easuring nze home erformance in the northeast
TRANSCRIPT
Headquarters: 120 Water Street, Suite 350, North Andover, MA 01845 With offices in: CA, CT, ME, NY, OR, TX, VT www.ers-inc.com
MEASURING NZE HOME
PERFORMANCE IN THE NORTHEAST
Nick Collins, ERS
Ryan Pollin, ERS
Project and Program Introduction
NZE Basics
M&V Methods
Review of Example Homes
Observations and Discussion
This evaluation is still in progress, all data and observations are preliminary and have
not been approved by the Organization
OUTLINE
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PROJECT AND PROGRAM
INTRODUCTION
02/02/2017 3
Measurement & Verification
3rd party revisits completed sites to reassess performance and savings
Compare assumed energy performance with more defensible, measured values
Identify what works and doesn’t, feed lessons back to program
PROGRAM M&V BASICS
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Establish the actual energy use and performance of a population of net zero homes in the Northeast
Examine the relationship between energy use and various independent variables
Examine the relationship between energy use and occupant behavior
THE SCOPE OF THE PROJECT
02/02/2017 5
Recruited 19 homes for extensive metering
Meters installed ~March ‘16 to Dec ‘16
Some preliminary site results
Aggregate analysis in process
THE STATUS OF THE PROJECT
02/02/2017 6
A Northeast Low-Rise Residential New Construction program provides technical and financial support for the construction of net zero energy homes
Participant homes are modeled in REM/Rate
HERS Index under 10 qualifies as NZE
NZE sub-program began 2008
PROGRAM INTRODUCTION
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02/02/2017 8
Program Years 2008 – 2015
26 units, predominantly single-family NC
Size range from 756 – 4,382 SF
Tightness range from 0.14 – 3.3 ACH50
1 Contractor built 50%+ of program homes
~75% GSHP and 25% ASHP
Std DHW, typically preheated
Most lighting still CFL
All homes generate with PV
PROGRAM POPULATION
NET ZERO BASICS
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2015 DOE Definitions
Zero Energy Building
Zero Energy Campus
Zero Energy Portfolio
Zero Energy Community
Net Zero Energy
Zero Net Energy
Nearly Zero
Blah Blah Blah
WHAT IS A ZERO ENERGY BUILDING?
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Zero Energy Building
An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.
ZEB / NZE DEFINITION
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Site Energy – The amount of energy consumed on-site as measured by utility meters.
Source Energy – The total amount of energy needed to deliver the consumed energy, including: Primary fuels extraction, processing and transport
Energy losses in thermal power plants
T&D losses to site
Electricity Factor: 3.1 (National) or 3.4 (Northeast)
Natural Gas Factor: ~1
SITE VS SOURCE ENERGY
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M&V METHODS
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Site Work
Recruit all homes
High-level energy inventory
• Equipment
• Plug loads
• Lighting technology
Occupant Interview
Deploy current transducers
• March-December 2016
METHODS OVERVIEW
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Data Analysis
Meter energy consumption of subsystems
Collect utility data to corroborate
Establish gross and net energy use
Identify correlations between independent variables and energy use
• Weather Normalization
• Occupancy Normalization as needed
METHODS OVERVIEW
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MTCOOI: “meter the crap out of it”
Whole Home Net
Solar Production
Heat Pumps
Domestic Hot Water
ERV
Well Pump
Electric Vehicles & other
METHODS - SITE WORK
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Regression analysis, corroborated using utility data
Weather normalized 8760 analysis
• kBtu/s.f. as prime metric
Consumption load profiles
Generation load profiles
Peak demand period analysis
End-use breakdown
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METHODS – DATA ANALYSIS
Look for correlations between systems/behavior and energy use
Small sample sizes, still informative
GSHP vs. ASHP
Occupied vs. Unoccupied energy use
• Impacted by temperature setbacks?
• Impacted by occupant use of plug loads?
