Passive Solar Technology Research Articles

Structure and regional optimization of a phase change material Trombe wall system

Trombe walls (TW) have been an effective passive solar technology for enhancing building energy efficiency. Considering the thermal storage and regulation capabilities of phase change materials (PCM) in solar energy utilization, TW with PCM (PCMTW) were designed and optimized to further improve building energy performance. This study investigated the combined effects of PCM phase change temperature, PCM location and ventilation strategies on a single-layer PCMTW. Moreover, a novel double-layer PCMTW was proposed and evaluated across various climate regions of China in consideration of the effect of PCM phase change temperature combinations. Results show that the single-layer PCMTW with PCM22 placed next to inner surface and ventilation achieved the lowest annual energy consumption. The selection of PCM phase change temperature was crucial for various climatic conditions. Compared to the traditional building, the highest heating energy-saving was 118.16 kWh/m2 achieved in Changchun with PCM22 + 28, and the highest cooling energy-saving was 45.71 kWh/m2 achieved in Haikou with PCM25 + 28. Additionally, the double-layer PCMTW was recommended for climate regions where the daily average temperature and the daily average solar emissivity were 20–25 °C and below 4 kWh/m2 in summer, and below 10 °C and 2–6 kWh/m2 in winter.

A Review of Passive Solar Heating and Cooling Technologies Based on Bioclimatic and Vernacular Architecture

The increase in global average temperature, mainly due to the high rate of greenhouse gas emissions, has triggered severe global warming and climate change. In Europe, the building sector accounts for a significant portion of emissions and energy consumption, prompting attention on nearly-zero-energy buildings (nZEBs) and zero-carbon buildings, as they play a pivotal role in reaching the goal of climate neutrality by 2050. Passive systems offer a promising solution, optimizing energy usage by better adapting buildings to their local climates. This paper reviews the state-of-the-art of passive heating and cooling techniques, exploring their contributions to contemporary architecture and showcasing their features and adaptability across different climates. Furthermore, the link between traditional and bioclimatic architecture is assessed. Recent years have witnessed a surge in publications on bioclimatic solar passive strategies, reflecting an intensified debate on climate change. Europe leads research in this area, aligned with initiatives like the Green Deal and Fit for 55. While dynamic simulation software is widely utilized for energy efficiency analysis, there remains limited integration of Building Information Modeling (BIM) and life cycle analysis (LCA) tools, which could enhance holistic assessments.

An application of the Random Forest algorithm for the prediction of Solar Envelope ‘Floor Space Index’ based on spatiotemporal parameters

It is becoming increasingly important to consider access to the sun in the early stages of a new building's design process. A Solar Envelope is an architectural form that meets required levels of density, whilst also assuring solar access to neighbourhood surfaces, thereby making it feasible to implement active and passive solar technologies there. This preliminary study investigated the cross-cutting intersection between urban morphology, Solar Envelope forms, and a Random Forest algorithm to predict the Solar Envelope's Floor Space Index. Recognizing that Solar Envelope forms depend on various spatiotemporal contexts, mainly the solar exposure cut-off period (equinoxes/solstices) and various neighbourhood geometrical attributes, simulations varying only the rooftop typologies (flat, gable, hip, sled, mansard, and pyramid) and façade orientations (south, east, west, and north) were conducted to evaluate how solar access to those surfaces affect the Floor Space Index of the Solar Envelope. Architectural tools were used to conduct simulations reflecting varying spatiotemporal scenarios. The data was extracted and represented geometrically, involving polar loci, and this synthetic dataset was subsequently utilized to train and evaluate a Random Forest algorithm. The results of this study show that the Random Forest algorithm was able to predict the Floor Space Index of the Solar Envelope with about 90.18% accuracy, though the only parameter influencing the regression model was the solar exposure cut-off period and not any other morphological features. Therefore, the study sheds insight into the need for the development of a more robust dataset through the simulation of randomized and diversified neighbourhood morphologies.

