Experimental investigation of phase change materials for insulation of residential buildings

In this paper, numerical study has been conducted for using PCM as thermal insulation materials by incorporating it with layers of walls and ceiling of buildings. The effect of PCM and its role in improvement of thermal performance and thermal comfort is numerically studied. ESP-r software program has been used for numerical simulation in this paper. Energy plus weather database software was used to create climate date for Kut city (32.5 oN 45.8 oE) that used for simulation in this study. Two identical rooms were inserted in software ESP-r with dimensions (1.5m*1.5m*1m), the first is standard room for comparison and the second is test room for experimenting. Many cases were studied according to the thickness of the PCM and according to the orientation (North wall, South wall, East wall, West wall, and ceiling). Results obtained showed a reduction in indoor temperature of the zone and the reduction in the cooling load and as a result saving in electricity consumption with using PCM as insulation materials.

In this paper, experimental research has been conducted intended for using Phase Change Materials (PCM) by incorporating it with the building layers walls. The effect of involving PCM volume ratio and orientation on the thermal efficiency and thermal comfort was experimentally studied. Two identical rooms models have been constructed. The first model was used as a standard room as a reference one without using PCM and the second model has the PCM layers and used for all experimental testing works. Both rooms are installed at National Research Center, NRC, Giza, 30.08° N latitude, Egypt. The PCM used in this experimental work was paraffin wax having a melting point of 29 °C. Many cases have been studied based on the south wall, east wall and west wall respectively. It is found that using PCM caused a considerable reduction in the indoor air temperature and consequently reduction in the cooling load that minimizes the building energy consumed. It is concluded that the Percentage of the cooling load reduction of the zone by using PCM and according to cases and for peak hour in day was 19.2 % with PCM for East, West and South walls together, followed by 16.8 % for South wall only, followed by 12.7 % with West wall only and followed by 10.5 % for East wall only. It is found that the best case in cooling load reduction of the room for peak hours of PCM for South, West and East walls together by 19.2 %. The experimental results of the present study were validated with the corresponding experimental study of Mushtaq 2018 with a considerable agreement between the daily cooling load reduction per space volume and the cooling load reduction ratio. It is known that the cooling load reduction ratio is referred to the energy-saving which proved that using PCM in the building will contribute to energy saving in residential building

The doorposts and the walls of the entranceway to this house were coarsely plastered and the pavement was of lavapesta. The walls have been much restored since excavation, prohibiting the identification of any breaches that might provide evidence for disturbance. Outside the entrance, on the west side, is a low, plastered, masonry bench (1.57 m × 0.38 m × 0.42 m), which Elia identified as a seat for waiting clients. Within the entranceway, a few centimetres above the pavement, a number of finds were made. These were all of iron—a large lock, two hooks, a handle, two keys, at least one door latch and numerous studs and nails—and no doubt mainly the fittings for the house door. One of the keys was large and probably a door key. Its discovery here suggests that the occupants were still in residence, or at least had not had the time or inclination to lock up their house, before fleeing from the eruption. A small ring was also found in this entranceway, and was probably a lost finger-ring. This room is closed to the street but almost completely open along its east side onto the entranceway. The walls had a high, pink-plastered socle, to 1.6 m above the pavement, with white plaster above, and the pavement was of tiles and mortar. There are breaches in the west and south walls, possibly the result of post-eruption disturbance. A stairway ran along the north wall, rising from east to west. Underneath was a low partition wall jutting out at right angles from the west wall, to partition off a latrine in the north-west corner. This partition wall post-dates the plaster on the west wall. A line of roof tiles, set into the floor and running from this partition wall to the south jamb on the east wall, is assumed to have been for flushing the latrine. A truncated amphora, with visible organic contents, was set into the pavement in the south-east corner. Other finds from this room, but with no precise provenances, include: two relatively small bronze strap hinges, possibly from furniture; a bronze casseruola; two ceramic jugs; a hoe, probably for gardening; an axehead, probably a woodman’s; and a bronze brooch.

To improve the thermal performance, storage and saving heat solar energy of conventional greenhouse, a passive solar greenhouse was built which its north wall was made of soil. The bottom part of the north, south, west and east walls were sloping and constructed below ground surface. The indoor air temperature was measured during January and February. To optimize the size of greenhouse in cold climate condition a TRNSYS model was created and validated using experimental data. According to the results obtained, Total Incident Solar Radiation (TISR) in the north wall was 484 MJ during January and February and there was the possibility of cultivation in it. More specifically, the variation of TISR during 60 days varied from 190 to 3811 kJ h-1 m-2. The indoor air temperature of the greenhouse varied from -4.3 to 42.4 °C while the outdoor temperature fluctuated between -13.8 to 10.6 °C. In addition, the differential temperature between modeled and measured data at climate conditions of snowy, rainy, cloudy and sunny days were 2.3, 0.2, 0.2, and 2.6 °C during daytime and -1.8, -2, 0.3 and 1 °C at nighttime, respectively. The obtained coefficient of determination (R2) was 95.95% for measured and modeled data.

