Passive Solar Research Articles

Energy conservation in residential buildings by incorporating Passive Solar and Energy Efficiency Design Strategies and higher thermal mass

In this study, two types of a detached residential house with two floors and four bedrooms in Sydney were analysed using a building energy simulation program. Several scenarios were built based on various parameters, such as Passive Solar and Energy Efficiency Design Strategies (PSEEDS) and different external walls and floor systems, to determine their influence on the total energy required to achieve thermal comfort in the house. This study shows that the total energy required for heating during winter is reduced by 37% and 36% using Passive Solar and Energy Efficiency Design Strategies for constructing standard fibro and brick veneer houses, respectively. On the other hand, increasing the thermal mass (building materials with higher R values) through utilizing different walls and flooring system, by replacing fibro house with brick veneer house and applying the PSEEDS, total energy requirement could be reduced by up to 58%. Thus incorporating PSEEDS and higher thermal mass in the construction of residential buildings can yield significant savings in energy costs over the considered lifetime of 50 years period. Energy consumptions obtained through simulation were verified with the real data and found to be within the tolerance limit of 16%.

Biogas from a full scale digester operated in psychrophilic conditions and fed only with fruit and vegetable waste

Abstract The aim of this work was to evaluate the feasibility of treating fruit and vegetable waste from a municipal market in a full-scale anaerobic digester with minimum implementation and operational costs, i.e. without pre-treatment, clean water consumption, active heating or mixing. For this purpose, a 13.9 m3 digester that forces the submersion of solids, gains heat through solar radiation and recirculates effluent was monitored during one year of real operational and weather conditions in Bolivia. The digester was initially loaded with cow rumen (inoculum source), and after eight weeks with only fruit and vegetable waste. The digester operated at an organic loading rate (OLR) of 1 kgVS/(m3d). The normalized specific biogas production averaged 0.26 m3/kgVS and increased to 0.34 m3/kgVS when OLR was halved to 0.57 kgVS/(m3d), while the passive solar design allowed an average digester temperature of 21 °C (4 °C above the average ambient temperature).

Zonal air exchange rate of a passive solar house and resultant sensible air heat transfer

A passive solar house was constructed in Alice, South Africa as a prototype for low-cost energy-efficient housing. Minimum air exchange rate was adopted to minimise heat transfer between the inner and ambient environment of the house. The aim of this study is to investigate the air exchange rate and sensible air heat transfer in a passive solar house. The tracer gas technique was used where CO2 was consecutively injected into the various zones of the house. The CO2 concentration was measured using a Non-Dispersion Infrared gas sensor, and the air change rate (ACH) in each zone was evaluated via the CO2 decay rate. Auxiliary parameters were also monitored, such as indoor air temperature, ambient air temperature, wind speed and direction. Zone 1 had the maximum ACH of 2.27 h−1 with all ventilation components open. The corresponding sensible air heat transfer was 275.59 W. With all ventilation components closed, the whole house’s ACH was found to be within the recommended domestic level. The windows were also found to have a significant impact on the ACH, resulting in a daily cumulative heat loss of 0.196 kWh/m2. Hence, proper operation of windows is recommended to minimise indoor thermal load without compromising comfort.

Parametric CFD analysis and impact of PCM intrinsic parameters on melting process inside enclosure integrating fins: Solar building applications

The overall aim of this work is to integrate PCM elements into passive solar buildings. To achieve this goal, several numerical studies were carried out to describe the complex behavior of PCM melting filling a rectangular enclosure initially set at a cold temperature Tc. The cavity is vertically heated from the right side wall with a temperature Th=38.3°C while and the left cold wall was maintained at the cold temperature Tc=28.3°C. The horizontal walls were insulated. A transient numerical model based on the enthalpy-porosity formulation is used to study the heat transfer and the melting behaviors through two-dimensional CFD simulations. To enhance the heat transfer and the melting process of the PCM, fins with a rectangular and triangular shape are proposed. Moreover, the effects of both thermophysical properties and fins integration on the flow structure and heat transfer characteristics are investigated in detail. The melt fraction contours with the natural convection driven flow are described and compared, as well as the temperature distributions for a Rayleigh number of around Ra=106. It is found that the rate of the melting increases with the increase in the values of specific heat capacity Cp as well as the thermal conductivity λ of the PCM Gallium. The results showed that the rectangular fin configuration accelerated the PCM melting faster than the triangular fin's shape (the melting time has improved from 35 min to 32 min) thanks to the increased exchange area, while the triangular fin uniformized the melting process inside the enclosure.