Sustainable passive solar and photovoltaic integrated technology interventions for climate responsive net zero energy buildings in western Himalayan mountainous terrain of India

The global warming concerns, greenhouse gas emission reduction, are not being addressed effectively in the energy-consuming building sector worldwide. This study presents a novel approach of solar technology interventions for sustainable buildings namely rooftop photovoltaic systems, use of carbon-free sustainable building materials, and passive solar heating systems. A methodology for achieving net zero energy and zero carbon emission buildings is described. This strategy is being implemented to develop an educational institution as a sustainable campus in a Western Himalayan cold region of India. The results show an energy yield of 1561 kWh/kWp/year from a proposed photovoltaic power system for a typical building at this location producing 10,928 kWh avoiding 7.7 t-CO2 emissions which means the system will produce enough electricity in 2.6 years to offset the amount of carbon emissions during manufacturing of PV modules. The modeling and simulation analysis using the developed mathematical model shows that the space heating system provides 37–56 % of total energy needs with a payback period of 3.5–5.8 years depending on the type of six different construction materials used. The innovative mandatory policy and solar technology interventions implemented can be followed in remote rural and semi-urban areas in developing countries.

Passive Solar Greenhouse-A Sustainable Option for Propagating Sweet Potato for Colder Climatic Regions

Sweet potatoes (Ipomoea batatas L.) are nutritious and well adapted to a variety of growing systems around the world. This widely consumed root crop is propagated using cuttings, known as slips. Slips are predominantly cultivated in commercial settings, outdoors under field conditions, primarily in warmer regions, such as the southern states of the United States. Canada's slip production capacity is restricted due to its colder climate. Production of slips within a greenhouse system could prove to be a profitable enterprise for Canadian propagators and growers, especially with the availability of cost-effective greenhouse technology to support efficient slip production. A 2-year study was conducted at Assiniboine Community College, Brandon, Manitoba, Canada (49oN, 99oW). in 2019 and 2020, in a controlled commercial greenhouse (C1) with two passive solar greenhouse systems (PS1 and PS2) to determine the most efficient and economical way to produce slips commercially. The results from this study indicate passive solar greenhouse, PS1 and PS2 greenhouse technologies, produced comparable numbers of sweet potato slips (286.5, 273.3 per square meter respectively) compared to commercial standard greenhouse C1 (278.8). Days to sprouting of slips between C1, PS1 and PS2 greenhouses differed significantly (P<0.05). However, slip growth parameters, including number of nodes, stem diameter and total marketable slips produced in each greenhouse were not significantly different between C1, PS1 & PS2 greenhouses. In conclusion, local slip propagators can use PS1 and PS2 passive solar greenhouses to grow affordable, quality slips for sweet potato growers for timely field production in Canadian growing regions. Additionally, implementation of adapted passive solar greenhouse systems underscores the advancement of passive energy-based technology, which not only diminishes environmental repercussions but also offers year-round production alternatives.

Indoor thermal comfort comparison between passive solar house with active solar heating and without active solar heating in Tibetan

Passive solar house technology has been spread for many farmers and herdsmen to improve the indoor thermal environment in Tibetan. However, due to lackage of fuels and arid cold in winter, dry cow dung and coal are popularly fired in stove in passive solar houses, which leads to indoor air pollution and poor indoor comfort. For improving indoor thermal comfort of Tibetan, an active solar heating system which consists of 7 sets of tandem solar water heaters with 30 glass evacuated solar tubes, low temperature floor heating and circulation controller was developed and tested for a common house without insulation in Gan-nan Tibetan area. Its indoor environment was compared and evaluated by PMV-PPD and LPD method to that of the same passive solar house heated by coal stove. On sunny, cloudy and snow days, the active solar heating system provided 113.1, 46.4 and 26.3 kWh of heat to room. The indoor humidity and wind speed of the experimental building were better. The indoor temperatures were 17.2-20.7, 14.9-20.5 and 11.0-14.8°C, while the compared building were 8.9-14.8, 10.1-12.1 and 7.2-10.5°C. The maximum temperature difference between head and ankle were 1.7, 1.6 and 0.9℃, and the compared building were 4, 4 and 4.7℃. The PMV-PPD on sunny day were class I and II; on cloudy day were class I, II and III; on snow day was class III. On sunny and cloudy days, the LPD were class I, on snow day was class I, II and III. The PMV-PPD and LPD for typical days of the compared building were class III. During the 179 days, the mean indoor temperature exceeded 14 ℃ for 81 days, the solar active heating system provided 12471 kWh of heat to room. The CO2 emission reduction was 12905 kg. The system's dynamic payback period were 2.57 years.

