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Low Energy Homes: Water Heating Observations & Implications Examining Patterns, Trends, & Implications of Varying Water & Energy Use ACEEE Hot Water Forum Wednesday, May 23, 2012, 10:30-Noon Berkeley, CA Linda Wigington, ACI lwigington@affordablecomfort.org www.affordablecomfort.org www.thousandhomechallenge.org 1
What happens outside of normal boundaries of energy & water use? 2
For Purpose of This Session Defining Deep Reductions 70% or better actual measured performance for a project Using Thousand Home Challenge as the benchmark Holistic not limited to building enclosure & mechanical systems www.1000homechallenge.org 3
Note About Energy Use Terms kwh/yr. does not refer only to electrical energy use In the Thousand Home Challenge & case studies, household energy use is converted to kwh site energy 4
Conversions 30 kwh = 1 therm natural gas 7,500 kwh = 25 MMBtu 7,500 kwh = 250 therms 7,500 kwh = 180 gallons/#2 oil 5
Average DHW Energy Use per Day? Month? Year? Electric 3,000-5,000 kwh/yr. 250-415 kwh/mo. ~ 8-12 kwh/day Natural Gas 150-200 therms/yr. 12-16 therms/mo..5 therms/day Energy use varies considerably in response to family size & incoming water temperature. 6
Mention of projects, products, & systems are not meant to be an endorsement 7
The Thousand Home Challenge 70%+ Deep Energy Reductions Access & Integrate Efficiency Behavioral Choices Renewables Community Solutions 8
OPTION A Thousand Home Challenge Threshold Determination 75% verifiable reduction in actual annual site energy use OPTION B Climate (ZIP Code or best match weather station) House size (FFA), converted to surface area (5 sides) Detached or attached Electric heat allowance = ½ fossil fuel or wood heat allowance Number of occupants (including partial occupancy) 9
Water Heating Allowance: Thousand Home Challenge 1 OPTION B 10 gal/person (1-2 persons) hot water @ 100% efficiency 7 gal/person (3 or more occupants) Consideration of incoming water temp Annual Hot Water Threshold Allowance (ZIP 15370) Occupants kwh/yr. kwh/day Therms/yr. 1 609 1.65 20 2 1,207 3.31 41 4 2,051 5.62 70 6 2,896 7.92 99 10 1 www.1000homechallenge.org
What Criteria to Use? Responsive to very low water use High performance over full range of use No regrets Synergies! Makes sense ($$, value, durability) Performs as expected over time 11
Low Energy/Water Approaches Gas tankless Behavior Low-flow fixtures Solar thermal DHW w/backup Solar thermal space & DHW combi HPWH Point source Community solutions (gym) Distribution & heat recovery 12
Watch Out for Gas Service Charges/Rates Fixed monthly gas varies widely Gas service charge higher than energy cost Ward Lutz: $266 Annual for 16 therms/yr. = $18/therm! 13
The Lutz Passive House Inspired Retrofit (Urbana, OH) Prior to PV installation, one of the first homes to meet the Thousand Home Challenge! Net zero since then. 3.5 KW PV Array Goal: 90% reduction in heating energy Case Study - www.thousandhomechallenge.org 14
Ward Lutz Comparing Pre- and Post-use (kwh/yr) with Average & THC Threshold Home Energy Yardstick (Average) Pre-retrofit Use (kwh) THC Opt B Threshold (kwh) THC Opt A Threshold (kwh) Post Use (kwh) Heating Cooling Hot Water All Else TOTAL Pre Period: 9/15/08-9/14/09 Post Period: 9/15/09-9/14/10; since then same energy use for DHW/yr. Hot Water (Rinnai Tankless Water Heater - 16 therms/year) Only use natural gas for water heating 15
Ward Lutz Home Rinnai Tankless Water Heating System Installed Nov. 2008 Installation cost $2,475.06 Plus $500 for gas line ISSUES: Using this system for space heating was not considered $266/yr for 16 therms/yr. (1) 6 gal shower/day $18/therm! Maintenance $200 ~ 2-3 yrs. 16
Next Step: Ward Lutz Installing GeoSpring HPWH in utility room May put on timer to run at night during winter DHP heating system 17
Water Heating Allowance: Thousand Home Challenge OPTION B Annual Hot Water Threshold Allowance 3 Pennsylvania Heat Pump Water Heater Houses (not THC projects - synergies not reflected) kwh/yr. kwh/day Therms/yr. 1 Occupant THC 609 1.7 20 House 1 1 occ 688 (<$65) 1.89 2 Occupants THC 1,207 2.9 41 House 2 2 occ ~1,000 (<$95) 2.55 5 Occupants THC 2,474 7.2 84 House 3 5 occ 1,542 (<$150) 4.22 Brownsberger - 5 occ (MA) 1,330 Electric Res w/solar w/solar 3.64 18
Pennsylvania House 2 2 adults, low water use New, relatively dry basement with heat pump & ductwork 50-gallon Marathon 2.55 kwh/day (<$100/year) ~1,000 kwh/yr. (See ACEEE Wigington HPWH presentation for additional info) 19
Installed May 2012 Danny Parker - NZE Cocoa Beach, Florida 4 in family Solar thermal with natural gas tankless backup $3/therm actual (low gas use) Heat Pump Water Heater (GeoSpring) 20
Impact of Site Vs. Source Not as Relevant w/pv Ward Lutz & Danny Parker ZNE+ with PV Are national site to source conversions relevant when they are exporting electricity? 21
Is Shiftability of DHW Load a Bigger Value to the Environment & the Grid? 22
Key Opportunities During System Design 23
Hummingbird House Larry & Suzanne Weingarten Salinas, California 05 04 11 24
