With the pandemic still posing a threat to the lives of many, the government of Saudi Arabia has set strategic plans to implement all necessary precautionary measures at the Two Holy Mosques for this year’s Ramadan to ensure the health and safety of the Guests of Allah.
Al Salem Johnson Controls (YORK), a leading ‘one-stop destination’ for integrated solutions, including HVAC, Building Management and Control Systems and Aftermarket Services, stated that the HVAC System is a vital part of these precautionary measures. It will control temperature, humidity and the purity and freshness of cold air inside the Two Holy Mosques for infection control and prevent its spread.
The two cooling plants for the Holy Mosque in Makkah (Shamiya and Ajyad) and the Prophet’s Mosque in Medina (the Central Cooling Plant) are among the largest cooling plants in the world. The YORK HVAC System in the Two Holy Mosques is divided into two parts: YORK Chillers inside the cooling plants, and the Saudi-made YORK Air Handling Units distributed inside the Two Holy Mosques, which distributes the cool and fresh air.
In light of the ongoing pandemic, the importance of Air Handling Units becomes more crucial than any other time, as these Units ensure the quality, freshness and purity of the indoor air through a highly efficient filtration technology. This limits the spread of diseases and airborne viruses and prevents dust particles from passing through the air-ducts. YORK’s Air Handling Units also guarantee the comfort of pilgrims and worshipers, as well as protect the structure of the Two Holy Mosques by controlling temperature and humidity levels and balancing the airflow.
The YORK Chillers cool the water and then pump it to the Air Handling Units, where a heat exchange occurs between the warm air entering the unit and the chilled water inside the tubes. As the cold fresh air flows to all parts of the Two Holy Mosques, the warmed water that absorbed the entering air temperature returns to the cooling plant to be re-cooled inside the chillers and re-pumped to the Mosques.
The chilled water flows in a closed circuit, meaning that it does not directly touch the air. Therefore, on the one hand, the air is not affected by the refrigerant, and on the other hand, no airborne microbes or bacteria enter this water. As a result, when the Chillers reject the heat absorbed from the air of the Mosques outside the district cooling plants into the atmosphere, accompanied by small amounts of water vapor, it is free of any biological or chemical pollutants. This preserves the safety of the environment and the health of individuals in the areas surrounding the cooling plants.
Ina continuous cycle, the air moves around the Two Holy Mosques, absorbing heat from the atmosphere and the pilgrims’ bodies, catching dust particles and some airborne bacteria or microbes on its way to the YORK Air Handling Units. Inside the Units, this air first passes through several highly efficient filtration stages to trap the dust and microbes, and then it flows over the cooling coils containing the chilled water. The filtered, fresh, cooled and dehumidified air then blows out of the Units into the Mosque to repeat its cycle. The YORK Air Handling Units control the fresh air flow rates through several technologies, including partial closure of the air outlets or through a Variable Speed Drive connected to the fans for speed control, thus the flow rates as needed.
In terms of energy efficiency, the company stated that this is achieved through controlling the fresh air flow from the Air Handling Units on the one hand, and controlling the cooling capacity and energy loads of the Chillers on the other hand, based on the congestion inside the Two Holy Mosques. For Chillers, the difference in temperatures of the chilled water flowing back and forth between the Chillers and Air Handling Units indicates the momentary congestion inside the Mosques. Thus, both the cooling capacity and power loads are reduced when the number of people is limited, while raised at peak times, such as prayer times.
It is worth mentioning that the YORK HVAC Systems in the Two Holy Mosques have been designed keeping in mind the crowded nature of both places throughout the year, especially during the peak seasons of Ramadan and Hajj.
The Aftermarket Team at Al Salem Johnson Controls (YORK) plays a pioneering role in the operation and maintenance of the HVAC system of the Holy Mosque in Makkah throughout the year. During the pandemic, with a lower number of visitors, some YORK Units have been shut down based on the decreased cooling capacity that has been required. The Team carries out regular preventive maintenance for these units (both Chillers and Air Handling Units) to ensure their full operational and cooling efficiency when restarted at any time.