geothermal heat pumps: a pathway to zero net energy … · geothermal heat pumps: a pathway to zero...
TRANSCRIPT
Lisa Meline, P.E. Meline Engineering Corp.
Office: 916.366.3458
Session C: Institutional Applications Empire C
Geothermal Heat Pumps: A Pathway to Zero Net Energy
(ZNE) for Schools, Homes and Businesses
Disclaimer
The opinions expressed in this presentation do not necessarily reflect the views of IGSHPA or its sponsors. They are solely reflective of years of associating with geothermal heat pump geeks, curmudgeons and malcontents.
Acknowledgements
• Dr. Steve Kavanaugh • Kirk T. Mescher, P.E. • Cannon Design • California Geo
• Understand how to define a Zero Net Energy Building project.
• Be able to list the steps towards achieving Zero Net Energy.
• Understand the importance of benchmarking
• Know what to look for in hiring a qualified geothermal engineering firm.
Learning Objectives
Steps to Zero Net Energy
1. Envelope Management 2. Conservation 3. Lighting 4. Energy Efficiency of HVAC and DHW
Systems 5. On-site Generation
Define Net-Zero Energy
Total Energy Consumed On-Site
Total Energy Consumed On-Site
Renewable Energy Generated On-Site
Define Net-Zero Energy
Total Energy Consumed On-Site
Renewable Energy Generated On-Site
Renewable Energy
Exported to Grid
Total Energy Imported from Grid
Define Net-Zero Energy
Total Energy Consumed On-Site
Renewable Energy Generated On-Site
Renewable Energy
Exported to Grid
Total Energy Imported from Grid
Is Greater Than or Equal To
Define Net-Zero Energy
© American Institute of Architects
Benchmarking
AB 1103 - 2007 • Applies to non-residential buildings >5000 sq.
ft. • Requires owners to rate their buildings using
Energy Star Software (Portfolio Manager) • Must disclose “Statement of Energy
Performance” to the CEC. • Latest rules:
– July 1, 2013 for buildings >50,000 sq. ft. – July 1, 2013 for buildings 10,000-49,999 sq. ft. – January 1, 2014 for buildings 5,000 – 9,999 sq. ft.
http://www.ab1103.com/
© ASHRAE AEDG50
What Drives Energy Consumption for HVAC Systems Setting an EUI Target
• CBECS (2003) EUI for College/University facilities is 120 kBtu/sf/year
• Regional average is 75 kBtu/sf/year
• ACB project is modeled at 28 kBtu/sf/year
• Better than regional average
by 63% • Better than ASHRAE 90.1 2010
by 48%
Predicted Energy Consumption
0 20 40 60 80
100 120 140
CBECS Average Regional Average
ACB Predicted EUI
Predicted Energy Use Intensity in kBtu/sf/year
HVAC System Strategies
B
BLDG 9
TO BUILDINGS
POOL
GROUND LOOP
DRYCOOLER
BOILER
TO WASTE
CHILLERS
Chilled Water
Hot Water
On-Site Generation = 2,107,973 kWh = 7,194,512 kBtu/yr ACB Predicted Use = 5,988,188 kBtu/yr
Provide On-Site Renewables
Whose definition of ZNE should be used?
• NREL/Federal Government • ASHRAE • The California Energy Commission
NREL
NREL
Geothermal heat pumps?
Geothermal Heat Pumps
• Generation avoidance • Electric generation – leveled • Simple, when done properly • Out of site, out of mind
Simple GHP System
1
2
3
Diagram courtesy of Water Furnace
Why GHPs? 1 kW Electrically Generated Energy to power the systems
3 kW of Geothermal Energy moved from the Earth
4 kW Heat Delivered
Definition of COP
Q: So isn’t the earth essentially ‘generating’ energy?
Seasonal Energy Usage
Seasonally Stored Energy for Cooling
Seasonally Stored Energy for Heating
• It is critical that the HVAC system be efficient in order for the GSHP to be efficient.
• Just because the system is ASHRAE 90.1-2013 compliant or LEED rated does not mean it is efficient
• Systems with large amounts of fan and pump power will require much larger ground loops to dissipate the additional heat in the cooling mode.
• Systems with large amount of fan power will operate in heating much fewer hours and thus fail to remove sufficient heat from the ground loop to balance cooling heat rejection.
