Hotels' cisterns to use air conditioning condensate to flush toilets

July 5, 2017

Photo courtesy of Adrian Sherratt Photography

What’s believed to be the world's first cistern to use condensate from air conditioning units to flush toilets has been launched and would save 2.4 billion liters of water a year for English hotels under construction.

Encore uses a free, sustainable water supply that has previously been drained to waste, according to a release. The technology is also suitable for villas, apartments, offices and any facility that houses toilets and air conditioning.

The Encore units will be installed in 302 MENA hotels being developed in England, officials said.

"Air conditioning units have a pipe that drains all the condensate away. When you consider how many buildings use air conditioning globally, billions of liters of condensate water is generated, all of which has been wasted – until now,” said David Davis, Encore technical director. "All buildings need toilets, so why wouldn't you use a cistern that recycles a free, sustainable water source especially when there is a global water shortage crisis?"

Encore allows architects, consultants and specifiers to secure two extra LEED points and BREEAM credits for using the cistern, according to the company.

Water savings 

Data from hotel specialist STR Global shows that 93,984 rooms in the 302 MENA hotels are currently being built in the region. Compared to traditional cisterns, using Encore would save the average 311-bed MENA hotel 7.9 million liters based on standard 80 percent occupancy levels. 

In total, Encore would save the operations 2.4 billion liters of water a year, filling the equivalent of 960 Olympic swimming pools.

How it works 

Encore units hold 18 liters of water – three times more than a conventional cistern but its dual-chamber design means it fits like standard models. 

The bottom chamber holds six liters, which comes from the main water pipe. The upper 12-liter chamber is filled with air conditioning condensate. 

When the toilet is flushed, the lower chamber empties then refills with condensate from the upper chamber. If there are multiple flushes close together or the air conditioning is not in use, the cistern is filled by the main fed pipe. 

If the toilet is not used for a period, surplus condensate is fed away.

Topics: Building Owners and Managers, Construction Firms, Consulting - Green & Sustainable Strategies and Solutions, Energy Saving Products, Engineering Firms, Environmental Firms, Hospitality, Plumbing, Sustainable Communities, Urban Planning and Design, Wastewater Management / Wastewater Treatment, Water Saving Strategies and Devices

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