How 40,000 people are kept cool during prayers inside the Sheikh Zayed Grand Mosque

Huge pipes under floors and in walls are flooded with chilled water, reducing air temperatures in the process

An engineer adjusts the settings at a Tabreed district cooling plant in Abu Dhabi. All photos: Khushnum Bhandari / The National

The system consists of a pipe network filled with water cooled by the plant

The water is piped to Sheikh Zayed Grand Mosque, where it lowers the temperature, before returning to the plant to be cooled again

The control room at the district cooling plant

The system has kept thousands cool, without the need for noisy and bulky air conditioners

Fatima Al Marzooqi, Senior Engineer.

The water piped to the mosque is about 5°C

In 2022, Tabreed added 34,454 refrigeration tons of new connections in the UAE

Chiller plant room with six units at Tabreed cooling plant, Abu Dhabi

Tabreed’s energy efficiency meant 2.31 billion kilowatt hours saved across the GCC in 2022

Staff on a control panel at the plant

Chiller plant room with six units at Tabreed cooling plant

A staff member at a control panel at the plant

An intricate energy-saving cooling system using chilled water has helped keep thousands of UAE residents cool inside the Sheikh Zayed Grand Mosque in Abu Dhabi during Ramadan prayers.

Tabreed, the district cooling provider that works around the clock, has kept the thousands of worshippers that arrived for prayers cool during the holy month.

This year, more than 60,000 people filled the grounds of the Grand Mosque on the 27th night of Ramadan, with about 40,000 inside.

Despite the nights being cooler at this time of year, having that many people inside one building can raise the temperature of the room significantly.

While not exerting energy, the human body radiates about 100 watts of heat per hour, which means that on Monday night up to four megawatts of heat need to be cooled at once.

How the process works

The system consists of a pipe network filled with water that is chilled by district cooling plants.

The chilled water travels from the plant to the building, cools the space and returns to the plant to be cooled again in a never-ending cycle of recycled cool and warm water.

The system is sustainable, energy-saving and keeps the temperature consistent.

During a tour of one of their plants, senior scheduling engineer, Fatima AlMarzooqi, said that a vital part of their job is to provide cooling to every single person.

“The temperature inside the mosque should be constant, whether there is only one person inside or thousands. So, we constantly monitor the temperature of the water that returns to the plant,” she said.

At the plant responsible for cooling the Grand Mosque, the screens blink showing a temperature rise and the pumps automatically start pumping more chilled water.

Providing cooling to tens of thousands of people, such as during the last ten days of Ramadan when thousands gather at the Sheikh Zayed Grand Mosque at one time, is not challenging but does require constant monitoring.

Constant cycle of reusable water

The water travelling through an underground network that goes around the mosque’s walls is at around 5°C. It comes back measuring around 10°C.

“So there is an obvious spike, which you can see on our screens and so in layman’s terms we open the taps further and increase the flow,” said Ms AlMarzooqi.

The peak time was between 1am to 2am, which was during midnight prayers.

At that time, up to 1,876 gallons of water was travelling through the pipes per minute.

“When you consider how much heat is generated by enormous groups of people sharing the same space, you can see how important it is for us to plan, monitor and adjust cooling loads in real time, all the while visitors remain unaware of what is going on behind the scenes.

"And it’s a process that we carry out proactively, gradually increasing the chilled water supply hours ahead of the arrival of worshippers to ensure there are no spikes in demand – our aim is to make everything as seamless and enjoyable as possible for everyone,” Ms Al Marzooqi said.

Chilling the region

From commissioning its first district cooling plant in Sweihan, Abu Dhabi in 1998, Tabreed has grown to 86 plants today across the GCC.

In 2022, Tabreed added 34,454 refrigeration tons of new connections in the UAE.

A refrigeration ton (RT) is a unit of power used to describe the heat-extraction capacity of air conditioning equipment.

In the same year it added 19,202 RT in Oman and 500 RT in Bahrain — increasing the company’s total connected capacity to 1,264,252 RT.

Tabreed’s energy efficiency meant 2.31 billion kilowatt hours saved across the GCC in 2022 — enough to power approximately 132,000 homes every year and prevent the release of 1.38 million metric tons of CO2 into the atmosphere, which is equivalent to the removal of approximately 300,000 vehicles from the roads annually.

The company also provides cooling to the Burj Khalifa, Dubai Mall, Dubai Opera, Cleveland Clinic, Ferrari World, Yas Mall, Aldar HQ, Etihad Towers, Marina Mall, World Trade Centre in Abu Dhabi featuring the Burj Mohammed Bin Rashid, Dubai Metro and Dubai Parks & Resorts.

Record 60,000 people pray at Sheikh Zayed Grand Mosque — in pictures

More than 60,000 worshippers attend Sheikh Zayed Grand Mosque in Abu Dhabi to mark Laylat Al Qadr. All photos: Wam

This is the largest number of worshippers hosted by the grand mosque since its opening, said news agency Wam

Laylat Al Qadr — or the Night of Power — has a special significance in Islam. It is one of the odd-numbered nights during the last 10 days of Ramadan in which the first verses of the Quran were revealed to the Prophet Mohammed

Many Muslims are keen to spend the last 10 nights of the holy month in worship, prayer and acts of kindness

The reward for any good deed or act of worship conducted on that night is counted as more than 1,000 months of doing it