SUSTAINABLE MICRO-VILLAGES AND THE CARWOOLA HOUSE PROJECT IN CANBERRA, AUSTRALIA

INTRODUCTION Our needs as social and familial beings change over the course of our lives; however, it has become common practice to build as though these needs remain static through time. The needs of a child, young adult, family, middle age and the elderly are dynamic between generations, and adding to these evolving life needs is the crisis of housing affordability. Three decades ago a house could cost 3–4 times an individual's annual income, today that cost is closer to 10–12 times. In response to these challenges, this article explores the concept of Sustainable Micro-Villages, providing insight into a new approach to energy-efficient housing with reference to our case-study project—Carwoola House. Sustainable Micro-Villages can be defined as a cluster of integrated dwellings, referred to here as Living Pods. Essentially a “single house” on a single site, these micro-villages can be comprised of two or more smaller buildings that provide private dwelling space for a single person, couples, couples with children, parents, elderly, friends and any combination of social groups. Living pods cluster around a natural garden setting, enhanced by water-harvesting, and are connected with covered, open or enclosed links depending on the climate of the site. The recent iterations of this type of dwelling also incorporate solar passive design, passive house and greenhouse technology. In Australia, new house designs are evaluated as part of an approvals process for their energy rating. 1 The Australian Building Code requires a minimum 6-star rating, ranging up to 10 stars for any new home to be built. A 6-star rating provides a good level of insulation and energy performance if built correctly, while 10 stars represent the highest level of energy performance and refers to a dwelling that needs no heating or cooling. Sustainable Micro-Villages consistently achieve an 8 to 10-star rating by combining Solar Passive Design principles (good orientation, thermal mass and thermal performance) and Passive House Technology (high thermally performing building with low air leakage, no thermal bridging, high performance glazing and heat recovery ventilation) in various combinations to suit the climate, context and budget.

Thermal Comfort Studies on Houses in Hot Arid Climates

The traditional houses in Ghardaia City in Algeria had been built using traditional construction materials and passive solar design (PSD) strategies for the hot desert climate. These thousand-year-old houses are still standing and conditioning the harsh desert climate while maintaining indoor thermal comfort for its occupants. Of late, two trends of modern housing and construction were observed to have evolved in Ghardaia. Firstly, were the modern houses (Mod.H) following the international style and secondly, the eco-friendly houses (Eco.H), modern houses but utilising passive solar design. The Mod.H was observed to implement some of the traditional features but using the modern construction material. Meanwhile, the Eco.H modified the characteristics of the traditional construction and materials carefully in a modern context. Analyses were conducted to investigate the thermal performances of the three house designs. The intention was to ascertain the best construction that can achieve and maintain thermal comfort according to ANSI-ASHRAE 2014, in this harsh desert climate. Based on the Trad.H model, comfort data the two more modern houses were also monitored. Data collection was carried out in July, which was one of the hottest months. The study indicated that passive solar techniques employed in the Trad.H were able to maintain the comfortable indoor environment for the occupants without any mechanical aid. The indoor temperature of the Eco.H was 3 to 9 °C higher, and the Mod.H difference was 5 to 9°C above the thermal comfort zone. The study ascertained that designs of buildings with traditional construction and material played a significant role in moderating the indoor environment when the outdoor climate of the Algerian desert was unbearable. Inadvertently, energy for cooling was saved creating a significant impact not only on the economy both at the national and global level, but on the environmental scale as well.

The Impact of Width of the Air Gap Channel on the Mass Flow Rate, Rayleigh Number, and Efficiency of Passive Solar Heating System

The mass flow rate and Rayleigh number has been investigated experimentally on the passive solar using Trombe wall consist of (industrial wax) used as phase change material (PCM). A test rig of a cubicle was made of PVC sandwich panel except the south wall, Trombe wall; covered with a clear glass of 6 mm thickness. The six experiments were carried out during the winter season in Kirkuk city with six different widths of the air gap channel (10, 15, 20, 25, 30, and 35) cm. The experimental resultts show that the mass flow rate proportional directly to a width of the channel and inversely with Rayleigh number. Moreover, the highest efficiency was obtained at a depth of 30 cm, where it was about 2.45 times the efficiency of 10 cm.

