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...
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Transcript of 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...
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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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
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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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
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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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
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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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 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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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
Adequate electricity supplies help prevent blackouts in California (this blackout in the Midwest equaled about $6B in damage)
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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
Total Electricity Use, per capita, 1960 - 2001
0
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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00
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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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
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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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
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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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
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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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
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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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
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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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
“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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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
“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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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
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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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
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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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
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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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
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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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
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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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 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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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
Take Note
Qualifying historic buildings (per Title 24, Part 8) are exempted from Title 24, Part 6 energy standards.
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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 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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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
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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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
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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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
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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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
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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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
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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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
Excerpt from CRRC Rated Product Directory (www.coolroofs.org)
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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
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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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
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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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
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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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
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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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
Thank you!