Transient System Simulation Tool Research Articles

Modeling and optimization of a passive building HVAC system based on improved PSO and H-J Algorithm

Passive buildings employ the principles of active optimization and passive priority to demonstrate their energy-saving, comfortable, and cost-effective qualities, thereby addressing energy consumption in an efficient manner. However, it cannot be ignored that the Heating Ventilation Air Conditioning (HVAC) system is still the largest energy consumer, especially when it is necessary to maintain the comfort of the indoor environment. Consequently, the control and optimization of the HVAC system is a research hotspot and a challenge in the field of building energy conservation, as it is the key to achieving ultra-low energy consumption operation in passive buildings while ensuring the thermal comfort of the indoor environment. This paper presents a comprehensive modeling, control, and optimization framework for the efficient operation of HVAC systems in a passive building located in Jinan, China. Firstly, the HVAC system is modeled using the transient system simulation tool (TRNSYS), GenOpt, Java, and other software. Secondly, the HVAC system’s year-round operation is simulated using specific configurations. In order to enhance the energy-saving effect, a strategy of increasing heat storage and return air ducts was proposed, and a significant energy-saving effect (approximately 17.31%) was realized. Lastly, the data communication interface with GenOpt is established utilizing the TRNOPT module, a method for actively optimizing the refrigerant temperature is proposed, and recalculation and optimization are carried out utilizing the swarm intelligence algorithm and the pattern search algorithm (Hooker-Jeeves algorithm, H-J algorithm). The final optimization results demonstrate a 19% reduction in energy consumption relative to the baseline heat recovery model, validating the applicability of the optimization method under this strategy. The control and optimization method of the HVAC system proposed in this paper can further exploit the energy-saving potential of the passive building HVAC system and will contribute to the advancement of building energy conservation.

TRNSYS MODEL OF THE COMBI BOILER DOMESTIC HOT WATER CIRCUIT WITH A FOCUS ON THE PARAMETER DEFINITION OF THE PLATE HEAT EXCHANGER

Combi boilers used for both space and domestic hot water heating are one of the common household appliances. Modelling the domestic hot water circuit of a combi boiler for the preliminary evaluation of the laboratory testing is of crucial importance since it decreases the time, cost, and energy spent on the trials. There are various modelling approaches established by the authors of this paper. Domestic hot water circuit of the appliance is modelled previously making use of the Transient System Simulation Tool (TRNSYS 18) and a good agreement is achieved with the experimental and numerical data for the economic mode simulations. The drawback of the current TRNSYS model is the dependence on the experimental data for some of the parameter definitions of the components selected from the TRNSYS library, i.e. UA (multiplication of the overall heat transfer coefficient and the heat transfer area) input of the plate heat exchanger and heat retention effect of the heat cell block. In this paper, a constant value is assigned to the parameter definition of UA instead of a time dependent varied profile. Mean absolute errors covering the steady-state and transient operating regions for the domestic hot water inlet and outlet temperature difference in economic mode simulations stay nearly the same around 0,46°C, 0,82°C, and 0,53°C for 5 l/min, 7 l/min, and 8,7 l/min, respectively, under constant and variable UA approaches. Comfort operating scheme model is established with a couple of experimental data as of the principal application of the constant UA approach. Mean absolute error of the overall domestic hot water inlet and outlet temperature difference profile decreases to 0,5°C in the comfort mode simulation.

