The North of England Zoological Society (NEZS) runs Chester Zoo, the UK's number one charity zoo, which cares for over 7,000 animals and over 400 different species. Some 1.3 million people visit the site every year. As part of its commitment to the care and conservation of these animals, the NEZS has recently upgraded the environmental controls in three of its animal enclosures at the zoo to achieve significant operational and energy efficiency gains.
Systems integrator, JBC Controls has been working on projects for Chester Zoo over the last five years and the company was appointed to work on this latest project, which involved the integration of variable speed drives on fans supplying air to the ‘Spirit of the Jaguar’, ‘Elephants of the Asian Forest’ and Penguins enclosures within an existing building management system (BMS).
The drives chosen were IP55 rated Danfoss VLT units, which were retrofitted adjacent to existing plant. The fan supplies were rewired to comply with current EMC practice as well as Danfoss’ own standards, the IP55 rating avoiding any need to provide additional protective enclosures.
This is the largest single energy saving project undertaken to date at Chester Zoo and, according to data gathered since the addition of the VSDs, it has more than met expectations, achieving the twin benefits of reduced running costs as well as improved animal welfare.
The VSDs optimise efficiency through the introduction of a ‘demand matching’ control strategy for the installed HVAC equipment. Previously, the motors had to run 24 hours a day at a fixed speed. Now, for the first time, the zoo is able to match the speed of fans (or pumps, in the case of the penguin enclosure) to the demand of the system, with ventilation and seasonal demands now easily met with no adverse effect on environmental conditions.
The area where the greatest success has been realised is in the elephant house. An outside air temperature sensor linked to the BMS controls enables the modes of operation to be determined between summer and winter settings, based on ambient conditions. This basic control optimisation, coupled with a ‘demand matched’ ventilation strategy has resulted in energy savings of up to 78% being recorded. Indeed, some 55% of the savings are directly attributable to the drives, thanks to the ‘cube law’ effect, which sees energy consumption halved for just a 20% reduction in fan speed. Moreover, speed control has eliminated the potentially disturbing effects of motor start/stop noise, resulting in an unforeseen animal welfare benefit.
Meanwhile, over at the penguin enclosure, the water filtration plant has been fitted with three 18.5kW drives - two in duty and one on standby - to control water circulation to the pool area where flow is reduced automatically to 70% at night via a timer. While the improvements were not as dramatic as those recorded in the elephant house, nonetheless a positive effect was evident immediately after the drives were installed. The average energy savings per month to date of 40% in this area are directly attributable to the drives. The total cost of electricity consumption in the penguin enclosure for 2008 was £29,000 and the estimated electricity bill at the end of 2009 is £17,000 based on year-to-date consumption figures - a potential cost saving of £12,000. The cost of installing and commissioning the drives was around £10,000, meaning that within 12 months Chester Zoo is likely to recoup its investment and, of course, profit from the greater energy efficiency of the plant thereafter. Two more unexpected benefits are reduced noise in the plant room, together with improved water quality due to more effective use of the continuous UV purification system.
Over at the jaguar enclosure there are two drives (one 11kW and one 7.5kW) controlling fresh air circulation via BMS control in a similar manner to the elephant area. The ventilation system is enabled by heating or cooling demand from room temperature sensors. However, as a safety measure, should the circulation system be off and the CO2 level increases, the ambient temperature system is overrided and fresh air is automatically recirculated. Clearly, in this application, environmental performance is equally as important as any longer term financial gain, as Chester Zoo’s maintenance manager, Ray Morrison explains.
“At Chester Zoo we adopt the principle of ‘triple accounting’; our performance is measured by how well we perform financially, environmentally and in terms of corporate social responsibility. Every pound saved is a pound that can be re-invested in animal welfare and conservation projects world wide, such as supporting Asian elephants in their natural habitat.”
In terms of environmental management, Chester Zoo has been ISO14001 compliant since 2004. It was the first zoo in the UK and the first major zoo in Europe to gain this accreditation and its commitment was once again recognised in 2006 when it received the Queen’s Award for Enterprise in the category of Sustainable Development.
These recent installations are part of Chester Zoo’s energy management plan, which is being implemented in order to reduce its environmental impact and to control costs. Energy use is constantly monitored and logged to identify opportunities for renewable technologies. The zoo has adopted the Building Research Establishment’s environmental assessment method (BREEAM), and its long term plan is to become carbon neutral, aiming for a 10% reduction in energy consumption across its 110 acre site. The drives installation is seen by all parties as being a major step towards this goal.
Monthly energy cost reductions are already estimated to be in the region of £3,000 thanks to the long term investment in technology, which by any standard is a financial success story. But beyond this simple cost accounting consideration, it is also a confirmation of the zoo’s dedication to animal welfare and the sustainability of its operations.