CHRISTCHURCH A q u i f e r C o o l i n g Justice and Emergency Services Precinct

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1 CHRISTCHURCH A q u i f e r C o o l i n g Justice and Emergency Services Precinct

2 AQUIFER COOLING Christchurch is built on an ancient river delta Gravel deposits have covered the surface, before the water flowed on top again The process has repeated again and again - there are now several layers flowing beneath our feet up to six at any point The Aquifer is a constantly replenished heat sink at a steady temperature of 14 C

3 ECONOMICS Situation Water cooled reversible chillers provide heating and cooling The coolant water exchanges heat with the Aquifer instead of the atmosphere. In Summer, it is more efficient to cool the condensers with 14 C aquifer water than 30 C air In Winter, it is more efficient to heat the evaporator with 14 C aquifer water than 2 C air

4 ECONOMICS For Engineers 40,000 m 2 building 3MW Cooling, 2MW Heating 150 l/s bore water take (est) $250,000 Aquifer Plant (bores, pumps, exchangers, filters, reticulation) (est) 60% Improvement to peak conditions cooling C.O.P. (est) 120%+ Improvement to heating C.O.P. at 10 C outdoors AND can operate when outdoors is below 8 C so it can operate when its below 0 C outdoors without boilers!

5 ECONOMICS For Clients (est) 3.5 years Simple payback (heating only) (est) 40% 25y NPV Improvement (heating only) (Compare LPG) (aprox) 0.1% Capital Additional Cost

6 6 C Plant 6-14 C Loop Additional Cooling 14 C Plant Up to 130 W/m 2 sens. Heat Exchanger Deep Aquifer 14 C Shallow Aquifer 19 C ENGINEERING Schematics

7 Chilled Beams Cooling in large buildings is done with chilled water, produced by our efficient giant heat pump. The chilled water is used by air-conditioners in each office or space. Most air-conditioners use chilled water at 6 C, and need a fan to blow air across the unit. Chilled Beams and Under Floor Cooling on the other hand use chilled water at C or warmer, and have no fan. Chilled water at C uses less energy to produce, and can normally be provided direct from the aquifer without the heat pump operating at all! ENGINEERING Wherever possible, the Precinct uses Chilled Beams. In doing so we save the taxpayer or $30 per year or 90 Chilled Beams kwh for every square metre in the building cooled by Chilled Beams, reducing the Government s Carbon Footprint. Underfloor Cooling

8 Selectable Fresh Air Fresh air is one of the highest consumers of energy in the building. It must be heated or cooled from its outdoor condition to the desired temperature in the space. Court rooms are placed between the outdoors and the public atrium, which is a second source of fresh air. Opus has implemented a fresh air system which can draw fresh air either from the outdoors or from the atrium, whichever best suits the conditions that need to be achieved in the court. In winter, when the courts need heating, the intelligent control system picks the warmer source for example, the atrium to draw fresh air from, reducing heating requirements. Likewise in summer, the intelligent control system picks the cooler source for example, the outer façade to reduce cooling energy consumption. ENGINEERING Fresh Air Selection

9 Heat Recovery Air has to be exhausted from a building from toilets, kitchens, and from general spaces to make way for fresh air to come into the building. While exhaust is necessary for air freshness, it is a shame from an energy perspective throwing away air at the right temperature for the space, then replacing it with fresh air that needs to be heated or cooled. That s where Heat Recovery comes in fresh air and exhaust air pass through a heat exchanger, recovering the energy from the exhaust air stream. This can be difficult for the design team all the fresh air and the exhaust must be brought to the same location, in a building that is already congested with lots of services through the ceilings. The Justice and Emergency Services precinct will set a standard for energy efficient heat recovery, with over 90% of exhaust air passed through Heat Recovery systems. Heat exchangers don t just save energy, they save capital by reducing the peak loads, they reduce AHU, chiller and boiler sizes. ENGINEERING Heat Recovery

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14 CHRISTCHURCH A q u i f e r C o o l i n g Tait Office Building

15 Heat Pump Heat Exchanger 1 Free Cooling Load Aquifers at different levels Abstract from the higher Re-inject to the lower Heat exchangers provide different services Free cooling through chilled beams Heat Pump cooling & heating through fan coil units Heat Exchanger 2 Aquifer 1 Aquifer 2 TAIT OFFICE System

16 Non-consumptive bore Re-injects the used water to a lower aquifer Free cooling represents 35-40% of full cooling load No cooling towers These have issues with bacterial contamination if not maintained properly Cooling System 450 kw Heating & Cooling system Bore water flow 25 l/s Reversible heat pump to create simultaneous chilled & heating water Temperature difference managed to maintain 5 C TAIT OFFICE Features

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18 CHRISTCHURCH A q u i f e r C o o l i n g Perimeter Data Centre

19 Original Design was built around 2 x 3 pod arrangements Cold aisle isolation Rittal Data Racks rated at 4 kw per rack In-row chilled water process coolers 3 process coolers per pod Rated at 60 kw each To achieve N+1 redundancy PERIMETER System

20 480 kw total at 240 kw per side 3 Pods per side at 80 kw per pod Each pod containing 20 data racks at 4 kw per rack Single Aquifer abstraction at 25 l/s with 5 C temperature difference at re-injection Operation based on: -Normal cooling source is the aquifer -Back-up generator driven chiller only on aquifer failure to maintain redundancy -Design PUE of 1.1 Expansion being designed for: 200 kw additional load, new total capacity will be 700 kw Aquifer pump upgrade Additional heat exchanger & backup chiller arrangement PERIMETER Features

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22 CHRISTCHURCH A q u i f e r C o o l i n g Resource Consenting

23 Aquifer water is an important resource covered by RMA nad the Canterbury Natural Resources Plan (NRRP). Consents for use are issued by ECan. Drill a test bore to see that flows can be taken without reducing the aquifer pressure or affecting neighbouring bores cost ~$10,000 Low depth aquifers are for drinking water and cannot be used. Process water is taken from the deepest bores, where temperature is the most constant. Ideally process water is re-injected, so that it is a non-consumptive resource consent. The process water is re-injected to mid level aquifers so as not to affect the temperature of the common take aquifer, and not to affect the temperature of the common drinking water aquifer (or potentially contaminate it in an accident involving the heat exchanger. Typically, do not raise the temperature by more than 5 C. There is a perception (perhaps the audience can comment (that re-injecting into the mid level aquifers raises the pressure of the low depth drinking water aquifers (a good thing). RESOURCE CONSENTING