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energy_rater_la

energy efficiency specs

energy_rater_la
9 years ago

this is a short version of the spec sheet I give my
clients for building an energy efficient home.

lots of posts about lots of things here, but
over and over I read about things that could
easily have been dealt with in planning & early
construction phases of the build.
hopefully, this will help to bring some of these
to light now in the decision making phase of
your build.

things that don't 'show' are important choices.
efficiency costs are always upfront & savings long term.

Summary of Energy Efficiency Specifications

Air Infiltration Goal is .25 Natural Air Changes per Hour�heating. Gaskets such as Owens-Corning FoamSeal R or Dow Sill Seal between sole plate and slab is recommended. For 2nd story or bonus rooms, insulate and seal openings between floor joists, under walls with foam board sheathing material. Seal all windows and doors jambs with minimal or non expanding foam.

Seal all wire penetrations especially those through top plate.
Incorporate Airtight Drywall Approach throughout home. Run sheetrock all the way to bottom plate behind showers and tubs, seal plumbing penetrations under tubs especially on upper floors.

Minimize use of recessed lights or install Insulation Contact Air Tight (ICAT) lights. Existing recessed lights that are not air tight can be retrofitted with air tight trim kits. Get name brand and model numbers of lights to order trim kits.

Windows Double-glazed with Low-E glass and non-heat-conducting frames are recommended. Look for U-values and SHGC (solar heat gain coefficient) of less than .3 for best performance in this area. Go to www.nfrc.org to learn more about window types and labels on windows.

DOORS Steel, polyurethane foam core (R 2.5 to 5.0) with high quality weather-strip. Solid wood door with double-glazing allowed for front door. Exterior-type foam-core doors with good air seals on doors to all attic spaces and knee-walls.

Walls 2x4 walls R-15 un-faced insulation with double sided 1" foil sheathing boards. 2x6 walls R-19 also with double sided foil sheathing boards.

Face unprinted side to exterior. Sheathing must cover top plate to sole plate. Seal all seams with foil tape. Use �" foil sheathing in between 2X headers instead of plywood. Insulate behind tub and shower units before installing units.

Ceilings R-30 minimum with a Radiant Barriers are recommended for this climate. Visit Florida Solar Energy Center�s web site for more information on radiant barriers www.fsec.ucf.org

Seal and insulate attic accesses when in the conditioned areas. If attic staircase s in conditioned area, seal with attic tent or build a box with 2x12 with �" plywood for top, insulate and weather-strip to seal well.

Unvented attics Open cell foam. foam must meet R-value
code requirements. No quanitive values accepted.
foam must fill rafter bays and faces of rafters.
Foam must seal from roof to attic floor to create true
unvented attic. Full inches to be installed, not
'average' fill. No areas with 1/2" of foam to 9" of
foam to be averaged for overall R-value. Unvented
attic with foam is a semi conditioned attic.

Use only closed cell foam in floors for homes
on piers. install minimum of 3"

Use Energy efficient (O.V.E.) framing at corners and partition walls, See LaDNR Builder�s Guide To Energy Efficient Homes in Louisiana or Doug Rye video.

Continuous ridge vents ( with wind baffles) and continuous soffits vents. One square foot of net free area for every 150-sq.ft. of attic floor space, divided equally between ridge and soffits vents.

NO ATTIC POWER VENTS !!!

Duct Leakage and Insulation Duct loss must be no more than 5%. Before insulating hard pipe seal all joints & seams. Use Mastic or an approved UL-181 rated mastic tape, such as Hardcast #1402 mastic tape.

Have HVAC contractor size A/C system using Manual J. Design duct layout using Manual D.
Upgrade insulation values from a standard R-4.2 to R-6 or R-8 is recommended.

Water Heaters Compare Energy Factors (E.F.) Gas E.F. of .65 on a standard tank and E.F. of .95 on an electric standard tank.

Adding an insulating blanket can also increase the efficiency of water heaters.

Instant, tankless gas water heaters have higher E.F. of .85.
Electric tankless water heaters are not efficient.
instead look at standard hign EF electric tanks
The most efficient for electric Heat Pump water heaters (also called heat recovery or desuperheaters) provide 90% to 100% free hot water in summer months.

Cooling 14 SEER, 0.75or less Sensible heat fraction (SHF) mandatory minimum requirement. 15 to 17SEER is recommended.
Heat pump if all electric.

Two speed or variable speed system if over-sizing of tonnage.
Consider Zoned system versus multiple units.
700 sq. ft. per ton as opposed to old
rule-of-thumb of 400 to 500 sq. ft. per ton.

Bigger is not better!

Heating Gas furnace AFUE 80% minimum.
Efficiency on these units up to 94% (condensing unit with PVC flue).
For Heat Pumps specify a minimum of HSPF of 8.0. Variable speed heat pumps will have up to 9.0 HSPF.
(May change to higher AFUE with IRC code changes)

Lighting Use fluorescent lighting whenever possible. Compact Fluorescent in all fixtures like recessed lights.

IC Air Tight recessed lights are mandatory requirements. Existing recessed lights can be retrofitted with air tight trim kits available at lighting stores and box outlets.

Appliances Purchase Energy Star Appliances for high efficiency, especially refrigerators, freezers and water heaters which run 24/7.
Look for Energy Guide labels in the lower range for more efficiency.

Additional Links:
La. Energy & Environmental Resource Building Science Corporation
www.laeeric.lsu.edu/energy www.buildingscience.com
LSU Ag Center Hot Humid Climates
www.lsuagcenter.com Builder�s Guide
Energy Star Program www.eeba.org
www.energystar.gov

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