Energy use vs. Occupant density
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METHODS – DATA ANALYSIS
EXAMPLE HOMES AND
PRELIMINARY PERFORMANCE
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EXTERIORS
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ENVELOPES
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Superior Wall
Insulated Concrete
Form (ICF)
Spray-Foam
Roof Insulation
MECHANICALS
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Heat Pump Furnace
Ground-Source
Geothermal
Well Pump
Energy Recovery Ventilator
Domestic Hot Water Preheat
ELECTRICALS
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PV Array
PV Inverters
Main Electrical Panel
Built 2008-2009
6 years of daily kWh consumption and production data
3,237 square feet
ICF walls
GSHP – two vertical wells
7 kW Solar PV
HERS Index 6
EXAMPLE HOME A
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Historical Average daily kWh consumption vs. OAT
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EXAMPLE HOME A
Historical Consumption over time
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EXAMPLE HOME A
Historical PV production over time
EXAMPLE HOME
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Is it a zero energy building?
RECS 2009 Average NE home 2000-2009 – 39.9 kBtu/s.f.
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Year
kBtu/s.f. -
consumption
Net Source energy
(kBtu/yr) Notes
2009-2010 8.4 (27,522)
2010-2011 9.4 (24,516)
2011-2012 8.7 (35,564)
2012-2013 9.4 (17,459)
2013-2014 8.4 (30,597)
2014-2015 10.7 (2,688) Purchased electric vehicle
EXAMPLE HOME A
1800s Farmhouse, renovated 2011
8 months meter data
2,134 square feet
Wood-frame walls, roll insulation
GSHP
10.6 kW Solar PV
HERS Index 7
EXAMPLE HOME B
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EXAMPLE HOME B
Property Value
Annual kWh Consumed 25,044
Annual kWh Produced (24,507)
Annual kWh Exported (2,949)
Annual kWh Net 537
Consumption EUI 36.9
Net EUI 0.8
kWh Consumed per Occupant 12,522
kWh Net per Occupant 268
Percent of Energy Offset by On-site Production 98%
Achieving Net Zero? No
Is it a zero energy building?
RECS 2009 Average NE home 2000-2009 – 39.9 kBtu/s.f.
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Year
kBtu/s.f. -
consumption
Net Source energy
(kBtu/yr) Notes
N/A 36.9 +5,802 Typical weather year
EXAMPLE HOME B
Finish site analyses
Aggregate analysis of performance metrics
Ground-Source vs. Air-Source
Construction Age
Occupant Density
Occupant behaviors and associated energy performance
NEXT STEPS
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OBSERVATIONS AND
DISCUSSION
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Net zero neighborhoods provide a natural laboratory for examining occupant impact
Numerous participants in one neighborhood, near identical construction methods and design
Very different occupant characteristics and attitudes
EARLY OBSERVATIONS
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88% of metered homes report they do not set back thermostats or make an effort to turn off lights
Paraphrasing: “I already made my investment by buying a NZE home, why bother to set back the thermostat?”
Rebound effect?
EARLY OBSERVATIONS
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What affect does the NZE label have on energy behaviors?
What expectation can we have of NZE homes to achieve further savings?
What is the role of super-efficient equipment and behavior change activities in a time of low-cost PV?
THOUGHTS FOR DISCUSSION
02/02/2017 36
Performance is reliably achieved in “normal” looking and feeling homes
Homes, at least those built by experienced NZE contractors, are cost competitive in the real estate market
If we can build NZE homes and sell them at a competitive cost, then what is the next barrier to overcome? How can the now-niche NZE market scale?
THOUGHTS FOR DISCUSSION
02/02/2017 37
Homes currently for sale or sold since 2015
2,000 s.f. – 3,000 s.f.
0.25-0.50 acre lots
Similar amenities
Similar age
FOR SALE AND SOLD COST
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FOR SALE AND SOLD COST
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100
120
140
160
180
200
220
240
260
280
0 2 4 6 8 10 12 14 16 18
$/s.f. Net zero homes
Traditional homes