Hummingbird House Wall radiant solar heating (passive circulation) Heats with low Δ T (80 F water!) Waste water heat recovery 25
Hard to Get Clear Signal Gas baseload includes cooking & clothes drying DHW solar thermal varies monthly Blending of DHW & space heating Load interaction (+ or -) HPWH 26
Bergamaschi/Soo Hoo Residence, Oakland, CA; Officially meets THC Tankless gas Annual gas baseload: 90 therms (also cooking, wintertime clothes dryer) 27
Mackey Deep Energy Reduction Case Study Chambersburg, PA 33-year-old home All electric 5,343 heating degree day (HDD) climate 2,500 ft 2 Full basement (1/2 unconditioned)! 03-01-2012 #5 28
Mackey Deep Energy Reduction Case Study Solar thermal evacuated tube collector 29
Mackey Deep Energy Reduction Case Study Beat Thousand Home Challenge Threshold by 3,500 kwh! Mackey Household Annual Energy Use (kwh) Pre & Post Compared to Threshold Allowance PRE USE (2007) THC THRESHOLD Option B, Electric Heat POST (No PV) May 2010 April 2011 POST NET kwh (With PV Credit 6332 kwh) May 2010 April 2011 25,308 6,488 9,645 2,696 Over 82% reduction from 2007 energy use! With e Monitor, upcoming end use breakout possible (all electric home) 0 5,000 10,000 15,000 20,000 25,000 30,000 30
Mackey Deep Energy Reduction Case Study Monthly Energy Use (kwh) Over Time 31
Feedback Drives Performance 32
Tom and Margaret Hall, Quincy, MA Deep Retrofit 96% efficient Phoenix Evolution, integrating solar & backup water heating 75 ft 2 Velux integrated solar DHW 33
Tracking & on track! Graphs: Thomas Hall & Matthew Shrago 34
Solar hot water with two electric backup tanks metered separately for each unit. Brownsberger Deep Energy Reduction Belmont, MA 35
Brownsberger Energy Use 3,000 kwh Below THC Threshold! (2011) THC OPTION B (Gas heat) 2011 Actual Household Energy (excluding PV) Heating Cooling Hot Water All Else 2011 kwh 2011 Solar PV Contribution 2011 Actual kwh (Net) DHW: Solar PV with 2 electric backup DHW tanks 0 5,000 10,000 15,000 20,000 36
Lesson: Don t Assume Performance 37
Bill Turner Utah Mountain House Solar Thermal w/100 gal. Marathon DHW tank & damp sand bed floor storage (2011) 128 ft 2 southeast 38
Turner Solar Performance Solid Line: ºF solar storage tank Dotted Line: ºF sand bed Note: Solar is working; however, gas & electric bills remained the same for Oct., Nov., & Dec. 2011 39
Solar Thermal Components (Turner) 1. Four 32 ft 2 panels 2. 10-gal. drain back tank 3. 100-gal. Marathon tank 4. Heat exchanger for tank 5. 3,000 lb. damp sand bed floor storage for excess 6. Backup water heating??? (was gas, now Seisco electric tankless as boost; system fully submonitored 40
DHW Power vented noncondensing hot water heater 65%??? efficiency (oops, much lower seasonally) Bill Turner - Utah 41
Lesson: Don t Assume Performance 42
Community Solutions & Behavior 43
Shea Net Zero Reduction Project Buffalo, NY THC OPTION B: (kwh/year) 4,069 Heat 1,761 DHW 2,228 Everything else Officially meet THC 44
Shea All Electric Home 10 KW PV System w/geothermal heating Very low hot water use Community solutions! Bosch Electric Demand DHW 45
House Within a House 100 Year-old San Mateo, CA Nickie Irvine-John Dorfman THC Candidate Retrofitting for deep reductions without a full gut remodel Behavior & community solutions significant (Gym) To reduce stand-by losses turn off hybrid tankless when not in use 46
Core Proposition 1 A performance target can be a powerful & useful determinant of energy use if it is: Transparent Logical Fair Easily tracked & verified Meaningful to the participants Within participants field of influence 47
Core Proposition 2 Rapid feedback is critical Make new mistakes, rather than repeat old ones! 48
Core Proposition 3 Need to go beyond energy reductions to make the value proposition Integrated solutions needed! Increased resilience Decreased peak Improved house durability & viability Improved comfort & IAQ 49
Implications Ongoing refinement over time Behavior significant impact Technical/behavioral integration can be challenging Source-Site & $/MMBtu barriers to lowest energy & water use options Opportunity for collaboration Thanks to A.O. Smith! LBNL 50
Feedback Welcome Linda Wigington 724-852-3085 lwigington@affordablecomfort.org www.affordablecomfort.org www.1000homechallenge.com Introduction to the Thousand Home Challenge Webinar Home Energy Pros THC Group http://homeenergypros.lbl.gov/ 51
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THC REDUCTION MATRIX (CA Example) ANNUAL HOUSEHOLD kwh (Pre, Post, & Threshold) Loads Pre-use Proposed Usage Reductions - kwh/yr Targetuse THC Threshold (breakout may be estimated) Efficiency Behavioral Renewables Community (kwh/yr) Building Upgrades Equipment Upgrades Choice Reductions On-site Offsets Solutions (kwh/yr) (kwh/yr) Heating 9,700 2,000 2,000 1,700 4,000 3,508 Cooling 2,500 1,000 500 800 200 Hot Water 5,500 500 2,000 1,200 300 1,000 1,431 All Else 9,900 3,700 2,000 4,200 0 2,231 Total 27,600 3,500 8,200 5,700 4,200 300 5,200 7,170 Pre Gas space & water heating, & cooking (~550 therms) Post All electric (DHP, HPWH, induction cooking) Reduction: 22,400 kwh/yr. 53