Techno-economic analysis of a hybrid heat recovery-renewable energy system for enhancing power reliability in cement factories in Pakistan

Pakistan is among the top twenty cement producing countries in the world, with an annual capacity of over 44 million tons. The growth of the cement industry in Pakistan is expected to be around 14% over the next five years. Nonetheless, this growth could lead to increased use of fossil fuels, contributing to global warming. This research proposes a novel grid-tied hybrid power supply scheme that can offer a more reliable source of electricity for the cement manufacturing process in Pakistan. The proposed hybrid power system stands out for its unique aspect of using both renewable energy sources and waste heat by integrating a solar thermal power cycle with heat recovery from exhaust gases and wind power turbines. The detailed simulation of the proposed hybrid waste heat recovery-renewable energy (WHR-RE) system is performed in the Transient System Simulation (TRNSYS18) Tool. The objective of the simulation is to identify the optimal size and configuration of the system that can fulfill the required electrical load of the Pakistan Cement factory located in the Kalar Kahar district of Chakwal, Pakistan. The techno-economic analysis indicates that the proposed WHR-RE is economically feasible, providing 40% of the total electricity demand with an annual generation of 109.2 GWh and a net present value of USD 25.69 million. Moreover, this system will reduce the factory's annual electricity bill by USD 19.66 million and mitigate CO2 emissions by 52.7 thousand tCO2e/year.

Building energy model automated calibration using Pymoo

This paper describes a two-stage calibration method, starting with detailed modeling and followed by optimization-based calibration. To put the proposed calibration method to the test, a real-life existing building was modeled using TRNSYS (Transient System Simulation Tool). The first stage approach emphasizes the significance of a detailed description of the building. In this regard, we compared the results of two different simulations: one that considers the dynamic behavior of infiltration and convective heat exchange, and the other that uses average values for the aforementioned quantities. The detailed model helped reduce the gap between simulation and measurement, where one of the simulated zones' mean absolute error (MAE) decreased from 1.11°C to 0.63°C. The calibration problem is viewed as an optimization problem in the second-stage approach, and the MAE between the simulated and measured values is regarded as an objective function to be minimized. In this work, we demonstrate the implementation of Pymoo (Multi-Objective Optimization in Python) as a calibration tool for building energy simulation software. The detailed energy simulation was fine-tuned using the genetic algorithm. The optimization results produced an MAE of around 0.3°C for both studied zones.

Multi-objective optimization of solar-assisted ground-source heat pumps for minimizing life-cycle cost and climate performance in heating-dominated regions

The use of solar-assisted ground-source heat pumps (SGSHPs) with serial and parallel configurations can reduce the energy consumption compared with conventional ground-source heat pumps (GSHPs). However, the environmental and economic issues associated with SGSHPs, which involve high initial costs and CO2 emissions, remain major barriers to their application. Therefore, SGSHPs should be carefully designed considering both the economic and environmental circumstances to guarantee their competitiveness over GSHPs. In this study, multi-objective optimization of SGSHPs with serial and parallel configurations was conducted to minimize the life-cycle cost (LCC) and climate performance (LCCP). Based on the estimated energy consumption using Transient System Simulation Tool (TRNSYS), the design parameters and refrigerants of the SGSHPs were optimized using an artificial neural network and multi-objective genetic algorithm in the four heating-dominated regions. The optimized SGSHP with a parallel configuration exhibited lower LCC and LCCP by up to 7% and 10%, respectively, compared to that with a serial configuration. Furthermore, as building insulation technology improves, the optimal system size decreases. In addition, R134a is the best option for minimizing LCC owing to its high performance, whereas R1234yf is the best option for minimizing LCCP in Helsinki and Stockholm, showing up to a 37% reduction in LCCP.

Model of the combi boiler appliance in TRNSYS for domestic hot water circuit: Experimental and numerical validations of economic mode simulations

