Rob McMonagle, SolarCity Program Manager, Toronto Atmospheric Fund March 26, 2010

1. Structural Requirements for Installing a Residential Solar Water Heater on a Roof The Toronto Experience Rob McMonagle, SolarCity Program Manager, Toronto Atmospheric FundMarch 26, 2010

2. Future Events All webinars run from 1-2:30 p.m. EST Webinar 1 – Developing a Building Permit Process for Solar Water Heating - Wednesday, March 24 Webinar 2 - Structural Requirements for Installing a Residential Solar Water Heater on a Roof - Friday, March 26 Webinar 3 - Inspecting Residential Solar Water Heating Systems - Wednesday, March 31 Webinar 4 - Permitting of Residential Solar Water Heating Systems - Wednesday, April 14 NOTE: All presentation will be posted on www.solarpermits.ca a few days after the webinar

3. Solar Permits Overview Developed by the Toronto Atmospheric Fund (TAF) to share knowledge gained through the largest single-city solar hot water project in Canada (Solar Neighbourhoods). TAF is the City of Toronto’s climate agency. TAF supports the development and implementation of leading-edge ideas with the potential for large emission reductions. TAF is working to support greater deployment of renewable energy in Toronto as a way of helping the City reach its emission reduction targets. Solar Permits is made possible by an investment by the Government of Ontario and the Government of Canada.

4. Webinar Agenda • 1. Introduction to Solar Water Heating • Solar Hot Water – A Brief History • Understanding the Technology • 2. Solar on the Roof and the Ontario Building Code • 3. Roof Conditions & Solar Systems • 4. Solar Span Tables • 5. How to Verify Roof Conditions for Truss Roofs • 6. Verification of Roof Conditions for Rafters • 5. Verifying That the Roof can Support Solar • 6. Supporting Solar - Is it a Concern? • Toronto’s experience • 7. Open Discussion

5. 1. An introduction to solar water heating

6. Solar Technologies • There are four distinct technologies that collect energy from sunlight • Passive Solar – collects heat and light through natural (passive) processes • Photovoltaic or PV – produces electricity directly as a result of the material’s properties • Solar Air – produces hot air for space heating • Solar Water – produces hot water for pools, industry and residential applications • We’re focusing on solar domestic hot water (SDHW)

7. Overview • For an overview of solar hot water in Canada and internationally, please see webinar #1.

8. 2. Solar on the roof and the Ontario Building Code

9. Just how heavy is that solar system on my roof? • Could this be an actual concern????

10. Solar as A Designated Structure in the Ontario Building Code • 1.3.1.1 Designated Structures • The following structures are designated for the purposes of clause (d) of the definition of buildings in subsection 1(1) of the Act: • (f) A solar collector that is mounted on a building and has a face value equal or greater than 5m2. • However - where solar modules are supported by and are connected to a building they are covered by the Building Code (regardless of size) – thus there is a need to carry out a review for conformance. • Requirement to review • Can the roof withstand the extra load? (both dead and uplift (wind)) • Will the solar collectors stay attached to roof? • International best practices • Its not a problem (Europe) – but roofs are built to higher standards • Ignore it OR require an engineers report for each installation (US & Canada) • Can we do better?

11. Design and Structure of Rooftop Solar Projects • Two Issues: • 1. Can roof hold the structure? • 2. Structural mounting of the system • How is it going to be installed on the roof? • Can be dealt with through a P.Eng stamped structural drawing of the system mounting (supplied by manufacturer) • If the design is used for multiple projects, it does not need to be a stamped drawing for a single project

12. Example Structural Mounting Drawing

13. 3. Roof conditions and solar systems

14. Solar on the Roof – Roof Conditions • Two roof types • Flat roof • Sloped roof • Two roof structure types • Rafter • Truss (prevalent in homes built after 1990s) • Two system types • Tank on roof (seasonal) • Tank in the utility room (year-round)

15. Solar on Sloped Roofs • Solar Neighbourhoods in an older downtown neighbourhood • Older buildings tend to have structurally stronger roofs

16. Solar on Flat Roofs • Solar Neighbourhoods in an older downtown neighbourhood • About 30% of installations done on flat roofs • Higher concern of water leakage • Increased wind loading • Variety of roof covering

18. Seasonal Systems with tank on Roof • Limited experience in Solar Neighbourhoods as no sales of this product were made • However the developed product span table for one seasonal system is comparable to span tables for systems with just the collector on the roof • Seasonal systems are about ½ the size of year-round systems