Techno-environmental assessment of outdoor glazing cover of a building with multi-passive solar systems

With the expansion of urban areas and the growth of welfare levels, the energy consumption of buildings will increase in the next decades. Passive solar systems are one of the technologies to reduce energy consumption. In this paper, a building-integrated passive solar energy technology was studied in six different Scenarios including photovoltaic (PV) and Building Integrated Photovoltaic (BIPV) glazing windows, PV glazing façades, PV glazing double-skin façade, and simple double-skin façade. They were compared to the base model, respectively. It has been determined each scenario may be superior in one or more cases compared to other scenarios. Results show in the BIPV model, the inside temperature of the building was decreased by up to 1.3 degrees. The annual energy consumption for heating in the double-skin Scenario was reduced by about 17% compared to the base Scenario. The annual energy consumption for cooling in the building with PV glazing façade compared to the base scenario has decreased by more than 21%. Annually, CO2 emissions by 140%, and the cost of energy have decreased by 3493.4$ in building with PV glazing double skin facade and building with PV glazing facade, respectively. Finally, the shadow effect of the energy of the building is examined.

Passive Solar Technology and its Techniques

Passive solar technique is which converts the natural energy into usable energy resources. The passive solar energy is the sunlight that is been got directly or indirectly are been converted to heating or cooling purpose. This process is been effectively used all over the world for the future development. As the usage such as the solar technologies and other innovative techniques this does not involve in most of the mechanical process. Solar energy is mostly environmentally friendly and eco friendly that are blending with day to day life. The light and heat that are been got naturally are used to provide electricity that can be used in building s interior and exterior purpose. The most possible ways that the passive solar technique is that the maximum use of the windows and doors, shading devices, louvers and angular roofing are the methods that can be used for the passive solar energy techniques. The next method passive solar heating is also an technique that makes or traps the heat and saves the heat in any part of building based on the required material. This allows heat that is needed at required times during different weather conditions the passive solar technique plays an important role during different climatic conditions. During the summer season it prevents the direct heat entering the building and can be reduced based on growth of the plant such as shrubs and creeper plants. During the winter season it emits the heat to the entire building such as the material been used such as concrete, thermal mass material ,stone slabs, these have more emitting power and makes the entire place more warm and heat. Most of the application techniques and methods will be studied later with following research ideas.

Evaluation of thermal performance and energy efficiency of a Trombe wall improved with dual phase change materials

Trombe Wall (TW) as effective passive solar design technology can improve the building's energy efficiency and thermal comfort. TW may not be very effective alone. Adding Phase Change Materials (PCMs) to TW improves the efficiency to compensate for this shortcoming. In this paper, for better efficiency, a new double-layer Phase Change Material Trombe Wall (PCMTW) containing two layers of different PCMs with different phase-changing points on the exterior walls of the building was proposed. This paper aimed to compare the thermal performance of different models of double-layer PCMTW in different air gap thicknesses and different PCM combinations with a base state. The results show that classical TW with an air gap thickness of 20 cm reduces energy consumption by 34% in winter. The best air gap thickness for the PCMTW was 20 cm too, and the energy consumption was reduced by 39% in this air gap thickness. Also, there was little difference in the energy consumption of the three models in the summer, and the overheating phenomenon was solved by considering external shading. for solving this effect in summer, the best length of external shading was 50 cm.

Design of Passive Solar Houses for Toilets in Rural Areas of Tibet

Passive solar houses are one of the main forms of solar heating. In order to fully utilize solar energy to solve the winter heating problem of toilet buildings, this article will compare and analyze different passive solar houses from three aspects: thermal characteristics, thermal comfort, and energy efficiency, select the most suitable technology, and further optimize and analyze the parameters, providing a basis for the subsequent use of active passive combined solar heating technology to improve the indoor thermal environment of toilets.