Structuring on the west (east) wall of eastward (westward) drifting airglow depletion under quiet (storm) time is common. Here, we report for the first time the rare occurrence of the east wall structuring of an eastward drifting depletion near the crest of equatorial ionization anomaly (EIA) in India on 16 April 2012 under quiet geomagnetic conditions. We observed a linear depletion having a westward tilt of ∼25° and eastward drift speed of ∼129 m/s in the beginning. First prominent structuring occurred on its west wall that later swiftly surged poleward within next 6–12 min and bifurcated, that is, behaved like a secondary depletion growing on the primary one. Second west wall structuring then occurred but had considerably subdued growth. Meanwhile, main depletion bent slightly eastward above its branching node, and two structuring appeared on the east wall in succession. Secondary depletion then slightly contracted equatorward, and structuring emerged from its east wall, too, that later stretched eastward, got linked with main depletion and formed grid mesh shaped feature. Second structuring on the west wall started fading; while, those on the east wall swiftly evolved, surged poleward and gained prominence. Also, their westward tilt decreased. During the occurrence of these events, gravity waves (GWs) and the retreat of EIA were active overhead. Current study serves as first imaging evidence of Zalesak et al. (1982, https://doi.org/10.1029/JA087iA01p00151) simulations that the east wall of a westward tilted depletion can become unstable and host secondary instabilities. Possibly these structuring were excited by GWs via Rayleigh‐Taylor instability.

Abstract. The energy consumption of a building is significantly impacted by its envelope design, particularly for greenhouses where coverings typically provide high heat and daylight transmission. Energy and life cycle cost (LCC) analysis were used to identify the most cost-effective cladding design for a greenhouse located in Ottawa, Ontario, Canada (45.4° N) that employs supplemental lighting. The base case envelope design uses single glazing, whereas the two alternative designs consist of replacing the glass with twin-wall polycarbonate and adding foil-faced rigid insulation (permanent or movable) on the interior surface of the glass. All the alternative envelope designs increased electricity consumption for lighting and decreased heating energy use except when permanent or movable insulation was applied to the north wall and in the case of permanent insulation on the north wall plus polycarbonate on the east wall. This demonstrates how the use of reflective opaque insulation on the north wall can be beneficial for redirecting light onto the crops to achieve simultaneous reductions in electricity and heating energy costs. A maximum reduction in LCC of 5.5% (net savings of approximately $130,000) was achieved when permanent insulation was applied to the north and east walls plus polycarbonate on the west wall. This alternative envelope design increased electricity consumption for horticultural lighting by 4.3%, reduced heating energy use by 15.6%, and caused greenhouse gas emissions related to energy consumption to decrease by 14.7%. This analysis demonstrates how energy and economic analysis can be employed to determine the most suitable envelope design based on local climate and economic conditions. Keywords: Artificial lighting, Consistent daily light integral, Energy modeling, Envelope design, Greenhouse, Life cycle cost analysis, Light emitting diode, Local agriculture.

Abstract: By using the D‐InSAR technique, we have acquired the temporal‐spatial evolution images of preseismic‐cosesimci‐postseismic interferometric deformation fields associated with the M 7.9 earthquake of Mani, Tibet on 8 November 1997. The analysis of these images reveals the relationships between the temporal‐spatial evolution features of the interferometric deformation fields and locking, rupturing, and elastic restoring of the source rupture plane, which represent the processes of strain accumulation, strain release, and postseismic restoration. The result shows that 10 months prior to the Mani event, a left‐lateral shear trend appeared in the seismic area, which was in accordance with the earthquake fault in nature. The quantity of local deformation on the north wall was slightly larger than that on the south wall, and the deformation distribution area of the north wall was relatively large. With the event impending, the deformation of the south wall varied increasingly, and the deformation center shifted eastward. Two and half monthd before the event, the west side of the fault was still locked while the east side began to slide, implying that the whole fault would rupture at any moment. These features can be regarded as short‐term precursors to this earthquake. Within the period from 16 April 1996 to two and half months before the earthquake, the most remarkable deformation zones appeared in the north and south walls, which were parallel to and about 40 km apart from the fault, with accumulated local displacements of 344 mm and 251 mm on the north and south walls, respectively. The south wall was the active one with larger displacements. Five months after the earthquake, the distribution feature of interferometric fringes was just opposite to that prior to the event, expressing evident right‐lateral shear. The recovered displacements are ∼179 mm on the north wall and ∼79 mm on the south wall, close to the east side of the fault. However, in the area of the south wall far from the fault there still existed a trend of sinistral motion. The deformation of the north wall was small but recovered fast in a larger area, while the active south wall began to recover from the east section of the fault toward the WSW.

