homeenergy score pilotresults: minnesota · “zone of unattainability” 1 to 4 existing– 27%...
TRANSCRIPT
Home Energy Score Pilot Results: Minnesota
Dave Bohac NorthernSTAR
Center for Energy and Environment [email protected], 612‐802‐1697
Residential Energy Efficiency Technical Update Meeting Denver, CO August 9 ‐ 11
Home Energy Score Goals
• Lower the cost hurdle for homeowners to receive a quantitative energy assessment
• Increase motivation for residential retrofits
• Develop consistent data collection process
• Collect comparative data on U.S. homes
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Part I: A Home’s Energy Score
Key Elements: Asset rating
36 to 67 data entry fields
Total Energy
Source Energy
19 Climates
Even Bins
Benchmark for home size
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Part II: Recommended Upgrades
Now
At Replacement
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CEE’s Residential Energy Programs
Community Engagement & Recruitment
Neighborhood Workshop
Home Visit & Materials
Follow up Calls Major Upgrades
Collect data at visit Email or mail report
Pilot Objectives
• Determine how the Home Energy Score integrates with field operations for residential energy visits – Additional data collection time requirements – Usability of data collection sheet and scoring tool interface
– Ability of different field personnel to make consistent estimations
• Assess the homeowner response to having their home scored – Do homeowners understand the score?
– Does it work as an effective motivational tool?
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Pilot Objectives
• Compare default house air leakage to actual measured.
• Measure the predictive capability of the building performance model against utility bill data, SIMPLE model and REM/Rate results.
• Assess the correlation of recommendations produced by the score with in‐person retrofit recommendations.
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Pilot Overview
• 154 Homes in Minneapolis and Apple Valley, MN
• February 1, 2011 – June 15, 2011
• Workforce: 2 Qualified Assessors • Process for selecting homes:
– Random selection of homes enrolled in our residential energy program
• Delivery mechanism to homeowner – Part of program: Community Energy Services, be.Apple Valley
– Score was mailed or emailed approximately 3 weeks after visit – No Home Energy Score recommendations
• Blower Door test performed
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Demographics of Pilot Homes: Construction Year
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Demographics of Pilot Homes: Number Stories
Foundation Type Basement ‐ 95% Slab‐on‐grade ‐ 4% Crawlspace ‐ 1%
Water Heater Nat. Gas ‐ 96% Electric ‐ 3% Oil ‐ 1%
Heating System Furnace ‐ 75% Boiler ‐ 25%
AC System Central ‐ 71% None ‐ 29%
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Wall Cavity Insulation by Construction Year
R > 11
4 ≤ R < 11
R = 11
R < 4
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Attic Cavity Insulation by Construction Year
R > 30
R < 15
15 ≤ R ≤ 30
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Home Energy Score Results for MN Pilot Homes
1
5
4
3
2
6
7
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All Homes (154 total)
Home Energy Score: Existing
Score With Upgrades
“Zone of Unattainability”
1 to 4 Existing – 27% With Upgrades – 6% (Two houses remained a 1)
7 to 10 Existing – 41% With Upgrades – 83% (no houses achieved a 10)
HES Recommended Upgrades
Recommendation % Houses Seal gaps and cracks 63%
Basement walls to R‐11 53%
Attic floor to R‐38 34%
Seal ducts 5%
No recommendations 15%
Average of 1.6 recommendations per house
Attic Insulation HES Recommendation
Lessons Learned: Process
• Did not add significant time to home visits, once “rhythm” was established: 30 minutes in‐home and 15‐20 minutes data entry
• Mechanical system info was hardest to obtain:
Percent of time the following inputs were available
Heating Cooling Water Heater Attic Insulation
AFUE Year SEER Year Eff Year
64% 36% 12% 78% 14% 77% 65%
Analysis: Utility Bill Comparison
• 51 homes with HES & utility data*
• Weather‐normalized Utility Bills to HES model Average
Home Energy Score
Average Utility Bill
Difference Between Average
Average Absolute Deviation
Source 253 MMBtu
215 MMBtu
18% 36%
Site Gas 1,558 therms
1,219 therms
28% 38%
Site Electric
7,192 kWh
7,123 kWh
1% 59%
And corrected basement floor area
Analysis: Gas Use Comparison
Recommendations for the National Launch
• Improve recommendations & cost estimates – Allow Qualified Assessor to tailor recommendations
• Consider shrinking the “zone of unattainability” – Group similar home types along different scales – Provide options for regional customization
Further Work
• Compare HES to program upgrade recommendations
• Methods to segment housing stock to provide more motivating existing/upgrade scores
• Compare utility/HES/SIMPLE energy results
• Will have 50 houses with REM/Rate analysis – compare to other data
• Compare actual to default house air leakage
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Extra Slides
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Homeowner Observations • Overall people were excited to participate and see their score
• Most common question was about survey (knowledge before or after visit?)
• People often asked if information sheet was their home
• Confusing or complex parts of the score and process – Source Energy
– Based on a model & concept of asset – Who they are being compared to
• CEE didn’t use in‐person delivery – 33 percent of email recipients didn’t open email – Provided as free add‐on to home visit
Demographics of Pilot Homes: Construction Year Wall Insulation
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33% with R‐value < 4
Demographics of Pilot Homes: Construction Year Attic Insulation
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Home Energy Score Results for MN Pilot Homes
HES Recommended Upgrades
Lessons Learned: Score and Recs
• Numerical scorecard is a helpful motivating tool – 83% with score ≥ 7 after upgrades
• Several homes did not receive motivating scores – 11% score a 5 or less after upgrades – 44% can only increase score by 1 or zero points – 15% had no recommendations
• Recommendations not consistent with program – No wall insulation and some attics with low R‐Values – High frequency of basement wall insulation
Analysis: Utility Bill Comparison
• 115 homes with gas + electric data
• Weather‐normalized Utility Bills to HES model Average
Home Energy Score
Average Utility Bill
Average Absolute Deviation
Average Deviation
Source 253 (278) MMBtu
215 (221) MMBtu
36% (45%) 28% (35%)
Site Gas 1,558 (1,779) therms
1,219 (1,200) therms
38% (57%) 33% (52%)
Site Electric
7,192 (7,279) kWh
7,123 (7,820) kWh
59% (53%) 38% (25%)
Subset of 51 with Corrected Basements (All Houses)
Conditioned vs. Unfinished Basements
61 homes post‐basement correction
Site Electricity Use
Post‐Basement Correction Pre‐Basement Correction
Site Gas Use
Post‐Basement Correction Pre‐Basement Correction
Analysis: Gas Use Comparison
Conditioned vs. Unfinished Basements
(1) Conditioned basement Unfinished basement that is 5‐10F (2) Unconditioned basement
cooler than above grade area??? (3) Vented crawlspace (4) Unvented crawlspace (5) Slab on grade
Apple iOS: iPhone, iPad Tablet
Google Android: Phone, Galaxy Tab Tablet
Blackberry OS6/QNX: Phone, Playbook Tablet
iPhone