Block of loose mineral wool insulation next to a pale blue rigid foam board on a wooden table

Home Energy Scope · Compare options

Energy retrofit comparisons: the five decisions inside a retrofit

Five choices decide most of a retrofit's cost and return: whether to insulate or replace windows first, blown-in or spray foam, vinyl or wood window frames, solar with or without a battery, and a walk-through or a diagnostic audit. Each comparison lays out the trade-offs in a table and states when each option wins.

See the comparisons

Contractors present the choice they sell, which hides the alternatives. ENERGY STAR estimates 9 in 10 homes are under-insulated, and yet windows are the retrofit homeowners ask about first, because glass is visible and insulation is not. The comparisons here put the two side by side, then do the same for the choices inside each scope.

The 5 decisions that move the price most

Grey ranch house with white trim, a covered front entry and an attached two-car garage beside a driveway

Air sealing and attic insulation vs Window replacement

Sealing and insulating the attic costs a few thousand dollars and saves about 15% of heating and cooling by EPA's estimate; a whole-home window project averages $7,347 and saves less on energy, though it fixes damage, operation and comfort. In most houses the envelope comes first.

Upfront cost: $1,661 blown-in to $2,888 spray foam (HomeAdvisor 2026); $7,347 whole-home average (HomeAdvisor 2026)
Lifespan: Decades if kept dry; 20–30 years; glass seals 10–20
Maintenance: None; inspect after roof work; Cleaning, weatherstripping, occasional seal failure

Full comparison, verdict and FAQs →

Cream single-storey house with a stone front, covered porch and curved paver path through a green lawn

Blown-in fiberglass or cellulose vs Spray foam

Blown-in is the standard for an open attic top-up after air sealing, at a fraction of spray foam's price; spray foam seals and insulates in one step and earns its cost at rim joists, roof decks and irregular cavities. Choosing foam for a flat attic is the common overspend.

Upfront cost: $987–$2,334 project, avg $1,661 (HomeAdvisor 2026); $1,455–$4,337 project, avg $2,888; attics to $9,000 (HomeAdvisor 2026)
Material cost: $0.50–$1.10/sq ft fiberglass; $2.00–$2.30 dense-pack cellulose; $0.60–$1.60/board ft open-cell; $1.30–$3.10 closed-cell
Air sealing: None; requires separate sealing first; Built in

Full comparison, verdict and FAQs →

Vinyl frames vs Wood frames

Vinyl costs less, needs no painting and recoups more at resale in Zonda's 2025 report; wood costs about $4,300 more for a ten-window project, suits historic homes and can be repaired. Glazing performance, not frame material, decides most of the energy result.

Upfront cost: $20,091 for 10 windows (Zonda 2025); $24,376 for 10 windows (Zonda 2025)
Lifespan: 20–30 years; 30+ years with maintenance; repairable
Maintenance: Cleaning only; Paint or stain every 5–10 years; exterior cladding reduces this

Full comparison, verdict and FAQs →

Solar with battery storage vs Solar only

A battery adds $10,000 to $20,000 and delivers outage backup plus better economics under time-of-use or export-rate rules; solar alone is cheaper and pays back faster under full net metering. The decision follows the utility's rules and how much outage protection the household wants.

Upfront cost: System at $2.60/W plus $10,000–$20,000 battery; System at $2.60/W, ~$31,135 for 12 kW (EnergySage 2026)
Lifespan: Panels 25+ years; battery 10–15; Panels 25+ years; inverter 10–15
Maintenance: Battery monitoring; replacement in year 10–15; Inverter replacement in year 10–15

Full comparison, verdict and FAQs →

Wall-mounted outdoor cooling units on a brick building

Walk-through assessment vs Diagnostic audit with blower door

A walk-through is a visual inspection with a checklist at $150 to $200; a diagnostic audit adds a blower door, thermal imaging and often duct and combustion testing at $212 to $698 or more, and produces measured numbers a contractor can be held to. The walk-through screens; the audit diagnoses.

Upfront cost: $150–$200 (HomeAdvisor); often free from utilities; $212–$698, avg $437 (Angi 2026); $500–$900 comprehensive
Instruments: Flashlight, ruler, checklist; Blower door, thermal camera, duct tester, CO meter
Output: General recommendations; Measured leakage, annotated images, prioritized measures

Full comparison, verdict and FAQs →

How to use these comparisons in an estimate

Ask each bidder to place their proposal in the columns and to explain the choice. A window bid on a house that has never been air sealed should be able to say why glass comes first; usually it cannot. An insulation bid that specifies spray foam for a flat attic should say what it does that blown-in over a sealed attic plane would not. The tables use published figures: EPA's 15% envelope saving, HomeAdvisor's 2026 material costs, Zonda's 2025 resale data, EnergySage's 2026 solar pricing.

