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

Customers walk into this conversation with a fixed idea: replace the windows, or buy a bigger furnace. Both are usually the wrong first move, and they are the two most expensive wrong moves available. Lead with the order of operations rather than the list of products.

The order that works: seal, insulate, then equipment. Air sealing costs the least and returns the most. Insulation only performs when the air leaks it sits above are closed, and a new high-efficiency system installed on a leaky, poorly insulated house is an expensive way to condition the attic. Doing it in this order also lets the new equipment be sized smaller, which saves money twice.

Windows are rarely the answer. Customers hear that windows are where the heat goes because they can feel the cold near them. What they feel is a cold surface radiating and a draft at the trim, and the trim is usually the fixable part. Replacement windows are worth doing when they are failed, rotten, or single pane, and they are worth doing for comfort and noise. They are almost never the fastest payback in the house, and telling the customer that before they spend the money buys you enormous credibility.

Explain comfort separately from cost. Some fixes save energy, some fix the cold room, and some do both. A customer who wants the bonus room over the garage to stop being unusable is not asking for a payback calculation. Answer the question they actually asked.

Warn them about the two things that go wrong when a house gets tight:

• Ventilation. A house sealed properly needs deliberate fresh air. This is not an upsell, it is how tight construction works, and skipping it produces humidity and stale-air complaints.
• Combustion safety. Any atmospherically vented appliance, a water heater or furnace that draws its combustion air from the room and vents up a natural draft flue, can backdraft in a house that has been tightened. Combustion appliances get tested after air sealing. That is a safety requirement, not a formality.

Set the savings expectation honestly. Savings depend on the starting condition, the climate, the fuel, and how the family lives in the house. A number promised at the kitchen table is a number you will be held to when the next bill comes with a cold snap in it. Talk in terms of what gets fixed and roughly how much of their loss it addresses, and point them at the utility's own audit and rebate programs, which carry the credibility of a third party.

Give them the one-page priority list before you leave. Biggest loss first, what it costs relative to the others, what it fixes, and what they can do themselves. Customers act on a short ranked list. They do not act on a long report.

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