How much is your current window spec really costing your client?
For new-build projects. Compare typical North American double & triple-pane windows against LuxHaus European systems across the five metrics that matter: thermal performance, acoustic isolation, solar control, service life, and projected HVAC bill. Adjust for your project, share the numbers with the client.
Step 1 · Project ParametersDefine the Build
Fine-tune window specsArchitects — override any parameter with your project's actual glazing package
Current window (North American spec)
Air leakage around sash and frame adds real heat transfer beyond the U-value. LuxHaus European systems tested to EN 12207 Class 4 are assumed effectively airtight (1.00× baseline).
LuxHaus window (European spec)
2,800sq ft home · ≈ 448 sq ft of windows (16%)
448sq ft of windows & doors
NFRC steady-state uses textbook U-value × HDD math. Real-world bills run much higher due to HVAC part-load inefficiency, duct losses, thermostat creep near cold glass, and non-linear infiltration in extreme temperatures. Multiplier auto-sets by climate on region change (cold = 2.0–2.5×, mixed = 1.5×, warm = 1.2×) based on NRCan, NREL, and LBNL retrofit studies. Override anytime.
$0.245per kWh · residential avg
$40,000competitor quote today · inflated to year 18 @ 3%
Step 2 · The Performance GapWhere LuxHaus Moves the Needle
Set your parameters above, then tap Calculate the Gap to see the comparison.
Thermal performance · lower U-value is better
Current
U-0.28
LuxHaus
U-0.13
Acoustic isolation · higher STC is better
Current
STC 28
LuxHaus
STC 40
Side by SideFull Specification Delta
Metric
Current Spec
LuxHaus System
Difference
Step 3 · The Long-Term Picture25-Year Outlook
Annual HVAC Bill Savings
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Projected heating & cooling bill reduction for this new build. Compares the full HVAC operating cost at each window spec, holding the rest of the envelope equal.
25-Year HVAC Cost
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vs. $— with current spec
Replacement Cost Avoided (inflated)
—
—
Total 25-Year Advantage
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Combined energy savings + avoided replacement cost over 25 years. Excludes resale value, occupant comfort, and health benefits.
Opportunity costWhat if your client invested the savings instead?
If both savings streams — annual energy savings and the avoided replacement cost — were invested in an S&P 500 index fund at the historical 10% average annual return. Annual savings compound across 25 years; the avoided replacement lump sum compounds from when it would have been spent through year 25.
How this is calculated (new-build methodology): This calculator projects the whole-home annual heating & cooling bill for a new construction project with each window spec, holding the rest of the envelope equal (code-compliant walls, roof, floor, doors). Step 1 — Direct window physics: Conductive heat transfer (U-value × glazing area × HDD+CDD × 24 hr ÷ 3,412 Btu/kWh, cooling divided by COP 3.5) plus solar heat gain (SHGC × climate-specific solar irradiance from NREL NSRDB × cooling-season days ÷ 3,412 ÷ COP 3.5). This is the NFRC-standard methodology used by ResCheck, REM/Rate, and PHPP. Step 2 — Scale to whole-home HVAC bill: Windows contribute a climate-dependent share of total HVAC load in a new code-compliant home: 55% in subarctic (windows + associated infiltration dominate envelope losses at extreme ΔT), 45% in cold, 37% in mixed, 40% in warm (solar gain through glazing drives cooling). These shares are sourced from NRCan Canadian new-build envelope studies and DOE Building America data. The window-attributable cost is scaled up by dividing by this share to reflect the full HVAC bill. Step 3 — LuxHaus systemic bonus: LuxHaus European windows deliver whole-home HVAC benefits that pure window heat-transfer math cannot capture: (a) airtight EN 12207 Class 4 assembly reduces whole-house infiltration, (b) warm interior glass surfaces eliminate radiant-discomfort thermostat creep (2–4°F setpoint drop), (c) stable envelope enables right-sized HVAC to run at high-efficiency part-load. A climate-dependent systemic discount is applied to the LuxHaus HVAC bill: 10% subarctic, 7% cold, 4% mixed, 5% warm. Modeling method (real-world multiplier): Applied to both specs before the whole-home scaling — auto-set by climate on region change with user override. Options: 1.0× NFRC steady-state (textbook, most conservative); 1.2× warm-climate typical (PNNL AC part-load); 1.5× mixed-climate typical (DOE Building America); 2.0× cold-climate typical (LBNL cold-climate research); 2.5× subarctic electric-heat verified (NRCan retrofit studies). Air infiltration: NA current-window conductive cost is multiplied by an NFRC AL-rating factor (1.05× tight → 1.40× leaky). LuxHaus tested to EN 12207 Class 4 is baseline airtight. Scope: This is the heating and cooling operating bill only. Hot water, lighting, appliances, plug loads, and other electrical use are excluded — those are the same regardless of window spec. Replacement cost = competitor's quoted price × 1.03N, where N is the current spec's lifespan (3% inflation); included in the 25-year total only if N ≤ 25. S&P 500 combines two compounded streams: (a) annual HVAC bill savings invested each year for 25 yrs at 10% nominal (future value of ordinary annuity), plus (b) the inflated replacement lump sum compounded from year N through year 25 at 10%. Architect-tunable ranges: Ug from 2.8 W/m²K (single-pane) to 0.4 W/m²K (top-tier PHI); SHGC from 0.11 to 0.60; STC from 25 to 52+.
Ready to spec LuxHaus on your next project?
Submit your plans and we'll return a free estimate within 5–7 business days. Factory-direct from Germany, Italy & Poland. Passive House suitable. No showrooms, no middlemen.
Window IQ is LuxHaus’s window cost calculator — a free tool that shows you the real 25-year financial gap between standard windows and high-performance European alternatives. Most window buyers focus on the purchase price. Window IQ shows you what that decision actually costs over time, across three dimensions that matter: energy savings, soundproofing value, and total ownership cost.
What the Window Cost Calculator Measures
Standard windows and high-performance European windows look similar on a spec sheet. The difference shows up in your energy bills, your indoor comfort, and the resale value of your home or building over time. Window IQ runs a 25-year analysis across three cost factors:
Energy savings — how much less you spend heating and cooling when your windows have a lower U-value and better air sealing
Soundproofing — the real-world acoustic improvement of double vs. triple glazing, and what that’s worth in livability and property value
Total ownership cost — purchase price, installation, maintenance, and energy costs combined over 25 years, so you can compare apples to apples
Grounded in Real Methodology
Window IQ calculations use heat loss and energy cost methodology consistent with U.S. Department of Energy guidance on residential window performance and Passive House Institute standards for high-performance fenestration. The numbers you see are based on real thermal physics, not marketing assumptions.
Who Should Use Window IQ?
This window cost calculator is built for anyone making a serious window buying or specification decision:
Homeowners renovating or building new, who want to see whether the upgrade to high-performance windows pays off over time
Architects and specifiers who need to justify premium window specifications to budget-conscious clients with real numbers
Developers and builders comparing the long-term cost impact of different glazing specifications across a project
Energy consultants modeling Passive House or near-zero energy building performance
From the Calculator to the Right Window
Once you’ve run your numbers in Window IQ, LuxHaus can match you with the right product from our European window and door range. Whether your analysis points to tilt-and-turn windows, lift-and-slide doors, or entrance systems, we can quote the exact specification your calculator results suggest. Ask Emma, our AI window advisor, is also available 24/7 to help you interpret your results and choose the right product for your project.
