an 11.35 % improvement in thermal comfort hours, culminating at 37.8 %.

Hybrid solar-biomass residential micro – Combined Heat and Power systems driven by the Partially Evaporating Organic Rankine Cycle – A case study in Southern Europe

In this study, a novel hybrid solar-biomass residential micro – Combined Heat and Power system driven by the Partially Evaporating Organic Rankine Cycle is proposed and its operation is simulated, by applying an in-house numerical model. The simulation tool is applied for a test case in Athens, Greece, where the micro-CHP system operates to cover the annual energy demand of a multi-family building. The proposed cogeneration unit covers 97.10 % and 25.85 % of the modeled building’s annual Space Heating and electricity demand, respectively, by using renewable energy sources. The annual average total energy and exergy efficiencies are equal to 53.33 %, and 10.35 %, respectively, while the power cycle can achieve thermal efficiencies as high as 9.73 %. Competitive Levelized Cost of Electricity (0.072–0.133 €/kWhel), and Levelized Cost of Heat (0.036–0.067 €/kWhth) values are estimated, with a PayBack Period between 5.17 and 9.64 years. The environmental impact of the proposed hybrid micro-CHP is anticipated to be significant, rising to 46.25 kWh of Primary Energy Savings, and 31.22 kg CO2-eq. reduction in carbon emissions per m2 of residence annually.

Rule-based energy management strategies for PEMFC-based micro-CHP systems: A comparative analysis

Commercial PEMFC-based micro-CHP systems are operated by rule-based energy management strategies. Each of these strategies constitutes a different way to meet the household energy demand (following the heat demand, following the electricity demand, the maximum of the two, etc.). Previous studies demonstrate that which of them is the best —i.e. the one that manages to meet the demand at the lowest operating cost— depends on the particular scenario in which the micro-CHP system works (gas and electricity prices, annual energy demands, ability to export electricity to the grid, etc.). This paper aims to explore this dependence relationship and to deepen our understanding of it. To this end, a parametric analysis is conducted and the performances achieved by four rule-based operating strategies are compared. The parameters whose influence is studied, and through which the scenario is jointly characterized, are: (1) energy prices (electricity and natural gas), (2) feed-in tariff, (3) stack degradation, (4) climate and (5) heat to power ratio of the demand. The results show this dependence relationship in a clear and more comprehensive way, and offer a better understanding of its nature. From this improved understanding it can be inferred, among other things, that adapting the strategy to the scenario can generate annual savings of up to 14.5 percentage points. Moreover, this enhanced characterization of that dependence relationship can be useful for the design of a new operating strategy, a strategy that, without falling into the complexity that an optimal energy management approach (based on linear programming) involves, manages to exploit the savings potential of micro-CHP systems, thus facilitating their future mass commercialization.

Climate change mitigation and adaptation in Spanish office stock through cool roofs

In a context of climate change, the cooling period of buildings is increasing every year in Mediterranean countries. This will become a relevant issue when existing buildings are retrofitted. Cool roofs have a passive cooling effect on a building and can contribute to decreasing the annual cooling demand. In office buildings, thermal comfort has a considerable influence on workers’ performance. In these buildings cooling energy demands tend to be high due to the high internal thermal loads. This paper describes annual energy simulations of Spanish office stock to evaluate the potential energy savings of cool roofs within the context of building retrofitting. The energy demand and thermal comfort of representative office buildings is compared before and after the application of a cool roof coating, in the present time and in the year 2050, for all climate areas of Spain, under the most optimistic and most pessimistic future weather scenarios. Results showed that the cooling energy demand of Spanish office stock can be potentially reduced by 25 % when a cool roof is applied, and the annual energy demand for heating and cooling can be cut by 6 %, 11 % and 12 % in the present, the optimistic future scenario and the pessimistic future scenario, respectively.

