Thermal Performance Analysis of Plaster Reinforced with Raffia Vinifera Particles for Use as Insulating Materials in Building

The present study focuses on the formulation of new composite consisting of plaster and raffia vinifera particle (RVP) with the purpose to reducing energy consumption. The aim of this study is to test this new compound as an insulating eco-material in building in a tropical climate. The composites samples were developed by mixing plaster with raffia vinifera particles (RVP) using three different sizes (1.6 mm, 2.5 mm and 4 mm). The effects of four different RVP incorporations rates (i.e., 0wt%, 5wt%;10wt%;15wt%) on physical, thermal, mechanicals properties of the composites were investigated. In addition, the use of the raffia vinifera particles and plaster based composite material as building envelopes thermal insulation material is studied by the habitable cell thermal behavior instrumentation. The results indicate that the incorporation of raffia vinifera particle leads to improve the new composite physical, mechanical and thermal properties. And the parametric analysis reveals that the sampling rate and the size of raffia vinifera particles are the most decisive factor to impact these properties, and to decreases in the thermal conductivity which leads to an improvement to the thermal resistance and energy savings. The best improvement of plaster composite was obtained at the raffia vinifera particles size between 2.5 and 4.0 mm loading of 5wt% (C95P5R) with a good ratio of thermo-physical-mechanical properties. Additionally, the habitable cell experimental thermal behavior, with the new raffia vinifera particles and plaster-based composite as thermal insulating material for building walls, gives an average damping of 4°C and 5.8°C in the insulated house interior environment respectively for cold and hot cases compared to the outside environment and the uninsulated house interior environment. The current study highlights that this mixture gives the new composite thermal insulation properties applicable in the eco-construction of habitats in tropical environments.

Optimization Method for Indoor Thermal Comfort Based on Interactive Numerical Calculation

In order to implement the optimal design of the indoor thermal comfort based on the numerical modeling method, the numerical calculation platform is combined seamlessly with the data-processing platform, and an interactive numerical calculation platform which includes the functions of numerical simulation and optimization is established. The artificial neural network （ANN） and the greedy strategy are introduced into the hill-climbing pattern heuristic search process, and the optimizing search direction can be predicted by using small samples; when searching along the direction using the greedy strategy, the optimal values can be quickly approached. Therefore, excessive external calling of the numerical modeling process can be avoided, and the optimization time is decreased obviously. The experimental results indicate that the satisfied output parameters of air conditioning can be quickly given out based on the interactive numerical calculation platform and the improved search method, and the optimization for indoor thermal comfort can be completed.

Analysis of indoor set-point temperature of split-type ACs on thermal comfort and energy savings for office buildings in hot-humid climates

In hot-humid climates,particularly in sub-Saharan Africa(SSA),ambient temperatures and relative humidity are as high as 35°C and 84%,respectively,requiring the use of mechanical cooling systems for indoor thermal comfort.Split-type vapor-compression air-conditioners(SVAC)are mainly used for space cooling in SSA and consume 60-80%of total energy consumption in commercial and public buildings.Appropriate control strategy of the indoor set-point temperature of SVAC can result in significant energy savings in these buildings.In this study,modeling and dynamic simulation have been conducted using EnergyPlus to predict the energy saving potential and indoor thermal comfort of buildings in hot-humid climates by controlling set-point temperature of the SVAC.In a case study,climatic data for Ghana,was used to predict the energy saving potential and indoor thermal comfort.The study results revealed that,to ensure indoor thermal comfort at high outdoor temperature condition of 35°C,the least and optimum set-point temperatures of the SVAC should be 21°C and 25°C,respectively.On the other hand,for low outdoor temperature condition,the least and optimum set-point temperatures were 22°C and 26°C,respectively.Considering 1-star and 2-star rated SVACs which are dominantly used in Ghana,operating at 21-25°C in the case of high outdoor conditions,and 22-26°C for low outdoor conditions relative to the least temperatures resulted in energy savings of 8-33%and 12-44%,respectively.

