Reading Home Energy Losses Reference

Why this matters

Customers often complain about "high bills" without knowing the cause. Energy losses happen in predictable places + patterns. The tech who can identify the worst losses + recommend prioritized fixes helps customers save real money + adds significant value. This is the field card.

Where homes lose energy

Typical residential energy loss breakdown:

• Heating + cooling: 50-60% (often largest)
• Water heating: 12-15%
• Lighting + appliances: 20-25%
• Other: 5-10%

For HVAC losses:

• Air leakage (drafts): 25-40%
• Insulation gaps: 15-25%
• Duct leakage: 15-30%
• Windows / doors: 10-20%
• Other: 10-20%

Addressing the biggest losses gives biggest savings.

Common loss locations

Attic:

• Insulation insufficient OR compressed
• Air leaks (recessed lights, plumbing penetrations, attic hatch)
• Bath fan vent leaks
• Knee walls without insulation

Walls:

• Outlets + switches (uninsulated boxes)
• Plumbing chases
• Wall-mounted AC units
• Cantilevers

Foundation / crawlspace:

• Rim joist (top of basement wall)
• Crawlspace vents (open year-round inefficient)
• Sill plate gaps
• Cracks in foundation

Windows + doors:

• Older single-pane: significant
• Newer double-pane: minor
• Weather-stripping failure
• Air infiltration around frame

Ductwork:

• Connections (often poorly sealed)
• Unconditioned space (attic, crawlspace) ducts
• Damaged duct (kinks, holes)
• Insulation degraded

Combustion appliances:

• Old furnace / boiler less efficient
• Single-pane vent issues
• Fireplace damper open

Visible signs

Drafts:

• Cold air felt at electrical outlets in winter
• Visible curtain movement near windows
• Cold floors near exterior walls

Insulation issues:

• Visible attic floor where insulation absent
• Insulation displaced from rafters
• Visible insulation below rated depth

Ice dams (winter):

• Snow melts on roof + refreezes at eaves
• Indicates poor attic insulation + warm air leaks

Damp basement / crawlspace:

• Moisture indicates air infiltration
• Air leakage + condensation

HVAC running constantly:

• Equipment can't keep up
• House losing heat / cool faster than added

Uneven temperatures by room:

• Some rooms colder / hotter than others
• Insulation OR duct issues
• Air leak in specific area

Tools for diagnosis

Hand on cold surface:

• Touch wall on cold day
• Cool wall = inadequate insulation
• Cold corner = air leak

Smoke pen / incense:

• Trace airflow
• Reveals leaks where smoke moves toward leak
• Inexpensive

Thermal imaging camera:

• Visualize heat distribution
• Find cold (winter) OR hot (summer) spots
• Air leaks + insulation gaps visible
• Moderate entry-level cost

Blower door:

• Pro tool
• Measures whole-house air tightness
• Identifies leaks
• Energy auditor uses

Duct blaster:

• Test ductwork specifically
• Measures duct leakage
• Used during home performance contracting

Walk-through assessment

For customer's home:

1. Outside in cold weather:

• Snow melt patterns on roof (ice dams)
• Frost / dew patterns
• Stain trails from water entry

1. Attic (if accessible):

• Insulation depth + condition
• Air seal at penetrations
• Bath fan venting

1. Basement / crawlspace:

• Rim joist insulation
• Foundation cracks
• Crawlspace condition

1. Walls (interior):

• Outlets cold (winter)
• Visible water damage
• Trim pulling away

1. Windows + doors:

• Weather-stripping
• Frame condition
• Single vs double pane

1. Equipment:

• HVAC age + efficiency
• Water heater
• Combustion appliances

Prioritizing fixes

Highest impact (do first):

• Air sealing (cheap; significant savings)
• Attic insulation (often easy upgrade)
• Duct sealing (if ducts in unconditioned space)

Medium impact:

• Wall insulation (if accessible during remodel)
• Equipment upgrade (when due for replacement)
• Window replacement (high cost; often slow payback)

Lower impact (cosmetic energy):

• Smart thermostat
• LED lights
• Window film

Air sealing details

Common air leak locations:

Recessed light fixtures:

• Older "can lights" leak significantly
• IC-rated cans seal better
• Cover with airtight box from above OR replace

Plumbing + electrical penetrations:

• Through-floor + through-wall holes
• Caulk OR spray foam to seal

Attic hatch:

• Often uninsulated + leaky
• Weather-strip + insulate

Bath fan vent:

• Sometimes ducted to attic (don't!)
• Re-route to roof / soffit
• Insulate vent in attic run

Range hood:

• Vented outside (not recirculated)
• Damper closed when not in use

Chimney:

• Damper closed when fireplace not in use
• Top sealing damper

Insulation considerations

R-value targets:

• Climate zone-specific
• Modern: R-49 attic; R-21 walls; R-30 floor
• Older: lower R-values

Type matters:

• Fiberglass batt: most common; depends on installation quality
• Cellulose: blown-in; good fill
• Spray foam (open OR closed cell): excellent; air seal too
• Mineral wool: fire-resistant; insulation

Installation quality matters more than type:

• Compressed insulation = lower R
• Gaps = thermal bridges
• Wet insulation = ineffective

Duct sealing

Often underappreciated:

• 20-30% energy loss in ducts
• Especially in unconditioned space
• Mastic OR aerosol sealing (Aeroseal)

Address before insulation upgrades for unconditioned-space ducts.

Windows

Honest assessment:

• Old single-pane: yes upgrade typically pays
• Double-pane existing: may not pay back
• Specialty (low-e, gas-filled): great new construction; expensive retrofit

Quick fixes:

• Weather-strip (cheap)
• Storm windows (mid-cost)
• Window film (low cost)
• Replacement (high cost; slow payback)

When upgrade equipment

HVAC:

• Old + inefficient + needs frequent service = consider upgrade
• New equipment efficiency often 50%+ better than 20-year-old
• Manufacturer SEER, AFUE, HSPF ratings

Water heater:

• 12+ years; consider replacement
• Heat pump water heater very efficient
• Tankless (with caveats per related article)

Appliances:

• Energy Star certified
• LED lighting (LED uses ~1/10 incandescent)
• Smart thermostat (sometimes; minimal savings vs setpoint discipline)

Common DIY approaches

Customer can DIY:

• Caulk windows / doors
• Replace weather-stripping
• Wrap water heater (insulation blanket)
• Insulate hot water pipes
• Add attic insulation (if accessible + comfortable)
• Replace light bulbs (LED)
• Set thermostat properly

Customer needs pro:

• Major air sealing
• Spray foam
• Duct sealing
• HVAC upgrades
• Electrical work

Energy audit

Professional energy audit:

• Blower door test
• Combustion analysis
• Duct testing
• Insulation inspection
• Customer report with priorities
• Some utilities offer free OR discounted

Customer's first step often: energy audit. Provides baseline + plan.

Customer education

References

• DOE Energy Star + Building America programs
• ASHRAE 90.1 + 90.2 (Energy Efficiency)
• IECC (International Energy Conservation Code)
• Home Performance with Energy Star
• Manuall internal: Insulation by Location, Reading HVAC Age + Condition