A GIS-Based Approach for Urban Building Energy Modeling under Climate Change with High Spatial and Temporal Resolution

The energy demand and associated greenhouse gas (GHG) emissions of buildings are significantly affected by the characteristics of the building and local climate conditions. While energy use datasets with high spatial and temporal resolution are highly needed in the context of climate change, energy use monitoring data are not available for most cities. This study introduces an approach combining building energy simulation, climate change modeling, and GIS spatial analysis techniques to develop an energy demand data inventory enabling assessment of the impacts of climate change on building energy consumption in Shanghai, China. Our results suggest that all types of buildings exhibit a net increase in their annual energy demand under the projected future (2050) climate conditions, with the highest increase in energy demand attributed to Heating, Ventilation, and Cooling (HVAC) systems. Variations in building energy demand are found across building types. Due to the large number of residential buildings, they are the main contributor to the increases in energy demand and associated CO2 emissions. The hourly residential building energy demand on a typical hot summer day (29 July) under the 2050 climate condition at 1 p.m. is found to increase by more than 40%, indicating a risk of energy supply shortage if no actions are taken. The spatial pattern of total annual building energy demand at the individual building level exhibited high spatial heterogeneity with some hotspots. This study provides an alternative method to develop a building energy demand inventory with high temporal resolution at the individual building scale for cities lacking energy use monitoring data, supporting the assessment of building energy and GHG emissions under both current and future climate scenarios at minimal cost.

Competition between insulation and phase change material to intensify the resilience of envelope against heat exchange to reduce overall energy consumption in buildings

ABSTRACT In this study, the effectiveness of two techniques was investigated to reduce annual building energy demand (ABED) located in hot and desert climates. In the first technique, thermal insulation was used to boost the thermal resistance of the envelopes, and in the second one, bio-based phase change material ( BioPC M R M 27 ) was used. Using numerical methods for five hot and desert regions, the effect of some parameters such as setpoint temperature, installation location, and thermal properties of insulation/PCM on the effectiveness of both techniques were investigated. By installing PCM in the middle layer of the walls, it was found that in 90% of the cases, the first technique had better effectiveness than the second technique in reducing ABED. To enhance PCM efficiency relative to insulation, three approaches were explored: increasing thickness, altering thermal properties, and optimizing installation location. Based on the results, the first two approaches did not yield substantial enhancements in PCM efficacy compared to insulation. The location of PCM installation is very effective in its effectiveness. By installing PCM in different places, it was observed that the presence of PCM in the outermost layer maximizes its effectiveness. In this case, the second technique is more efficient than the first one by 23.63% to 40.4% depending on the climate zone weather.

Energy Losses or Savings Due to Air Infiltration and Envelope Sealing Costs in the Passivhaus Standard: A Review on the Mediterranean Coast

To obtain the Passivhaus Certificate or Passivhaus Standard (PHS), requirements regarding building envelope air tightness must be met: according to the n50 parameter, at a pressure of 50 Pa, air leakage must be below 0.6 air changes per hour (ACH). This condition is verified by following the blower door test protocol and is regulated by the ISO 9972 standard, or UNE-EN-13829. Some construction techniques make it easier to comply with these regulations, and in most cases, construction joints and material joints must be sealed in a complex way, both on façades and roofs and at ground contact points. Performing rigorous quality control of these processes during the construction phase allows achieving a value below 0.6 ACH and obtaining the PHS certification. Yet, the value can increase substantially with the passage of time: as windows and doors are used, opened, or closed; as envelope materials expand; with humidity; etc. This could result in significant energy consumption increases and losing the PHS when selling the house at a later point in time. It is therefore important to carefully supervise the quality of the construction and its execution. In this study, we focused on a house located in Sitges (Barcelona). The envelope air tightness quality was measured during four construction phases, together with the sealing of the joints and service ducts. The blower door test was performed in each phase, and the n50 value obtained decreased each time. The execution costs of each phase were also determined, as were the investment amortisation rates based on the consequent annual energy demand reductions. Air infiltration dropped by 43.81%, with the final n50 value resulting in 0.59 ACH. However, the execution costs—EUR 3827—were high compared to the energy savings made, and the investment amortisation period rose to a 15- to 30-year range. To conclude, these airtightness improvements are necessary in cold continental climates but are not applicable on the Spanish Mediterranean coast.