The pattern behind the five

Each pair contrasts the measure that is cheap and invisible with the one that is expensive and visible, or the diagnosis that measures with the one that guesses. Insulation, blown-in, vinyl, solar-only and the diagnostic audit are the value column in most houses; windows, spray foam, wood, batteries and walk-throughs earn their place under specific conditions the verdicts name. Choosing by what shows is the most common way to overspend on a retrofit.

The incentive landscape shifted on December 31, 2025, when the federal 25C and 25D credits ended for property placed in service after that date. Each verdict is written for 2026 economics without them; where state HEAR rebates change the math, such as the $8,000 heat pump / $1,600 insulation cap, the verdict says so. Use the polls to see how other homeowners chose, and the calculator to price the assessment that settles the first pair.

Outdoor heat-pump unit in a shaded planting areaPhoto: Everett Pachmann · License

What the comparisons deliberately leave out

Brand rankings, because products change yearly and the structural choices do not. Local prices, because labor and material costs vary by region; the ranges are national figures from published guides with their year attached. And any claim that one column is right for every house. A cathedral-ceiling home needs foam where a flat-attic home needs blown-in; a historic district needs wood where a tract house is better served by vinyl; an outage-prone rural home wants the battery that a suburban home under full net metering can skip.

Heat pumps and water heating are not paired here because they are HVAC and plumbing scopes rather than envelope choices, but the numbers are on the service pages: HomeAdvisor's $6,088 average heat pump installation, ACEEE's Texas finding of a two-year payback replacing resistance heat, and ENERGY STAR's $550/yr annual saving for a heat pump water heater in a family of four. Both belong after the envelope and before solar in the sequence.

Homeowner polls

Which option are homeowners picking?

See all poll results

Which would you do first?

EPA estimates sealing and insulating saves about 15% of heating and cooling costs.

No votes yet. Yours will be the first. · saved on this device

Which insulation material are you considering?

No votes yet. Yours will be the first. · saved on this device

Which frame material do you prefer?

Zonda's 2025 report found vinyl recoups 68.5% at resale and wood 61.2%.

No votes yet. Yours will be the first. · saved on this device

Comparison questions

Which comparison should I read first?

Insulation versus windows, because it settles the sequence and usually sends the first dollars to the attic. Then walk-through versus diagnostic audit, because the audit tier decides how much you know before spending. The material and solar comparisons apply once the scope is chosen.

Are these comparisons biased toward the cheaper option?

They are biased toward the option that returns more per dollar for the typical house, which is often the cheaper one in this niche because the envelope is so commonly neglected. Each verdict names the conditions under which the more expensive option wins: failed openings, rim joists, historic districts, outage-prone areas, gas appliances.

How do the federal credit changes affect the comparisons?

They remove a 30% discount from windows, doors, insulation, heat pumps, solar and batteries for property placed in service after December 31, 2025. Insulation's advantage over windows grows slightly, since its cost was already low. Solar's payback lengthens by a few years. Batteries lose the credit that made them easier to justify. State HEAR rebates partly replace it for insulation and heat pumps in launched states.

Can I mix options?

Yes, and most good retrofits do: blown-in for the attic and foam for the rim joist, vinyl windows on the sides and wood on the historic front, solar with a small battery for critical loads. The mistake is mixing by accident or by what the salesperson had on the truck. Write each choice into the specification so bidders price the same design.

Where do heat pumps fit?

After the envelope and before solar. A tighter house needs a smaller unit; HomeAdvisor's 2026 average installation is $6,088, and ACEEE found a heat pump replacing electric resistance heat in Texas pays back in about two years. HEAR rebates offer up to $8,000 in launched states for eligible households. Request it as an HVAC scope with the audit report in hand.

Do these comparisons apply to renters?

Partly. Renters cannot choose insulation or windows, but a walk-through or audit gives the owner a prioritized list, and a renter can request the diagnostic tier if the owner agrees. The comparisons also tell a renter what to ask about before signing a lease: attic insulation, window type and heating fuel.

How current are the figures in the tables?

HomeAdvisor's insulation, window and heat pump costs are from June 2026, Angi's assessment benchmark from April 2026, EnergySage's solar pricing from June 2026, Zonda's resale data from September 2025, and the EPA and DOE savings estimates from current program pages. The incentive rows reflect the December 31, 2025 end date for the federal credits.

More free tools

Free toolEnergy audit cost calculator: size the assessment before the retrofit
Size, material tier and complexity in, a realistic budget range out.
Free toolEnergy retrofit readiness quiz: do you know the sequence and the tests?
10 questions that show what you already know and what to check next.
Free toolEnergy retrofit polls: how other homeowners weighed the same decisions
See what other planners chose and add your vote.