On Impact of the Ventilation Components on the Ventilation Rate in a Passive Solar Energy Efficient House

On Impact of the Ventilation Components on the Ventilation Rate in a Passive Solar Energy Efficient House

Investigating the potential for energy flexibility in an office building with a vertical BIPV and a PV roof system

Building Integrated Photovoltaics (BIPV) are becoming an attractive solution in the context of high penetration of photovoltaics (PV) in buildings caused by the strive to achieve net or nearly zero energy status. Besides retrieving solar radiation to produce electricity, BIPV also offers aesthetical advantages because of its architectural feature. This paper reports on the electrical energy performance of a passive solar office building, Solar XXI, located in Lisbon, Portugal, which has installed on the South façade a BIPV (12 kWp) and an additional photovoltaic roof system in a nearby car park facility (12 kWp) for electricity generation. The main objective is to investigate the potential to increase load matching between energy generation and consumption and improve grid interaction for two scenarios using the energy flexibility enabled by the integration of Battery Energy Storage Systems (BESS) with capacities ranging from 13.5 kWh to 54 kWh. To collect the required results, real consumption and generation data are used, together with numerical simulations related to the integration of the BESS. The results show that load matching and grid interaction related metrics can be significantly improved by using the energy flexibility provided by a BESS and that the implementation of such system can be economically viable for a 10-year period.

Energy efficiency and supplement interior comfort with passive solar heating in Saharan climate

ABSTRACTThe huge energy amount demanded for heating, during cold seasons is among the most complicated and cost energy supply problems in our life. Since free solar gains are spreading evenly on a part of the ground surface, the contribution of this passive heating concept has been assessed, through the current work. One must determine its impact on both the variation in energy efficiency and the main comfort parameters. The heat produced by the sun’s rays constitutes a promising option source of heating supply. In this view, a recent approach has been implemented in the way to create an energetic label by providing parameters, occupancy scenarios, lifestyle and all required data. Based on the assessed climate data, recorded on Saharan area, it has been averred that the passive solar heating represents only about 8.06% from the total energy supply, provided by the used thermally insulated building. The results show that the total needed energy consumption is about 441.27 kWh/m2/year ‘type F: building with high energy demand’. According to the energy labelling of buildings and regarding some considerable measures, the mentioned current structure type will be involved with the buildings that have an energy label of type D.

Building performance and end-user interaction in passive solar and low energy housing developments in Scotland

ABSTRACTIn the UK housing sector, changes to building regulations have raised standards for fabric performance, bringing about a demand for affordable, low energy housing. Housing Associations have been at the forefront of adopting these measures, but as owners of long term rented stock it is important for them to understand and evaluate the performance of both ‘as-built’ and ‘as-occupied’ dwellings. This paper describes a detailed evaluation of three new-build social housing demonstration projects located in Glasgow (Scotland). The study included occupant surveys in each scheme, fabric testing and detailed monitoring of environmental conditions, energy consumption, and evaluation of occupancy behaviours in eight dwellings. A particular focus of this paper is the ventilation performance as the homes are ventilated differently using natural, mechanical extract and mechanical heat recovery methods. The results showed a wide discrepancy of energy consumption and poor levels of ventilation, particularly in bedrooms. Causes of this included the design and installation of the ventilation provision but occupant interaction with the systems was also a significant factor. Two sites included sun-spaces that, despite having good potential for preheat ventilation and drying spaces, were underperforming. The study highlights significant impacts of the complex interactions between heating and ventilation systems, and the apparent need for more effective ventilation strategies and systems in bedroom spaces, but also improved strategies for end-user understanding of, and interaction with, both mechanical systems and natural ventilation opportunities. The papers aims to provide robust and credible evidence on which to base critical regulatory and design decisions on the most effective means of ventilating low carbon social housing in Britain.

Evaluation of the low technology tubular digesters in the production of biogas from slaughterhouse wastewater treatment