Evolution of Energy Efficiency of Buildings Using the Guidelines of the European Green Deal Plan

In contemporary literature, there are not many analyses taking into account changing heat transfer coefficients over the years and examining and comparing the variability of insulation thickness in different thermal standards. The article presents the evolution of energy demand taking into account the requirements of the Green Deal. The analysis was carried out using two materials, showing how their thickness changed in relation to the evolving energy requirements. The research was illustrated with an example of thermal modernization for a building in specific time periods. The analysis was carried out using a numerical program, comparing warming variants for individual years using the Index of annual primary energy demand. Following the requirements contained in the EPDB directive, a comprehensive reduction of the penetration coefficients for building partitions was proposed and requirements for the mandatory use of mechanical ventilation and photovoltaics were introduced.

Energy efficiency evaluation of green roofs as a passive strategy in the mediterranean climate

Green roofs are comprised of living vegetation that is installed on rooftops, serving as a sustainable architectural tool that offers numerous environmental, economic, and social advantages to the community. Green roofs have emerged as a prominent sustainable development strategy and architectural element in numerous urban centres worldwide. As for the effectiveness of green roofs in terms of boosting energy conservation in the Mediterranean climate of Amman, this research focuses on a standard medium-sized office building in Jordan. The main evaluation is carried out on the feasibility of enhancing the passive sustainability and energy performance of the building by applying extensive green roof technology. To determine the energy-saving potential, an annual energy demand in the absence of a green roof is estimated by a simulation program. In this paper, the analyses were performed in the form of parametric studies for assessing the impact of variation in soil depths on energy use, indoor temperature and carbon reduction. The study also indicates that green roofs can store heat and provide insulation enough to lessen the demand for comfortable temperature regulation indoors. The findings on energy savings indicate that energy consumption had reduced annually by up to 12 %. This means that large-scale green roofs have the real opportunity to become an efficient sustainable passive design strategy for increasing the energy performance of office building in Amman climatic conditions.

Techno-economic analysis of a PV/WT/biomass off-grid hybrid power system for rural electrification in northern Morocco using HOMER

The increasing environmental concerns associated with fossil fuels have elevated the significance of sustainable energy sources such as solar, wind, and biomass. This study aims to design a hybrid renewable energy system capable of meeting the annual energy demand of residential areas in Zoumi's circle, estimated at 15545.13 kWh/day. Using HOMER Pro software, we analyze various combinations of renewable resources (solar, wind, biomass) and storage solutions (batteries) to assess their electricity generation, cost implications, and environmental impact. The study identifies an optimal hybrid configuration that includes solar, wind, biomass, batteries, and converters. This integrated system proves to be the most cost-effective option, achieving an energy cost of 0.125 $/kWh and a net present cost (NPC) of 8.29 $ million. It generates 11.14 GWh/year and achieves a 100 % renewable energy ratio, significantly reducing CO2 emissions by approximately 5900 tons/year compared to diesel generators.

Evaluation of static and dynamic PV-Integrated shading systems for office spaces in Australia

The paper summarizes a comprehensive analysis to determine the energy and cost benefits of static and dynamic photovoltaic (PV)-integrated shading devices when applied to windows of office spaces located in different climate zones across Australia. The evaluated dynamic shading systems consist of rotating overhangs placed above the windows and operated to minimize the annual energy demands of office spaces. For the first time, the study determines through optimization-based controls the best angle settings for the rotating overhangs on hourly, daily, or monthly basis to minimize the energy consumption of office spaces in Australia. The analysis results indicate that both optimally designed static and optimally operated dynamic PV-integrated overhangs have substantial potential to reduce the annual energy needs of office spaces for all Australian climates with annual energy savings ranging from 45% to over 100% depending on the building orientation, window size, glazing type, and overhang depth. This high energy benefits are attributed to the multi-function capability of the PV-integrated shading systems to minimize cooling and space thermal loads while maximizing on-site electricity generation. Unlike the case of static shading devices, it is found that dynamic PV-integrated overhangs allow office spaces to reach net-zero energy operation for certain climate zones in Australia.