Thermal Indices Influence on Occupants’ Window Opening Behaviours: A Case of Ibadan and Ogbomoso, Oyo State, Nigeria

Window opening operations are considered as one of the significant way of regulating indoor climate and maintaining thermal comfort in buildings,even when alternative active devices such as fans and air conditioners are available.This study investigates responses of occupants of the traditional core areas of Ibadan and Ogbomoso to thermal comfort conditions(thermal stress)through window opening behaviours.Climatic data of the two cities were subjected to Evans scale to predict their day and night thermal stress and questionnaires were administered to know how occupants respond to changing thermal conditions through window opening behaviours.Descriptive and inferential statistics were used in analysing the data.The study found the morning periods to be the most comfortable,the afternoon periods offer the most hot discomfort condition and cold discomfort is mostly experienced in the evening periods in both cities.Findings revealed that majority of occupants in both cities prefer to keep their windows opened in the morning and afternoon periods and an increase was observed in the numbers of occupants who prefer to keep their windows closed in the evening periods.This is an indication that building occupants in both cities actively respond to thermal stress using window opening operations.Results obtained from chi square analysis concluded that there is a significant relationship between occupants’window opening behaviour and thermal conditions at different periods of the day in both cities.Recommendations were given on how to improve on window opening systems in the future.

Energy Efficiency Assessment of Building Wall with PCM Layers in the Hot Summer Locations

This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experiments. One wall included (phase-change material) spheres, integrated into one styrofoam layer, installed at different positions, from 1 to 5, from the outside to the inside of the room. The other wall included one styrofoam insulation layer, perforated with holes, with changeable positions, from 1 to 5, from the outside to the inside of the room. The temperatures in the experiment corresponded to high summer temperatures in the tropical or subtropical zones. The obtained experimental results were further analyzed, while HVAC is off, for an indoor thermal comfort range, from 20˚C to 25˚C. This manuscript has analyzed the thermal comfort, effectiveness and optimal position of PCM spheres, incorporated in styrofoam thermal insulation, for a previously determined temperature range. The wall with integrated PCM should not be thick, (in total), but rather slender so that PCM can show its effectiveness. The farthermost position of the PCM layer should be the third because PCM combined with a lot of thermal insulation is not so effective and the thermal insulation has a buffer effect. The honeycomb or hollow-core thermal insulations should be avoided to put alone, because of natural air convection in them, which raises the heat flow. The monthly monetary saving, for a PCM-integrated wall, is calculated and amounts to 55.5 $, which shows that the integration of PCM in building walls, in hot summer locations, is very beneficial.

Evaluating the improvement effect of low-energy strategies on the summer indoor thermal environment and cooling energy consumption in a library building:A case study in a hot-humid and less-windy city of China

Public buildings such as libraries consume a vast amount of cooling energy for maintaining a comfortable and stable indoor environment in summer,especially in the hot-humid climate.This study used a case study approach to discuss the effect of low-energy strategies that can be applied to improve indoor thermal environment and cooling energy consumption of library buildings in hot and humid cities like Nanning City(a southern city,China).The use of cooling window shutters(a shutter with the effects of shading and evaporative cooling)and ceiling fans for generating airflow was considered as applicable energy-saving measures in this study,and a university library was selected as the study building in which the two energy-saving measures were employed.The SET*and annual cooling load before and after the adoption of the proposed measures were quantitatively investigated with a building energy consumption simulation software(DesignBuilder).Simulation results showed that the daytime SET*values can be reduced by 3.0℃and 4.5℃respectively on a typical summer day after the use of the cooling shutters and ceiling fans.Moreover,the cooling loads can also be decreased by 8.4%and 16.6%respectively.Particularly,the combination of these two measures enabled the daytime SET*value and annual cooling load lower by 7.0℃and 60.8%respectively.