design and economics of commercial ground loop water ......ground loop portion turn key cost: $...

Design and Economics ofCommercial Ground Loop Water Source Heat Pump Systems

Presented byAlan NilesWestern Region Commercial Sales ManagerWaterFurnace International

Presents

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methods, and services will be addressed at the conclusion of this presentation.

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Approval date:

Course ID: 0920010524

Alan Nilesby

09/12/2016

Approved for:

1General CE hours

1LEED-specific hours

Commercial Ground Loop Heat Pump Systems: Design & Economics

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Commercial Ground Loop Heat Pump SystemsDesign & Economics

Learning Objectives:

1) Describe the components of a commercial GLHP system and the details of the installation and operation of the system

2) Learn the project specific data required by software used to design a commercial ground loop and understand the economic impact for changes in each of these project specific design variables

3) Apply hybrid design enhancements to achieve additional savings on initial cost with minimal increase to operating costs

4) Discuss and identify LEED points for Energy and Atmosphere Credit 1 "Optimize energy performance" and additional points for water efficiency and points for sustainable sites as GLHP Hybrid Systems are a clear path to a net zero energy building

Ground Loop Systems

GeothermalGround SourceGround CoupledGeoExchange

Vertical Bore Hole

Pump & Dump Pond Loop

Lower Operating Costs

Lower Life Cycle Costs

Lower Maintenance Costs

Simple Path to Net Zero Energy

Why a Ground Loop Heat Pump System

Lower Operating CostsNeed Building Loads and Ground Loop Design Software for Monthly Average Water Temperatures to Determine the Operating Efficiency of WSHP's

Lower Life Cycle CostsNeed Estimated Ground Loop Installed Cost

Lower Maintenance CostsGround Loop HDPE Pipe has a standard 50 year warrantyWSHP's have 24 Year Estimated Life - ASHRAE

“…the cost advantage of the ground-source systems over the other HVAC systems was 23.09 cents/ft2 with a standard deviation of 2.51 cents/ft2…

… with 99% confidence, the cost advantage is no less than 15.56 cents/ft2”

From ASHRAE Journal, 1998, V. 104Maintenance and Service Costs of Commercial Building Ground-Source Heat Pump Systems

Use the ground’s constant temperature as the sourceof heat in winter and as a high efficiency heat sink in summer

City Winter Design Ground Temperature Summer Design

Salt Lake City 6 F 50 - 56 F 96 F

Denver 4 F 50 – 57 F 91 F

Las Vegas 27 F 73 - 77 F 108 F

Minneapolis -16 F 44 - 47 F 91 F

85 FSupplyWater

95 FReturn Water

10F Across the Cooling Tower

90 FReturn Water

85 FSupplyWater

95 F87 F

Only 5F Across the Cooling Tower

One unit in each zone with individual local temperature control

86.8 FReturn Water

85 FSupplyWater

95 F84 F

Only 1.8F Across the Cooling Tower

Heat Recovery To OA AHUSnow MeltDomestic Hot Water Pre-Heat130 F or 160 F Hot Water

Water-to-Water Unit

86.8 FReturn Water

85 FSupplyWater

95 F84 F

Water-to-Water Unit

Boiler/Cooling Tower 20% to 25% of Total HVAC Operating Cost

86.8 FReturn Water

85 FSupplyWater

Heat Recovery To OA AHU:125 F Hot Water

Water-to-Water Unit

Supply Water approaches Ground Temperature

Typical Water Source Heat Pump Cooling Performance

33% Increase

33% IncreaseIMPORTANTGround Loops approach ground temperature when the Building is not at Peak Loads

80% - 90% of the time, building loads are at 50% of the Peak Load or Less

Installation Costs

GLHP Design Basics

NEED TO KNOW:

From the Ground: Thermal Conductivity and Average Ground Temperature

From the Building: Monthly/Daily Loads

From the Equipment: GLHP Efficiency of Each Specific Heat Pump

GLHP Design Basics

The Ground

GLHP Design Basics

20 10 Tm 10 20

WET SOIL(0.96 sq. ft./day) or

(0.40 sq. ft./hr)

AVERAGE SOIL(0.6 sq. ft./day) or(0.025 sq. ft./hr)

LIGHT DRY SOIL(0.26 sq. ft./day) or

(0.011 sq. ft./hr)

GLHP Design Basics

Thermal Thermal

Conductivity Diffusivity

Material (Btu/hr-ft-F) (ft2/day)

Dense Rock 2.00 1.2

Average Rock 1.40 0.96

Heavy Soil, saturated 1.40 0.84

Heavy Soil, damp 0.75 0.60

Heavy Soil, dry 0.50 0.48

Light Soil, damp 0.50 0.48

Light Soil, dry 0.20 0.26

GLHP Design Basics

Thermal Conductivity Test

Required Test Duration – A minimum test duration of 36 hours is recommended, with a preference toward 48 hours.

TC Test: $12,000 to $17,000

GLHP Design Basics

Drillers Need to Know

to bid competitively

Thermal Conductivity (k) =

3.412 (BTU/Whr) * W(watts)4p x L(ft of loop) x Slope(F)

Thermal Diffusivity (a) =

k /rcp

r = average density of the soil

cp = specific heat of the soil

Usually measured in ft2/day but sometimes reported as ft2/hour

Ground Loop Site Layouts

Old Fashion Ground Loop Site Layout

Valve Vault

Reverse Return Piping for Ground Loop

Each Bore hole has identical pressure dropSo no balancing valves required under ground

GLHP Design

Reverse Return Piping for Ground Loop

Save Pipe with separate supply & return trenches

GLHP Design

GLHP Design - Deeper is Cheaper

10 bore holes at 200 foot deep180 foot overall

5 bore holes at 400 foot deep120 foot overall

30 ‘

5 Rows of 10 Bore Holes – each row on Reverse Return

Supply/Return From Building

GLHP Design

Same Number of Bore Holes in Same Location Only 5 Bore holes on reverse return - Lower Water Pressure Drop, Lower Installed Cost

Supply/Return From Building

GLHP Design

Same Number of Bore Holes in Same Location Smaller Diameter Supply & Return Header Piping

Supply from Building Return to Building

GLHP Design

400 Foot Bore Hole Layout

Ground Loop Site Layout

High School – Row of Vertical Loops

High School – Rows Returned

High School – Headers In Mechanical Room

Mechanical Room

Installing Pipe

Typical vertical bore detail

Vertical Loop Cross Section

Vertical Loop Pipe with U-Bend

PE 3408 HDPE (High Density Polyethylene Pipe)

1” IPS SDR-111.25” IPS SDR-112” IPS SDR-113” IPS SDR-15.54” IPS SDR-15.56” IPS SDR-15.5 8” IPS SDR-15.5

Standard Dimension Ratio (SDR) is the Side Wall Thickness to the Pipe Diameter Ratio

GLHP Design

PE Pipe Cell Classification PE 355434C

PE: Polyethylene3: Density (0.941 - 0.955 g/cm3)5: Melt Index (ASTM D-1693, 10.1.4)

Molecular Weight5: Flexural Modulus4: Tensile Strength at Yield3: Environmental Stress Crack Resistance4: Hydrostatic Design Basis at 23CC: Color and UV Stabilizer

GLHP Design

Selecting Pipe Size for the Bore Hole

GLHP Design

Selecting Pipe Size for the Bore Hole Design Goal: 15 Ft H2O pressure dropfor entire ground loop

GLHP Design

Vertical bore without backfill

GLHP Design

Bentonite

Grout backfill

Geothermal pipe

GLHP Design

• Built in 1996

• 1600 Students

• 239,000 square feet

• 140 units (average size 3 tons )

• 414 total tons

• 240 bore holes at 330 ft deep

Middle School, Ohio

• Mechanical HVAC System was installed for $ 10 per square ft

($ 2.4 million)

Ground Loop Portion Turn Key Cost: $ 500,000

$ 6.30 per foot of bore hole

• System projected to operate at 25 cents per square ft.

