District GeoExchange Systems

District GeoExchange Systems

Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide 1

Ed Lohrenz, B.E.S., CGD

1503 – 220 Portage Avenue

Winnipeg, Manitoba

204-255-5959

[email protected]

Green Building Festival

2012-10-12

District

GeoExchange

Systems


Green Building Festival – Evergreen Brick Works, Toronto, ON – October 11 & 12, 2012 Slide

The earth is a heat source in winter

2

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 10C even though the

air temperature may be -25C.

It’s a good heat source for a heat pump.



A heat sink in summer

3

In summer, even though the air temperature may be 30C, the temperature of the earth

is still 10C.

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.



A ground heat exchanger transfers energy to and from the ground

4

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.



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.



Different methods of building a GHX

6

A GHX can be buried in a horizontal trench or excavation, inserted in a deep borehole,

or laid into a body of water.



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



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



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.

27,000 m2

35,000 m2

36 40

23

52

20

18 40

42

24 43

46



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.

36 40

23

52

20

18 40

42

24 43

46 A single ice arena has to get rid of enough

energy to heat 75 to 150 homes.

27,000 m2

35,000 m2

School Ice arena



Synergies between buildings

11

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.



Ambient temperature district geothermal energy system – Gibsons, BC

12

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.

Vancouver

Gibsons



Looking at the big picture for energy

13

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.

Phase

1

Future phases

Future phases

Commercial

development

Hockey rink &

commercial

development

Ocean



Connecting to other energy sources / sinks

14

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.

Phase

1

Future phases

Future phases

Commercial

development

Ocean

connection

Hockey rink &

commercial

development

Ocean –

10-12 C year

round



Lot size is limitation for horizontal GHX configuration in Gibsons

15

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.

72 80

66

66

132

132

132

132



Aquifer is limitation for vertical GHX in Gibsons

16

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



Phase one

17

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



Simplified system schematic

18

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.



Pump house

19

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



Typical home heat pump installation

20

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.



Individual homeowner’s installation cost comparison

21

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.



Benefits to the homeowner

22

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.



Responsibility for construction

23

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

The Town built the GHX &

pump house

Home builder

or home owner responsible to

connect to

distribution piping

Developer responsible for

construction of

distribution piping

to homes



Responsibility for construction cost

24

• 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 Distribution System

for 75 Homes

$178,300

$2,377 / home

TOWN GHX for 133 Homes

$601,300

$4,521 / home TOWN

Pump House for

275 Homes

$194,900

$709 / home

HOMEOWNER Connection to system

$500 / home



Incentives provide start up capital

25

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.



Economics – Town of Gibsons return on investment

26

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

Homes in

Phase 1

Monthly

Geothermal

Utility Bill

Total Annual

Utility

Revenue

Annual Loan

Repayment

Single 42 $948 $39,816 ---

Cluster home 36 $264 $9,504 ---

Cottage 55 $372 $20,460 ---

Total 133 $69,780 $48,250



Optimization of building & GHX is needed to make the economics work

27

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



Finding room for another utility

28

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

box Curbstop

box

Geothermal distribution lines



Future expansion of system

29

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.



Why district geothermal systems and why Gibsons would want one

30

• 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.



Future energy sources – data centers

31

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.



Future energy sources - waste

32

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.



Making full use of systems provides greater benefits

33

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.



Questions or comment?

34

Ed Lohrenz, B.E.S., CGD

1503 – 220 Portage Avenue

Winnipeg, Manitoba

204-255-5959

[email protected]

Green Building Festival

2012-10-12

District

GeoExchange

Systems

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District GeoExchange Systems

Design