Harnessing rooftop solar photovoltaic potential in Islamabad, Pakistan: A remote sensing and deep learning approach

Solar energy shines as a beacon for sustainable development, with rooftop solar photovoltaic (PV) installations playing a crucial role. This study proposes a novel framework to precisely assess citywide existing solar power generation and analyze future potential under various rooftop utilization scenarios (10–50 %). To illustrate the methodology, the existing solar PV yield and future potential of Islamabad are explored as a case study. Employing open-source satellite data and deep learning (DL), this study quantified the electricity generation from current solar infrastructure and projected future possibilities. DL models like Mask R–CNN and Deeplab-v3 are trained on extensive custom datasets for solar panels and rooftops extraction. The study delineated 19,000 solar arrays, covering an area of 0.8 sqkm, and extracted 75.08 sqkm of suitable rooftops for future installations. The analysis revealed, current solar infrastructure generates 141.42 GWh electricity, satisfying 6.34 % of Islamabad's annual energy demand. Utilizing 50 % rooftop area could generate 6578 GWh annually, meeting 294 % of the city's electricity needs. This research contributes to the strategic planning for solar energy infrastructure, demonstrating the substantial role rooftop solar can play in meeting urban energy needs. This can inform policy decisions and guide investment opportunities for expanding clean energy in the city.

The Impact of the Location of a Passive Frame House on Its Energy Demand for the Purpose of Heating—A Case Study

The reduction of energy demand in buildings is one of the key challenges in contemporary construction. To this end, the application of structural and material partitioning solutions that provide a high level of thermal insulation and the employment of technical installations with high energy performance have become widespread. However, there are a number of other factors that can reduce energy demand. These include the optimal use of heat gains from solar radiation. An aspect that is often discussed in the literature is the overheating of buildings due to excessive heat gains from solar radiation. This article is a case study showing the impact of the orientation of a single-family passive house on its heating energy demand. The building under consideration is located in Central Europe. External climate parameters measured directly at the site during experimental examinations were used for the calculations. This paper adopts six calculation options, considering the different orientations of the glazed façade. As the simulations showed, the effect of solar radiation on the energy demand between two extreme options of glazing orientation, that is south and north-facing orientation, reached 4.7% of the annual energy demand for heating, while for the option corresponding to the actual location of the building and the option involving south-facing windows, the difference was 0.3%, respectively.

Techno-economic evaluation of a seawater source heat pump system with auxiliary heat source in cold region of China

The utilizing of renewable seawater energy through seawater source heat pumps (SWHPs) in coastal areas is considered as a sustainable technology with minimal environment impact. Promotion of this technology needs clear understanding of its techno-economic performance but there are limited relevant studies. An empirical study was conducted in Qingdao, China, based on a practical installation comprising SWHPs supplemented by electric boilers. On-site measurements revealed considerable COP of 3.81 for SWHP and COPs of 2.87 for the whole system, implying SWHP as a viable and efficient solution for space heating in mild winter in this region. Results from TRNSYS simulations showed SWHP with auxiliary gas boilers (SWHP-GB) achieved the lowest annual primary energy demand and best economic and environmental benefits compared with other three schemes, namely SWHP with electric boilers (SWHP-EB), chillers with gas boilers (Chiller-GB) and air source heat pumps with gas boilers (ASHP-GB). SWHP played important roles in energy efficiency of the whole system with a considerable seasonal COP of 3.72 and 3.22 respectively for heating and cooling. Annual primary energy demand of SWHP-GB accounted for 55 %, 78 % and 56 % of SWHP-EB, Chiller-GB and ASHP-GB, respectively. SWHP-GB achieved the lowest life cycle costs and a rapid payback period of 10.9 years. Moreover, using direct or indirect heat exchange with seawater was found with limited impact on techno-economic performance of the system. To conclude, SWHP-GB could be used as an efficient solution for building heating and cooling in northern coastal cities in China.

