energy codes and the building envelope
DESCRIPTION
Energy Codes and the Building Envelope. Goal of Energy Efficient Design. A Few Acronyms. ASHREA = American Society of Heating, Refrigerating, and Air-Conditioning Engineers ICC = International Code Council IECC = International Energy Conservation Code. Codes, Standards, and Model Codes. - PowerPoint PPT PresentationTRANSCRIPT
Energy Codes and the Building Envelope
Goal of Energy Efficient Design
A Few Acronyms
ASHREA = American Society of Heating, Refrigerating, and Air-Conditioning Engineers
ICC = International Code Council
IECC = International Energy Conservation Code
Codes, Standards, and Model Codes
Commercial Energy Usage
• Office, retail, and service buildings are the largest consumers of energy in the United States
• About half of this energy is consumed by lighting
• Energy Codes and Standards set a minimum level of energy performance with which the building must comply
Commercial Energy Codes
Commercial energy codes apply to all buildings EXCEPT:
• One- and two-family residential buildings
• Multi-unit residential buildings three stories or less in height
Energy Codes
• Codes and standards may be enforced at the state, local, or jurisdictional level
• Voluntary Energy-Efficiency Programs– Home Energy Rating System (HERS) – ENERGY STAR– Good Cents– LEED
Commercial Energy Codes• A few states have adopted the
most recent versions (dark green)
• Some states have no statewide energy code (white)
• Most have adopted an older version of ASHRAE/IECC but will typically update as code requirements periodically change
Most recent standard/model code is ASHRAE 90.1-2007/2009 IECC
Courtesy US DOE
We’ll Look at
• ASHRAE/IESNA Standard 90.1-2007• Chapter 5 of the IECC General
Prescriptive Approach• Use for ≤ 40% of gross wall area in vertical
fenestration• Use for ≤ 3% of gross roof area in skylights
2009 IECC Climate Zones
Code requirements are based on climate zones
Keystone Library
Commercial Energy Codes
What is a Building Envelope?
• Roof/ceiling
• Exterior walls
• Vertical fenestration (glazing) and skylights
• Lowest floor
• Slab edge
• Below grade walls
Building Envelope
Sealing Requirements
• All fenestration, openings, joints, and seams in the building envelope must be sealed with one of the following– Caulk– Gasket– Tape– Moisture vapor-permeable wrapping material
Insulation RequirementsBuilding Envelope Requirements for Climate Zone 5
Roof Insulation RequirementKeystone Library
Insulation entirely above deck: R-20 c.i.
SURFACING
INSULATION
METAL DECK
STEEL OPEN WEB JOIST
Where c.i. = continuous insulation
Wall Insulation RequirementKeystone Library
Mass wall above grade: R-11.4 c.i.
BRICK
AIR GAP
R-11.4 INSULATION
8” CMU
What types and thicknesses of insulation would meet the code in this application?
Floor Insulation RequirementsKeystone Library
Mass floor (slab-on-grade) unheated: no requirement
Note: When required, this perimeter insulation must be placed around the exterior edge of the slab.
Accepted perimeter insulation configurations
Opaque Door RequirementsKeystone Library
• Opaque doors have < 50% glass area
• Door type
– Swinging door: U-0.700 (or less)
– Overhead door: U-0.500 (or less)
Reminder: U-Factor
Fenestration
• All areas (including the frames) in the building envelope that let in light– Examples include windows, plastic panels,
clerestories, skylights, glass doors that are more than one-half glass, and glass block walls
• A skylight is a fenestration surface having a slope of less than 60 degrees from the horizontal plane
Fenestration Requirements
• Fenestration selection is often strongly influenced by energy codes
• U-Factor and Solar Heat Gain Coefficient may be specified in codes
Wonder Window, Co.
Fenestration RequirementsKeystone Library
Fenestration area must be less than 40% maximum of above grade wall area
Building Envelope Requirements for Climate Zone 5
Fenestration RequirementsDefinitions
Curtain Wall – Fenestration products used to create an external non-load bearing wall that is designed to separate the exterior and interior environments
Storefront – A nonresidential system of doors and windows mulled as a composite fenestration structure that has been designed to withstand heavy use
Entrance Door – Fenestration products used for ingress, egress, and access in nonresidential buildings, including but not limited to, exterior entrances that utilize latching hardware and automatic closers that contain over 50% glass specifically designed to withstand heavy use and possible abuse
Solar Heat Gain Coefficient (SHGC)
Overhangs and Fenestration Requirements
• Overhangs can decrease requirement for SHGC (in some climates)
• Calculate the Projection Factor, PF
B
APF
• Southern climates with high cooling loads– SHGC is more important than the U-factor in
promoting energy efficiency– Choose lowest SHGC possible
• Northern climates with insignificant cooling loads– Choose highest SHGC to promote solar heat
gain during cold weather
Solar Heat Gain Coefficient (SHGC)
SHGC RequirementsKeystone Project
• If : U-0.40 or less
• Otherwise: no requirement
25.0PF
Vestibule RequirementsA small entrance area between the outer door and the interior door
ConditionedSpace 3000 FT2
Vestibule
Self Closing Doors
Exterior Doors
ConditionedSpace 3000 FT2
Vestibule
Self Closing Doors
Exterior Doors
DOE
• Required at entrance leading to spaces ≥ 3000 ft2
• Doors must have self-closing devices
• Exceptions:−Buildings in climate zone 1−Doors from guest room or
dwelling−Doors for vehicles, material
handling, and adjacent personnel doors
Resources
Barlett, R., Halverson, M.A., & Shankle, D. L. (year). Understanding building energy codes and standards. Publication no. PNNL-14235: U. S.
Efficient Windows Collaborative. (n.d.). Retrieved December 15, 2009, from http://www.efficientwindows.org/
Department of Energy. (n.d). Building energy codes program. Retrieved December 15, 2009, from http://www.energycodes.gov/implement/
International Code Council (2009). International energy conservation code and ANSI/ASHRAE/IESNA standard 90.1 2007 energy standard for buildings except low rise residential buildings. Country Club Hills, IL: Author.