Post on 15-Jun-2015
From the Ground UpA Review of
Residential Energy Efficiency
Joseph LaquatraCornell University
Energy Use in the Residential Sector
Residential Use –21% ofU.S. energy consumption
(27% in NYS)
Many opportunities to decrease this.
Applications of energy efficiency to a home can result in substantial reductions in energy bills.
Comparison of energy used in an average house
in the Northeast and an energy efficient house
The energy bill in the efficient home is $1,180 less than that of the average home.
through the foundations walls, and upward to the surface;
downward to the deep earth;
A basement loses heat:
In new construction - many ways to make foundation walls more energy efficient.
One way : insulate the exterior side of the walls with rigid board insulation.
Loss through basement walls
Another way: assemble foundation walls with polystyrene forms
The forms become part of the foundation system and insulate the walls.
and then fill them with concrete.
Another way is to assemble a foundation wall with pre-cast, insulated concrete panels.
Continuous Drainage Plane
• Design Issues• Micro-conditions• Material components• Surface & below grade
details• Drain Everything!• Weatherlapping Rules!
EEBA WMG/HTWII
Dampproofing ≠ Waterproofing
Can’t be done(requires water barrier
without holes)
Wood decay
No vapor retarderbelow grade
Insulate rim joist
Now consider the walls of a house.
Dampnessand/or mold
Perfect wall: environmental separator*Keeps outside out
Keeps inside in
To do this, must control rain, air, vapor, heat
* Building Science Corporation
Vapor Retarder
Most effective strategy to increase energy efficiency
• Air sealing
• Attic insulation
• Improve heating/air conditioning efficiency
Air LeakageUncontrolled and/or unintended
airflow through a building enclosure
Air leakage (30% space conditioning losses)
House Wrap: Wind barrier, drainage plane
Sealants
Many homeowners can do their own caulking, weatherstripping, and insulating.
BUT – none of these are very effective if there are leaks in a home.
MANY LEAKS CANNOT BE FOUND WITHOUT SPECIAL EQUIPMENT.
blower door test
duct blaster
Thermography
Details- 24-inch OC 2X6 in-line- 2-stud corners- load-tuned headers- single top plate
- minimized cripples- open web floor truss- insulating sheathing- modular dimensions
Advanced Framing
Structural Insulated Panels (SIPs)
Structural Insulated Panels (SIPs)
4 1/2" 6 1/2"EPS 14.4 21.6XPS 19.5 29.5Polyurethane 21.7 32.9
Panel Thickness
R-va
lue
Insulation Type R-Value Per Inch Made FromCellulose 3.5 - 3.7 Ground wood or paperFiberglass batt 3.0 - 3.8 Strands of molten glassFiberglass loose-fill 2.2 - 3.0 Strands of molten glass
Rockwool or mineral wool 2.7 - 3.0 Molten rock or slag
Denim (or cotton) batt 3.7 Recycled fibersRigid Board extruded polystyrene 4.6 - 5.0 Petrochemical
Rigid Board polyurethane or isocyanurate 6.0 - 8.7 Petrochemical
Open cell polyurethane spray foam 3.5 Petrochemical
Closed cell polyurethane spray foam 6.0 Petrochemical
Cementitious foam 3.9 Air, water, MgO
Open cell Closed cell
Soy Based: Still has petrochemicals. USDA: 7% spray foam product must be bio-based.
Denim batts
In wall cavities, heat is lost through the wooden studs -a thermal bridge. Also happens through floor joists at wall intersections.
Thermal Bridges
stud
Thermal break: insulating material that prevents a structural element from acting as a thermal bridge.
Thermal Breaks
ThermablokTM : aerogel strips
R-2.58/1/4”
After a house is sealed, the furnace or boiler may have to be derated – it doesn’t need to produce as much heat anymore.
Or –
upgrade to an energy efficient, sealed combustion system.
Usually, insulation can be added to an attic easily.
U.S. DOE recommendationfor NYS:R 49 - 60
ENERGY STAR WINDOWS, DOORS, & SKYLIGHTS HAVE THIS LABEL.SHADED AREA OF MAP INDICATES REGION PRODUCT IS DESIGNED FOR
ACEEE’s 2010 State Energy Efficiency Scorecard
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table