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Cool Roofs in California’s Title Building Energy Efficiency Code

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Presentation on theme: "Cool Roofs in California’s Title Building Energy Efficiency Code"— Presentation transcript:

1 Cool Roofs in California’s Title 24 2005 Building Energy Efficiency Code
Elaine Hebert, Energy Efficiency Specialist California Energy Commission, Sacramento

2 What We Will Cover Today
How Cool Is a Cool Roof? How California’s Title 24 (Part 6 is Energy Code) Works Title 24 Cool Roof regulations Contact Information/Resources

3 How Cool is a Cool Roof? (1)
Sacramento, CA July 12, 2000 89 ºF, about noon, with local delta breeze BUR topped with aggregate 159 °F BUR topped with capsheet 158 °F EPDM single-ply 173 °F Courtesy Dan Varvais, Applied Polymer Systems

4 How Cool is a Cool Roof? (2)
Sacramento, CA July 12, 2000 89 ºF noon delta breeze Cool single-ply 121 °F Cool coating over BUR 108 °F Courtesy Dan Varvais, Applied Polymer Systems

5 This is important because we still have an electricity crisis.
Cool Roofs and Energy Cooler roof surfaces can save 15% of electricity needed to cool a building This is important because we still have an electricity crisis. Not quite enough supply to meet demand and have mandated reserve Transmission lines – aging, inadequate capacity

6 Adequate electricity supplies help prevent blackouts in California (this blackout in the Midwest equaled about $6B in damage)

7 Through Energy Efficiency Measures, California Keeps Per Person Use of Electricity Steady While Rest of US Goes Up

8 Title 24, Part 6, California’s Energy Code: How It Works (1)
Sets an energy budget for residential and nonresidential buildings New buildings and additions/alterations (alterations can include re-roofing) Budget is in kBtu/square foot/year Budget varies by climate zone 16 climate zones in California

9 California’s 16 Climate Zones
Climate Zone 1, coastal, foggy most of year Climate Zone 16 – mountains, snows in winter, less than 80°F in summer Many inland climate zones – mild winters, hot dry summers (population increasing most, air conditioning needs increasing)

10 Title 24, Part 6: How It Works (2) Regulates the Following:
Insulation levels in walls, floors, and ceilings/attics/roofs Tightness of air ducts Allowed square footage of windows, doors, and skylights And more ... Efficiency of Lighting Windows, doors, skylights Water heating systems Space heating and cooling systems Nonresidential Roofs (as of Oct. 2005)

11 Title 24, Part 6: How It Works (3) How to Meet the Energy Budget
Design the building or addition/alteration with appropriate energy efficiency features Submit documentation to bldg. dept. with permit application Construct the building/addition/alteration with those features Building Inspectors are responsible for confirming that the installed energy features match the features in the paperwork you submitted

12 Meeting the Energy Budget: Design and build a building …
…using items from previous slide that comprise: Prescriptive Measures OR Performance Method Mandatory Measures (for energy efficiency) AND Provide documentation to bldg dept with bldg permit application

13 “Prescriptive” means - -
Title 24 provides a list of the minimum efficiencies of some energy features. The list is like a prescription for how to construct a building to meet the energy budget. Follow the ‘prescription’ exactly to construct the building and it automatically complies with Title 24 – no calculations or computer needed

14 “Performance” means - -
Model how the entire building will perform energy-wise using approved computer program – Allows flexibility - can trade off among energy efficiency measures – Energy budget for your (modeled) building is established by a similar modeled building (“standard building”) having all mandatory and prescriptive measures Buy software yourself, or hire a Title 24 consultant - see for trained Calif. energy consultants; most have the software

15 Cool Roofs Are a Prescriptive Measure for Nonresidential Buildings (Cool roofs are NOT mandatory)
WHICH MEANS if you use the prescriptive compliance method, you must install a cool roof (or do an allowed tradeoff among building envelope components only) OR if you use performance compliance, you can install a cool roof or not, but a cool roof helps set the energy budget for your proposed project

16 What is a (Prescriptive) Cool Roof under California’s Title 24 Energy Standards?
Roof material must Be rated through Cool Roof Rating Council (Title 24, Part 1, §10-113) Be properly labeled (Title 24, Part 1, §10-113) Have reflectance ≥ 0.70 and emittance ≥ 0.75 (or if emittance is lower, need higher reflectance) [Part 6, §118(i)1 and 2] For coatings liquid-applied in the field, meet performance requirements [Part 6, §118(i)3 & Table 118-C]