Combi boiler type heating appliances are used nearly in every residential building for both space and domestic hot water (DHW) heating functions. There are challenging targets regarding both of these functions. Since there is a huge laboratory testing procedure behind each appliance design and the structural or operational changes on the regular designs, simulation models could be established for the initial evaluations of the appliance testing. Therefore, due to the estimations from the preliminary results of the simulations, the number of the laboratory tests could be decreased with cost, time, and energy savings. In this study, the main objective is modelling DHW heating circuit of a combi boiler appliance with the help of Transient System Simulation Tool (TRNSYS 18) to calculate DHW outlet temperature under various operating conditions. The TRNSYS model is validated experimentally and compared with the previous works of the authors. A good agreement is achieved in both transient and steady-state regions and the TRNSYS model is found superior when compared to the previously established one-dimensional model of the authors. DHW circuit model is validated only for economic (eco) working mode simulations in this study. Mean absolute error (MAE), mean square error (MSE), and root mean square error (RMSE) values are compared for the outcomes of the previously constructed one-dimensional model and currently established TRNSYS model with reference to the experimental data. TRNSYS model decreases all of these errors calculated according to the overall temperature profiles including the transient region for the central heating water at the heat cell inlet, central heating water at the heat cell outlet, and the inlet and outlet temperature difference of DHW at the experimentally investigated DHW flow rates of 5 l/min, 7 l/min, and 8.7 l/min.

Indoor Climates and Energy Consumption by Air Conditioning System in a Learning Resource Centre in Malaysia

A Learning Resource Centre is a type of library that houses books and all other media facilities as well as daily newspapers and journal articles. Indoor climates such as the indoor dry bulb temperature and relative humidity must be controlled at the recommended level in a Learning Resource Centre in order to keep the collections and archival materials in good condition. Based on the ASEAN Energy Organization report, 50-60% of the total energy consumption of a building goes to Heating, Ventilating and Air Conditioning (HVAC) systems operation. As such, energy savings for HVAC systems is crucial and should be studied, especially after climate change has taken place. In this paper, the author installed data loggers in the Resource Centre for a period of a month to monitor the indoor climate changing trend. Due to the lack of cooling and dehumidification processes when the HVAC systems were turned off, there were peaks in both indoor dry bulb temperature and relative humidity during the night. The ambient high relative humidity had caused an increase in the indoor relative humidity at night. At the same time, the energy consumption simulation of the HVAC systems was run using the Transient Energy System Simulation Tool (TRNSYS). Different operating modes were set in the simulations to obtain the comparison of energy consumption for the different operating modes of the HVAC systems under four different weather elements, namely the present-day, 2020’s, 2050’s and 2080’s time scenarios. Electricity bills for the different scenarios based on current electricity tariffs were analyzed. The results show that a significant saving can be obtained if the HVAC systems were operated under the All-day Operating Mode.

Deep Reinforcement Learning-Based Joint Optimization Control of Indoor Temperature and Relative Humidity in Office Buildings

Indoor temperature and relative humidity control in office buildings is crucial, which can affect thermal comfort, work efficiency, and even health of the occupants. In China, fan coil units (FCUs) are widely used as air-conditioning equipment in office buildings. Currently, conventional FCU control methods often ignore the impact of indoor relative humidity on building occupants by focusing only on indoor temperature as a single control object. This study used FCUs with a fresh-air system in an office building in Beijing as the research object and proposed a deep reinforcement learning (RL) control algorithm to adjust the air supply volume for the FCUs. To improve the joint control satisfaction rate of indoor temperature and relative humidity, the proposed RL algorithm adopted the deep Q-network algorithm. To train the RL algorithm, a detailed simulation environment model was established in the Transient System Simulation Tool (TRNSYS), including a building model and FCUs with a fresh-air system model. The simulation environment model can interact with the RL agent in real time through a self-developed TRNSYS–Python co-simulation platform. The RL algorithm was trained, tested, and evaluated based on the simulation environment model. The results indicate that compared with the traditional on/off and rule-based controllers, the RL algorithm proposed in this study can increase the joint control satisfaction rate of indoor temperature and relative humidity by 12.66% and 9.5%, respectively. This study provides preliminary direction for a deep reinforcement learning control strategy for indoor temperature and relative humidity in office building heating, ventilation, and air-conditioning (HVAC) systems.