To explore the independent influence of the main factors affecting heating on the radiant floor heating system, CFD was used to simulate the simplified multi‐storey multi‐family building model under different working conditions, and focusing on the calculation and comparative analysis of these four factors (heating supply, the location of room, outdoor temperature and the neighboring heating situation). The results showed that heating supply is the most important factor affecting indoor temperature, and the change of heating supply has the most obvious effect on the change of indoor temperature in the middle of the bottom layer, and the least effect on the edge of the top layer, which is a 1.6–1.7 times relationship. The influence of outdoor temperature on indoor temperature mainly depends on the area proportion of external envelope structure, and the changing rates of the indoor temperature of the edge of the top layer, the middle of the top layer, the edge of the bottom layer, the middle of the bottom layer with the outdoor temperature are 0.94, 0.93, 0.88, and 0.86. The influence of the neighboring heating situation on indoor temperature mainly depends on the surface area proportion of inner envelope structure, and the proportion of heat gain (dissipation) of each envelope to the total heat supply is basically the same, the heat dispersed through the north wall, south wall, east wall and west wall of the room at the middle of the bottom layer account for about 34%, 37%, 9%, and 9% respectively.

This paper presents the development of an experimental test house for real-world measurements of heat transfer in a building composite of hemp shive and magnesium binder with microencapsulated phase change material (PCM) to increase the thermal mass of the building material and improve internal thermal comfort. The test house was developed as a small building erected from prefabricated three-layer blocks with dimensions of 600×400×240 mm3 (length × width × height). The outer layers of the blocks had a density of approximately 400-450 kg/m3 and a thickness of 50 mm (without PCM) and 60 mm (with PCM), while the inner layer had a density of approximately 200-250 kg/m3 and a thickness of 290 mm. The building had dimensions of 2.60×3.10 m2 and a height of 3.36 m, with walls facing in the cardinal directions. A door was placed in the north wall. The east and south walls had a layer of PCM facing outwards, while the west wall faced inwards. The temperature inside the building was stabilized at 20°C using a specially designed heating/cooling system. Six temperature and relative humidity sensors (HDC 1080) were placed inside the two blocks in each wall, except the north wall. In addition, heat flux sensors were mounted under the internal plaster on the east and south walls. Indoor and outdoor air parameters, solar radiation, and wind speed were also monitored. In addition to the description of the test house, exemplary data for two measurements over a period of one week in two different months are discussed.

Testing of perfluorocarbon gas tracers (PFT) on a subsurface barrier with known flaws was conducted at the Waldo Test Site operated by Science and Engineering Associates, Inc (SEA). The tests involved the use of five unique PFTs with a different tracer injected along the interior of each wall of the barrier. A fifth tracer was injected exterior to the barrier to examine the validity of diffusion controlled transport of the PFTs. The PFTs were injected for three days at a nominal flow rate of 15 cm{sup 3}/min and concentrations in the range of a few hundred ppm. Approximately 65 liters of air laced with tracer was injected for each tracer. The tracers were able to accurately detect the presence of the engineered flaws. Two flaws were detected on the north and east walls, and one flaw was detected on the south and west walls. In addition, one non-engineered flaw at the seam between the north and east walls was also detected. The use of multiple tracers provided independent confirmation of the flaws and permitted a distinction between tracers arriving at a monitoring port after being released from a nearby flaw and non-engineered flaws. The PFTs detected the smallest flaw, 0.5 inches in diameter. Visual inspection of the data showed excellent agreement with the known flaw locations and the relative size of the flaws was accurately estimated. Simultaneous with the PFT tests, SEA conducted tests with another gas tracer sulfur hexafluoride (SF{sub 6}).

