All buildings interact with the ground for its ability to support their foundations. However, very few buildings interact with the ground for its ability to provide thermal energy storage. We have all experienced the moderate temperatures within a cave at depths of just a few metres. These temperatures are a function of average annual air temperature and are the result of the ground absorbing and storing solar energy. The use of this indirect and renewable solar energy can provide significant energy savings for heating and cooling systems. A Ground Heat Exchanger (GHX) provides the ability to utilise the ground for thermal energy storage, essentially transforming the ground into a thermal battery. It enables us to extract heat from it in winter (heat source) and return that heat in summer (heat sink). It is a dynamic thermal battery that operates both simultaneously and over the annual heating / cooling cycle. This presentation will provide an overview of how the ground is being utilised for its thermal energy storage capabilities around the world, with focus on a local installation at the Tumut Council owned Riverina Highlands Building, located in Tumut NSW. The installation has provided Council with energy savings on heating and cooling of 80 %, reduced peak energy loads by 40%, reduced maintenance costs and, importantly, provided significantly higher levels of occupant comfort. This has also increased the capacity and effectiveness of the concurrently installed solar PV array and will ensure that future solar energy storage will have greater impact.

1. Thermal Energy Management in the
Built Environment
Presented by:
Yale Carden, Managing Director, GeoExchange Australia Pty Ltd and
Jo Spicer, Environmental / GIS Officer, Tumut Shire Council
3 June 2015
Using the Ground for Thermal Energy Storage:
The Experience of the Riverina Highlands Building,
Tumut NSW

2. Presentation Overview
 Why Thermal Energy Storage?
 Thermal is Energy Too
 Ground Heat Exchanger as Thermal Energy Storage
 The Riverina Highlands Building Energy Efficiency Project (RHBEEP)
 Contacts
Australian Energy Storage Conference: 3-4 June 2015

3. Why Thermal Energy Storage
 Up to 80 % annual energy savings
 Reduce peak load up to 50 %
 Remove cooling towers
 Remove external plant and free up building design
 Disconnect natural gas and other fossil fuels
 Increase renewables potential for full load capacity
 Easily integrates with other energy solutions
Australian Energy Storage Conference: 3-4 June 2015

4. Thermal is Energy Too
 ClimateWorks: Top 10 Energy Productivity Solutions
 Thermal energy can also be renewable – not just gas and fossil fuels
 Thermal sources in the built environment:
 Atmosphere
 Ground
 Building Foundations / Car Parks
 Water Bodies
 Sewer and Wastewater
 Other Buildings
 Flexibility to optimise demand requirements with available source(s):
 Heating, cooling and hot water demands:
 Simultaneous
 Diurnal
 Seasonal
 Available thermal sources – mix and match
Australian Energy Storage Conference: 3-4 June 2015

5. Geoexchange: Thermal Connectivity
Australian Energy Storage Conference: 3-4 June 2015
Distribution –
Heating and
Cooling
Ground Heat
Exchanger
Refrigeration Circuit –
Ground Source Heat
Pump
Hot Water
Circuit

6. Ground Heat Exchangers
 Use of constant, stable temperatures as:
 Heat Source (heating)
 Heat Sink (cooling)
 Thermal Energy Storage
 Generic term that includes the ground, water bodies, sewer, building
foundations
Australian Energy Storage Conference: 3-4 June 2015

7. Ground and Water Loops
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8. Energy Piles
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9. Sewer Heat Recovery
Australian Energy Storage Conference: 3-4 June 2015
 Also includes wastewater / treated effluent
 Not just heating – cooling also possible
 20-25C heat source / sink is common
 Match ‘water’ flow to heating / cooling requirements
 Local projects using treated effluent:
 Hobart Aquatic Centre, Hobart
 Grand Chancellor Hotel, Hobart

10. Aquifer Thermal Energy Storage
Australian Energy Storage Conference: 3-4 June 2015
Source: www.building.co.uk

11. District Geoexchange Systems
Australian Energy Storage Conference: 3-4 June 2015

12. Case Study: Tumut Council, NSW
Australian Energy Storage Conference: 3-4 June 2015

13. The Situation
Australian Energy Storage Conference: 3-4 June 2015
 A thermally inefficient building
 Summers were hot and uncomfortable. Winter was not much better
 The HVAC plant failed on a regular basis
 HVAC simply did not meet the building occupant’s requirements
 Inefficient and expensive lighting

14. Objectives and Actions
Australian Energy Storage Conference: 3-4 June 2015
 Riverina Highlands Building Energy Efficiency Project (RHBEEP)
objectives:
 Reduce energy expenditure
 Reduce reliance on imported energy
 Reduce GHG (Green House Gas) emission
 Improve comfort levels in the building
 What we did:
 GeoExchange HVAC/GSHP system installed
 Lighting upgrade
 Sub metering
 Ceiling insulation

15. The Installed System
Australian Energy Storage Conference: 3-4 June 2015
 The Ground Heat Exchanger:
 35 Boreholes
 92 m deep
 40 mm diameter polyethylene pipe
 7 m spacings
 Ground Source Heat Pumps:
 26 x WaterFurnace 7 series
 Variable speed compressor
 Variable speed fan
 Energy performance monitoring
 Pumping System:
 Variable speed pumps to match heating / cooling load

16. RHBEEP and Thermal Energy Storage
Australian Energy Storage Conference: 3-4 June 2015
Short term storage:
Simultaneous or diurnal
Annual storage
Heat
Rejection
Heat
Extraction
Heat
Rejection

17. Before and After: Building Energy
Australian Energy Storage Conference: 3-4 June 2015

18. Before and After: Building Energy
Australian Energy Storage Conference: 3-4 June 2015

19. Before and After: HVAC only
2012: 961 633 MJ
2014: 282 279 MJ
Australian Energy Storage Conference: 3-4 June 2015

20. Before and After: Ancillary Benefits
 RHBEEP is demonstration that:
 Integration of technologies
 Site specific design
 Programmed optimisation
 Is effective in
 Reducing energy consumption, whilst
 Maintaining a comfortable and pleasant
work environment
 Increased storage capacity in the
plant room by approximately 500%
Australian Energy Storage Conference: 3-4 June 2015

21. Before and After: Summary
 Building energy savings: ~80 % and $94 000 per annum
 HVAC energy savings: ~71 % and $85 000 per annum
 Maintenance / tenancy savings: ~$80 000 per annum
 Electricity demand reduction: 151 kVA (75 %) Geoexchange at 49 %
 GHG Reduction: 79 tCO2
 Simple Payback: ~7.6 years
 Return on Investment: 11-12 %
Australian Energy Storage Conference: 3-4 June 2015

22. Contact Details
Yale Carden
GeoExchange Australia Pty Ltd
IGSHPA – Australasia
Phone: 02 8404 4193
Email: ycarden@geoexchange.com.au
Website: www.geoexchange.com.au
Joanne Spicer
Tumut Shire Council
Phone: 02 6941 2555
Email: jspicer@tumut.nsw.gov.au
Website: www.tumut.nsw.gov.au
The RHBEEP Project
http://www.tumut.nsw.gov.au/riverina-highlands-building-energy-efficient-project-
rhbeep.aspx
Australian Energy Storage Conference: 3-4 June 2015