Roof and Wall Systems - · PDF fileNew construction low-slope roofing sales ... Energy Savings...
Transcript of Roof and Wall Systems - · PDF fileNew construction low-slope roofing sales ... Energy Savings...
Tampa Convention Center • Tampa, Florida
Roof and Wall Systems
Using Your Building’s Envelope to Minimize Heating and Cooling Loads
Kaushik Biswas, Ph.D.Oak Ridge National Laboratory
August 16, 2017
Energy Exchange: Connect • Collaborate • Conserve
Presentation summary
2
• The building code• The market• Technology options
• Roofs• Insulation• Cool roofs• Thermal mass
• Wall types• Case Studies:
• Retrofit of masonry wall system• Resources
Energy Exchange: Connect • Collaborate • Conserve3
Roof Systems
Energy Exchange: Connect • Collaborate • Conserve
ASHRAE Standard 90.1 has changed appreciably in recent years
4
0
5
10
15
20
25
30
35
1975 1980 1989 1999 2001 2004 2007 2010 2013
R-va
lue, h
r ft °
F/Bt
u
Data for Climate Zone 4 (Kansas City, MO) DOE Climate Zone
2013 Non-Res Roof
R-value
1 20
2 25
3 25
4 30
5 30
6 30
7 35
8 35
Energy Exchange: Connect • Collaborate • Conserve
Insulation used in low-slope roofing
5
• Expanded Polystyrene (EPS)+ Low cost option.– Low softening temperature precludes its use under
dark colored membranes.• Extruded Polystyrene (XPS)
+ Excellent moisture resistance.– Softens similar to EPS.
• Polyisocyanurate (PIR)+ Fire resistance and higher R/inch.
• Fiberboard and Perlite+ Structural or thermal protection layer.– Low R-value.
Energy Exchange: Connect • Collaborate • Conserve
Insulations used in low-slope roofing
6
8%
75%
5% 2%9%
New construction market share, percent
EPS & XPSPolyisocyanurateFiberboardPerliteOther
2014-15 NRCA Market Survey
Energy Exchange: Connect • Collaborate • Conserve
Low-slope waterproofing market
7
05
101520253035
BUR Mod Bit EPDM Metal Other SprayFoam
PVC TPO
Mark
et S
hare
, Per
cent
New construction low-slope roofing sales
• Cool roofs (PVC, TPO, and Spray Foam) represent 48% of market.• BUR, Mod Bit, and Metal (22%) can be any color based on
aggregate/paint.• Cool roofs are now about 60% of market.
Energy Exchange: Connect • Collaborate • Conserve
When do cool roofs save energy?
8
• http://energy.gov/sites/prod/files/2013/10/f3/coolroofguide.pdf
• What climate zone?• What happens when they
get dirty?• How about more
insulation…..• Ballast…...
Energy Exchange: Connect • Collaborate • Conserve
Cool roof impact on an energy bill
9
Energy Exchange: Connect • Collaborate • Conserve
Impact of demand charges
10
Energy Exchange: Connect • Collaborate • Conserve
DOE cool roof calculator
11
Estimates energy and peak demand savings for flat roofs with non-black surfaces
• http://web.ornl.gov/sci/roofs+walls/facts/CoolCalcPeak.htm• Input:
– Roof location (city and state); – Roof characteristics (R-value, solar reflectance, thermal emittance);– Equipment data (heating and cooling energy costs and efficiencies); and– Demand charge details (demand charge and duration).