Design and Evaluation of a Water-Based, Semitransparent Photovoltaic Thermal Trombe Wall

Trombe walls are a passive solar technology that can contribute to the reduction of building heating loads. However, during warmer weather conditions, Trombe walls may cause overheating. In this work, we investigate the feasibility of using Trombe walls to perform multiple functions during warm weather conditions including (1) heating and storing water for building applications, (2) providing occupants with visibility to the outdoors, and (3) generating electric power. Experiments are performed on a small-scale prototype comprising a clear water storage container with a transparent window and a tinted acrylic sheet that is immersed in the water. Photovoltaic cells are placed on the bottom half of the front face of the water storage container. Results show that water at the top of the clear container can be heated to temperatures as high as 45 °C when subjected to solar-simulated radiation for five hours. Numerical simulations predict that similar temperatures can be reached if the Trombe wall is scaled to full size. Furthermore, the cooler water at the bottom of the water storage container acts as a heatsink that reduces the extent to which the temperature of the PV cells is elevated. Results show the temperature and open circuit voltage of the PV cells are about 50 °C and 0.66 V, respectively, when water is present. However, when the water is absent from the container, the temperature of the PV cells increases up to 90 °C and their open circuit voltage drops to 0.60 V. The results show that water-based, semitransparent photovoltaic thermal Trombe walls have the potential to operate as multifunctional building envelopes that simultaneously provide for daylighting, heated water and electric power, and further research in this area is warranted.

Analysis of Solar Chimney Application for Building Heating and Cooling in Different Climates in China

Solar chimneys have been applied widely to various buildings under different climate conditions because of their superiority in improving the indoor environment and saving energy. A series of comparative studies of the performance of solar chimneys used in 12 cities in China under different climatic conditions was carried out. A typical solar chimney in a representative building was studied using numerical simulation and analyzed using orthogonal experiment methods. Results show that the optimal structural configuration and the significance of influencing factors of the solar chimney have strong seasonal consistency. The window-to-wall ratio and wall-to-south wall ratio are the most significant influencing factors. Among the 12 cities, the highest average indoor temperature of the case room could be decreased by 5.7°C in summer and increased by 6.7°C in winter. The cooling and heating loads could be reduced by 30%–100% and 46%–56% respectively. The research results can provide practical guidance for future passive solar technology design.

Heat recovery capacity and water desalination performance of passive solar vacuum tube distiller

The direct thermal distillation utilized the solar vacuum tube was a seawater desalination technology with quite a development potentiality. Therefore, an efficient passive solar vacuum tube distiller (P-SVTD) with a heat recovery function was developed in this paper, which realized the integration operation of raw water vaporization and high-temperature steam self-pressurization. It also had the character of simultaneously carrying out boiling vaporization and interfacial vaporization. The mechanisms of photo-thermal conversion and heat-mass transfer in the whole operation process of P-SVTD were analyzed. The theoretical calculation models of water yield (msh) and heat recovery rate (HRR) were presented. The water desalination performance, temperature level of recovered heat, and HRR of P-SVTD were measured to obtain the comprehensive photo-thermal conversion efficiency (HE) of P-SVTD. The results showed that the optimal depth ratio of the vapor–liquid interface to the vaporized-pressurized cavity was 0.9718. The water yield of P-SVTD was positively correlated with the total solar irradiance on the inclined plane by the trend of an exponential function. The average temperature level of recovered heat, HRR, and HE of P-SVTD were 74.30 °C, 28.68 %, and 87.43 %, respectively. And the rejection capacity (REJ), the decreased degree of conductivity, and the pH of P-SVTD were close to 100.00 %, 100.00 %, and 7.00, respectively, which showed excellent desalination capacity. The research provided solid technical and theoretical support for promoting the large-scale application of passive solar distillation technology.