Investigation of solar powered sorption cooling and heating systems to supply hospital’s thermal requirements in pandemic periods

Abstract In pandemic periods such as COVID-19, economic and sociological problems threaten human life and public order on a global scale. In these periods, the use of solar powered heating–cooling systems to meet the thermal needs of hospitals and to provide thermal comfort conditions offer important solutions for the elimination of technical, economic and environmental problems related to energy supply. In this study, the heating, cooling and hot water supply of a sample hospital building for the three largest cities of Turkey with a novel solar powered Li-Cl absorption heat pump system was investigated using the Transient System Simulation Tool (TRNSYS) simulation program. The use of a unique NH3-H2O resorption system as a solar powered auxiliary system was also investigated. It was determined that the total annual hot water and cooling needs of the hospital buildings in all three provinces are supplied almost completely by the solar energy powered system without compromising the hygiene and thermal comfort of the occupants. The average annual solar fraction of total heating demands are calculated as 50, 54 and 65% for İstanbul, Ankara and İzmir, respectively. In addition, depending on the use of solar energy, it has been observed that 126 tons of CO2 emissions were saved annually, and an economic saving of 524 375 TL was achieved in total. Considering the problems with energy supply during the epidemic periods, it was concluded that meeting the energy requirements of hospitals with clean, renewable and independent energy source will provide significant benefits to the countries.

The cost savings potential of controlling solar thermal collectors with storage for time-of-use electricity rates

Homes and commercial buildings account for roughly 40% of U.S. energy consumption. A significant portion of this energy consumption, and therefore utility cost, comes from domestic hot-water use. Solar collectors such as flat plate collectors, evacuated tubes, and combined photovoltaic/thermal panels, are renewable options that collect thermal energy and could help reduce utility costs. Hot water is generated by pumping a working fluid through the solar collector, where the fluid captures thermal energy via absorbed solar radiation incident on the collector surface. The collection of heat coincides with the availability of solar radiation, but the best time to use this thermal energy depends on the utility rate at a given time, which often changes throughout the day. In this work, we implement and simulate a control strategy using Transient System Simulation Tool (TRNSYS) that reduces utility costs by controlling when the system stores and uses thermal energy based on solar availability and time-of-use electricity rates. Our modeled results show that the control strategy can reduce utility costs associated with using hot water between 3% and 30%. We also show how the on-peak utility rates, the size and type of the solar collectors, and the location’s climate impact the results.

An efficient renewable hybridization based on hydrogen storage for peak demand reduction: A rule-based energy control and optimization using machine learning techniques

The present study proposes and thoroughly examines a novel approach for the effective hybridization of solar and wind sources based on hydrogen storage to increase grid stability and lower peak load. The parabolic trough collector, vanadium chloride thermochemical cycle, hydrogen storage tank, alkaline fuel cells, thermal energy storage, and absorption chiller make up the suggested smart system. Additionally, the proposed system includes a wind turbine to power the electrolyzer unit and minimize the size of the solar system. A rule-based control technique establishes an intelligent two-way connection with energy networks to compensate for the energy expenses throughout the year. The transient system simulation (TRNSYS) tool and the engineering equation solver program are used to conduct a comprehensive techno-economic-environmental assessment of a Swedish residential building. A four-objective optimization utilizing MATLAB based on the grey wolf algorithm coupled with an artificial neural network is used to determine the best trade-off between the indicators. According to the results, the primary energy saving, carbon dioxide reduction rate, overall cost, and purchased energy are 80.6 %, 219 %, 14.8 $/h, and 24.9 MWh at optimal conditions. From the scatter distribution, it can be concluded that fuel cell voltage and collector length should be maintained at their lowest domain and the electrode area is an ineffective parameter. The suggested renewable-driven smart system can provide for the building's needs for 70 % of the year and sell excess production to the local energy network, making it a feasible alternative. Solar energy is far less effective in storing hydrogen over the winter than wind energy, demonstrating the benefits of combining renewable energy sources to fulfill demand. By lowering CO2 emissions by 61,758 kg, it is predicted that the recommended smart renewable system might save 7719 $ in environmental costs, equivalent to 6.9 ha of new reforestation.