• Output:– Cooling and heating energy savings– Demand savings
Energy Exchange: Connect • Collaborate • Conserve
Comparison between a cool and black membrane
12
Location Energy Savings per square foot, $ or Percent
Cooling Heating Demand Total % Demand
Miami $0.083 -$0.002 $0.069 $0.150 46%
Atlanta $0.049 -$0.015 $0.067 $0.101 66%
Baltimore $0.040 -$0.018 $0.063 $0.085 74%
Fargo $0.017 -$0.015 $0.061 $0.064 95%
• Assumptions:– Roof R-value = 15 – Solar reflectance = 10% vs. 75%– Thermal emittance = 90%– Equipment (air conditioning for cooling; electric resistance for heating in
Miami, heat pump for heating in Atlanta, and gas for heating in Baltimore and Fargo)
– Demand charge = $20/kW
Energy Exchange: Connect • Collaborate • Conserve
Ballasted roof systems available since the early 1970’s
13
Energy Exchange: Connect • Collaborate • Conserve
Temperature profiles of “cool” roofs
14
0 2 4 6 8 10 12 14 16 18 20 22 24Hours into 4/22/2007
0 2 4 6 8 10 12 14 16 18 20 22 24Hours into 4/22/2007
0 2 4 6 8 10 12 14 16 18 20 22 240 2 4 6 8 10 12 14 16 18 20 22 24 Heat
Flu
x thr
ough
Insu
latio
n [B
tu/(h
·ft²)]
0 2 4 6 8 10 12 14 16 18 20 22 24
Mem
bran
e Tem
pera
ture
(°F)
0 2 4 6 8 10 12 14 16 18 20 22 2430
70
90
110
150
170
-8
8
12
20
0
Under 21 lb/ft² Coated Paver Under 16 lb/ft² Coated PaverBare White TPO
Bare Black EPDM Under 10 lb/ft² Stone
Under 17 lb/ft² Stone
Under 24 lb/ft² Stone
Under Uncoated Paver
4
130
50 -4
16
Energy Exchange: Connect • Collaborate • Conserve15
Wall Systems
Energy Exchange: Connect • Collaborate • Conserve
IECC 2015 wall R-value requirements
16
• Some buildings can also contain R20 cavity insulation with lower levels of continuous insulation (C.I.)
Energy Exchange: Connect • Collaborate • Conserve
Adoption of IECC
17
• IECC adopted statewide or at a local level in 46 states.– Others (CA, IN, MN & OK): State-code (CA) or ASHRAE 90.1 with
amendments.
IECC adoption by vintage
Energy Exchange: Connect • Collaborate • Conserve
Exterior commercial wall material distribution
18
Total number of buildings: 5,557,000Source: Energy Information Administration (EIA): Commercial Building Energy Consumption Survey (CBECS 2012)
Energy Exchange: Connect • Collaborate • Conserve
Commercial building renovations
19
• Renovation in pre-2008 buildings, per CBECS 2012:– Any type of renovation – 2,094,000 (out of 5,254,000 buildings)– Exterior wall replacement – 194,000 (9.3% of all renovations)– Interior wall reconfiguration – 889,000 (42.5% of all renovations)– Insulation upgrade – 382,000 (18.2% of all renovations)
Energy Exchange: Connect • Collaborate • Conserve
Wood- and metal-framed walls
20
Cavity + Exterior continuous insulation (C.I.)
Prefabricated wall panels with open-cell spray foam insulation (fibrous batt insulation also used)
Exterior spray-applied closed-cell foam insulation on stud wall assemblies
• Primary applications – Office buildings, schools, retail buildings (pre-1980), restaurants, apartment buildings, etc.
• Utilize both cavity and exterior continuous insulation (C.I.)
Energy Exchange: Connect • Collaborate • Conserve
Mass walls
21
Insulated concrete form (ICF)
Polystyrene foam
Concrete fill
• Primary applications – Large office buildings, retail buildings, supermarkets, large hotels, hospitals, etc.
Concrete masonry unit wall with exterior C.I. (spray-
applied or rigid foam insulation)
Mass wall with exterior C.I. (mineral fiber)
Energy Exchange: Connect • Collaborate • Conserve
Precast concrete walls
22
Insulated precast concrete basement walls; challenging to form & pour foundation walls during winter in cold climates.
ORNL’s MAXLAB
Precast panels: 3-inch exterior concrete wythe, 2 inch of insulation (center) and 4-inch interior structural wythe.
New ORNL and Industry R&D: Lighter, lower-cost panels; 3D printed forms; advanced composites for reinforcement.
Energy Exchange: Connect • Collaborate • Conserve
Metal buildings
23
Interior spray-applied foam insulation
Fiberglass insulation for interior application
Interior reflective insulation
• Primary applications – warehouses, aircraft hangars, etc.
