Passive Solar Research Articles

Thermal design of insulation on the outside of the cavity for a Trombe wall with phase change materials

A Trombe wall with a phase change material (TW-PCM) is a practical and low-carbon passive solar heating method. However, the heat efficiency is not high due to the large amount of heat loss at night. Insulation on the outside of the cavity is a suitable solution, but the design method has not been obtained, which hinders the realization of zero energy buildings. In the present study, we analyzed the thermal performance of a TW-PCM with insulation on the outside of the cavity at nighttime to develop the design approach. A mathematical model was established and validated based on experiments. This model was used to analyze the heat efficiency in different outdoor climates for a TW-PCM with insulation on the outside of the cavity. As well, the solar heating fraction (SHF) was analyzed. The results indicated that insulation on the outside of the cavity could significantly improve the thermal performance due to the reduced heat loss during the nighttime. The recommended additional thermal resistance due to the insulation on the outside of the cavity was negatively correlated with the average outdoor air temperature in January based on the analysis of various climates in China. The thermal resistance of the closed air cavity, formed by the TW-PCM and the insulation component, at the same wall emissivity was similar under the recommended additional thermal resistance in different outdoor climates. The SHF was improved significantly for the TW-PCM buildings with insulation on the outside of the cavity and it had a linear relationship with the solar heating load ratio (SLR).

Preparation and characterization of palmitic acid/polymer composite phase change materials supported with cross-linked poly(limonene-co-ethylene glycol dimethacrylate) copolymers for low-temperature thermal applications

Limonene-based polymers have a growing interest as being renewable source-derived materials. Here, highly cross-linked porous polymers were synthesized by free radical copolymerization of water-in-oil (w/o) high internal phase emulsions (HIPEs) of limonene and ethylene glycol dimethacrylate (EGDMA). The bio-derived monomer content in the total monomer composition was set to 50 vol%. To vary the openness and permeability of the resulting porous copolymers, synthesized poly(limonene-co-EGDMA) (PLE-x) copolymers were processed via two different approaches as extraction (E) and lyophilization (L). Ultimately, the ring-porous PLE-E or PLE-L copolymers with different degrees of permeability were used as supporting matrices for the development of form-stable palmitic acid@poly(limonene-co-EGDMA) (PA@PLE-E and PA@PLE-L) composite phase change materials (PCMs). The chemical structure, pore morphology, specific surface area, and thermal properties of the PLE based supports and PA@PLE-E / PA@PLE-L composite PCMs were explored. BET specific surface areas of the ring-porous PLE-E and PLE-L frameworks were measured to be 20.5 m2.g−1 and 4.8 m2.g−1. In addition to that, the latent heats of the resulting composite PCMs were found to be 77.4 J.g−1 and 64.1 J.g−1, while the peak melting temperatures were 63.4 °C and 60.7 °C, for PA@PLE-E and PA@PLE-L, respectively. The bio-derived matrices based thermally stable leak-proof PA@PLE-x composite PCMs with proper latent heat storage (LHS) characteristics are ideal candidates as energy materials for passive solar heating applications due to their favorable phase change temperatures.

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.

Energy Benefits of Tourist Accommodation Using Geodesic Domes

Over the last decade there has been a proliferation of glamping architecture. This study analyses the energy performance of geodesic domes for use in tourist glamping compared to more conventional prismatic architectural solutions. The energy analysis of geodesic domes applied to this type of singular construction project currently lacks detailed studies that provide conclusions about their relevance and suitability with respect to other types of architecture. The main objective of this research is to demonstrate the energy benefits of tourist accommodations that use geodesic structures compared to those with a simple geometry. A comparative study of a traditional and a geodesic geometry accommodation is carried out, considering that they share the same characteristics and they are built with the same construction solution. An energy simulation of both architectures is carried out by using DesignBuilder software. The most influential strategies, such as Direct Passive Solar Gain, Heating, Natural Ventilation Cooling, Fan-Forced Ventilation Cooling and Window Solar Shading are considered. After demonstrating the greater efficiency of geodesic domes, this study analyses the relevance of subdividing the accommodations into several geodesic dome spaces. The results quantify an energy benefit of 52% for cooling consumption using the geodesic dome solution compared to a traditional prismatic solution.