Performance of aerogel as a thermal insulation material towards a sustainable design of residential buildings for tropical climates in Nigeria

The Lung Khê Citadel site is located on the natural levee of the old Dâu River at Lung Khê hamlet, Thành Khu'o'ng village, Thuân Thành district in Bac Ninh Province. The citadel includes a large rectangular walled fort (north wall: 680m, south wall: 520m, east wall: 320m, west wall: 328m).Previous studies have identified the Lung Khê Citadel as the central citadel of Luy Lâu district, which was established as the capital of Chiao Chih (Giao Chi) Prefecture in the Western Han period and was also a place where Si Nhiêp, the prefect of Chiao Chih, resided. Recent studies have reshuffled the previous understanding.Excavations and field research have revealed that the citadel was built in the 2nd century AD and continuous occupation can be confirmed to the end of the 5th or early 6th century AD. A large-scaled bronze workshop has been confirmed in the north central area inside the walls. A mold fragment of a bronze drum found in this area indicates a part of the workshop was used for casting late Heger I type drums. Although the majority of the artifacts are of Chinese-origin, several types, such as end roof tiles, a table-shaped stone mortar (pesani) and kendi, show cultural affinity with artifacts found in Trà Kiêu and Óc Eo, where the early Southeast Asian states were formed.Among the early citadels or fort sites in the Red River Delta, Lung Khe is the largest one next to Cô Loa. The construction of Cô Loa can be dated between the 1st century BC and 1st century AD, but it seems that after its construction Cô Loa was not used for a very long time. On the other hand, the scale, occupation period and material culture of Lung Khê are worthy of the central capital of the Red River Delta, which must have been Long Bien. While there are many historical or legendary relics of Si Nhiêp around Lung Khê, no early document mentions any relation between Si Nhiêp and Luy Lâu. The title Long Ben Hâu conferred to Si Nhiêp as the lord of the district recorded in the San kuo chih is supporting evidence for this hypothesis.The development of the Nan Hai trade from the end of the 1st millennium BC between China and Southeast Asia or further west stimulated the socio-economic development of the Red River Delta as an entrepôt, and the political power at Lung Khê should have been related to trade. However, from the late 3rd or 4th century a change in the trade route may have brought about a decline in the economic position of the Red River Delta. The later period of the Lung Khê Citadel were less connected with the south, so more domestic factors inside the Red River Delta need to be understood in a historical context.

Statistical analysis of solar radiation on variously oriented sloping surfaces

Based on the introduction characteristics of capillary plane radiation air conditioning systems, we focuse on the analysis phenomenon of radiation asymmetry in the radiant air conditioning systems in the engineering practice , and discuss the condition that produces this phenomenon, and establish mathematical model of radiation asymmetric in the capillary plane air conditioning systems. And we work out the radiation angle coefficient between the human body and the floor, south wall, north wall, east wall , west wall in air conditioning rooms, and expound the radiation asymmetry degree in different parts of air conditioning rooms. The result is of positive significance to research capillary plane radiation air conditioning systems deeply and to improve occupant comfort .

Thermal insulation is a reliable strategy for achieving optimal thermal comfort in built environments and is among the most effective energy-saving measures. Currently, environmentally friendly insulation materials produced from plant and animal fibers constitute a significant component of the building industry, largely due to their minimal embodied energy and concerns about certain synthetic insulation materials’ potential adverse health effects. The main objective of the present study is to encourage and facilitate the utilization of environmentally friendly thermal insulation materials derived from biological sources, including vegetal and animal fibers, to improve thermal comfort and consequently reduce energy consumption in buildings. The study attempts to simulate the indoor air temperature profiles of a single building constructed using locally sourced materials and insulated in a series of stages with the aforementioned insulation materials. Firstly, insulation is applied exclusively to the roof. Secondly, the insulation is applied to the remaining wall surfaces. Alternatively, the insulation is applied to both the roof and the wall surfaces simultaneously. The objective is to ascertain the optimal combination of bio- and geo-insulating materials to achieve thermal comfort in buildings constructed with local materials in tropical climates. The Gauss-Seidel iterative method was employed to solve the energy equations that had been written on the walls and roof of the building. The equations were then discretized using the nodal method. To ascertain the thermal comfort of the simulated buildings, a comparison was made of the indoor air temperatures. The results of the simulations demonstrated that the utilization of wood fiber, reed panels, and straw bales as insulation materials led to a notable enhancement in comfort levels across all five building types, with an average increase of 17.5%. Among these materials, wood fiber emerged as the most effective insulation option, reducing temperatures by up to 19%. Its integration into the sheet metal-clad Banco building would be particularly advantageous. The findings demonstrate that the simultaneous insulation of walls and roofs with natural fiber thermal insulation materials markedly reduces indoor air and wall temperatures in buildings by up to 19% in comparison to uninsulated walls and roofs.