The aim of this research is to identify the operational conditions and performance of low cost tubular digesters producing biogas from the slaughterhouse wastewater treatment. Three full scale sequenced tubular digesters (of more than 8 m3 each), operating in a slaughterhouse in Cochabamba (Bolivia), have been monitored during one year. The Organic Load Rate (OLR) varied from 0.04 to 1.13 kgSV/m3d (0.04–1.07 kgCOD/m3d), and the Hydraulic Retention Time (HRT) from 3.2 to 87.4 days. The passive solar heating design considered drove the slurry temperature to 27 °C, 8 °C more than mean ambient temperature. The first digester has been filled with soda bottle plastic rings in order to increase the internal effective surface and evaluate, obtaining that an increment in 67% of the internal effective surface, more than doubles the biogas production and enables higher OLRs. A Biogas Production Rate (BPR) peak of 0.2 m3/m3d was observed for OLR = 0.37 kgSV/m3d, HRT = 9.7d and Specific Biogas Production (SBP) = 0.55 m3/kgSV. COD removal achieves values above 70% from HRT>19 d. A comparison with other anaerobic digestion technologies demonstrates that low cost tubular digesters with biofilm carriers, are competitive for OLR<0.5 kg COD/m3d of biogas production, and for 0.25 kgCOD/m3d, when the focus is on COD removal.

Pressure-Retarded Osmosis Thermosyphon

The basis of a novel method for passive solar water heating homologous to the traditional thermosyphon but driven by salinity gradient induced by changes of salinity gradient induced by evaporation at the collector is outlined. Its purpose, likewise than a thermosyphon, is to simplify the transfer of liquid while avoiding the cost and complexity of a conventional pump. However, in this concept, the fluid motion is not obtained from the tendency of a less dense fluid to rise above a denser fluid (natural convection) but rather by taking advantage of the energy released during the spontaneous mixing of the low-concentration (evaporated fraction) solution and the high-concentration (no-evaporated fraction) solution, which have been previously separated into two streams in the evaporator module. Finally, the possibility of driving the thermal osmosis by the strong thermal dependence of the solubility featured by many solutions rather than evaporation is envisaged. One important point in favor of the proposed thermosyphon driven by thermo-osmosis is that makes possible downward heat and mass transfer, i.e., heat and mass transport from the top roofs (where solar collectors are generally placed) to the bottom (inside the homes), and then the use of expensive and voluminous tanks so characteristic of current thermosyphons driven by natural convection is no longer needed.

Solar irradiance forecasting and energy optimization for achieving nearly net zero energy building

Solar energy and the concept of passive solar architecture are being increased in several areas to attain the net-zero energy concept. This paved the way for an increase in the need of solar irradiance forecasting for both solar PV applications and Passive Solar Architectural buildings. First, solar irradiance forecasting was done with 131 400 data sets (1-h data for 15 years) which was split into monthly mean for every year. This model was evaluated by forecasting the post-consecutive years one by one with the pre-consecutive years which includes the pre-forecasted years. This model was shown to have RMSE values of 11% to 24% for various seasonal forecasting using the Random Forest Algorithm in WEKA, which gave the annual irradiance results nearer to the PV Sol energy forecasting results. The R-value was in the range of 0.8 to 0.9 for various seasons which is good. Building Energy Optimization was carried out using BEopt 2.8 software designed by NREL. The chosen building was set to the standard parameters in India, and then, the optimization was done with various customized parameters and systems available in India to reduce the energy consumption from 192.2 MMBtu/yr to 109.1 MMBtu/yr with a 7 kW Solar PV System to attain the net-zero energy concept.

Gravitational Wave Speed: Undefined. Experiments Proposed

Since changes in all 4 dimensions of spacetime are components of displacement for gravitational waves, a theoretical result is presented that their speed is undefined, and that the Theory of Relativity is not reliable to predict their speed. Astrophysical experiments are proposed with objectives to directly measure gravitational wave speed, and to verify these theoretical results. From the circumference of two merging black hole's final orbit, it is proposed to make an estimate of a total duration of the last ten orbits, before gravitational collapse, for comparison with durations of reported gravitational wave signals. It is proposed to open a new field of engineering of spacetime wave modulation with an objective of faster and better data transmission and communication through the Earth, the Sun, and deep space. If experiments verify that gravitational waves have infinite speed, it is concluded that a catastrophic gravitational collapse, such as a merger of quasars, today, would re-define the geometry and curvature of spacetime on Earth, instantly, without optical observations of this merger visible, until billions of years in the future.

A simple model for temperature response of single-zone passive buildings

This article presents a method for calculating interior air temperature as a function of ambient conditions for simple structures (single-zone passive buildings with low infiltration). Examples of such structures are unconditioned greenhouses, storage facilities, and wholly passive solar houses. The method was tested in a partially unoccupied apartment building for 8 days. A simple model was applied to the data in which interior air temperature was taken as an exponential step response to a change in exterior temperature. The time constant calculated from this relationship exhibited periodic fluctuations from day to day. A method is described for reconstructing the interior temperature record using these findings in the step change model. The average difference between the recorded and modeled data was −0.1°C for the period of monitoring. This was unexpected considering that insolation was not monitored or taken into account in the model. The simple step response model was thus sufficient to reconstruct the recorded interior temperature data at this test site. The paper concludes with recommendations for further testing of the method.

