Muhamad Zahin Mohd Ashhar’s research while affiliated with National University of Malaysia and other places

Building energy consumption in Malaysia has increased by 31% over the past 10 years, primarily driven by the high demand for air conditioning in response to the country’s hot and humid climate. An effective way to address this problem is to increase building energy efficiency with the aid of thermal insulation. This paper presents a techno-economic analysis of roof assembly retrofits for commercial and residential buildings in Malaysia. Various roof configurations incorporating insulation materials such as radiant barriers, reflective insulation, mineral glass wool, and stone wool are investigated. The first section of this paper details the use of Sefaira building energy simulation software to evaluate the annual reduction in cooling energy consumption achieved by various roof configurations for commercial and residential buildings. Subsequently, an economic analysis is conducted by calculating the internal rate of return (IRR) and payback period for investment in each type of roof configuration. The findings show that roof assembly retrofits can reduce annual cooling energy consumption in commercial buildings by 8.65% to 16.25% and in residential buildings by 11.1% to 13.8%. Additionally, the total annual energy consumption decreases by 4.70% to 8.83% for commercial buildings, such as hypermarkets, and by 4.10% to 6.10% for residential buildings, depending on the insulation system applied. The economic analysis shows that the roof assembly insulated with a radiant barrier and thick enclosed air gap is the most economically beneficial option, offering the highest IRR of 20.60% and 6.79% for commercial and residential buildings, respectively, and the shortest payback periods of 4.6 years and 11.2 years, respectively. These results provide valuable insights to guide building owners and designers in choosing the most cost-effective type of roof insulation for new or existing projects.

Previous researchers have detailed the problems in measuring the thermal resistance value of a whole roof assembly under hot conditions due to the uncertainty of the outdoor environment. Currently, no established method exists to experimentally investigate an entire thermal roof performance under a steady-state condition. This article details the properties of the indoor solar simulator and the research methods undertaken to measure the thermal resistance value of roof assembly. The indoor solar simulator utilizes 40 halogen bulbs to accurately replicate sun radiation. Thermocouples and heat flux sensors are installed at several locations on the roof assembly to quantify the heat transmission occurring through it. The thermal resistance value is determined by adding up the average difference in temperature across the external and internal roof surfaces and dividing the total amount by the total of all averaged heat fluxes. Subsequently, this study investigates the thermal efficiency of residential roof assemblies that comprise various insulation materials frequently employed in Malaysia, including stone wool, mineral glass wool, reflective bubble foil insulation, and radiant barriers. The analysis showed that the roof configurations with bubble foil reflective insulation produce superior thermal resistance values when coupled with enclosed air space or mass insulation, with thermal resistance values ranging between 2.55 m2K/W and 3.22 m2K/W. It can be concluded that roof configurations with bubble foil reflective insulation resulted in high total thermal resistance and passed the minimum thermal resistance value of 2.5 m2K/W under the Malaysian Uniform Building By-Law 38 (A) requirements. Furthermore, the radiant barrier produced a high thermal resistance value of 2.50 m2K/W when installed parallel to a 50 mm enclosed air space, emphasising the crucial function of an enclosed air space next to a reflective foil to resist the incoming heat radiation. The findings from this research can help building professionals determine the optimum insulation for residential building roofs in Malaysia.

During severe flood and natural disaster scenarios, electricity power becomes an essential and critical element to ensure the operation of medical services, equipment and communication systems as the power stations will most likely be shut down. Delivering power source and potable water to disaster areas becomes a major obstacle during severe flooding following the rise of water level causing road transportation becomes inaccessible. Therefore, an amphibian trailer equipped with a hybrid solar photovoltaic (PV) and an ultra-water filtration system is a good solution as it can be deployed or towed to the disaster areas by either a boat or a pickup truck. The amphibian trailer is equipped with a hybrid standalone solar PV system with battery storage and a generator set that can supply approximately 25 kWh of electric power per day. An ultra-water filtration system is also installed on the trailer, and it is powered by the hybrid solar PV system. Aluminium is used to construct the chassis of the trailer to ensure that the trailer is lightweight, strong, durable, and anti-corrosion. The wheeled trailer is integrated with a fiberglass floatable pontoon to allow it to operate on land and water. More importantly, the amphibious trailer can be relocated easily based on the situation and needs. This paper describes comprehensively the design and development process of the solar amphibious trailer.

The trend in building energy consumption has been steadily increasing and will continue to rise significantly in the future. The application of a reflective insulation system in roof assembly is proven to be effective in reducing heat gain across the roof and can enhance indoor thermal comfort. This paper presents the development of an Indoor Solar Simulator to evaluate the thermal resistance (RSI value) of reflective insulation systems for roof assemblies. This paper also compares RSI values obtained experimentally and the RSI values listed in ASHRAE Standard. The roof assemblies studied in this paper incorporate the same reflective insulation systems as listed in ASHRAE Standard. Thermocouples and heat flux transducers are installed at various locations and the RSI values are calculated using the average method as detailed in ISO 9869-1:2014. From the error analysis, it can be concluded the RSI values obtained experimentally using the Indoor Solar Simulator and ASHRAE Standard are in a good agreement with MAPE value of 6.13%. These discrepancies could be due to the thermal bridges from mechanical supports inside the air gap, or possibly the air gaps are not completely airtight and unventilated.