GSHP System Equipment and Distribution Options
© Steve Kavanaugh, Energy Information Services, 2015
CEC’s Revised Definition of ZNE (IEPR Meeting July 11, 2011)
“The societal value of energy consumed by the building over the course of a typical year is less than or equal to the societal value of the on-site renewable energy generated.”
National Park Service Intern Center
Net Zero Energy • 3400 sq. ft. • (10) horizontal slinky
loops (8-ton WTW) • 36 kW rooftop PV • 2-pipe fan coil system • 9kW Electric water
heater • Treated waste water
on-site used to ‘cool’ loop and for irrigation
Other Public Projects
Spooner Summit Fire Guard Station/Support Sports Facility • 3100 sq. ft. • Integrated Geothermal-Solar Thermal project • (6) vertical bores • (6) solar thermal panels
CCSF - Central Plant Loop Field
Public Projects to Neighborhoods
CA’s Big Bold Goal • All homes ZNE by 2020 • All businesses ZNE by
2030
How do we get there? • Passive Haus • SMUD (Utilities) Home
Performance Program • Geothermal Heat Pumps • Solar thermal for DHW • PV for on-site generation
(CEC – solar ready)
Now Let’s Talk About Businesses
10,000 s.f. - Forced air heating and cooling
How Do You Measure Efficiency?
• Title 24 Goals(ASHRAE 90.1) /CalGreen • LEED and other ‘point’ systems • NZEB (ZNE) What’s the total annual power bill?
• Forced air heating and cooling
• Domestic hot water
• Pool and spa heating
An Early Adopter
Identifying and Hiring a Competent Design Team
© Steve Kavanaugh, Energy Information Services, 2015
What makes a competent design team?
• More Skill than just Marketing • Design for Maintainability • KISS • The Engineering Portfolio • Energy Star Ratings
Westside Elementary is a 38,000 ft2, two-story structure opened in 1929. A 2008 renovation included a geothermal heat pump (GHP) system, lighting upgrade, window replacement, and an energy recovery ventilation system. Energy performance has exceeded expectations as indicated by the EPA ENERGY STAR rating of 98. The GHP installation cost was $863,210 and energy savings indicate a 5-year payback. Occupants rate comfort, air quality, lighting, acoustics, and maintenance at 3.9/5.0 (Satisfied). Client contact to verify results: John Smith ([email protected])
Building Details Floor area = 38,000 ft2, 500 occupants, 10-month operation Energy Use: 307,800 (8.1 kWh/ft2), Demand: 118 kW (3.1 W/ft2), Energy Cost: $30,475 ($0.80/ft2)
HVAC Equipment 32 water-to-air heat pumps (90 tons), 36 pumps (5.5 hp total), four 2500-cfm energy recovery units Ground Loop 88 vertical bores at 225 ft. each, 1-inch HDPE U-tubes, individual circuits to each heat pump
Installation Costs HVAC Ground Loop Total HVAC & Loop Heat pumps (32) $128,000 Drilling/Installation $158,400
$863,210 Pumps (36) $19,800 HDPE U-tubes $29,700 $22.72/sq. ft. ERUs (4) $120,000 Exterior Headers $27,000
Ductwork $144,000 Thermal Grout $18,810 Interior Piping $56,000 Controls $66,500 Cost per bore ft. $11.81 Electrical Upgrade $95,000 Total $629,300 $233,910 Total per sq. ft. $16.56 $6.16
Occupant Satisfaction Cooling Comfort 3.7/5.0 Heating Comfort 4.4/5.0 Indoor Air Quality 3.9/5.0 Lighting 4.4/5.0 Acoustics 3.7/5.0 Ability to Control 3.1/5.0 Maint. Frequency 4.2/5.0 Maint. Response 3.5/5.0
Maintenance Staff Serviceability 3.0/5.0 Quality of Installation 3.5/5.0 Satisfaction Quality of Design 4.0/5.0 Quality of Equipment 2.5/5.0
The Engineering Portfolio – Individual Building Description
© Steve Kavanaugh, Energ y Information Services, 2015
To Be Successful • Find a Design Team that you like and think
you can work with (for better or for worse). • Verify references and ask to see examples of
their ‘work product.’ • Make sure their engineering team is
experienced or at least willing to learn. • Ask to see their portfolio of Energy Star
Scores or similar system performance data. • Look for practical engineer, one with common
sense.
Run! Run from shiny black shoes!
Steps to Zero Net Energy
1. Envelope Management 2. Conservation 3. Lighting 4. Energy Efficiency of HVAC and DHW
Systems 5. On-site Generation 6. User Education