System actually operating at 18 cents per square ft.

Poor energy modeling added 38% to the estimated operating cost!

Middle School, Ohio

New Public School built in 2006

Loop Field Layout

Construction Cost Comparison

1st Year Operating Cost Comparison

High School, Utah

316 – 300’ boreholes Under North Parking Lot

High School, Utah

• Conventional System Bid: $19.00 / sq ft

• Ground Source System Bid:

Mechanical/Plumbing bid: $3,065,161

Loop Field bid: $930,784

Total: $3,995,945

Mechanical Cost: $14.95 /sq ft

HVAC Construction Cost Savings: = $1,082,387

• Savings by reducing the “tilt up” wall height saved an additional $ 600,000.00

High School: GLHP System with Lower 1st Cost

Pond Loops

Spacer

Pond Loops

Great River Medical Center – Burlington, Iowa2002 ASHRAE Technology Award1500 Tons in a 15 Acre Man-made Lake

Pond Loops

Ground Loop Software

SOFTWARE VENDOR

GLD2014 Gaia Geothermal

GLHEPRO 4.0 IGSHPA

ECA ELITE SOFTWARE, INC. BRYAN, TX

Geo CALC FERRIS STATE UNIVERSITY, BIG RAPIDS, MI

GchpCalc ENERGY INFORMATION SERVICES, Tuscaloosa, AL

GL-SOURCE KANSAS ELECTRIC UTILITY, TOPEKA, KS

G L Design GBT, Inc., Maple Plain, MN

GS2000 Buildings Group, Natural Resources Canada

LUND Programs University of Lund, Sweden

Wright-Loop Wrightsoft, Lexington, MA

75.5 Connected Tons of GLHP’s97/77 F Summer; 28 F Winter

1.19 Thermal Conductivity

74.6 F Ground Temperature

Impact of system efficiency and waste heat to a ground loop

Basis of Design Ground Loop:

60 bore holes x 305 ft per hole x $10/ft

Total: $ 183,000.00

Add for Alt #1:

60 bore holes X 5 ft per hole = 300 bore ft

Plus 8 holes X 310 ft = 2,480 bore ft

Total: 2,780 bore ft X $10/ft = $ 27,800.00 15% add

Add for Alt # 2:

16 holes X 305 ft = 4,880 bore ft

Add for Alt # 3:

60 holes X 10 ft per hole = 600 bore ft

Plus 16 holes X 315 ft = 5,040 bore ft

75.5 Connected Tons of GLHP’s

Cost of Heat Pumps with Accessories

$ 75,000.00

Upgrade to High Efficiency WSHP’s

• Standard efficiency 12 EER means for every 1 watt of electricity consumed, 3.52 watts

of energy is removed from the conditioned space resulting in 4.52 watts of waste heat

delivered to the net energy water loop

• High efficiency 21.6 EER reduces the electricity consumed from 1 watt to only 0.56

watts to remove the same amount of energy from the zone and reduces the waste

heat delivered to the net energy water loop from 4.52 watts to 4.08 watts

Building and Heat PumpInformation

Ground and LoopInformation

Loads Imported Directly from Trace 700 .GT File

Ground Loop Peak Water Temperature Design

Building and Heat PumpInformation

Ground and LoopInformation

Ground Loop Peak Water Temperature Design

If Guessing at 1.0 Thermal Conductivity

Using correct 1.44 Thermal Conductivity Saved 26 bore holes and 9,708 feet of drilling = 18% smaller loop

Loop Designed for the Cooling Peak Loop Temperature And the Heating Peak Loop Temperature

150 bore holes @ 308 ft deep 246 tons of Block Load Cooling116 bore holes @ 400 ft deep 287 tons of Connected Cooling

Ground Loop Peak Water Temperatures Are only for brief periods of time

Maximum Peak Loop Temperature in 30 years during the cooling mode

Loop Design Using Original Peak Loop Temperatures and the resulting WSHP Efficiencies

Modify the Peak Loop Temperatures resulting in new WSHP Efficiencies (19.4 EER versus 16.9 EER) at the system’s maximum peak.