The use of reflective insulation as roof insulation has become increasingly popular in Southeast Asian countries. It is proven to be effective at reducing heat gain through the roof and building energy consumption, as well as improving indoor thermal comfort. The present work is divided into three sections: field measurements of the thermal performance of reflective insulation in Malaysia, Computational Fluid Dynamics (CFD) analysis of reflective insulation in a gable roof system, and techno-economic analysis of roof thermal insulations for a hypermarket under the equatorial climate of Malaysia. Reflective insulation has proven to be an effective type of roof insulation for buildings in Southeast Asia, where the predominant heat flow direction is downward. Measured thermal resistance (RSI values) of roof assemblies with reflective insulations showed results in the range from 2 to 3 m2·K/W. A ceiling heat flux reduction of 80% was obtained for roofs with reflective insulation as compared to uninsulated roof attic. A validated CFD model showed that increasing the reflective air gap from 25 to 100 mm increases the RSI value of the roof assembly by 26%. Besides that, increasing the roof pitch from 30° to 45° increases the RSI value of the roof assembly by 30%. The techno-economic analysis showed that small bubble aluminum foil has the highest life-cycle savings and internal rate of return, as well as the shortest payback period. Although it does not yield the lowest annual cooling energy consumption, it is the most cost-effective type of insulation to be used as roof insulation under the hot and humid climate of Malaysia.

Global energy use shows that cooling and heating are responsible for the highest energy use in buildings. The trend in building energy consumption has been steadily increasing and is expected to continue to rise significantly in the future. The application of reflective foil in the form of reflective insulation and radiant barrier as a roof thermal insulation system is a potential means of reducing cooling energy in buildings, especially in the tropics. It is proven effective in reducing the heat gain across the roof and can enhance indoor thermal comfort. This paper reviews the thermal performance of reflective insulation and radiant barrier as a roof insulation system. Moreover, this paper also discusses and analyses various types of thermal performance test methods such as laboratory equipment, indoor test rig, field measurement, computational fluid dynamics, and building performance simulation. This paper also discusses several factors such as emissivity value, air gap thickness, weather, and climatic conditions on the thermal performance. Dust accumulation and prevention methods will also be discussed.

The ever-increasing temperature of current climate has brought the attention on reducing the incoming solar heat energy into buildings. The efforts on reducing the dependency on air-conditioning for indoor cooling has led to the implementation of passive cooling strategies in buildings. This paper investigates the implementation of reflective technologies in the form of reflective insulation and radiant barrier systems in a gable roof assembly. The thermal performance of reflective insulation and radiant barrier systems was investigated by using Computational Fluid Dynamics (CFD) simulation. The thermal performance of the reflective technologies was presented in terms of thermal resistivity, RSI value. The study was conducted for several roof configurations where the thickness of reflective air space, roof pitch and the roof material were varied. The results obtained from the CFD simulation was validated against empirical measurements to ensure the simulation gives high accuracy prediction. From the parametric analysis, it was found that thicker reflective air space would provide better air ventilation in the air space area which led to higher thermal resistivity. Besides that, steeper roof pitch would enhance the buoyancy effect and increases the heat exhaustion through the ridge which also results in higher thermal resistivity. In terms of roof tiles material, only small difference was observed in terms of thermal resistivity when switching the roof tiles material between clay tiles and concrete tiles. This research was able to demonstrate the use of CFD simulation in investigating thermal insulation technologies in buildings and this method should be explored further in the future.

The increasing demand of reducing energy consumption in buildings has led to the implementation of insulation material in roof assemblies to reduce heat gain through the roof. This paper investigates the thermal performance of reflective insulation and radiant barrier systems in a gable roof assembly by using computational fluid dynamics (CFD) simulation. In the first part of the paper, the experimental measurements using test huts under actual outdoor environment were detailed. The CFD simulation was then conducted and the results obtained from the simulation were validated against the experimental measurements. In the second part paper, the validated CFD model was then used to evaluate the reduction of heat flux transmission through the roof and the thermal resistance (RSI value) of the roof assemblies for various roof configurations, which are the thickness of reflective air space, the roof pitch and the roof material. The study showed that increasing the reflective air space thickness from 25 mm to 100 mm has increased the total RSI by 26% for both roof pitch of 30° and 45°. Besides that, increasing the roof pitch of the roof from 30° to 45° showed that biggest impact on the thermal performance of the roof, as the RSI value increases by 30%. In terms of roof tiles material, only small difference was observed in terms of thermal resistivity when switching the roof tiles material between clay tiles and concrete tiles.