by Ed Lohrenz District GeoExchange Systems case study (Gibsons, B.C.) including cost benefit analysis and return on investment

1. District GeoExchange Systems
Green Building Festival
2012-10-12
District
GeoExchange
Systems
Ed Lohrenz, B.E.S., CGD
1503 – 220 Portage Avenue
Winnipeg, Manitoba
204-255-5959
ed@geoxergy.com
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 1

2. District GeoExchange Systems
The earth is a heat source in winter
The temperature of the earth a few meters below the surface is very constant. In
southern Ontario, the temperature of the earth in winter is about 10C even though the
air temperature may be -25C.
It’s a good heat source for a heat pump.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 2

3. District GeoExchange Systems
A heat sink in summer
In summer, even though the air temperature may be 30C, the temperature of the earth
is still 10C.
It’s a good place to get rid of heat removed from a building…much more efficiently than
trying to reject heat to an air cooled condenser.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 3

4. District GeoExchange Systems
A ground heat exchanger transfers energy to and from the ground
To move heat to the ground from a building, or extract heat from the ground, all we
need is a ground heat exchanger (GHX)
It’s simply plastic pipe buried in the ground under or around a building.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 4

5. District GeoExchange Systems
Typical geothermal systems
Geothermal systems are typically designed and built for individual buildings… one
building, one GHX. This can be limiting in urban areas because small properties limit
the size of the GHX and make it more challenging to build.
In larger commercial properties the GHX is often built under the footprint of the building.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide

6. District GeoExchange Systems
Different methods of building a GHX
A GHX can be buried in a horizontal trench or excavation, inserted in a deep borehole,
or laid into a body of water.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 6

7. District GeoExchange Systems
District GeoExchange systems in cities
Small urban building lots prevent many homeowners from taking advantage of
renewable energy from the earth on their own property.
http://maps.google.ca/maps/mm?q=housing+development&hl=en&gbv=2&ie=UTF8&ll=43.744918,-79.755374&spn=0.000439,0.0012&t=h&z=20
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 7

8. District GeoExchange Systems
District GHX for homes and buildings on small properties
Urban areas often have land areas that can be used to install a GHX including school
yards, parks and greenbelt areas.
This approach requires cooperation between the city, school board and the developer.
The area shown on the previous slide is
adjacent to large areas of land that can easily
accommodate the GHX needed for the
homes shown.
27,000 m2
35,000 m2
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 8

9. District GeoExchange Systems
The district GeoExchange system approach
There are about 360 homes in the blocks immediately surrounding 62,000 m2 of land
(6.5 ha) that can provide the energy needed for these homes.
The school, about 4,000 m2 in area, could also benefit from the free, renewable energy
available from the land.
20
46 23 36
40
27,000 m2
43
52
24
35,000 m2
40 18
42
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 9

10. District GeoExchange Systems
Thinking about energy use while planning a development
A single ice arena must get rid of 1,500,000 to 2,000,000 kWh of energy per year. A
home withdraws 10-20,000 kWh of energy from a GHX.
Synergies between different types of buildings benefit by reducing the size and cost of
the GHX needed. Understanding energy profiles of buildings and taking advantage of
them may influence city planning.
20
A single ice arena has to get rid of enough
46 23 energy to heat 75 to 150 homes.
36
40
27,000 m2
43
52
School 24 Ice arena
35,000 m2
40 18
42
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 10

11. District GeoExchange Systems
Synergies between buildings
Different buildings operate differently. Single family homes in the cold Canadian climate
tend to require much more heating than cooling. Large office buildings, stores, schools,
multi-family residential and industrial buildings tend to require cooling even in winter.
If different types of buildings are connected to the same GHX, it can be much smaller.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 11

12. District GeoExchange Systems
Ambient temperature district geothermal energy system – Gibsons, BC
A new housing development is being built in the Town of Gibsons, BC, near Vancouver.
The community wished to minimize green house gas emissions as much as possible
and wanted to promote the use of geothermal systems.
Gibsons
Vancouver
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 12