Application of Novel Phase Change Material Constructive Solution for Thermal Regulation of Passive Solar Buildings

A comprehensive investigation regarding the hygrothermal behavior of a constructive solution containing phase change materials (PCMs) was performed on a full-scale test cell, divided into two similar compartments. This involved hygrothermal monitoring (indoor air temperature) of the two compartments, in which one had PCM incorporated into the floor mortar. The main goal of this research was to investigate the potential of this kind of solution for overheating mitigation. The numerical study was conducted using EnergyPlus® software (version 9.0), exploring different natural ventilation flow rates to gauge the novel solution’s potential to reduce overheating rates. The results from the monitoring studies revealed prolonged periods of thermal discomfort in both test cells, particularly overheating. However, it was proven that the PCM application in one of the test cells led to a reduction of almost 10 °C in the maximum peak of air temperature. In the simulation analysis, the increase in the ventilation rate led to a linear decrease in the overheating hours of up to one renovation per hour, and then the reductions were attenuated.

A Facile and Effective Design for Dynamic Thermal Management Based on Synchronous Solar and Thermal Radiation Regulation.

Passive solar heating and radiative cooling have attracted great interest in global energy consumption reduction due to their unique electricity-free advantage. However, static single radiation cooling or solar heating would lead to overcooling or overheating in cold and hot weather, respectively. To achieve a facile, effective approach for dynamic thermal management, a novel structured polyethylene (PE) film was engineered with a switchable cooling and heating mode obtained through a moisture transfer technique. The 100 μm PE film showed excellent solar modulation from 0.92 (dried state) to 0.32 (wetted state) and thermal modulation from 0.86 (dried state) to 0.05 (wetted state). Outdoor experiments demonstrated effective thermal regulation during both daytime and nighttime. Furthermore, our designed PE film can save 1.3-41.0% of annual energy consumption across the whole country of China. This dual solar and thermal regulation mechanism is very promising for guiding scalable approaches to energy-saving temperature regulation.

Elevacione zemunice sa selektivno premazanim južnim fasadnim zidovima

This paper presents a new passive solar design in buildings, which can be used to reduce the consumption of (final and primary) energy for heating and CO2 emissions. Namely, the positive effects from the construction of the elevational earth-sheltered buildings can be additionally enhanced by coating the southern facade walls (building elements that are not in direct contact with the soil) with appropriate selective (absorption and low-emission) coatings. The elevational earth-sheltered building on the territory of the city of Kragujevac, modeled by the Rulebook on Energy Efficiency of Buildings, was subjected to numerical research. The simulation scenario was based on the following variables: the thickness of styrofoam in the construction of the southern facade walls (the first variable) and the optical (absorptivity and emissivity) characteristics of the selective coatings (the second variable). Although the use of selective coatings is mostly limited to absorbers in thermal solar collectors, their application in buildings would also be of great importance.

Energy Efficient Building Design With Solar Passive Heating and Ventilation Systems

Energy Efficient Building Design With Solar Passive Heating and Ventilation Systems

Performance study of an isolated small scale Trombe wall with partially evacuated air gap

The Trombe wall is a passive solar heating system that aims to mitigate heating load. However, its efficiency is impeded by significant heat loss through the glazing. To address this issue, a novel technique has been developed that involves partial evacuation of the space between the storage wall and the glazing. This approach, which has already found successful application in double-paned windows and solar collectors, is examined in this study to evaluate its impact on the performance of an isolated Trombe wall. An effectiveness criterion based on the ability of a system to preserve its stored thermal energy is defined and used for assessing the performance of a vacuumed system relative to a non-vacuumed one. An experimental test cell, composed of a solid concrete wall serving as a thermal storage and a glazing separated from the wall by an air gap, facing south is constructed in Kirkuk, Iraq. The wall is insulated at all its sides except the side facing the glass. The gap has been sealed meticulously to maintain a vacuum. Due to unrepeatability of the testing conditions experimentally, a numerical method and a computer code is also developed for simulation of the system. Measurement results obtained from the test cell under normal atmospheric pressure and a gage pressure of −0.3 bar of the air gap are used to validate the numerical method. The code is then used to simulate the performance of the system under the same ambient conditions but at different vacuum pressures of the air gap. Results obtained from the numerical tests show that partial evacuation of the air gap can be an efficient way to enhance the performance of the Trombe wall and the absolute pressure of 0.1 bar results in the most significant increase in the effectiveness of the studied model.

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.