Application of renewable energy systems in seaports towards sustainability and decarbonization: Energy, environmental and economic assessment

The application of green energy technologies to supply berthed ships in ports with the necessary power instead of using their diesel generators is considered an initiative towards sustainability and climate change mitigation. Therefore, the current paper investigates the implementation of solar panels, offshore wind turbines, and hydrogen fuel cell systems as green technologies to supply the berthed ships with power in three Egyptian ports. The power requirements are determined by analyzing the annual ship traffic data and estimating the energy demand for each ship type. As a relevant result, the annual energy demand for ships berthed in Alexandria, Damietta, and Safaga ports is about 44.2 × 103 MWh, 22 × 103 MWh, and 5.6 × 103 MWh, respectively. The analysis results reveal a potential annual carbon dioxide reduction of 31.7 k-tons, 15.7 k-tons, and 4.2 k-tons in Alexandria, Damietta, and Safaga ports, respectively. From an economic perspective, the levelized cost of energy (LCOE) of solar panels is estimated to be 80.7–90.1 $/MWh, while hydrogen fuel cells have a cost of 166.8–172 $/MWh. On the other hand, LCOE in the case of wind turbines is estimated to be 140.8 $/MWh for Alexandria ports, 178.3 $/MWh for Damietta port, and 103.9 $/MWh for Safaga port.

Evaluating future building energy efficiency and environmental sustainability with PCM integration in building envelope

The energy demand in the building sector is anticipated to increase with climate change and the high energy consumption is responsible for releasing enormous amounts of CO2 into the environment, intensifying climate change. Phase change material (PCM) integration into the building envelope has a high potential to reduce the building's energy demand without compromising environmental sustainability. This research investigated the impact of PCMs (PCM 18–PCM 30) on building cooling, heating, and annual energy efficiency for future climate scenarios (2095) in 13 different climate zones worldwide. For this purpose, the Fanger comfort model was implemented and numerical simulations were performed using Energyplus. The performance of PCM was evaluated using novel Predicted Mean Vote fluctuation reductions (PMVFR), and the Total Predicted Mean Vote drop (TPMVD). Further, for the first time, a time series-forecasting model for the estimation of CO2 emissions originating from various energy production sources in the future was developed using gene-expression programming (GEP) algorithm. Finally, the two different maps showing the PCM efficiency for energy conservation and environmental sustainability at the global level are presented. The results evidence a maximum of 12.9% reduction in annual energy demand in the future with the integration of PCM. The GEP-based prediction model demonstrated good accuracy as determined by the statistical parameters and satisfied the external validation requirements. The environmental analysis exhibits that PCM integration can reduce carbon emissions up to 204 CO2-e Kg/year. Overall, the integration of PCM is regarded as a sustainable solution for building energy efficiency, considering climate change.

An Outlook on the Adoption of Renewable Energy Solutions at South African Beverage Manufacturers

To decarbonise industry, which accounts for half of the total energy demand, renewable and sustainable energy solutions must be embraced. Not only to meet electricity requirements but, more importantly, to substitute fossil fuels used to generate process heat. This research assesses the cost-benefits of renewable and sustainable energy solutions for the South African beverage sector, representing an estimated 3020 GWh in annual energy demand, and provides a framework for the broader adoption of these technologies. For South African beverage producers, the study concludes that investments in photovoltaic and battery energy storage systems will continue to take priority, given the favourable 17–21 % Year-1 return on capital. However, given spatial and capital constraints, the judicious planning of solar thermal energy system requirements is advocated, to address the in-situ nature of process heat generation.