• Typically contain insulation compressed between metal members.
Energy Exchange: Connect • Collaborate • Conserve
Insulated metal panel and curtain wall
24
Prefabricated insulated metal panels (IMP)(Serve as cladding and interior finish)
Curtain wall insulation(Typically used in high-rise buildings)
IMP with rock wool insulation sandwiched between metal sheets
(foam insulation is also used)
Energy Exchange: Connect • Collaborate • Conserve
Case study: interior retrofit of a masonry wall
25
• Target market: Masonry walls on pre-1980 buildings in climate zones 4 (mixed climate, needing heating and cooling) and 5 (cold climate, heating-dominated).
• Goal: Exceed ASHRAE 90.1-2010 requirements with a payback of 10-15 years with façade retention and moisture durability.
Solution category No. Retrofit strategyRetain existing wall 1 2” polyisocyanurate (PIR) foam board over
existing drywallRemove existing fiberglass insulation
2 6” open-cell spray polyurethane foam (SPF) within extended stud cavity
3 4.5” closed-cell SPF within stud cavity
Remove existingfiberglass insulation and steel studs
4 2.5” continuous cellulose + 3.5” cellulose
5 1.5” continuous closed-cell SPF + 2” closed-cell SPF
6 2” continuous closed-cell SFP + 3.5” cellulose
7 1.5” continuous closed-cell SPF + 3.5” cellulose
8 2.5” foam board w/ separate air barrier layer
9 2.5” foam board w/ taped seams
Baseline: Typical pre-1980s commercial construction around
Philadelphia, PA.
ORNL’s Flexible Research Platform
Build
ing
inte
rior
Energy Exchange: Connect • Collaborate • Conserve
Interior retrofit of a masonry wall
26
Final ranking* Retrofit strategy Cost
($/ft2) R-value Conden-sation
A 2” PIR foam board over existing drywall 4.35 25.5 No
6” open-cell SPF within extended stud cavity 8.75 19.2 No
4.5” closed-cell SPF within stud cavity 8.65 15.2 No
2.5” continuous cellulose + 3.5” cellulose 9.75 22.1 Yes
C 1.5” continuous closed-cell SPF + 2” closed-cell SPF 9.40 22.1 No
2” continuous closed-cell SFP + 3.5” cellulose 10.10 25.0 No
1.5” continuous closed-cell SPF + 3.5” cellulose 9.00 22.0 No
B 2.5” foam board w/ separate air barrier layer 8.05 20.8 No
2.5” foam board w/ taped seams 6.55 20.8 No
* Additional evaluation criteria: Air tightness, indoor air quality and lack-of-disruptiveness.
PoorLowModerateHigh
Effectiveness Indicator
Exterior
Existing insulation and studs removed
Existing insulation and studs removed
Exterior
• Only option with payback <15 years.
• Assuming existing insulation performing as expected.
Energy Exchange: Connect • Collaborate • Conserve
Resources
27
• National Roofing Contractors Association Roofing Manual, www.nrca.net, the ‘bible” on how to construct commercial roofs.
• Single Ply Roofing Industry, www.spri.org, technical information pertaining to single ply roof systems.
• Asphalt Roofing Manufacturers Association, www.asphaltroofing.org, technical information pertaining to asphaltic roof systems.
• Polyisocyanurate Insulation Manufacturers Association, www.polyiso.org, technical information pertaining to polyisocyanurate foam.
• Annual Book of ASTM Standards Volume 04.04, Roofing and Waterproofing Standards and Specifications, www.astm.org.
Energy Exchange: Connect • Collaborate • Conserve
Tools
28
• Roof Savings Calculator, http://rsc.ornl.gov, calculation tool that estimates roof design energy performance.
• Cool roof peak demand calculator, http://web.ornl.gov/sci/roofs+walls/facts/CoolCalcPeak.htm, estimates energy savings and peak demand reduction for roofing systems.
Energy Exchange: Connect • Collaborate • Conserve
Questions and answers
29
Kaushik Biswas, Ph.D.
Visit our website: www.ornl.gov/buildings
Follow us on Twitter: @ORNLbuildings