13. District GeoExchange Systems
Looking at the big picture for energy
As the development grows additional commercial space added to the GHX will help
balance the heating and cooling loads to the GHX. Heat rejected from cooling
commercial buildings will replace heat extracted by the heating dominant homes.
Taking advantage of these synergies reduces the size and cost of the GHX needed for
a district GeoExchange system.
Future phases
Phase
1
Future phases
Commercial Hockey rink &
development commercial
development
Ocean
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 13

14. District GeoExchange Systems
Connecting to other energy sources / sinks
The storm sewer servicing the development is being rebuilt in the near future. A
connection to the ocean water can be installed at the same time. The moderate
temperature of the ocean will be used to ensure the temperature of the GHX can be
maintained at efficient operating temperatures.
Future phases
Phase
1
Future phases
Commercial Hockey rink &
development commercial
development
Ocean Ocean –
connection 10-12 C year
round
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 14

15. District GeoExchange Systems
Lot size is limitation for horizontal GHX configuration in Gibsons
Many of the building lots are fairly small...some as small as 49’ x 92’. Horizontal GHX
configurations were not possible...only realistic option was vertical configuration.
132
72 80
132
66
132
66
132
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 15

16. District GeoExchange Systems
Aquifer is limitation for vertical GHX in Gibsons
The Town of Gibsons draws it’s drinking water from an aquifer directly beneath the
proposed development. The Town was hesitant to allow drilling into the aquifer, or even
penetrate the 70’ to 90’ silt and clay overburden overlying the sand & gravel aquifer
because of perceived danger to their drinking water supply.
Upper Gibsons
development
Gibsons drinking
water aquifer
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 16

17. District GeoExchange Systems
Phase one
The first phase of the development plan includes approximately 133 single family
homes, duplexes and cluster homes.
Green belt and park areas owned by the Town can be used for construction of a GHX.
Park & greenbelt areas
Homes under construction
Phase 1
Phase 2
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 17

18. District GeoExchange Systems
Simplified system schematic
GHX modules connect to a header in a central pump house. Fluid is circulated through
the GHX modules by individual pumps in the pump house.
Supply and return distribution lines are installed along the street by the developer much
like water and sewer lines, with shutoff valves at the property lines of each home.
The home builder connects the heat pump & pump to the distribution lines.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 18

19. District GeoExchange Systems
Pump house
The pump house connects the distribution lines to the GHX modules. The first three
GHX modules are connected and will serve up to 35-40 homes. An additional 11 GHX
modules can be connected and will serve approximately 250 to 300 homes.
Connections to a second pump house and a commercial development will provide load
diversity and facilitate energy transfer between buildings.
Future GHX module
connections
Distribution lines
to homes
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 19

20. District GeoExchange Systems
Typical home heat pump installation
Home owner connects to curb stop valves at the property line. Energy meters allow
monthly energy billing…similar to water meter. Heat pump installations inside the
building are almost identical to a typical residential geothermal installation.
The cost of the system to the homeowner is similar to installing a gas furnace and air
conditioner when the cost of installing the GHX is eliminated.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 20

21. District GeoExchange Systems
Individual homeowner’s installation cost comparison
The cost of installing the heat pump inside the home is almost identical to the
installation of a gas furnace and air conditioner.
The capital investment for the district GHX is made by the Town and amortized over 20
years…the homeowner doesn’t have to make the investment for the GHX.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 21

22. District GeoExchange Systems
Benefits to the homeowner
Monthly energy cost to the homeowner is approximately 35% less than electric
resistance heating and 16% less than natural gas. In addition to energy cost savings,
there is no outdoor air cooled condenser as with a conventional HVAC system.
The homeowner pays the electric utility for the electricity used to run the heat pump as
well as a bill from the Town for the energy withdrawn or rejected to the district GHX.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 22

23. District GeoExchange Systems
Responsibility for construction
Components of the system are the responsibility of different parties:
• The Town of Gibsons installs the GHX and pump house.
• The Developer installs the distribution piping and curb stop valves.
• The home builder / home owner is responsible for connections & heat pump.
• The Town maintains the GHX, pump house and distribution system
Home builder
or home owner
Developer responsible to
responsible for connect to
construction of distribution piping
distribution piping
to homes
The Town
built the GHX &
pump house
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 23

