The Department of Energy s Roofing Science Program Andre Desjarlais Oak Ridge National Laboratory 19 January 2012 Managed by UT-Battelle
Buildings energy use is large and growing 40% of U.S. Primary Energy Consumption (39% of U.S. Carbon Emissions) Industry 377 MMTC (25%) Buildings 658 MMTC (43%) Sales (Billion kwh) 3000 2500 2000 1500 1000 Buildings Drive Electricity Supply Investment Buildings Industry 500 0 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 Source: 2007 Buildings Energy Data Book. Tables 1.1.3, 1.2.3, 1.3.3 73% of U.S. Electricity Source: EIA Annual Energy Review, Table 8.9, June 2007 Buildings Energy Use Growing Fastest 45 40 35 Industrial Transportation Buildings Total 34% of Natural Gas Directly (55% Incl. Gen) Quads 30 25 20 15 10 5 2 Managed by UT-Battelle 0 1980 1985 1990 1995 2000 2005 Year
FY11 key tasks and milestones Field study on attic performance Hot climate roof and attic design guidelines Advances in cool roof technologies Impacts of radiant barrier systems PV roof integration 3 Managed by UT-Battelle
Roofs and attics project is a highly leveraged public-private partnership 4 Managed by UT-Battelle
NET facility used to evaluate attic systems Low density foam, 15-lb felt Non breathable Cool shingles 15-lb felt 15-lb felt Perm membrane Low perm Adhered 2 3 4 5 6 1 7 Sealed 1/300 1/300 ASV 1/300 1/300 1/150 Fascia Radiant barrier 5 Managed by UT-Battelle
Instrumentation plan Temp Roof surface, underlayment, deck Rh Underlayment, deck, rafters, Insulation Heat flux Roof deck, attic floor Temp Air Pressure Air South T4,R3 (joist) T2,RH1 (under felt) T1 HFT1 P2 T13 HFT2 T6 T7,RH5 (under felt) Single Bay P1 T11 T12 T3,RH2 (sheathing underside) T5,RH4 T14 T10,RH8 T8,RH6 (sheathing underside) T15 P3 T9,RH7 (joist) T16 HFT3 In each bay 8 temperature sensors, 6 Rh sensors, 3 heat flux sensors Total 17 sensors per bay + 7 for air temperature and Rh 6 Managed by UT-Battelle 3 attic pressure and 3 sensors for insulation = 30 sensors per bay These sensors are all in the Same vertical plane, both sides
7 Managed by UT-Battelle CONFIDENTIAL
Sealed attic (R US -22) has lowest roof deck heat flux South Roof Deck Heat Flux (W/m 2 ) Solid Lines 160 140 120 100 80 60 40 20 0 Lower Attic Air Temperature (20 C ) Attic Air Temperature (C ) Dashed Lines 55 50 45 40 35 30 25 20 15 10 5 0-5 0 24 48 72 71% Lower Flux Through Roof Deck Attic 1 Conventional control attic Attic 2 Low density foam sealed Attic 5 Low perm underlayment with ASV 8 Managed by UT-Battelle
Sealed attic (R US -22) has highest ceiling heat flux Ceiling Heat Flux (W/m 2 ) Solid Lines 32 28 24 20 16 12 8 4 0 16 0 24 48 72 HIGHER Flux Through Ceiling (NO INSULATION) Breathable membrane (16 perms) Attic 1 T-30 DeckArmor UDL S/R 1/300 Attic 2 Polyicyene Sealed Attic 5 T-30 15lb LowPerm ASV 1/300 Time of Week (hrs) JULY 23-25 16% Higher Ceiling Temperature (5 C ) Ceiling Temperature (C ) Dashed Lines 27 26 25 24 23 22 21 20 19 18 17 9 Managed by UT-Battelle
AtticSIM/Energy Plus simulation model ASTM C 1340-99 Standard For Estimating Heat Gain of Loss Through Ceilings Under Attics NET Attic 01 Benchmark Roof Energy Balance Miller et al. (2007), Natural Convection Heat Transfer in Roofs with Above-Sheathing Ventilation. 10 Managed by UT-Battelle
Hot climates: ASHRAE zones 1, 2, and 3 11 Managed by UT-Battelle
Roof and attics design Insulated and Ventilated Shingle Roof Conventional or cool color shingle; 1-in. (0.0254-m) air space made by profiled and foil-faced 1-in. (0.0254-m) EPS insulation placed above deck (retrofit practice) or fitted between roof rafters (new construction); two low-e surfaces. 12 Managed by UT-Battelle
AtticSim/EnergyPlus estimated energy savings Duct R US -5.5 with 10% Air Leakage; Thermostat 70 Heating / 74 Cooling 13 Managed by UT-Battelle
