HVAC resilience is becoming increasingly important in the context of a changing climate both in terms of long term warming trends and shorter frequency extreme weather events. This presentation explores how the concept of thermal potential and renewable thermal energy can be used as a foundation for ensuring resilience

1. #ResilienceForum

2. Thermal Potential and HVAC Resilience
 Insights from Outside
 Evolution of Resilience
 What is Thermal Potential?
 Thermal Potential 101
 Fundamental to Resilience
 Case Studies
 Conclusions

3. Insights from Outside
Renewable (Electrical) Energy Sector
 Use locally available sources of energy potential
 Storage is increasingly important
 Decrease peak demand and smooth out load profiles
 Role of smart meters / controls
 Centralised and/or decentralised systems

4. Insights from Outside
Permaculture
 Much more extreme definitions: ‘Perma’, peak oil, etc
 Think holistically and integrate systems
 Every system has multiple services / outputs
 Every service / output is possible from multiple systems
 Don’t just minimise impact - repair damage while increasing
sustainable productivity

5. Evolution of Resilience
RESILIENCE
Maintaining modern
human lifestyles (or is
it survival?) in a
(human-induced)
changing environment
SUSTAINABILITY
Minimise impact of
human systems on
the environment
ENERGY
EFFICIENCY
Minimise energy
(costs) of human
systems

6. Resilience in HVAC
 Objective is to maintain indoor comfort levels in spite of:
 Long term: Trend of warming climate
 Short term events: Increasingly extreme weather events
 Lets start with (often by others):
 Building: façade, insulation, glazing etc etc etc
 Powered by renewable (electrical) energy
 Then we:
 Design with resilience as parameter
 Eliminate fossil fuels (eg gas)
 Minimise synthetic chemicals (eg refrigerants)
 Expand our design life
 Future-proof for technology and regulatory changes

7. What is Thermal Potential?
 Demand Management Tool: Forgotten half of the energy equation
 Thermal is energy too!
 Thermal energy can also be renewable – not just about burning gas
and fossil fuels to heat
 Thermal potential consists of:
 Heat sources (heating)
 Heat sinks (cooling)
 Thermal energy storage
 Multiple thermal sources in the built environment

8. Thermal Potential 101

9. Ground and Water Bodies

10. Energy Piles

11. Sewer Heat Recovery
 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

12. District / Other Buildings

13. Thermal Energy Storage
0
5000
10000
15000
20000
25000
30000
35000
40000
0 2 4 6 8 10 12
TotalLoads(kWhrs)
Time (Months)
Cooling (kWhrs)
Heating (kWhrs)
Short term storage:
Simultaneous or diurnal
Annual Storage
Heat
Rejection
Heat
Extraction
Heat
Rejection

14. Resilience through Thermal Potential
 Multiple sources of heat and cool:
 Redundancy
 Time of use efficiency
 Thermal storage component:
 Generate and use as required / when renewable (electrical) energy available
 Modulate peaks and troughs
 Long life cycle design and equipment
 No external exposure to elements or weather events
 Minimises use of fossil fuels and chemicals

15. Case Study: St Peters College
 Existing system uses ambient air only
 Thermal potential approach considered the following:
 Gas
 Ambient air (used for heat recovery)
 Ground with vertical borehole GHX
 Ground with horizontal GHX
 River water under existing irrigation license
 Treated effluent

16. Case Study: St Peters College
 River water was initial Client preference
 However, logistical and future proofing issues
 Vertical GHX preferred over horizontal GHX
 Minimise impact on sport fields
 Enable future expansion of system

17. Case Study: St Peters College
56%
8%
3%
25%
8%
Energy Efficiency Opportunities
Geoexchange Plant Upgrade Fresh Air Heat Recovery Roof Pool Blanket Ducted GSHPs

18. Case Study: BoM - Darwin
 Installed in late 1990s
 ~50 kW capacity using 4 GSHPs
 Vertical boreholes
 Resilience: No external or rooftop plant
 Increased longevity as no exposure to elements
 Cyclone-proof
 Resilience: Low maintenance

19. Case Study: SBRC – UoW
 A Living Building Challenge certified ‘Living Lab’ installed in 2013
 Thermal source is ground or ambient air pending temperature
 Vertical boreholes and 2 horizontal loops (R&D focus)
 Resilience: Multiple thermal sources
 Provides redundancy
 Use most efficient thermal source
 Resilience: Energy positive
 Resilience: Living Building Challenge!

20. Conclusions
 Thermal potential can be a fundamental principle of resilience
 Long term climate trends:
 Higher annual and peak efficiencies
 Integration with renewables
 Eliminate gas
 Minimise chemicals
 Longer life system
 Short term extreme weather events:
 Redundancy through multiple local thermal energy sources
 Absence of external plant
 Higher peak efficiencies
 Thermal storage capability

21. Contact Details
Yale Carden
GeoExchange Australia Pty Ltd
Phone: 02 8404 4193
Email: ycarden@geoexchange.com.au
Website: www.geoexchange.com.au
St Peters College, Adelaide
https://www.geoexchange.com.au/commercial_showcase/st-peters-college-
adelaide-sa/
Sustainable Buildings Research Centre, University of Wollongong
www.sbrc.uow.edu.au