Energy cost analysis of growing strawberries in a controlled environment chamber

The purpose of this paper is to examine the energy cost of strawberry cultivation in a controlled environment chamber. To determine the energy cost, a 2.25 × 5.05 × 2.2 m3 testing room for growing strawberries was set up for the experiment in Chiang Mai, Thailand. Light-emitting diode (LED) grow lighting and air conditioning were used to regulate the environment inside the room to satisfy the strawberry growing requirements. There were 180 strawberry plants in the room. The energy consumption of the room was recorded for about 20 weeks. A computer model of the controlled environment chamber was developed and validated using the TRaNsient SYStem simulation tool (TRNSYS). The validated model was then used to predict the energy cost for one strawberry crop. In addition, the TRNSYS model was used to predict the energy consumption and costs of the room using weather data from five Southeast Asian cities (Chiang Mai, Kuala Lumpur, Yangon, Ho Chi Minh City, and Vientiane). It was found that the energy cost of growing strawberries in the controlled environment chamber in Chiang Mai was 2170 USD/crop cycle (71,500 THB/crop cycle) which is equivalent to 12 USD/plant. It was assumed that the average yield of strawberries would be around 150–400 grams per plant under protected cultivation for about 35 days from the fertilisation of the first flower. Consequently, the predicted energy cost for growing strawberries in the controlled environment chamber in Vientiane was the lowest, at 906 USD per crop cycle (5 USD/plant or 14 USD/kg), because of the low ambient temperature and low electricity tariff.

Developing a collaborative control strategy of a combined radiant floor cooling and ventilation system: A PMV-based model

The development of collaborative control strategies for radiant cooling and ventilation systems improves thermal comfort and energy efficiency. This study used the Transient System Simulation (TRNSYS) tool integrated with the parametric simulation manager jEPlus to determine the optimal starting and operation mode of a combined radiant floor cooling (RFC) and ventilation system. The results were validated by an experiment. The optimization process was constrained by the thermal comfort defined by the predicted mean vote (PMV) with the objective of minimizing energy consumption. The results showed that the ventilation system was started 1 h earlier than the RFC system at an initial indoor humidity of 85% to prevent condensation, whereas both systems were started at the same time at 75% in the starting stage. In the operation stage, the self-regulation potential of the RFC system and the adjustment of the cooling capacity of the ventilation system were coordinated to counter dynamic internal heat gains. Moreover, the proportion of the total sensible heat removed by the RFC system to the total sensible heat removed by the ventilation system (Sv/SR) was positively correlated with the total energy consumption. The Sv/SR must be sufficiently high to prevent a large PMV deviation from the comfort zone of −0.5 to 0.5. A collaborative control strategy using the PMV-based model was proposed to adjust the Sv/SR according to the PMV range, resulting in a highly efficient operation and maximum energy savings of 26.2%.

Prediction of the Energy Consumption for Indoor Strawberry Cultivation in a Tropical Climate

This article addresses the lack of information for predicting the energy consumption of strawberry plantations inside plant factories located in tropical climate regions. This study aims to investigate the energy consumption of the cultivation of strawberries in the controlled environment room and to develop a TRNSYS computer model for the controlled environment room. Experiments were conducted in a 25 m3 controlled environment room. There are 180 strawberry trees inside the room. Light Emitting Diode (LED) grow light substitutes for natural sunlight. An air conditioner was used to regulate the indoor air condition. A computer model was developed using TRNSYS (TRaNsientSYStem simulation tool) and was validated using the collected data. There are three main components of the room heat load: transmission, lighting, and evapotranspiration. The lighting heat load shares more than 96% of the total heat load — the evapotranspiration load increases when the LED turns on. However, the lighting consumes only about 36% of total electricity consumption, while the air conditioner consumes 64%. Most of the electricity is used during the runner stage. Electricity consumption can be saved by 40% if the runners are grown outside the plant factory. Therefore, the high heat load is a feature in the plant factory. In this study, the lighting heat load is the most significant parameter. The strawberry light intensity requirement is the high lighting heat load. Consequently, the electricity for the air conditioner becomes high since the air conditioner removes the generated heat from the high light intensity. Therefore, the air conditioner electricity consumption is enormous in this study. Moreover, the required lighting intensity, photoperiod, and low air temperature factors affect electricity consumption. Therefore, the results from this study could provide strategies for energy cost reduction and plantation management for plant factories cultivation.

