C A L I F O R N I A E N E R G Y C O M M I S S I O N Cool Roofs in Californias Title 24 2005 Building Energy Efficiency Code Elaine Hebert, Energy Efficiency

C A L I F O R N I A E N E R G Y C O M M I S S I O N

Cool Roofs in California’s Title 24 2005 Building Energy Efficiency

Code

Elaine Hebert, Energy Efficiency SpecialistCalifornia Energy Commission, Sacramento

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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

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How Cool is a Cool Roof? (1)Sacramento, CA July 12, 2000

89 ºF, about noon, with local delta breeze

EPDMsingle-ply

173 °F

BUR toppedwith capsheet

158 °F

BUR topped with aggregate

159 °F

Courtesy Dan Varvais, Applied Polymer Systems

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How Cool is a Cool Roof? (2)

Sacramento, CA July 12, 200089 ºF noon delta breeze

Cool coating over BUR108 °F

Cool single-ply121 °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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Total Electricity Use, per capita, 1960 - 2001

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2,000

4,000

6,000

8,000

10,000

12,000

14,000

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60

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62

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66

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68

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70

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72

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98

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KW

h

12,000

8,000

7,000

California

U.S.

kWh

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, 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

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California’s 16 Climate Zones

www.energy.ca.gov/maps/

climate_zone_map.html

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)

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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 Budget:Design and build a building …

Prescriptive Measures

OR

Performance Method

ANDMandatory Measures

(for energy efficiency)

…using items from previous slide that comprise:

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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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

Cool Roofs Are a Prescriptive Measure for Nonresidential Buildings

(Cool roofs are NOT mandatory)

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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]

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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

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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

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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, etcExpanded list on page 8 of www.energy.ca.gov/2005publications/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

55°F, and spaces held over 90°F• Buildings cooled by evaporative coolers/swamp

coolers• Roofs with slopes over 2:12

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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 space’s 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 Council’s rated product directory has over 650 roof materials – some comply with Title 24 and some don’t

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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), [email protected]

• Title 24 Office – 916/654-4064– Elaine Hebert – 916/654-4800, [email protected]

• 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,

(866) 465-2523

• CABEC (Calif. Assoc. of Building Energy Consultants) - www.cabec.org, (866) 360-4002

• 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!

Documents

C A L I F O R N I A E N E R G Y C O M M I S S I O N Cool Roofs in Californias Title 24 2005 Building Energy Efficiency Code Elaine Hebert, Energy Efficiency