24. District GeoExchange Systems
Responsibility for construction cost
• Town installs, owns and operates the GHX and pump house.
• Developer installs the distribution piping & curb stop valves, & turns it over to town
• Home builder / owner is responsible for connections mechanical system
The total cost of the energy source (GHX, pump house, distribution piping and
connections to home is approximately $8,100…20% to 40% less than individual GHX.
DEVELOPER HOMEOWNER
Distribution System Connection to system
for 75 Homes
$500 / home TOWN
$178,300 GHX for 133 Homes
$2,377 / home $601,300
$4,521 / home
TOWN
Pump House for
275 Homes
$194,900
$709 / home
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 24

25. District GeoExchange Systems
Incentives provide start up capital
To enable this project to move ahead the Town was able to take advantage of
approximately $569,000 of incentives to bridge the gap between the time construction
started and the Town could begin collecting enough revenue to service the debt.
This is similar to the investment a gas or electric utility must make to build generating
stations and distribution infrastructure.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 25

26. District GeoExchange Systems
Economics – Town of Gibsons return on investment
The Town of Gibsons will be invoicing customers like any other utility. Expected
revenues from each type of home are shown in the chart below. The chart shows an
investment of $695,590 for the homes in Phase 1 amortized over 20 years with an
interest rate of 3.5%.
Return on investment is positive, but the Town must deal with the gap between building
the infrastructure and collecting revenue from it.
Number of Monthly Total Annual
Annual Loan
Homes in Geothermal Utility
Repayment
Phase 1 Utility Bill Revenue
Single 42 $948 $39,816 ---
Cluster home 36 $264 $9,504 ---
Cottage 55 $372 $20,460 ---
Total 133 $69,780 $48,250
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 26

27. District GeoExchange Systems
Optimization of building & GHX is needed to make the economics work
A GeoExchange system can be designed and built cost-effectively with:
• Accurate energy modeling
• Taking advantage of synergies between different buildings
• Working with contractor resources available in the area
• Determining a cost-effective GHX configuration for geology & land area available
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 27

28. District GeoExchange Systems
Finding room for another utility
Streets in new developments are filled with utilities. Minimum distances must be
maintained from water supply lines and access to lines must be considered for future
repairs and connections.
In heating dominant climates consideration must be given to minimum GHX
temperatures if temperatures are expected to drop below freezing.
Curbstop Curbstop
box box
Geothermal distribution lines
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 28

29. District GeoExchange Systems
Future expansion of system
As the development expands additional buildings are easily added to the system.
Thoughtful city planning and architectural design can help make a district system more
viable.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 29

30. District GeoExchange Systems
Why district geothermal systems and why Gibsons would want one
• Environment: BC mandates that communities reduce GHG emissions. When
complete the estimated CO2 emissions will be reduced by 1,400 tonnes annually.
• Revenue source: The investment in the complete district system is expected to
have an internal rate of return of approximately 15% to 20%.
• Community development: It is hoped forward thinking and demonstrating concern
for the environment will help attract people to the community.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 30

31. District GeoExchange Systems
Future energy sources – data centers
Cooling data centers is costly…
Waste energy from a data center could be fed into a GHX. This can be used to balance
energy loads to and from a GHX reducing size and cost of the system, improve energy
efficiency ensure long term sustainability.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 31

32. District GeoExchange Systems
Future energy sources - waste
Technologies are available that convert waste into heat and electricity…helping urban
areas deal with several issues.
A GHX can be used to integrate various energy sources and technologies.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 32

33. District GeoExchange Systems
Making full use of systems provides greater benefits
The Enwave deep water cooling system, downtown Toronto, is one of the largest district
GeoExchange systems in the world.
But it’s used only for cooling. If used for heating as well the system would be more
balanced and could do more.
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 33

34. District GeoExchange Systems
Questions or comment?
Green Building Festival
2012-10-12
District
GeoExchange
Systems
Ed Lohrenz, B.E.S., CGD
1503 – 220 Portage Avenue
Winnipeg, Manitoba
204-255-5959
ed@geoxergy.com
Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 34