Investigating the Impact of Plumbing Configuration on Energy Savings for Falling-Film Drain Water Heat Recovery Systems

Falling-film drain water heat recovery (DWHR) systems are heat exchangers utilized in residential buildings for recovering energy from greywater. A recent publication by the authors contained a validated model that can be used to predict the performance of DWHR heat exchangers under variable flowrates and temperatures, and this work shows the implementation of the model into Transient System Simulation Tool (TRNSYS) software to perform energy simulations. This work aims to show the different plumbing configurations in which DWHR heat exchangers could be installed, and to simulate their performance under various conditions. The results show that plumbing configuration has a significant impact on energy savings expected from DWHR heat exchangers, and maximum savings are achieved in equal-flow configuration. However, other plumbing configurations provide significant savings, and the mains temperature could dictate which configuration provides higher energy savings.

Effects of Using Air Curtains on Energy Consumption During Cooling Season Under Different Climate Conditions

In zones separated by doors with many entrances and exits, it is crucial in terms of energy consumption to protect the conditioned air in the indoor environment from the effects of outside air. The increase in door dimensions and opening frequency make this effect even more evident. Various methods are used to prevent leakage of outside air into the indoor environment. In this study, we investigated the effects of using air curtains on energy consumption during the cooling season in a factory building. The door width and height in this building, which has a high story height, were also large. These 26 doors must remain open all the time because of the production process. With a transient model developed on Transient System Simulation Tool (TRNSYS) coupled with Contaminant Transport Analysis Software (CONTAM), we showed the effects of using the air curtains in different climate conditions. As a result, we demonstrated that using air curtains will provide great savings, especially in cities with high cooling requirements.

Dynamic Simulation and Thermoeconomic Analysis of a Hybrid Renewable System Based on PV and Fuel Cell Coupled with Hydrogen Storage

The production of “green hydrogen” is currently one of the hottest topics in the field of renewable energy systems research. Hydrogen storage is also becoming more and more attractive as a flexible solution to mitigate the power fluctuations of solar energy systems. The most promising technology for electricity-to-hydrogen conversion, and vice versa, is the reversible solid-oxide cell (SOC). This device is still very expensive, but it exhibits excellent performance under dynamic operating conditions compared to the competing devices. This work presents the dynamic simulation of a prototypal renewable plant combining a 50 kW photovoltaic (PV) field with a 50 kW solid-oxide electrolyzer cell (SOEC) and a compressed hydrogen tank. The electricity is used to meet the energy demand of a dwelling located in the area of Campi Flegrei (Naples). The SOC efficiency is simulated by developing a mathematical model in MATLAB®. The model also calculates the cell operating temperature as a function of the input current. Once the optimal values of the operating parameters of the SOC are calculated, the model is integrated in the transient system simulation tool (TRNSYS) for dynamic analysis. Furthermore, this work presents a parametric analysis of the hydrogen storage system (HSS). The results of the energy and environmental analyses show that the proposed system can reach a primary energy saving by 70% and an amount of saved CO2 of 28 tons/year. Some possible future market scenarios are considered for the economic analysis. In the most realistic case, the optimal configuration shows a simple pay back lower than 10 years and a profit index of 46%.

