• Energy Research

Energy consumption to cool an indoor environment is a substantial part of total energy end-use, particularly in a tropical climate with high energy demand for cooling. To improve energy efficiency, cooling systems can be optimized using a variety of neutral indoor temperatures to maintain a balance between an occupant’s thermal comfort and cooling energy demand. This explanatory study investigated the thermal quality and cooling energy demand of a Platinum-certified office building in the tropical climate of Malaysia. The investigation aimed to suggest a balance between occupant thermal comfort and cooling energy demand. The thermal investigation includes an objective field measurement that implements environmental equipment to monitor thermal quality and a subjective occupant’s thermal feedback using a questionnaire survey. To calculate cooling energy demand, the total equivalent temperature difference method (TETD) is applied. The results suggested an occupant’s cooling sensation of around 24 °C, with no significant difference concerning age and gender. Cooling load calculation indicated a 36% energy reduction by increasing air temperature to 26 °C, for occupants to feel thermally comfortable in a tropical climate. These findings contribute to improving sustainable energy policies, sustainable construction, and thermal comfort improvement for a tropical climate.

Abstract Identifying new energy saving methods in the building sector is essential due to limited natural energy sources and the rising population. Thermal mass materials have the ability to absorb and store heat before releasing it later on when necessary. They act as heat sinks during the daytime and as heat sources during the nighttime. Thermal performance is evaluated according to the specific heat capacity and specific latent heat. Applying thermal mass materials such as concrete is deemed a suitable strategy to reduce the energy consumption of buildings. Concrete with low thermal conductivity and high specific heat capacity is desirable in building construction. The aim of this study is to review factors affecting the heat storage capacity of concrete. In addition, common measurement methods of cement-based materials’ thermal conductivity, thermal diffusivity and specific heat capacity are reviewed. Various studies reveal that temperature, humidity, aggregate type, cementitious material type as well as phase change material (PCM) used influence the thermal properties of concrete. The advantages and limitations of PCM-concrete are also summarized in this study.

The quality of the indoor environment has become a vital component for buildings due to the time spent indoors. To this extent, the performance of the indoor environment is considered as part of the greenery criteria by green rating schemes such as the Green Building Index in Malaysia. This study aims to investigate and assess the quality of the indoor environment of Platinum-certified office buildings in a tropical climate. This research applied a case study approach over two Platinum-certified office buildings. Post-occupancy evaluation is employed integrating full-scale measurement with an occupants’ survey. The measurement was carried out from May to August, and 112 questionnaires were retrieved to evaluate occupants’ satisfaction with aspects of the indoor environment. Thermal comfort, indoor air quality, acoustic, lighting, furniture, and cleanliness are considered as the main study variables. The findings of full-scale measurement indicated high relative humidity, and low air velocity and illuminance. While occupants reported overall indoor environment quality (IEQ) comfort, a significant correlation of variables was observed. The main sources of dissatisfaction were identified as overcooling around 24 °C, high relative humidity (RH), around 70% RH, glare, and background noise around 51.9 dB. Statistically, a significant difference between occupants’ responses to IEQ of two cases was identified, although both buildings are labelled with a Platinum certificate.

Replace the normal weight aggregate with wastes or by-products materials is an appropriate method for producing a sustainable cement-based material. The replacement helps to have an energy-efficient component that reduces environmental impact. Time lag and decrement factors are vital wall system variables to evaluate thermal energy consumption in buildings. Thus, this study investigates the thermophysical properties of an innovative sustainable mortar and concrete containing oil palm boiler clinker (OPBC) as fine and coarse aggregate through an experimental approach. Then, time lag and decrement factor in different wall systems are calculated based on EN ISO 13786 through Python 3.7 (NumPy and math modules) and optimized using the response surface methodology (RSM). The results indicated mortar with OPBC has a slightly reduced decrement factor and increased time lag compared to a typical mortar. More significantly, the decrement factor of OPBC concrete was reduced by 34%, and its time lag increased up to 58% compared to conventional concrete.

Indoor Environmental Quality (IEQ) is an important topic which impacts on occupant health, productivity and also energy consumption in buildings. The four main parameters for IEQ evaluation are: Thermal comfort, indoor air quality, visual comfort and aural comfort. The occupant behavior in buildings defines as any direct or indirect act which an occupant selects to change the displeasure environmental condition into the comfort conditions. The selected behavior by human has a significant impact on the energy consumption in buildings. This paper reviews the methods which used to simulate IEQ parameters, energy consumption and human behavior in buildings. It aims to promote the idea of more consideration about the relation between occupant behavior and energy usage in buildings. This summary of existing studies about the importance of human behavior factor in energy simulation software helps to identify new methods and strategies for simulating IEQ, Energy and behavior.