Maximum Average Loop temperature during the cooling mode is even lower than 80F

33% Increase

I told you this was

IMPORTANT

Hybrid GLHP Systems

• Cooling Load is out of balance with the Heating Load

• Property Area is insufficient

• Install only as much ground loop as meets the client’s desired economics – just like PV panels

Cooling Load is out of balance with the Heating Load

• Clark County School District (Las Vegas)

60% ground loop plus fluid cooler allows for winter, spring and fall operation on ground loop but runs a fluid cooler at peak loads.

• Lincoln Public Schools (Nebraska)

Boiler hybrid to eliminate anti-freeze and the 30% pumping penalty from anti-freeze.

Hybrid GLHP Systems

Take Advantage of Part Load Operation

Bin Weather Data: 8760 Hours/Year

205 Hours or 2.3%

Cooling Load is out of balance with the Heating LoadLincoln Public Schools

Hybrid GLHP Systems

Lincoln Public Schools

50% of the hours In the year

27% Flow

80% of the hoursIn the year

54% Flow

552 GPM System (2.8 GPM/ton) with VFD Pumping

Hybrid GLHP Systems

Project name: Motor Speedway

Description: Media Center64,000 Sq. ft.Vertical Loop w/ Cooling Tower

Ground Temperature: 73.5 – 77.5ºF

Cooling load: 4,500,000 BTUH (375 tons)EFLH (cooling): 1325 - 1000

Heating load: 2,640,000 BTUH (220 tons)EFLH (heating): 400

Hybrid GLHP Systems

Loop Details (375 tons)

Full Geo

Number of bores: 563

Depth of bores: 400 feet

Bore hole spacing: 25 feet

Loop field installed costs: $ 2.1 million

Building energy consumption/yr: $ 92,700

Maintenance costs / yr: $ 8,250

Hybrid GLHP Systems

Loop Details (375 tons)

Hybrid Full Geo

Number of bores: 150 563

Depth of bores: 400 feet 400 feet

Bore hole spacing: 25 feet 25 feet

Loop field installed costs: $ 780,000 $ 2.1 million

Building energy consumption/yr: $ 98,000 $ 92,700

Maintenance costs / yr: $ 11,856 $ 8,250

Summary

Hybrid Loop installed costs reduced by $ 1,320,000

Operating costs increased by $ 5,300 / yr.

Maintenance increase $ 3,606 / yr.

Hybrid GLHP Systems

Loop Details Hybrid Full Geo

Number of bores: 150 563

Depth of bores: 400 feet 400 feet

Bore hole spacing: 25 feet 25 feet

Loop field installed costs: $ 780,000 $ 2.1 million

Building energy consumption/yr: $ 98,000 $ 92,700

Maintenance costs / yr: $ 11,856 $ 8,250

Summary

Hybrid Loop installed costs reduced by $ 1,320,000

Operating costs increased by $ 5,300 / yr.

Maintenance increase $ 3,606 / yr.

