Cool Roofs in Californias Title 24 2005 Building Energy Efficiency Code

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Cool Roofs in Californias Title 24 2005 Building
Energy Efficiency Code

• Elaine Hebert, Energy Efficiency Specialist
• California Energy Commission, Sacramento

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What We Will Cover Today

• How Cool Is a Cool Roof?
• How Californias Title 24 (Part 6 is Energy Code)
  Works
• Title 24 Cool Roof regulations
• Contact Information/Resources

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How Cool is a Cool Roof? (1)

• Sacramento, CA July 12, 2000
• 89 ºF, about noon, with local delta breeze

BUR topped with capsheet 158 F
BUR topped with aggregate 159 F
EPDM single-ply 173 F
Courtesy Dan Varvais, Applied Polymer Systems
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How Cool is a Cool Roof? (2)

• Sacramento, CA July 12, 2000
• 89 ºF noon delta breeze

Cool coating over BUR 108 F
Cool single-ply 121 F
Courtesy Dan Varvais, Applied Polymer Systems
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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

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Adequate electricity supplies help prevent
blackouts in California (this blackout in the
Midwest equaled about 6B in damage)
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Through Energy Efficiency Measures, California
Keeps Per Person Use of Electricity Steady While
Rest of US Goes Up
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Title 24, Part 6, Californias 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

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Californias 16 Climate Zones www.energy.ca.gov/ma
ps/climate_zone_map.html
Climate Zone 1, coastal, foggy most of year
Climate Zone 16 mountains, snows in winter,
less than 80F in summer
Many inland climate zones mild winters, hot dry
summers (population increasing most, air
conditioning needs increasing)
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Title 24, Part 6 How It Works (2) Regulates the
Following

• Efficiency of
• Lighting
• Windows, doors, skylights
• Water heating systems
• Space heating and cooling systems
• Nonresidential Roofs (as of Oct. 2005)

• Insulation levels in walls, floors, and
  ceilings/attics/roofs
• Tightness of air ducts
• Allowed square footage of windows, doors, and
  skylights
• And more ...

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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

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Meeting the Energy BudgetDesign 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
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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

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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 www.cabec.org for trained Calif.
  energy consultants most have the software

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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

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What is a (Prescriptive) Cool Roof under
Californias 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

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What Are Reflectance and Emittance?

• Reflectance straightforward suns 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

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Title 24 (Prescriptive) Cool Roofs Apply to - -

• Conditioned space (heated or cooled)
• Low slopes ( 212)
• 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

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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 www.energy.ca.gov/2005p
  ublications/CEC-400-2005-053/CEC-400-2005-053.PDF

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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
  55F, and spaces held over 90F
• Buildings cooled by evaporative coolers/swamp
  coolers
• Roofs with slopes over 212

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Take Note

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

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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)

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Reroofing Existing Unconditioned Warehouse
Containing Conditioned Office Space - Cool Roof??

• Consider two cases
• 1. Conditioned spaces ceiling is lower than
  warehouse roof

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Unconditioned warehouse containing conditioned
space (see the air ducts!) Energy Commission
considers this building unconditioned, so no cool
roof rules are triggered
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Case 1 Reroofing unconditioned warehouse
containing conditioned office walls of office
do not reach warehouse roof

• No cool roof requirements are triggered!

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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

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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 Councils rated product
  directory has over 650 roof materials some
  comply with Title 24 and some dont

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Excerpt from CRRC Rated Product Directory
(www.coolroofs.org)
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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

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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

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Resources

• Title 24 Website www.energy.ca.gov/title24
  (Title 24 Energy Standards and support documents)
• Title 24 Energy Hotline - 1-800-772-3300 (within
  CA),
• 916-654-5106 (outside CA), title24_at_energy.state.ca
  .us
• Title 24 Office 916/654-4064
• Elaine Hebert 916/654-4800, ehebert_at_energy.state
  .ca.us
• Approved energy compliance software
• MicroPas (residential), www.micropas.com
• EnergyPro (res nonres), www.energysoft.com

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Resources

• Cool Roof Rating Council - www.coolroofs.org,
  [phone]
• CABEC (Calif. Assoc. of Building Energy
  Consultants) - www.cabec.org, [phone]
• Title 24 Energy Information Videos (free) -
  www.energyvideos.com
• Coming soon cool roof website, insulation
  calculator, shortened form for cool roof
  reroofing permits, training materials for roofing
  contractors other parties, 2008 Standards

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Thank you!