Geothermal HVAC Metered
Comparison
for
National Chain Quick
Service Restaurant
Keith Swilley
Energy Sales and Efficiency Manager
Key Points:
•
How GSHP’s are more efficient and offer the greatest
potential for energy savings
•
Air Source HVAC efficiency goes down when outdoor
temperatures go up
•
GSHP’s are environmentally better, why not take
advantage of the constant temperature of the earth….
•
GSHP’s can be feasible in cooling dominant regions
•
Metered Project – Cost, Payback and ROI
The Earth is an Efficient Place to Reject Heat in the Summer… and to Extract Heat in the Winter… 74°F Outdoor air design temperature: 95°F summer, 30°F winter Delta T = $ to operate!!! Insula@ng layer of earth 70-­‐74°F Northwest Florida
Geothermal Heat Pump Efficiency Yields: 4-­‐6 kWh of energy for the building 1kWh of energy from the grid Plus: 3-­‐5 kWh of energy from the earth 400-­‐600% Efficient (COP of 4-­‐6) Electric Heat – 1.0 COP
Gas Heat - .8 to .9 COP
Project Details •  Loca@on: Pensacola, FL •  Mul@-­‐Geothermal HPs (40 tons @ 15 EER-­‐2 speed cap) •  1” loops in 4” boreholes with no grout on 30’ centers •  56 ground loops – 4 x 14 grid •  Single variable speed pump (3 HP w/ redundant •  Ground Proper@es(average in a 350’ borehole) –  Temperature: 72 deg F –  Thermal Conduc@vity: 1.37 Btu/hr-­‐d-­‐deg F Specific Equipment Metered
Conventional Store RTU’s
Ground Source Geothermal HP Test Store
2 – 17.5 Ton --11.5 EER
60 kW Heat each unit
6 – 6 Ton GHP’s --15 EER
5.0 COP
No kW Supplemental Heat
1 – 4 Ton Heat Pump
(13.5 SEER, 11.5 EER)
7 kW Supplemental Heat
1 – 4 Ton GHP –15.8 EER
5.1 COP
No kW Supplemental Heat
Total – 39 Tons
Total – 40 Tons
1- 3HP Loop Pump w/VFD w/redundant spare
Hot Gas Reheat
Hot Gas Reheat
HVAC Consumption of Total Bill
Energy Usage “Geothermal Store” Energy Usage “ConvenQonal Store” 16% 25% 75% 84% Only 1% Heating Load
HVAC Other HVAC Other Hourly Summer Temperatures 100 95 90 10-12 hours/day above 85
T
e
m
p
e
r 85 a
t
u
r
e 80 A better question to ask when comparing HVAC efficiency is:
75 What’s the efficiency (EER) when it’s 90-95 degrees outside?
70 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 DAILY HOURS Hourly Summer Temperatures (Equip Eff – 75 IDT)
100 Air Source RTU’s
95 GSHP’s
9.7 EER
15 EER
System
Efficiency
90 T
e
m
p
e
r 85 a
t
u
r
e 11.5 EER
80 No change – “GHP Advantage”
15 EER
75 What happens to A/C system Efficiency?
70 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 DAILY HOURS Actual Hourly Temperature for August
Averaged 2011/2012
Roof Temp Airport Temp 95.00 Average Temperature 90.00 85.00 80.00 Roof is 5-6 Degrees Hotter than Ambient
75.00 70.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 HVAC Equipment Efficiency at Peak
100.00 Geothermal A/C
15 EER
95.00 54% > Efficiency
30% > Efficiency
Average Temperature 90.00 85.00 16% Efficiency Reduction
from hotter ODT
11.5 EER
80.00 75.00 Roof Top Unit
ARI 11.5 EER , 12.3 IPLV
70.00 1 2 3 4 5 6 7 8 9 10 11 12 Hour 13 14 15 16 17 18 19 20 21 22 23 24 RTU HVAC
GSHP’s
RTU’s
GSHPs
HVAC System Metered Building – 40 Tons
Peak Load ~35 Kw
.9 Kw/ton
RED -- RTU’s
100-103 Roof Top Temp
(.4-.5 Kw/ton less)
Peak Load ~19 Kw
.48 Kw/ton
Blue --GSHP’s
2-Year Average Energy Consumption Comparison
19,000 Conventional Rooftop Units
48% Annual Savings
17,000 Geothermal Units
KwH 15,000 13,000 11,000 9,000 31%
20%
7,000 17%
5%
54%
63%
64%
63%
60%
10%
49%
27%
5,000 Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec 2-Year Average Energy Consumption Comparison
19,000 Conventional Rooftop Units
17,000 Geothermal Units
KwH 15,000 13,000 Air Source Roof Top Units
11,000 9,000 Geothermal Heat Pumps
7,000 5,000 Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Note: Due to mild winters, 98% of the savings was space cooling
Geothermal Break Even & 20 Year Cost Benefit Analysis
450,000
$407,998
Project Cost
400,000
Energy Savings + Replacement costs
(Cumulative)
350,000
Equipment
Replacement Cost
Dollars
300,000
250,000
20% ROI
200,000
150,000
100,000
Break Even
Point
50,000
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Years
w/Tax credit & incentives
22% annual escalation
Geothermal HVAC Cautions
GSHP’s work great when designed and installed correctly!
If you want a successful geothermal project:
•  Use experienced design engineers
•  Use experienced drillers
•  Use experienced installers
•  Don’t cut corners and you will get what you expect!
Ground Source Heat Pumps
Conclusion……
Conclusion
What are you waiting for?