Retrofit options hot climate Austin, TX 14 Managed by UT-Battelle
New construction hot climate Austin, TX 15 Managed by UT-Battelle
Tracer gas testing used to compute ACH of attics Regression analysis for decay rate of concentration yields ACH of 2.71 16 Managed by UT-Battelle
Ventilation benchmark Major assumption in using the AtticSim tool is the accuracy of the ventilation prediction. Simulations were run for test period when gas tracer analysis performed. 17 Managed by UT-Battelle
Control roof winter temperature profile Data averaged in bin hours over the 3 winter months Jan through Mar Average Temperatures ( C) 45 40 35 30 25 20 15 10 5 0 Shingle Underlayment Sheathing Joist Outdoor Attic Condensate Concerns 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time of Day (EST) 113 108.5 104 99.5 95 90.5 86 81.5 77 72.5 68 63.5 59 54.5 50 45.5 41 36.5 32 ( F) 18 Managed by UT-Battelle
Winter surface condensation potential Attic Hours T sheath <T dp (2015 total) % Time for Condensation on Sheathing Hours T joist <T dp (2015 total) % Time for Condensation on Joist 03 - NB 110 5.5% 72 3.6% 04 - CS 103 5.1% 62 3.1% 01 - CTRL 102 5.1% 48 2.4% 06 - RB 83 4.1% 26 1.3% 07 - FF 75 3.7% 32 1.6% 05 - ASV 20 1.0% 10 0.5% 19 Managed by UT-Battelle
Cool roof roadmap Outline of upcoming DOE work on cool roofs Includes Buildings level Urban Level Global Level International activities Draft roadmap is available for stakeholder review www.eereblogs.energy.gov/buildingenvelope 20 Managed by UT-Battelle
Buildings level Key accomplishments: Cool roof selection guide Cool roof calculator DOE cool roof policy Key upcoming work Aged rating protocol Advanced materials 81C 34C 21 Managed by UT-Battelle
DOE cool roof policy A low-sloped roof (pitch less than or equal to 2:12) must be designed and installed with a minimum 3-year aged solar reflectance of 0.55 and a minimum 3-year aged thermal emittance of 0.75 in accordance with the Cool Roof Rating Council program, or with a minimum 3-year aged solar reflectance Index (SRI) of 64 in accordance with ASTM Standard E1980-01. Steep-sloped roofs (pitch exceeding 2:12) must have a 3-year aged SRI of 29 or higher. Requires R30 Insulation Required unless determined to be not economical by life cycle cost analysis 22 Managed by UT-Battelle
Cool roof selection guide 23 Managed by UT-Battelle
Roof savings calculator Collaboration by ORNL and LBNL with funding from DOE and CEC Provides cool roof assessments and advanced roof options Runs full simulations See RoofCalc.com 24 Managed by UT-Battelle
Urban level Key accomplishments: Major literature review Key upcoming work Study of urban pollution abatement 25 Managed by UT-Battelle
Global level Key accomplishments: Peer review panel Key upcoming work Validation of global cooling models India project Source: IPCC Total emitted CO 2 offset for cool roofs and cool pavements = 44 GT CO 2 26 Managed by UT-Battelle
Design load chamber for simulating and accelerating roof contamination rate Chamber built for accommodating a sample size up to 15 in dia. or multiple samples of smaller area size Real-time monitoring capability for contaminant loading Easy access to sample for reflectance measurement and loading verification Design for loading dry and or wet contaminants 27 Managed by UT-Battelle
Loading and reflectance reduction rates Dirt Mass, g 2.5 2 1.5 1 0.5 R² = 0.9048 0 0.0 20.0 40.0 60.0 80.0-0.5 Loading Duration from To, min Reflectance Reduction 0.050 0.000 0.0-0.050 20.0 40.0 60.0 80.0-0.100-0.150-0.200-0.250-0.300-0.350 R² = 0.9807 Loading Duration from To, min Hi-fidelity simulation of atmospheric dust loading using real-world test dusts, e.g., Arizona test dust(iso 12103-1 standard) Total surface reflectance measurement tested on Arizona test dust Mass loading function linear (R 2 >0.9) following deposition theory Reflectance reduction also linear following dust load (R 2 > 0.98) 28 Managed by UT-Battelle