17 What Are Reflectance and Emittance?
Reflectance – straightforward – sun’s energy (heat) bouncing off roof surface Emittance – not ALL energy bounces off; some is absorbed. Absorbed energy is given off – emitted – at different rates by different materials. “Emittance” is a measure of how quickly or efficiently the absorbed energy is given off. Important because slowly emitted heat has time to penetrate downward into the building - - undesirable in most Calif. climate zones; increases air conditioning

18 Title 24 (Prescriptive) Cool Roofs Apply to - -
Conditioned space (heated or cooled) Low slopes (≤ 2:12) Nonresidential buildings only, Occupancy Groups A, B, E, F, H, M, S, and U (next slide) EXCLUDES Occupancy “I”- hospitals, prisons, mental institutions, other institutions hotels/motels refrigerated warehouses

19 Occupancy Groups (from CBC/UBC)
A = Assembly – theaters, churches, restaurants, etc B = Businesses – office buildings, colleges/univers. E = Educational facilities (12th grade & under) F = Factories, low and moderate hazard H = High hazard facilities M = Mercantile; sale of merchandise S = Storage, low and moderate hazard U = Utility – garages, towers, agric. buildings, etc Expanded list on page 8 of

20 Cool Roofs Are Only Optional (NOT prescriptive, NOT mandatory) for - -
Hotels and motels ALL residential buildings (including houses and high-rise apartments/condos) Unconditioned buildings Refrigerated warehouses, other spaces held under 55°F, and spaces held over 90°F Buildings cooled by evaporative coolers/swamp coolers Roofs with slopes over 2:12

21 Take Note Qualifying historic buildings (per Title 24, Part 8) are exempted from Title 24, Part 6 energy standards.

22 Cool Roofs 2005 - Nonresidential Re-roofing
Still prescriptive If >50% or >2,000 sf of low-sloped roof, whichever is less, is being replaced, recovered, or recoated, cool roof “requirements” kick in [§ 149(b)1B] Install a cool roof OR Install a noncool roof plus roof insulation This is how a garden roof or BIPV* roof can be installed when re-roofing Coming soon: easy calculator for how much insulation *BIPV = Building-integrated photovoltaics (solar electric pv modules become the roof)

23 Reroofing Existing Unconditioned Warehouse Containing Conditioned Office Space - Cool Roof??
Consider two cases: 1. Conditioned space’s ceiling is lower than warehouse roof

24 Unconditioned warehouse containing conditioned space (see the air ducts!)
Energy Commission considers this building unconditioned, so no cool roof rules are triggered

25 Case 1 – Reroofing unconditioned warehouse containing conditioned office – walls of office do not reach warehouse roof No cool roof requirements are triggered!

26 Case 2 – Reroofing unconditioned warehouse containing conditioned office – walls of office reach up to warehouse roof (Sorry, no photo yet) Cool Roof requirements apply OVER THE CONDITIONED SPACE(S) ONLY not over the entire warehouse roof

27 TAKE NOTE! Energy Star is a different program (Federal not state)
An Energy Star roof does not automatically qualify as a cool roof in California Cool Roof Rating Council’s rated product directory has over 650 roof materials – some comply with Title 24 and some don’t

28 Excerpt from CRRC Rated Product Directory (

29 NOTE: “Partly” Cool Roofs
Roofing materials not meeting the FULL 0.70 reflectance/0.75 emittance Title 24 levels can get “partial” energy credit for some building types when using computer performance modeling and overall envelope prescriptive compliance Materials NOT rated through CRRC are assigned a default value in Title 24 for reflectance – it is LOW – so you must meet the energy budget using other energy-efficient features

30 Help Is on the Way Energy Commission has started a collaborative for training on cool roof regulations for Roofing Contractors Building departments And eventually, architects/specifiers, building owners, consultants

31 Resources Title 24 Website – (Title 24 Energy Standards and support documents) Title 24 Energy Hotline (within CA), (outside CA), Title 24 Office – 916/ Elaine Hebert – 916/ , Approved energy compliance software: MicroPas (residential), EnergyPro (res & nonres),

32 Resources Cool Roof Rating Council -, (866) 465-2523
CABEC (Calif. Assoc. of Building Energy Consultants) - (866) Title 24 Energy Information Videos (free) - Coming soon: cool roof website, insulation calculator, shortened form for cool roof reroofing permits, training materials for roofing contractors & other parties, 2008 Standards

33 Thank you!

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