A numerical study of adaptive building enclosure systems using solid–solid phase change materials with variable transparency

Buildings currently consume about 40% of all energy use in the US and therefore play an important role in mitigating global greenhouse gas emissions. Passive solar design strategies can be used to limit building heating and cooling demands. Current passive solar design strategies, however, require substantial design effort for each individual project, often require mechanical and electrical control systems, and the approach is also difficult to implement in building retrofit projects. Solid–solid phase change materials (SS-PCM) are currently emerging as alternative materials for thermal energy storage. Here we present an exploratory study on two innovative climate responsive building enclosure systems that employ the transparency change and latent heat storage capacity of SS-PCMs as mechanisms to passively control building temperature. The first system is based on a thin layer of SS-PCM that is placed on top of a highly reflective film to control solar heat gain. The second system uses a layer of SS-PCM foam to store thermal energy and control heat flow. The performance characteristics of the systems are evaluated using finite element modeling techniques. Simulation results shed light on the synergistic interactions between different components of the systems and indicate that both systems can reduce undesirable heat exchange between the building and its environment if designed properly. Recommendations are made regarding various material and system parameters, including the attenuation coefficient of the SS-PCM, system thickness, void ratio and distribution of the void ratio of the SS-PCM foam based system, and phase transition temperature.

The potential of energy savings and the prospects of cleaner energy production by solar energy integration in the residential buildings of Saudi Arabia

Abstract In this study, various energy conservation techniques and clean energy utilization prospects are investigated for the residential buildings of Saudi Arabia. A base case study of a distinctive residential building in Saudi Arabia is performed using simulation packages and its energy performance is optimized by incorporating the design standards of International Energy Conservation Code (IECC). The optimized results show that the energy consumed by the IECC standardized building is less by 56% for space cooling, 37% for space heating, 46% for lighting, and 27% for appliances. The IECC standardized building is integrated with a passive solar water heating system and a grid-connected solar PV system to meet the water heating load and lighting load, respectively. The use of solar water heating system shows 76% reduction in energy consumption as compared to the electric water heater. The feasibility of integrating a grid-connected solar PV system in the residential buildings is justified in terms of subsidy provided by the government and eco-environmental benefits. Finally, the prospects of utilizing solar energy in buildings are discussed with their economic and environmental benefits.

Thermal performance of phase change materials (PCM)-enhanced cellulose insulation in passive solar residential building walls

Building walls outfitted with phase change materials (PCM) offer the potential for energy savings, peak space cooling load shifting, and increased thermal comfort in occupied buildings. However, integrating PCM into already established wall types, which are comprised of several layers (e.g., siding, insulation, wallboard, etc.) poses several challenges and extra construction time. One potential solution to incorporate PCM into walls would be to directly mix the PCM with insulation during the manufacturing process of the insulation. Cellulose insulation offers this opportunity. This paper evaluated the thermal performance of PCM-enhanced cellulose insulation in residential walls. The PCM was integrated via direct mixing with the insulation. Differential scanning calorimeter (DSC) tests showed that the cellulose would not affect the latent heat of fusion of the PCM in the mixture in a significant manner. The thermal performance of north, east, south, and west facing residential walls with and without PCMs was experimentally evaluated using two identical test houses under full weather conditions. The results showed that the daily average peak heat flux reduction for individual walls was 25.4%, while the hourly average peak heat flux reduction for the sum of all four walls was 20.1%. The thermal performance was evaluated in terms of wall heat flux comparisons between standard and PCM-enhanced insulation walls.

Thermal Feature of a Modified Solar Phase Change Material Storage Wall System

This work is to study a novel solar PCM storage wall technology, that is, a dual-channel and thermal-insulation-in-the-middle type solar PCM storage wall (MSPCMW) system. The system has the following four independent functions, passive solar heating, heat preservation, heat insulation, and passive cooling, and it can agilely cope with the requirements of climatization of buildings in different seasons throughout the year and is exactly suitable for building in regions characterized by hot summer and cold winter. The present work experimentally analyzes thermal feature of the system working in summer and winter modes, respectively.