Microbial analyses Sampling protocols for cultivation and nucleic acid analysis was tested at sites in TN, PA, and FL. One sample from each site is undergoing 454 sequencing analysis 29 Managed by UT-Battelle
Cool roof coatings with ceramics Cool roof coatings are promoted based on the presence of ceramic particles. Unclear that particles improve performance. Tests begun in March 2010 of four cool roof coating products. Temperature and heat flux through the roof measured to quantify performance. 30 Managed by UT-Battelle test panels with ceramic paints reference black/white panels
Cool roof coating results Sample data for sunny day, April 16, 2010 A coating with no ceramic beads (SR initial = 0.88) keeps roof cooler than paints with ceramic particles (SR initial about 0.8). and requires less cooling than other samples and heating penalty only relative to the black surface. Temperature ( o F) 180.00 160.00 140.00 120.00 100.00 80.00 74 test panels o F with ceramic 60.00 paints 40.00 black, T max =160 o F Paint B w/ ceramic particles Paint A w/ ceramic particles reference black/white panels Paint D, no ceramic particles Paint C w/ ceramic particles White reference Black reference white, T max = 92 o F paint w/ no particles, T max = Roof membrane temps 20.00 0 2 4 6 8 10 12 14 16 18 20 22 Time (hour) 31 Managed by UT-Battelle
Performance of attic radiant barrier systems Attic 1 Oriented strand board (OSB) without radiant barrier (RB), ε = 0.89 Attic 2 OSB with perforated foil faced RB, ε = 0.03 Attic 3 RB stapled to rafters, ε = 0.02 Attic 4 Spray applied low-e paint on roof deck and rafters, ε = 0.23 32 Managed by UT-Battelle
Performance of attic radiant barrier systems Cooling load through attics 2, 3, and 4 were 33%, 50%, and 19% lower than the load from attic 1 during summer daytime conditions During winter conditions, a 6 to 10% reduction in heat loss through the ceiling was observed The test attic had R US 13 fiberglass batt insulation on the floor Summer daytime condition: climate chamber air temperature 100 F, roof exterior surface temperature 140 F Winter Night condition: climate chamber air temperature 32 F 33 Managed by UT-Battelle
ORNL/MCA PV-PCM Roof Shingle Roof PV-PCM Roof Evaluation of a roof system with (PV) laminates integrated with metal panels and PCM. Collaboration between Metal Construction Association, CertainTeed, Uni-Solar, Phase Change Energy Solutions, and ORNL. Shingle roof used as control for comparison and evaluation of the PV-PCM roof. 34 Managed by UT-Battelle
PV-PCM roof construction Bio-based PCM on roof deck Foil-faced fiberglass insulation Metal panels with preinstalled PV laminates 2-inch air gap for above-sheathingventilation (ASV). 35 Managed by UT-Battelle
Winter data Roof Heat Flux Substantially lower heat flow through PV-PCM roof, and warmer attic. Mid-day heat addition increases the shingle attic temperature; possible heating penalty in PV-PCM. Attic Center Temperature 36 Managed by UT-Battelle
Summer data Substantial lower peak daytime heat addition through PV-PCM roof. PV-PCM attic temperatures show lower fluctuations; Also evident is a ~2 hr. peak shift. Roof Heat Flux Attic Center Temperature 37 Managed by UT-Battelle
Closing summary Working in partnership with industry, DOE is undertaking both development and enabling research in the roofing market to make available to building owners more energy efficient and affordable roofing system choices. 38 Managed by UT-Battelle
Earthrise from Apollo 8 (December 24, 1968) We came all this way to explore the moon and the most important thing is that we discovered the Earth. Bill Anders, Apollo 8 Astronaut 39 Managed by UT-Battelle