RACA Journal June 2016 - Page 33

Feature Continued from page 29 Mediclinic – the proof is in the figures In the September 2015 edition of RACA Journal, we featured the Mediclinic Morningside project on our front cover, the country’s first ice storage system in a medical facility.  Mediclinic Morningside’s original chilled and hot water generation systems were installed 28 years ago. The eventual plant unreliability necessitated replacement of this system. The existing HVAC plant was tired, and cooling and hot water supply were problematic. And so, the upgrade of the system was approved, giving the go-ahead to replace the old heat pumps and chillers with newer, more efficient equipment. The team decided to go with an ice storage system, originally considered to manage maximum demand and counteract the ‘time of use’ electrical tariff structure by Eskom. “Although the tariff structure has to date not yet been implemented, the possibility of managing the demand by using ice rather than starting another chiller, proved, in fact, to be very economical,” said Rudolf Burger, Mediclinic’s regional technical operations manager for southern Africa at the time.  The retrofit HVAC system consists of two new Clint chillers: one 488kW (base load chiller) and one 421kW (ice chiller), five 500kW Calmac ice storage tanks, and two Mtech heat pumps (45kW heating capacity each). The biggest challenge according to Burger was to ensure that the equipment was the right size and to integrate the new system with the existing one without too much down time or inconvenience to the hospital. It was vital to ensure that the ice storage system could accommodate the constant demand of the medical facility without wasting energy or capacity. The tricky part is to keep in mind that technology changes constantly as does the heat load and ambient temperatures. “You have to provide for all of these variables without oversizing,” says Burger.  Now, 18 months later, we checked back with Burger to see how things were running. “We are very happy with this system and we’re thinking of possibly converting another one of our chiller plants,” says Burger. They have seen huge savings in their energy bills, especially by being able to manipulate the maximum demand. “The load clipping has been much more beneficial than we could ever have anticipated,” says Burger. On cool days, the ice will get the facility through most of the day, but usually it can provide for about half a day. The team is now planning on adding extra ice storage tanks to the system as the chillers aren’t ru nning at full capacity yet. Currently the chillers make ice for about five and a half hours of the night and with the extra ice tanks, they will be working the full eight hours.  All and all, the figures are looking positive for this installation. “Not to mention that we get a lot less complaints from employees and patients alike compared to our previous (much more unreliable) system,” says Burger.  So if it works so well, why don’t more people go the ice storage way? “Well, it’s a huge investment,” says Burger. “People tend to go for the low hanging fruit and proven systems first when it comes to energy savings – things like changing the lighting and doing normal heat recovery. It’s much cheaper (and a lot less complicated) than changing your chiller. It’s definitely worth it, though – but you have to evaluate each system on a case-by-case basis.” Check out below the difference in electricity use since the system came online. There is a significant drop. Continued on page 33 www.hvacronline.co.za RACA Journal I June 2016 31