Cool for cats...

...and elephants and penguins - all saving energy thanks to the North of England Zoological Society, a charitable organisation that runs Chester Zoo, which recently installed variable speed drives in three of its enclosures

Since the installation of varial speed drives at Chester Zoo, energy savings of up to 78% have been achieved. The new plant will pay for itself within a year and after that the zoo will save approximately £12K a year in electricity bills alone.

The zoo has 1.3 million visitors a year, cares for more than 7,000 animals, representing over 400 different species, and contributes to their protection through a combination of zoo and field-based conservation. JBC Controls, in conjunction with Danfoss Drives, have installed VSDs in three of its animal enclosures: jaguars, elephants and penguins. Existing systems were upgraded to save energy and increase efficiency.

Glyn Berry, sales director of JBC Controls explains: "All drives have been retrofitted adjacent to the plant they control. As the plant is existing we have had to rewire the fans' supplies to comply with the EMC directive and standards set out by Danfoss. The beauty of the drives being in IP55 enclosures meant there was no need to provide additional protective enclosures."

JBC Controls and the zoo have a longstanding relationship. This combination of applications is the largest single energy saving project undertaken to date and looks to be the most rewarding according to data gathered since the addition of the VSD's, reducing running costs while improving animal welfare.

The greatest success has been realised in the elephant house. Controls have been optimised with the installation of an outside air temperature sensor so modes of operation can vary between summer and winter. This optimisation, the installation of the Danfoss drives and a demandmatched ventilation strategy has resulted in energy savings of up to 78%; 55% of the savings are directly attributable to the drives. A reduction in speed of 20% has reduced energy
consumption over 50%. The ability to control speed has eliminated motor start/stop noise that could potentially disturb the elephants, an unforeseen welfare enhancement benefit for animal management purposes.

The water filtration plant in the penguin enclosure has three 18.5kW drives that control water circulation to the pool area and automatically reduce the flow of water to 70% at night. Its positive effect was evident immediately.

Average energy savings per month to date of 40% in this area are directly attributable to the drives. The cost of electricity in 2008 was £29K and the estimated penguin plant electricity bill at the end of 2009 is £17K, a potential saving of £12K. The cost of installing and commissioning the drives was £10K, meaning that within a year the zoo may profit from a greater return on their
investment than projected.

The jaguar enclosure has two drives controlling the surrounding fresh air in a similar manner to the elephant area, via a BMS control.

Ventilation is triggered by heating or cooling demand from room temperature sensors. In addition, should the system be off and the CO2 level increase, it will automatically turn back on.

VSDs have enabled the zoo to improve efficiency by adopting a demand-matching
controls strategy, fundamental to the reduction in energy consumption on the HVAC equipment in the elephant house and the jaguar enclosure.

Previously, motors had to run for 24 hours at one speed. Now, the speed of the motor can be matched to the demand of the system and the AHU switched off if heat, cold or a change in air quality is not required.

As part of Chester Zoo's compliance with Environmental Management Standard ISO14001, awarded to the zoo in 2004, the company pledges in its environmental policy statement "to achieve such improvements in environmental performance, the zoo has set, and will maintain, review and revise, environmental objects and targets with the aim of continually improving our environmental performance".

The zoo was the first in the UK and the first major zoo in Europe to gain accreditation and see this international management standard as their bible in terms of demonstrating and improving environmental credentials, a commitment recognised in 2006 when the zoo received the coveted Queen's Award for Enterprise for Sustainable Development.

Chester Zoo is implementing its energy management plan, aimed at delivering energy conservation and efficiency by developing operational and technological excellence to reduce environmental impact and control costs.

Energy usage is monitored using data loggers in high consumption buildings to identify opportunities for renewable technologies. The buildings environmental assessment method has also been adopted in relation to the zoo's capital development programme. A long-term plan is to become carbon neutral, aiming for a 10% reduction in energy consumption.

The purchase and installation of Danfoss VSDs via JBC Controls is seen as a major step towards continual global environmental compliance and best practice, with an estimated £3,000 reduction in monthly energy costs.

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