Trombe wall's thermal and energy performance—A retrofitting approach for residential buildings in arid climate of Yazd, Iran

A Trombe wall is a passive solar technology attached to the building envelope to reduce energy demands. In warm climates, due to overheating problems in the cooling season, its efficiency is limited and proper operation is required. In this study, the thermal behavior of a bedroom of a house equipped with a Trombe wall in Yazd with a hot and arid climate under different design configurations and various masonry materials were investigated using the dynamic simulation software DesignBuilder. Monthly ventilation strategies and a schedule of blinds for external glass cover throughout the year were proposed to optimize its energy efficiency. The blinds are applied for shading solar irradiance during summer. They also increase the system's thermal resistance during winter nights. According to the results, a concrete Trombe wall with 2/3 of the façade area is capable of reducing the heating load by 86%. However, its function for summertime is negative, and even in the insulation mode, it can increase the cooling load by 5%. Natural ventilation with the Trombe wall is applicable during moderate seasons; however, its cooling efficiency is limited compared to cross ventilation. The results also highlight that retrofitting a room with a Trombe wall can reduce the annual energy demand by 63%, which is equal to a reduction of 124 kg CO2 emission.

Interaction Effect of Room Size and Opening on Trombe Wall Performance in Sichuan–Tibet Alpine Valley Areas

The Trombe wall (T-wall) system is one of the most effective systems for passive solar energy utilization technology, which is of great significance for the alleviation of the energy crisis and the protection of the environment. Taking as an example Tibetan dwellings in the Sichuan–Tibet alpine valley which have installed T-walls for heating, the effects of the length of the room (Factor A), the width of the room (Factor B), the width of the opening on the north wall of the room (Factor C), and the distance from the lower edge of the opening to the floor (Factor D) on the indoor air temperature and room energy consumption are studied by orthogonal experiment and numerical simulation. Results show that the four factors all have a significant effect on the two analysis indicators. The rankings of the factors are consistent for their impact on the two analysis indicators, as, in both cases, Factor A > Factor B > Factor C > Factor D. Therefore, the influence of room configuration cannot be ignored in the optimization of T-wall design. Additionally, the optimal parameter combination for the highest indoor temperature and low energy consumption in winter is also proposed. This research can further improve the study of T-walls, and provide a reference for the thermal environment design of buildings.

Energy-Efficiency Passive Strategies for Mediterranean Climate: An Overview

Among all the activities in a society, construction has a key role in environmental, social, and economic pillars. Construction is also responsible for a considerable amount of waste production, energy consumption, pollutant gas emissions, and consumption of nonrenewable natural resources. Regarding energy consumption, a high demand for building operational energy has been observed in the last decades due to the more demanding requirements of the users with a continuous search for better thermal comfort in their homes, namely in developed countries. In Portugal, for instance, more than 20% of the electricity consumed is related to residential buildings, which is based on CO2 emissions and other pollutants that negatively affect the environment. Much of this consumed energy is a result of the HVAC systems installed inside buildings to provide users with thermal comfort. One exciting opportunity to mitigate buildings’ operational energy consumption while contributing to thermal user comfort is the use of passive solutions. Even though several passive options are available and constantly under research, their use is still considered limited. This paper overviews and highlights the potential of energy-efficiency passive strategies, namely for Mediterranean-climate countries, where passive solar technologies can be set as a viable solution, as this climate is mainly known for its solar availability (solar hours and solar irradiance). A comprehensive overview of innovative and traditional housing passive solutions currently available is presented and discusses the main advantages, disadvantages, and concerns contributing to the optimal use of climatic conditions and natural resources in those regions.

Numerical Study on the Suitability of Passive Solar Heating Technology Based on Differentiated Thermal Comfort Demand

