Better Buildings By Design 2013 Building the Renewable Energy Ready Home Solar Thermal Lessons Learned and Results

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1 Image Courtesy of Harvestar Better Buildings By Design 2013 Building the Renewable Energy Ready Home Solar Thermal Lessons Learned and Results Doug Merrill, Sunward Systems

2 Doug Merrill 20 + years of manufacturing experience General Electric Husky Injection Molding Consulting, Teaching 5 Years of Solar Hot Water experience Consulting (supply chain) Monitoring development Principal in Sunward Systems

3 Solar Hot Water System Advantages Reduces need for electricity or fossil fuel Saves money Easy to integrate

4 Comparison of Energy Standards DHW Heating is Typically Second Highest Building Load

5 Why Solar Hot Water? Saves money a good investment ROI is good for most any fuel Propane 9% Oil 7% Electricity 7% Gas 3% Few alternatives in New England Heat pump & geothermal economics not great Wood is good, but labor intensive in the summer

6 Solar Hot Water Siting Building Compromises: Collector orientation Collectors facing true South are ideal Fall-off in production is gradual up to 45 from South OK Makes tracking unnecessary Collector tilt is also a gradual falloff nominal is angle=latitude Steeper is better (up to 5-10 degrees) Helps boost production in winter Assists in snow shedding Shading Partial shading OK- do analysis! Small feature shading (sticks, power lines) not a factor Want at least 5-6 hours of direct sunlight a day For new home sites consider the landscaping choices and how they will look in 10 years

7 Roof Design Considerations Orientation & pitch determine if roof is viable square feet of space Check border around collectors for fire access No penetrations or features within space Design for 6 lbs/ft 2 more than code Access to attic makes installation easier Slate & ceramic roofs are a challenge!

8 Integrating a SHW System Ground mount options Usually lower, so watch for shading Tubing & wiring run in trenches Easier to service & clear snow Typically more flexible, slightly more expensive

9 Integrating a SHW System Integration with backup DHW system SHW acts as a pre-heater Not cost-effective to produce 100% solar in New England Fuel agnostic works with gas, oil, electricity Functions most effectively with storage type heater Indirect fired systems are much less efficient than their ratings (due to summer cycling)

10 Mechanical Integration Integrated tank/heater/heat exchangers available, but force many compromises Lower efficiency (less storage, mixing) Higher lifetime costs Less space required Review total rise of system versus pump spec s Mixing valve is necessary Preferably on the output of the backup system This is consistent with current building codes in most places

11 Minimize DHW Load! Insulate hot water piping throughout the home Minimize hot water piping run length Install low flow shower heads and aerators

12 Water & Space Heating Readiness Much larger collector footprint required (roughly 10% of heated area) Radiant heating with high thermal mass ideal Maximize passive heating to minimize solar collection system needs Must address summer heat over-production Mechanically Physically Heat Dump

13 Benefits of building Solar-Ready Cost to contractor/homeowner minimal ~$150 Some design compromises may be required System effectiveness far higher Installation cost savings about $600 Builder can finish home before customer makes final installation decision

14 Lessons Learned: Performance Data 500+ Systems sold A dozen monitored Two case studies. Low use passive home High use passive home

15 Lessons Learned Case Study Home occupied 2011 Typically 2 residents Low hot water usage 38 gallons per day

16 800, ,000 Passive House Solar Hot Water Data Solar Hot Water Production Low Load Home Found October Heat Exchanger Output Well 100% Plugged Under Expectation 90% 600, ,000 80% 70% 60% 400,000 50% 300, , ,000 40% 30% 20% 10% - Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec DHW BTU SHW BTU % from Solar 0%

17 Passive House Solar Hot Water Low Load Home Conclusions 70% of the 2012 DHW energy needs have come from solar $70.00 $35.00 $60.00 $30.00 $50.00 $25.00 $40.00 $20.00 $30.00 $ Hot Electrical Water Electricity Cost Bills $20.00 $10.00 $5.00 $10.00 $0.00 $0.00 Jan Feb March April May June July Aug Sept Oct Nov Dec With SHW Without SHW Compared to an identical home with no SHW What about a home with a higher DHW Load?

18 Passive Home SHW Study #2 250 South of home #1 SHW system installed in July 2012 Monitoring installed in August 2012 Data is fresh! 3-5 Residents Very high DHW use 100 Gallons/Day

19 Passive Home SHW Study #2 Daily DHW Energy Usage Sept /6 9/7 9/8 9/9 9/10 9/11 9/12 9/13 9/14 9/15 9/16 9/17 9/18 9/19 9/20 9/21 9/22 9/23 9/24 9/25 9/26 9/27 9/28 9/29 9/30 DHW BTU SHW BTU 81% of DHW energy from solar (Compares with 86% on low use home) 2X Energy produced (45KBTU per day!)

20 Passive Home SHW Study #2 $ Electric Cost $90.00 $80.00 SHW System Installed $70.00 $60.00 $50.00 $40.00 $30.00 $20.00 $10.00 $- Mar-12 Apr-12 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 Nov-12 Dec-12 Savings of $40 - $70 per month

21 Questions?