19. This is Not Just a Solar Hot Water Issue

20. This Would Have Serious Uplifting Load Issues(perhaps its designed as a house that can fly?)

21. Typical Weights on Roof

22. Where to Draw the Line? • If the solar collectors weigh similar to other products with long term use on roofs (i.e. 2 layers of shingles) then they are structurally acceptable due to past equivalent satisfactory performance. Toronto Building Official • Thus PV modules and solar pool collectors (unglazed) fall below the weight if mounted flush to roof • However there still is a concern about roof connections • Toronto Building has yet to make a definitive ruling about the need for a structural building permit for PV and pool collectors • But hopefully soon... • Some solar hot water collectors are close to weight (3.3 – 5.3 vs. 3.8 for shingles) so there are some opportunities

23. 4. Solar Span Tables

24. The “Toronto Solution” • City of Toronto’s Building Department has developed a simple methodology to determine if the roof conditions can withstand the structural loading of the renewable energy projects for rafter roofs • Truss roofs require a different solution • Step 1: Development of product structural drawings • Stamped structural drawings • Span Table • Sample load calculation (for review by Toronto Building) • Letter of conformance by P. eng.

25. Structural Drawing (example) SAMPLE

26. Structural Drawing (example) SAMPLE

27. Sample Load Calculations SAMPLE

28. Engineer’s Letter of Conformance to OBC SAMPLE SAMPLE

29. Solar Thermal Structural Load Span Table • As part of the structural drawing a span table is developed showing the types of roof conditions that the product can be installed on

30. Product Span Tables • Product Span Tables are dependent on collector specs (weight) but also mounting methodology

31. Solar Neighbourhoods Standard Structural Drawings • Once the methodology was proven there was sufficient comfort level at Toronto Building to use a standard drawing for all solar collectors with similar conditions • Solar Neighbourhoods developed standard sloped roof span tables for flat plate collectors • This standard drawing is a publicly available document that can be used for any solar collector • A possible future step would be to turn this into a “standard construction detail” (similar to prefab chimneys or wooden decks) through TACBOC or LMBOC

32. Solar Neighbourhoods Standard Drawings Letter of Conformance

33. 5. How to verify roof conditions of truss roofs

34. Verification of Roof Capacity for Truss Roofs • Trusses are an engineered product – not listed in the OBC • Two methods identified that can verify that the truss has the additional structural capacity to hold solar collectors • Verification from the manufacturer • Site report from a structural engineer • There are engineers that specialize in truss inspections • Reported experience from some solar contractors is that the cost of site inspection by truss engineer costs $600

35. Structural Engineer’s Report SAMPLE

36. Structural Engineer’s Report SAMPLE

37. 6. Verification of Roof Conditions

38. Process for Roof Verification Truss

39. Verification of Roof Conditions Inspection requirements will vary depending on type of roof rafter or truss Rafters are easier to verify as they are defined in the Ontario Building Code

40. Toronto Solution for Rafters – Solar Roof Report • Roof inspection report is done showing the conditions of the roof at site of proposed solar installation

41. Roof Report – Specs looking for

42. Roof Report – who does? • Under the OBC the homeowner is exempt from requirement to be a qualified designer

43. Last Step • Verify that the solar span table is inside the actual roof conditions

44. Verify that roof conditions are greater than product span table If the roof is composed of 2x8 rafters on 16” (400 mm) spacings then this solar collector can be installed on a maximum rafter span of 3.18 m with no structural alterations However this does not work for truss roofs

45. How to Assess A Roof for Conditions • Solar Neighbourhoods has developed a Bulletin Guide on methodologies to assess roof conditions • i.e. How to measure roof rafter sizes • Will be posted on website soon

46. 7. Supporting solar – Is it a concern?

47. Solar Neighbourhoods Experience Through Solar Neighbours, TAF has evaluated 65 Roof Reports Only 1 project ran into structural challenges (rafter span greater than required by the solar span table) Project was able to proceed by moving the collectors onto the flat roof No contractor reported that a sale was lost due to inadequate roof structural conditions On average project roofs had a 30% greater rafter span than required by the solar span table It appears that for downtown Toronto roofs have adequate structural capacity to hold solar collectors without any required structural modifications

48. Level of Concern • The proof of conformance to the Ontario Building Code should be linked to the level of potential structural concern

49. The Cost of Regulatory Compliance for Roof Mounting

50. Some Possible Next Steps to Reduce Structural Concerns • Solar manufacturer’s can reduce weight of there collectors • Some are close to weight limit already • Document more roof conditions (rafter and truss) • Is there an actual problem? Initial indicators are it is not • Analyze the OBC roof structural requirement • Is there already capacity to allow solar collectors onto roofs built to the OBC? • Solar Ready Roofs • Change the OBC to make new roofs (rafter and truss) “solar ready.” • Work with new home builders to make homes “solar ready” • Work with truss manufacturers to make “solar ready” trusses • Develop standard construction details for solar collectors • Which eliminates cost of companies developing P.eng stamped structural drawings