Hybrid GLHP Systems

Turn Key Cost about $13 per ft of bore hole

Full Size Ground Loop – Unbalanced Loads

Hybrid GLHP Systems

Full Size Ground Loop – Unbalanced Loads

Hybrid GLHP Systems

Boiler Hybrid Sizing

Hybrid GLHP Systems

Hybrid with 20% Boiler Saved 34 bore holes and 10,384 feet of drilling = 22% smaller loop

Hybrid GLHP Systems

Hybrid with 26% Tower (10 ton) Saved 9 bore holes and 3,191 feet of drilling

Hybrid GLHP Systems

Integrate non-HVAC equipment:

ice making machines, freezer cases, refrigeration cases, snow melt, ice

rinks, process water, black water waste, grey water, sprinkler water

Hybrid GLHP Systems

Ice Making Machines, Freezer Cases, Refrigeration Cases,

Walk-in Freezers

AHRI Certified EER improves 20% using water cooled Ice

Making Machines as compared to air cooled machines.• Units are quieter

• Units do not add a heat load to the zone

• Units require less maintenance

Freezer and Refrigeration Cases are free sources of energy for

the Ground Loop and selecting "water cooled" improves

efficiency, reduces refrigerant charge, and improves comfort by

reducing sound levels

Hybrid GLHP Systems

The GLHP system in this Minnesota gas

station heats and cools the building: provides

hot water, food refrigeration, and ice making;

and melts snow to and from the carwash.

5 HP Cooler Case downsized to 3 HP

3 HP Freezer Case downsized to 1 HP

Integrating Hybrid Ground Loop, Snow Melt, DHW, Freezer Cases,

and Refrigeration Cases

Hybrid GLHP Systems

LEED Version 4

Energy and Atmosphere Credit 1: Optimize Energy Performance

Points are awarded for exceeding the base line energy performance for the entire building

New Construction

Major Renovation

Core and Shell

Points (except Schools, Healthcare)

Points Healthcare

Points Schools

6% 4% 3% 1 3 1

8% 6% 5% 2 4 2

10% 8% 7% 3 5 3

12% 10% 9% 4 6 4

14% 12% 11% 5 7 5

16% 14% 13% 6 8 6

18% 16% 15% 7 9 7

20% 18% 17% 8 10 8

22% 20% 19% 9 11 9

24% 22% 21% 10 12 10

26% 24% 23% 11 13 11

29% 27% 26% 12 14 12

32% 30% 29% 13 15 13

35% 33% 32% 14 16 14

38% 36% 35% 15 17 15

42% 40% 39% 16 18 16

46% 44% 43% 17 19 -

50% 48% 47% 18 20 -

LEED Version 4

Energy and Atmosphere Credit 1: Optimize Energy Performance

New Construction

Major Renovation

Core and Shell

Points (except Schools, Healthcare)

Points Healthcare

Points Schools

6% 4% 3% 1 3 1

8% 6% 5% 2 4 2

10% 8% 7% 3 5 3

12% 10% 9% 4 6 4

14% 12% 11% 5 7 5

16% 14% 13% 6 8 6

18% 16% 15% 7 9 7

20% 18% 17% 8 10 8

22% 20% 19% 9 11 9

24% 22% 21% 10 12 10

26% 24% 23% 11 13 11

29% 27% 26% 12 14 12

32% 30% 29% 13 15 13

35% 33% 32% 14 16 14

38% 36% 35% 15 17 15

42% 40% 39% 16 18 16

46% 44% 43% 17 19 -

50% 48% 47% 18 20 -

Baseline ASHRAE 90.1 for GLHP: 13.4 EER

Most GLHP’s at AHRI Rating:

17.0 EER to 30.0 EER

20 EER = 49% Increase

Lower Life Cycle Costs

Lower Maintenance Costs

NEED TO KNOW:

From the Ground: Thermal Conductivity and Average Ground Temperature

From the Building: Monthly/Daily Loads

From the Equipment: GLHP Efficiency of Each Specific Heat Pump

GLHP Design Basics

33% IncreaseIMPORTANT

Use Hybrid Design

Use Grey Water/Black Water/Process Water

Integrate non-HVAC Equipment

Commercial Ground Loop Heat Pump Systems:Design & Economics

by Alan Niles

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