David Davis, Technical Director of Encore Cistern with their product at Bramley Baths, Leeds (12 April 2017).
LEEDS, UNITED KINGDOM—The world’s first cistern to use condensate from air-conditioning units to flush the toilet has been launched and would save 4.7bn liters of water a year for the 1,477 U.S. hotels currently being built.
Encore is the most environmentally friendly cistern as it uses a free, sustainable water supply that has previously been drained to waste.
Encore is also suitable for offices, apartments, leisure centers and anywhere with toilets and air-conditioning.
In another first for cisterns, Encore allows architects, consultants and specifiers to secure two extra LEED points—the US Green Building Council’s gauge for sustainability.
Encore Technical Director, David Davis, said, “Air-conditioning units have a pipe that drains all the condensate away. We’ve developed the only cistern that uses this free water to flush the toilet.”
“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.
“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?” Davis asked.
Water Savings
Data from hotel specialist STR shows 191,832 rooms in 1,477 hotels are currently being built in the United States. Compared to traditional cisterns, using Encore would save the average 130-bed U.S. hotel 3.19m liters based on standard 80 percent occupancy levels.
In total, Encore would save them 4.7bn liters of water a year, filling the equivalent of 1,880 Olympic swimming pools.
How It Works
Encore holds 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 6 liters, which comes from the mains 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 air-conditioning is not in use, the cistern is filled by the mains fed pipe. If the toilet is not used for a period, surplus condensate is fed away.
The Invention
Encore was invented by David Davis and Graham Kelly, directors of the U.K.-based G&H Group, a $31 million Building Services company.
“For decades we’ve designed and installed schemes and watched the stream of water produced by air-conditioning units literally go down the drain but not via the toilet,” adds Davis. “Responsible businesses striving to construct the greenest buildings know how hard to get LEED points are. Gaining two for choosing an Encore cistern is simple and a great advantage.”
Encore is as easy to fit as a conventional cistern, is compatible with industry standard rack mounting and unlike other environmentally friendly technology that uses reclaimed water such as rainwater harvesting systems, there’s no expensive initial cost or long pay back period.
Encore does not use electric pumps. Instead gravity feeds condensate water into the cistern.