Heat pipes for passive solar heating systems

In the presented research work, heat pipes of gravitational and ring type were investigated. Two types of heat pipes were fabricated and tested under natural conditions for the study. According to the results of experiments, depending on the materials and dimensions of the heat pipes under study, the average value of the temperature difference in the gravitational heat pipe is 1.7 times higher, and the thermal resistance is 1.3 times lower.

Examination of the Use of Solar Chimney as a Passive Solar Energy Ventilation Method in Buildings through Case Studies

Basit ve pratik bir pasif güneş enerjili havalandırma ve soğutma sistemi olarak güneş bacaları; işletme maliyetinin azlığı, enerji gereksiniminin sıfıra yakın oluşu ve karbondioksit emisyonuna olumlu katkısı nedeniyle hem ticari binalarda hem de konutlarda ısı yükünü azaltmak, doğal serinletme, havalandırma veya ısıtma sağlamak adına büyük ilgi görmektedir. Bu çalışmada pasif güneş enerjili sistemler ile ilgili kısa bir bilgi verildikten sonra pasif havalandırma ve mekân ısıtmasında kullanılan güneş bacalarının binalardaki kullanım yöntemlerine dair bilgiler verilmiş çalışma prensibi, katmanları ve sınıflandırılması detaylı olarak anlatılmıştır. Son olarak pasif havalandırma ve serinletme amacıyla güneş bacası kullanımları üzerine yapılmış örnekler incelenerek değerlendirilmiştir.

ANALYZING HEAT TRANSFER FLUIDS FOR IMPROVED SOLAR WATER HEATER PERFORMANCE

The First Chapter, discussed the Research background in the first section due to its potential to lower carbon emissions and energy costs, the use of solar water heaters for an environmentally friendly power alternative has increased. Also, it explained Current issues in that section Although rooftop water heater technology has advanced, choosing and optimizing heat transfer fluids (HTFs) continues to be a difficult task. The Second Chapterexplained first section is Passive solar water heating system in a passive solar water heating system uses the concept of radiation from the sun to heat water for domestic, commercial, or industrial usage without the use of active mechanical equipment like pumps or fans. It has also discussed Active solar water heating system as well as aspects affecting the performance of a solar water heater. Effective implementation of the Simulink model of the solar water heater has been adequately structured and interpreted. Additionally, proper implication over the entire work has been structured within this paper.

Thermal storage characteristics of microencapsulated phase change material coatings in low-energy rural prefabricated building walls

ABSTRACT Prefabricated buildings in rural areas of China waste a large amount of energy due to poor thermal insulation. Phase change materials (PCMs) are able to stabilize room temperature by latent heat absorption and release during the phase change process. This study incorporated PCMs in the form of microcapsules into the interior wall coatings of prefabricated buildings, and by taking advantage of PCMs’ energy storage capacity, the thermal storage characteristics of PCM-coated bricks were investigated. The results show that microencapsulated phase change material(MPCM) coatings for prefabricated walls exhibit excellent thermal stability properties and effectively reduce the heat flux of prefabricated walls, with coatings having a MPCM mass fraction of 15% and a thickness of 5 mm providing the highest overall benefits. By fitting the numerical simulation results with experimental data, a novel multifunctional passive solar phase change heat collection and storage wall system was developed. This study innovatively combines energy storage materials with interior wall coatings in prefabricated walls of modular buildings investigating how it enhances the thermal stability of the external insulation walls and effectively reduces the reliance on heating equipment for auxiliary heating in rural residences. This essay aims to provide feasible recommendations for optimizing the dual-stage energy-saving and carbon reduction goals in both the construction and operation of rural areas.

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.

Numerical simulations on the thermal performance of ventilated walls with passive solar heating and latent heat storage in winter

Numerical simulations on the thermal performance of ventilated walls with passive solar heating and latent heat storage in winter

A Comparative Study on the Distribution Models of Incident Solar Energy in Buildings with Glazing Facades

