Isolation rooms are crucial in healthcare facilities to prevent the spread of infectious diseases. Infectious diseases can be transmitted to humans from humans or through animals known as zoonoses. With the increase in the number of COVID-19 cases, isolation rooms have become one of the most critical facilities in hospitals. Maintaining the correct temperature and humidity in these isolation rooms is a challenge, considering the heating, ventilation, and air conditioning (HVAC) systems that continuously consume large amounts of energy. With the application of energy conservation methods, the total energy consumption of HVAC systems can be reduced. Many studies have shown that the heat pipe heat exchanger (HPHE) technology can contribute significantly to energy savings using HVAC systems. In this study, the effectiveness of an HPHE on an HVAC system in an isolation room was examined, and the total energy reduction was quantified. The HPHE consisted of two rows with ten heat pipes in each row, arranged in a staggered configuration with fresh air temperature and mass flow variations. The inlet fresh air temperatures varied at 32, 35, 37, and 40 °C and fresh air velocities at 1.2, 1.6, 2.2, and 2.6 m/s. Using a chiller, the inlet fresh air was cooled to a comfortable temperature zone, approximately 24.4–25.2 °C, in the isolation room. Notably, higher velocities decreased the effectiveness of the HPHE. An increase in the flow rate enhanced the system, thereby improving the heat recovery value. The increase in the inlet fresh air temperature from 32 °C, that yielded an energy saving of 1.23 W, to 40 °C, resulted in a further energy saving of 1.85 W. The application of the HPHE in the HVAC system in isolation rooms represents a significant innovation that contributes to a reduction in total energy consumption.

One way to overcome the scarcity of clean water through sustainable approach is by utilizing a solar distillation system. This easy-to-use technology is adopting tubular solar distillation. The three main components, which are the most essential for producing the amount of permeate, are the solar collector, tubular and heat exchanger (HE). This study aims to determine the performance of a tubular solar distillation device equipped with HE using a parabolic trough collector (PTC). The PTC has an area of 5.1 m² covered with a solar reflective chrome film. Aluminum tubular acts as the feedwater heater. The HE is placed inside the tubular, which acts as a coolant to convert the steam phase into freshwater/permeate and as a feedwater heater to flow into the tubular. In the present study, several parameters were tested: comprise temperature, solar radiation, pressure, humidity, mass flow rate, permeate productivity and efficiency. This study demonstrated the production of a sufficient amount of permeate, which was 5.32 L for 6 h. The efficiency of this device yielded a peak of 48.2% during solar radiation of 813 W/m² in an average ambient temperature of 32 °C, with an overall average of 44.59%.

Indonesia has been blessed with excellent solar heat distribution, which can be used as renewable energy to heat water. Various technologies have been developed to utilize these inexhaustible thermodynamic resources, in the form of photons arrays, converted into concentrated heat for daily use, i.e., solar water heater. This renewable-based water heating system can provide significant energy efficiency, benefit the environment, and reduce energy use costs. This experimental study attempts to harvest the energy from the sun using a cylindrical through collector (CTC) type solar concentrator. The CTC was made of the solar reflective film (SRF) affixed to concentrator collector surfaces which was then mounted on an adjustable angle frame of the concentrator collector support. The heat generated from the concentrator was stored in water, and phase change material is embedded in the system to retain the heat longer. The research was carried out in Langsa City, Aceh, Indonesia. The results showed that water heaters using CTC systems could produce 16 L of hot water retained at 40–60 °C for four hours. With the addition of beeswax, the water temperature of the same capacity can be maintained at 40–60 °C for around 5 h. This technology demonstrated an excellent result that produces as much as 60 L of water per day, increasing solar thermal energy efficiency. This technology presented a great potential for replication or even for further development on an industrial scale.

The air conditioning system is the most common way to provide comfortable room temperature for its inhabitants. However, the energy required for its operation is extremely high and cost-intensive. Therefore, a more efficient HVAC system with a lower energy consumption is desirable. The experimental results and performance analysis demonstrated that the outlet air temperature through the evaporator side of HPHE (precooling) has the potential to save some amount of energy utilizing an HVAC system equipped with HPHE. This research aims to study the performance of HPHE with the precooling process applied in commercial room HVAC system applications. This research on the utilization of HPHE for heat recovery in air conditioning systems was carried out with variations in temperature of fresh air intake ranging between 32–42 ℃. The airflow speed was set constant at 1.0 m/s. This experiment demonstrated the highest effectiveness at a value of 21%. The HPHE heat recovery analysis results show that the best heat recovery performance is achieved when the fresh air intake temperature exceeds the exhaust air leaving the room. The phenomenon was compared at a low fresh air intake temperature of 32 ℃, which succeeded in recovering 0.05 W, and when the temperature rose to 42 ℃, 0.21 W was recovered.

Generally, the foam concrete that designs as the current building wall is without considering the heat absorbent. Therefore, it is necessary to find additional materials that able to absorb the heat energy. One of them is Phase Change Material (PCM). Beef tallow is an organic material of PCM that has a high heat storage capability. Commonly, an aggregate requires in the manufacture of foam concrete as reinforcement materials. This aggregate can be changed with macro-encapsulation of PCM. This study aimed to find the ability of foam concrete based macro-encapsulation of beef tallow/damar gum in absorb heat energy that will be applied in building walls. This research was conducted experimentally with the primary materials of cement, fine sand, water, foam agent, catalyst, sika, and macro-encapsulation of beef tallow/damar gum. This foam concrete wall was made with the dimension of 80 x 80 x 10 cm and varied with a mixture of beef tallow / damar gum of 0%, 1%, 3%, and 5%, respectively. The wall concrete heater was simulated with using four lamps with the power of 200 watts. The type-K thermocouple was placed on samples at 2 points, inside and on the surface, which connected with Agilent 34970A. The results showed that the effect of adding PCM resulted in a decreasing of the temperature inside and on the surface of foam concrete walls. The amount of temperature decreases due to the addition of 5% PCM is from 51.9 °C to 44.7 °C or decreased by 13.87% inside of foam concrete walls and 75.64 °C to 51.9 °C or down to 21.87% on the surface of foam concrete walls. Overall, this foam concrete based macro-encapsulation of beef tallow/damar gum is better to use as heat-absorbent in building wall application compare with foam concrete wall without using macro-encapsulation of beef tallow/damar gum.