Theoretical and experimental investigation to calculate heat gain of multilayered walls by using rts method

This study delves into the application of the ASHRAE Radiant Time Series (RTS) method for calculating heat gain in multilayered walls within the context of Iraq. The primary objective is to assess the thermal performance of commonly used wall constructions, offering insights to enhance energy efficiency and thermal comfort in buildings. Commencing with an overview of the RTS method, the study highlights its significance in evaluating heat gain for effective cooling systems and energy management strategies. A critical literature review evaluates prior research on heat gain calculations and multilayered wall performance, emphasizing the necessity for tailored investigation in Iraq. This was followed by the collection, summarization, and selection of key papers related to energy savings through heat gain reduction. Based on these findings, a test rig was designed, considering cost, effectiveness, and material costs. The test rig, a small room of dimensions 115 x 100 x 100 cm, incorporated three walls (A, B, and C), each with three layers, a concrete roof of two layers, and a double-glazed window/door. Instruments such as K-type thermocouples, a data logger, sensors, a power supply, and SD memory were utilized for temperature measurements. The subsequent stage involved the analysis, quantification, and testing of heat gain and cooling requirements for various building and insulation materials. Results from these tests were compiled, and discussed, and key conclusions, benefits, drawbacks, and preventative measures were defined. The methodology section also detailed the theoretical framework and experimental approach. It introduced the development of a MATLAB code for computing heat gain using the RTS method and explained the experimental setup for data collection. The ASHRAE RTS Procedure spreadsheet served as a reference for comparative analysis. Detailed analysis of incident solar flux on multilayered walls offers key observations for optimizing thermal performance. Wall B consistently receives the highest incident flux, indicating pronounced exposure to direct sunlight. Walls A and C receive moderate levels of incident flux, suggesting comparable solar radiation exposure. The roof records the highest incident flux, signifying substantial solar radiation exposure. Wall B, facing east (sunrise), consistently garners the highest incident solar flux throughout the day, reflecting a higher degree of solar radiation and thermal absorption than Walls A and C. Variations in solar flux reveal Wall B experiences the highest fluctuations during peak hours, while Wall C exhibits the least variation. The time of peak solar flux varies for each wall, highlighting differences in positioning and solar irradiation levels. Further investigation into wall orientation using MATLAB code and ASHRAE spreadsheet indicates that when Wall A faces south, the highest heat gain is achieved, peaking at approximately 65 W around 12:00. In contrast, the other three orientations result in lower heat gain, with a maximum of 52 W at 14:30. These findings provide valuable insights for optimizing building design, considering the impact of incident solar flux variations and wall orientation on heat gain. The study enhances our understanding of thermal dynamics, contributing to the development of energy-efficient and comfortable building environments. The main conclusions drawn from the study are as follows; The research analyzed solar energy factors, including incident solar flux, sol-air temperatures, conduction heat gains, window solar heat gain, and sensible cooling load. The data underwent analysis to understand heat gain patterns in various wall layers and their impact on overall building thermal efficiency. The findings indicated significant differences in heat gain measurements across wall layers, emphasizing the effects of solar radiation exposure and the crucial role of insulation in mitigating heat gain. The RTS method was proven to be a dependable and precise method for estimating heat gain in multilayered walls. The thermal properties of the materials used in multilayered walls significantly impact heat gain. Conductivity, density, and specific heat must be accounted for in calculations. Solar radiation incident on walls plays a substantial role in heat gain. Incorporating solar exposure patterns into the RTS method enhances heat gain forecast precision. Heat gain is significantly influenced by the arrangement and composition of layers in multilayered walls. Different configurations result in varying heat transfer characteristics. There are several recommendations arising from the study. First, the importance of wall components to overall room thermal performance underscores the need for insulation and careful orientation to optimize solar radiation exposure and minimize heat gain. Window design should be approached with caution, considering both solar heat gain limitations and the need for adequate daylighting. The analysis of cooling requirements suggests implementing energyefficient cooling systems. The decreasing trend of the cooling load throughout the night suggests the potential for utilizing natural cooling during cooler hours, reducing reliance on mechanical systems and energy consumption. Future research should explore additional parameters such as external shading devices, thermal mass, and HVAC system efficiency to gain a more complete understanding of multilayered wall thermal performance. In conclusion, this study provides a thorough examination of the ASHRAE RTS method's efficacy in assessing heat gain in multilayered walls, with practical implications for optimizing thermal performance in Iraqi buildings. Key Words: Heat gain, Multilayered Walls, RTS, ASHRAE, MATLAB, Cooling load