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Table 1: Office heating and cooling energy data
Heating
Heating load (peak) 1,500 kW
Annual heat demand 1275 MWh/y
Design temperatures heating system 60-40ºC
Cooling
Cooling load (peak) 1,700 kW
Annual cold demand 825 MWh/y
Design temperatures cooling 10-18ºC
Table 2: Energy consumption comparison (per year)
Conventional system  ATES/HP system  
Heating  Heating  
Gas boilers 170,000 m³ Gas boiler51,000 m³
  Electricity (well pumps)20 MWhe
Cooling  Cooling  
Electricity chillers275 MWheElectricity (heat pumps) 30 MWhe
  Electricity (well pumps) 20 MWhe
Chillers 570 kWeHeat pumps 175 kWe
Table 3: Investment and maintenance costs
Conventional system ATES/HP system
2 boilers, 750 kW each£95,0001 boiler, 800 kW £50,000
Gas grid connection boilers£25,000Gas grid connection boiler£15,000
2 chillers with cooling towers, incl controls and installation.£300,0002 HP's, heat exchangers, overall control, piping and installation in MR £270,000
Electrical grid connection chillers£20,000Electrical grid connection (heat pumps)£5,000
  2x2 wells 130 m. deep, well housings, well pummps and equipment and fiels piping and cables£370,000
  dry-cooler, incl piping£20,000
Total investment (excl tax)£440,000 £730,000
    
All-in maintenance per year:All-in maintenance per year:
boilers 3%£2,900boiler and dry-cooler 3%£2,100
Chillers and cooling  Heat pumpd 6%£8,400
towers 6%£18,000Wells, heat exchangers etc 3% £15,000
Total maintenance cost £20,900 £25,500
Table 4: Energy consumption comparison (per year)
Conventional system GSHP system
Heating Heating
Gas boilers 170,000 m³ Gas boiler 51,000 m³
 Electricity (heat pumps) 220 MWhe 
Cooling Cooling
Electricity chillers 275 MWhe Electricity (heat pumps) 115 MWhe 
  Electricity (chillers) 80 MWhe  
Electrical loads
Chillers 570 kWe Heat pumps 470 kWe
Table 5: Investment and maintenance costs
Conventional system GSHP system
2 boilers, 750 kW each £95,000 1 boiler, 800 kW £50,000
Gas grid connection boilers £25,000Gas grid connection boiler 2 heat pumps, heat exchange, overall control, piping and in installation in MR£15,000
2 chillers with cooling towers including controls and installation£30,0002 chillers with cooling towers, inc controls and installation£180.00
Electrical grid connection chillers£20,000Electrical grid connection heat pumps and chillers £15,000
Chillers Borehole field, incl field piping£330,000
Total investment (excl taxes) £440,000 £790,000
All-in maintenance per year:  All-in maintenance per year:  
Boilers 3% £2,900Boiler, heat exchanger, etc 3% £3,300
Chillers and cooling towers 6% £18,000%3Cbr /%3EHeat pumps and chillers 6% £19,200
  Borehole field 1% £3,300
Total maintenance cost£20,900 £25,800