The accurate distribution of solar energy on indoor walls is the basis of simulating the indoor thermal environment, and its specific distribution changes all the time due to the influence of solar azimuth and altitude angle. By analyzing the assumptions of each model, the existing solar energy distribution models are eight kinds in all and are divided into three categories. The solar radiation models in TRNSYS, EnergyPlus, and Airpak software all use the absorption-weighted area ratio method, which assumes that a single interior surface is a whole, but the detailed assumptions of the models used in the three software are different. In the Radiosity-irradiation method, the indoor surfaces are discretized into small surfaces for calculation. The calculation accuracy of solar radiation distribution indoors can be controlled by the number of discrete small surfaces. The Radiosity-irradiation method is implemented by using Matlab software programming in this paper. Through the numerical calculation and analysis of typical cases, the solar distribution results of the absorption-weighted area ratio method and the Radiosity-irradiation method all show the asymmetry. The asymmetrical ratio of direct solar radiation varies during the time between 7.96–9.89, and the minimum turns up at 11:30 in the summer solstice. The asymmetrical ratio of diffuse solar radiation is 3.23 constantly. The asymmetrical ratio of total solar energy is mainly influenced by the direct and diffuse solar feat gain and its value changes in the range from 3.4 to 4.45 in the summer solstice. Calculation comparison and error analysis on the solar radiation models used in TRNSYS, EnergyPlus, and Airpak software are conducted. There are significant errors in the simulation results of all three software. TRNSYS has the highest error among the three software as its results do not change over time. For EnergyPlus, the distribution ratio of floor 1 is too large. Airpak has the smallest error, but the solar radiation distribution ratios of the indoor surfaces near the south glazing facade are underrated, especially the indoor surfaces that have not been exposed to direct solar radiation.

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.

Simulation of photothermal building and thermal comfort analysis of PMV

Nowadays, with the development of technology and the improvement of human economic level, the energy consumption of buildings is gradually increasing. China is very rich in solar energy resources and the development of solar buildings can save a lot of energy by taking advantage of solar energy resources. The Trombe Wall to be studied in this paper are passive solar buildings. Trombe Wall can achieve good indoor natural ventilation and can meet the requirements of human thermal comfort. However, solar energy is unstable and intermittent, which can easily lead to excessive fluctuations in indoor temperature, so the use of suitable phase change or energy storage materials is also a very important measure. In this paper the mathematical model corresponding to Trombe Wall is specifically investigated and simulations are carried out using COMSOL Multiphysics software to verify the thermal characteristics of Trombe Wall at different temperatures in a given room and the natural ventilation effect they achieve. The simulations are followed by a PMV thermal comfort analysis of the room. The analysis is carried out for four scenarios: “Summer - day”, “Summer - night”, “Winter - day” and “Winter - night”, thus enabling the analysis of Trombe Wall at different temperatures.

A holistic digital workflow methodology to shifting towards net zero energy urban residential buildings in a semi-arid climate

Given the looming threats of climate change and the rapid worldwide urbanization, it is a necessity to prioritize the transition towards a carbon-free built environment. This research study provides a holistic digital methodology for parametric design of urban residential buildings with regard to the Mediterranean semi-arid climate zone of Morocco in the early design phase. The morphological parameters of the urban residential buildings, namely the buildings’ typology, the distance between buildings, the urban grid’s orientation, and the window-to-wall ratio, are evaluated in order to identify the key combinations of passive and active solar design strategies that determine the high energy performing configurations, based on the introduced Energy Performance Index (EPI), which is the ratio between solar BIPV production to maximum available installed BIPV capacity and the normalized thermal energy needs. Through an automated processing of 2187 iterations via Grasshopper, we simulate daylight autonomy, indoor thermal comfort and solar rooftop photovoltaic and building integrated photovoltaic (BIPV) energy potential. Then, we analyze the conflicting objectives of energy efficiency measures, active solar design strategies, and indoor visual comfort in the decision-making process that supports our goal of getting closer to net zero urban residential buildings. The digital workflow showed interesting trends in reaching a balanced equilibrium between performance metrics influenced by the contrasting impact of solar exposure on indoor daylight autonomy and thermal energy demand. Furthermore, the study's findings indicate that it is possible to achieve an annual load match exceeding 66,56 % while simultaneously ensuring an acceptable visual indoor comfort (sDA higher than 0.4). The findings also highlight the important role of the BIPV system in shifting towards the net zero energy goal, by contributing up to 30 % of the overall solar energy output and covering up to 20 % of the yearly self-consumption. Moreover, the energy balance evaluation on an hourly basis indicates that BIPV system notably enhances the daily load cover factor by up to 5.5 %, particularly in the case of slab SN typology, throughout the different seasons.Graphical representations of the yearly, monthly and hourly load matches and the hourly energy balance of the best performing configurations provide a thorough understanding of the potential evolution of the urban energy system over time as a result of the gradual integration of active solar electricity production.