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Julie Lynch MAS2019

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Presentation at the 2019 Massachusetts Sustainable Communities and Campuses Conference on March 29, 2019 in Cambridge, MA

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Julie Lynch MAS2019

  1. 1. CITY OF CAMBRIDGE Municipal Facilities Improvement Plan Photovoltaic InstallationsFletcher Maynard Academy 76.6kW Completed 2018
  2. 2. Agenda; 1. Existing conditions analysis • Daylight • Comfort • Ventilation 2. Temporary solutions 3. Strategies “The goal of the Municipal Facilities Improvement Project is to use whole building thinking to define a plan for the City of Cambridge to provide and maintain high- performance buildings for staff, occupants, the public and the environment.”
  3. 3. Agenda; 1. Existing conditions analysis • Daylight • Comfort • Ventilation 2. Temporary solutions 3. Strategies The philosophy of looking at a building as a series of interrelated systems and buildings as part of an integrated portfolio. A high performance building is not only low carbon and energy efficient, but also provides a comfortable and healthy indoor environment, is resilient, easily maintained and responds to the larger community it serves. WHOLE BUILDING THINKING
  4. 4. City of Cambridge Initiative Timeline • 2012 Municipal Solar Feasibility Study by CDM Smith • “Rooftop review” identified the top 15 City-owned sites *See Dept. of Energy Solar Mapping Resources • 2015 Municipal Facilities Improvement Plan (MFIP) • 2015 Net Zero Action Plan • 2015 5% Onsite Renewable Goal by 2020 • 2016 Cambridge Community Shared Solar (CSS) - Additional Site Feasibility Review by Cadmus • CDM’s shortlist of 15 City-owned sites starting point. • Phase 1: First Street Garage - carport CSS project. • Phase 2: Feasibility of rooftop solar development • 2016 MFIP projects evaluated solar in existing building portfolio
  5. 5. Cambridge Solar Installations Photovoltaic (PV) systems in operation include: MLK School 670.3kW Main Library 66.6kW DPW Frazier Building 2.5kW Cambridge Rindge and Latin School 72.8kW Sullivan Water Treatment Plant 840.3kW Frisoli Youth Center 3kW Kennedy Longfellow School 175kW Russell Youth and Community Center 36.1kW Citywide Sr. Center 12kW Fletcher Maynard School 76.6kW 859 Broadway City Hall Annex 26.5kW
  6. 6. Cambridge Solar PV in Construction or Design PV Arrays in construction or design: King Open School 2.386.5kW Graham and Parks School 219kW Russell Youth and Community Center Expansion 53.3kW Taylor Square Firehouse 24.4kWac • City is on target to exceed 5% goal by 2019, one year ahead of schedule with the opening of the King Open School. • Several additional arrays are under consideration, as the City looks beyond 2020 toward Net Zero Action Plan and GHG 2020 and 2030 emissions reduction targets.
  7. 7. Solar Photovoltaic (PV) 
 Installation….. Parts and Process Site Selection Owner or with Designer Designer Selection Solar (Electrical)/ Architectural/Structural Design Documents Feasibility Study Schedule Budget & Funding Eversource Evaluation MassACA Registration Bidding & Contracting Inspectional Services, Eversource & MassACA Commissioning (Cx)
  8. 8. Getting Started….Design Considerations • Electrical Infrastructure Assessment • Network or Radial Grid • Historic Buildings • Occupied Buildings • connect to the grid; safety; access; staging area; parking. • Structural Assessment • Coordinate PV design with structural engineer. • Uplift from wind is critical. • Allowable loads may vary on a building.
  9. 9. …additional Design Considerations • Data Acquisition System (DAS) Reporting • Shading assessment and tree management • Orientation & Roof Edge Setbacks • Roof Warranty • Access to all roof levels for O&M • Ballasted vs. mechanical fastening for installation of racking • DC or AC runs along rooftop – Locate inverters accordingly. Essential to manage wire runs & identify trip hazards in snow with flags. • Cx is essential
  10. 10. Case Study: Kennedy Longfellow School (Klo) 175kW Initial design was peer reviewed by SDA and nearly doubled size of array. Assess existing conditions • Occupied school • New roof • Tree canopy • Structural integrity of the roof • allowable psf may vary • Ballasted or mechanically fastened • Wind uplift • Electrical infrastructure – work with utility • network vs. radial grid • Condition of switchgear • Location of utility required AC disconnect • 521 CMR MAAB – accessibility triggers Tree shading Roof access Loading varies Edge Setback New roof Shading
  11. 11. Case Study: Kennedy Longfellow School PV Array Layout • Allowable structural loads varied 5.9 to 8.6 psf with no structural modifications undertaken.
  12. 12. Case Study: Kennedy Longfellow Design 175kW • Occupied building with limited access • Summer construction • Followed installation of new roof with 30 year warranty. • No electrical upgrades – network grid • MAAB upgrades - toilet room & entrance.
  13. 13. Case Study: Kennedy Longfellow School (KLo) 175kW • East/West facing panels • Minimized DC runs • Ladders provide for O&M • Trees trimmed prior to construction & ongoing scheduled maintenance • Roof inspected at start and finish - warranty requirement.
  14. 14. • 12kW • Structural upgrades at underside of deck to accommodate wind uplift • Network vs. radial grid connection • Design by Arup • Electrical Contractor subconsultant Solar Design Associates refined design in shop drawings Citywide Senior Center 
 Rooftop Patio PV Canopy 12kW
  15. 15. Citywide Senior Center 
 Rooftop Patio PV Canopy 12kW
  16. 16. • Participator Budget Project • Array size of 33kWac was increased to 66.6kWac • Larger capacity panel • additional panels • Newer roof • Occupied building • Adjacent to High School Cambridge Main Library 
 System Size: 66.6kW ac
  17. 17. • SunPower 360 W PV modules • Helix mounting racks • SolarEdge P800 DC-DC optimizers (1 optimizer per 2 PV modules) • 33.3kWac SolarEdge inverters. • East/West panel orientation Cambridge Main Library 
 System Size: 66.6kW
  18. 18. Thank you


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