Go deeper on a service

Service guideHome Energy Audits
A home energy audit connects comfort complaints and utility bills to the measured condition of the house through a blower door test, thermal imaging, duct leakage testing and combustion-safety checks, then delivers written, prioritized recommendations.
Service guideInsulation & Air Sealing
Air sealing closes the gaps that move air through the attic plane, rim joist and penetrations; insulation slows heat conduction through the assemblies around them.
Service guideWindow & Door Replacement
Window and door replacement addresses openings with a defined problem: damage, failed seals, poor operation, drafts, single-pane glass in a cold climate, or a door that leaks and does not latch.
Service guideSolar Panel Installation
Solar panel installation covers the roof and shading assessment, equipment selection, electrical and structural permits, utility interconnection and the production and financial assumptions in the proposal.

Ready to price your home energy improvements?

Tell us the size, the condition of what is there now, and what you want to change. Home Energy Scope passes your request to independent local professionals, who reply with written, no-obligation estimates. The service is free to use.

Get a free estimate →

Energy retrofit comparisons: the five decisions inside a retrofit

See the comparisons

The 5 decisions that move the price most

Air sealing and attic insulation vs Window replacement

Upfront cost: $1,661 blown-in to $2,888 spray foam (HomeAdvisor 2026); $7,347 whole-home average (HomeAdvisor 2026)
Lifespan: Decades if kept dry; 20–30 years; glass seals 10–20
Maintenance: None; inspect after roof work; Cleaning, weatherstripping, occasional seal failure

Full comparison, verdict and FAQs →

Blown-in fiberglass or cellulose vs Spray foam

Upfront cost: $987–$2,334 project, avg $1,661 (HomeAdvisor 2026); $1,455–$4,337 project, avg $2,888; attics to $9,000 (HomeAdvisor 2026)
Material cost: $0.50–$1.10/sq ft fiberglass; $2.00–$2.30 dense-pack cellulose; $0.60–$1.60/board ft open-cell; $1.30–$3.10 closed-cell
Air sealing: None; requires separate sealing first; Built in

Full comparison, verdict and FAQs →

Vinyl frames vs Wood frames

Upfront cost: $20,091 for 10 windows (Zonda 2025); $24,376 for 10 windows (Zonda 2025)
Lifespan: 20–30 years; 30+ years with maintenance; repairable
Maintenance: Cleaning only; Paint or stain every 5–10 years; exterior cladding reduces this

Full comparison, verdict and FAQs →

Solar with battery storage vs Solar only

Upfront cost: System at $2.60/W plus $10,000–$20,000 battery; System at $2.60/W, ~$31,135 for 12 kW (EnergySage 2026)
Lifespan: Panels 25+ years; battery 10–15; Panels 25+ years; inverter 10–15
Maintenance: Battery monitoring; replacement in year 10–15; Inverter replacement in year 10–15

Full comparison, verdict and FAQs →

Walk-through assessment vs Diagnostic audit with blower door

Upfront cost: $150–$200 (HomeAdvisor); often free from utilities; $212–$698, avg $437 (Angi 2026); $500–$900 comprehensive
Instruments: Flashlight, ruler, checklist; Blower door, thermal camera, duct tester, CO meter
Output: General recommendations; Measured leakage, annotated images, prioritized measures

Full comparison, verdict and FAQs →

How to use these comparisons in an estimate

The pattern behind the five

Outdoor heat-pump unit in a shaded planting areaPhoto: Everett Pachmann · License

What the comparisons deliberately leave out

Comparison questions

Which comparison should I read first?

Are these comparisons biased toward the cheaper option?

How do the federal credit changes affect the comparisons?

Can I mix options?

Where do heat pumps fit?

Do these comparisons apply to renters?

How current are the figures in the tables?

Go deeper on a service

Hands holding a thermal imaging camera against worn window trim, with a notepad and tape measure on a bag

Service guideHome Energy Audits

A home energy audit connects comfort complaints and utility bills to the measured condition of the house through a blower door test, thermal imaging, duct leakage testing and combustion-safety checks, then delivers written, prioritized recommendations.

Gloved hands trimming foam sealant along a stud between yellow fiberglass batts in an open wall

Service guideInsulation & Air Sealing

Air sealing closes the gaps that move air through the attic plane, rim joist and penetrations; insulation slows heat conduction through the assemblies around them.

Yellow expanding spray foam filling the gap between a white vinyl window frame and rough wood framing

Service guideWindow & Door Replacement

Window and door replacement addresses openings with a defined problem: damage, failed seals, poor operation, drafts, single-pane glass in a cold climate, or a door that leaks and does not latch.

Brick and beige-sided house with a chimney and a row of black solar panels on the grey shingle roof

Service guideSolar Panel Installation

Solar panel installation covers the roof and shading assessment, equipment selection, electrical and structural permits, utility interconnection and the production and financial assumptions in the proposal.