Research on operation strategy of radiant cooling system based on intermittent operation characteristics

Radiant cooling systems have become increasingly prevalent due to their great potential in comfort and energy saving. Nevertheless, their applications are limited by condensation and slow response. This study aims to explore the intermittent operation characteristics of radiant cooling systems and propose an effective operation strategy to improve system reliability. An operation strategy called standby cooling was proposed, and a none standby cooling scheme and four standby cooling schemes were simulated with the transient system simulation tool (TRNSYS). The results show that the none standby cooling scheme was difficult to satisfy the indoor comfort of the rooms with long shutdown periods. The indoor dry-bulb temperature and dew-point temperature when the air-conditioning mode is turned on have the approximate monotonic relationships with the maximum predicted mean vote (PMV) during the occupied period, and the Spearman correlation coefficient were 0.8809 and 0.8019, respectively. By contrast, with increased energy consumption, the standby cooling schemes can satisfy the comfort well and ensure the smooth operation of the radiant cooling system. With the same radiant system setting, the extra energy consumption of the schemes with continuous fresh air supply is 67.71%∼157.42% more than that of schemes that supply fresh air intermittently. With the same fresh air system setting, the schemes turning off the radiant cooling system need 11.67%∼71.41% more extra energy consumption than the schemes turning on the radiant system. Accordingly, from the perspective of energy consumption, one should turn off the fresh air system and turn on the radiant system as much as possible. This study provides a theoretical basis for understanding intermittent operation characteristics of radiant cooling systems and can direct the design and operation to enhance system reliability with less energy consumption.

Energy, emissions and economic impact of the new nZEB regulatory framework on residential buildings renovation: Case study in southern Spain

Spanish residential buildings built in the decade of the housing bubble (2000–2009) had to comply with the Basic Buildings Standard on thermal conditions in buildings. At the end of this period, the Basic Energy Savings Document of the Technical Building Code published in the Royal Decree 314/2006, transposing European Directive 2002/91/EC, entered into force. Recently, this regulatory framework has been updated by the Royal Decree 732/2019, which transposes European Directives 2010/31/EU, 2012/27/EU and 2018/844/EU. A case study is used to analyse the energy, emissions and economic impact of these regulatory changes on an attached house located in all municipalities of Andalusia (South of Spain). The thermal behaviour of this house is compared with the one adapted to the new regulations. The TRNSYS transient system simulation tool is used for the energy study. The house adaptation is carried out by partially modifying the envelope, including a solar-thermal contribution to domestic hot water supply, and photovoltaic energy production to reduce electricity consumption. The results showed that the European objectives are greatly exceeded. Energy savings range from 69% to 127%, carbon dioxide emissions decrease by 65%–118%, and energy bills are reduced from 71% to 125%.

Economic and Environmental Assessment on Implementing Solar Renewable Energy Systems in Spanish Residential Homes

In Europe, buildings are responsible for more than one third of the total final energy demands and greenhouse gas emissions. In the last twenty years, the European Union has published a succession of energy performance of building directives to define and ensure the fulfilment of a series of objectives regarding greenhouse gas emissions, energy consumption, energy efficiency and energy generation from renewable sources in buildings. For its part, Spain is adapting its legal framework, transposing these directives with the aim of achieving greater energy efficiency and sustainability for buildings. Under this context, an energy, economic and environmental assessment is performed to analyze the impact of these regulatory changes on a single-family home including a photovoltaic installation for self-consumption with surpluses and/or a solar thermal installation for domestic hot water supply, located in each one of the eight thousand one hundred thirty-one municipalities that make up Spain. The energy behavior of the original house is compared with that obtained after it is updated with these new facilities. The transient system simulation tool is used for the energy study. The results show that the European objectives are far exceeded. The energy savings achieved range from 67% to 126%, carbon dioxide emissions decrease by 42% to 100% and energy bills are reduced in cost by 32% to 81%. The findings of this work can be used by policymakers as guidelines for the development of national strategic plans and financial incentives for the promotion of small-scale residential photovoltaic and solar thermal applications, as well as by designers, supervisors, managers and developers to include them in their projects.