Indoor thermal comfort and passive solar heating technologies have been extensively studied. However, few studies have explored the suitability of passive solar heating technologies based on differentiated thermal comfort demands. This work took the rural dwellings in Northwest China as the research object. First, the current indoor and outdoor thermal environment in winter and the mechanism of residents’ differentiated demand for indoor thermal comfort were obtained through tests, questionnaires, and statistical analysis. Second, a comprehensive passive optimized design of existing buildings was conducted, and the validity of the optimized combination scheme was explored using DesignBuilder software. Finally, the suitability of passive solar heating technology for each region in Northwest China was analyzed based on residents’ differentiated demand for indoor thermal comfort. The regions were then classified according to the suitability of the technology for these. The results showed that the indoor heating energy consumption was high and the indoor thermal environment was not ideal, yet the solar energy resources were abundant. Indoor comfort temperature indexes that match the functional rooms and usage periods were proposed. For the buildings with the optimized combination scheme, the average indoor temperature was increased significantly and the temperature fluctuation was decreased dramatically. Most regions in Northwest China were suitable for the development of passive solar heating technology. Based on the obtained suitability of the technology for the regions of Northwest China, these were classified into most suitable, more suitable, less suitable, and unsuitable regions.

Research on the application of passive solar heating technology in new buildings in the Western Sichuan Plateau

Aiming at the problems of backward heating mode and low indoor thermal environment quality of new buildings in Western Sichuan Plateau, this paper selects the typical indoor thermal environment of new buildings in Seda County to carry out actual measurement. The temperature in three rooms without heating in winter is in the range of -0.4∼6.7 °C, the temperature at night is below zero. The temperature throughout the day is below 10 °C that the human body can tolerate. The test results show that the comfort of indoor thermal environment is very poor. As the Western Sichuan Plateau is very rich in solar energy resources, this paper proposes to transform the existing new buildings into passive solar heating buildings with low cost and easy maintenance, and uses DeST-h software to simulate and analyze the existing new buildings and passive solar heating buildings. The simulation results show that the indoor temperature of solar heating buildings fluctuates between 8.5 ∼21.2 °C, the indoor minimum temperature is 11.9 °C higher than that of the original building, and the indoor temperature remains above 10 °C most of the time, which significantly improves the indoor thermal comfort. The solar building finally meets the indoor thermal comfort demand without auxiliary heat source, and has good economic benefits. It also provides a good foundation for the wide promotion of passive solar heating buildings in this area.

Building Façade Retrofit with Solar Passive Technologies: A Literature Review

Worldwide, buildings have been presented as one of the main energy consumers and, for that matter, there is an increased tendency to invest in policies and measures that promote more efficient buildings. Among the chosen strategies, the need to promote the use of passive solutions and retrofit the existing building stock is often pointed out. Portuguese building stock has proven to be obsolete in terms of thermal comfort, which can directly affect the energy demand for climatization purposes. Considering the great solar availability in the country, when compared to other European locations, building retrofit with solar passive technologies can be a suitable solution. This paper aims to review studies on the application of solar passive technologies to retrofit façades in the Mediterranean climate context, with a special focus on Portugal. Four retrofit passive solar technologies were reviewed, namely glazing, sun shading, sunspaces and Trombe wall technologies.

Passive Solar Systems in Low-Rise Housing Architecture in Southern Primorye

This article examines the effectiveness of passive solar technologies in individual housing construction in the climatic conditions of southern Primorye. Three versions of the architectural solution of the passive solar heating “Direct Systems” model selected as the object of research, compositionally differ in the architecture of the enclosing structures interacting with the thermal massive and the location of the thermal massive in the planning structure of the house. In version 1, design of an additional roof slope shading the living area reduced the area of the south-facing stained glass and the efficiency of the passive system but solved the problem of light comfort in the house. Solar heat gains compensate heat losses by 57%. In version 2, the atrium stained-glass window open to the sun creates an uncomfortable light regime, which was compensated by a sun-shading glass unit. The loss of thermal radiation from the sun on the stained glass was almost 80%, but due to the large area of the stained glass, the contribution of the passive solar heating system remained similar to version 1 - about 50%. In version 3 of a simplified solar house of minimal dimensions, the heat-receiving stained glass window and the thermal massive are placed in the entrance zone. This placement of the passive system made it possible to maintain light comfort, and in general, a decrease in the heated volume of the house made it possible to compensate for heat losses by 94%. As these data show, with a careful architectural solution of passive solar systems, in the climatic conditions of southern Primorye engineering heating systems of a low-rise residential solar house, including renewable energy systems, can be considered as auxiliary.