Embodied Carbon, Insulation Comparison & Preliminary Envelope Loads
Embodied carbon of material options from user-entered EPD factors; insulation R-value comparison from user-entered R per inch; steady-state conductive heat loss Q = U A dT per surface. Not a carbon database, not an energy-code compliance check and not an equipment sizing load.
Method
energy-carbon 1.1
Engine
1.1.0
Output status
Preliminary - review required
Review
Awaiting review
Formulas
- kg CO2e = quantity (EPD declared unit) x GWP (kg CO2e per declared unit, from the EPD); option total = sum of its lines
- R = R per unit thickness x thickness; with the rest of the assembly, R total = R rest + R insulation (layers in series)
- Thickness for a target R = target R / R per unit thickness
- Q = U x A x (indoor - outdoor design temperature); 1 Btu/h = 0.29307107 W
Conventions
- Quantities are entered in each EPD’s own declared unit.
- U-factors come from the Envelope calculator or are entered with a source.
- Every factor carries the source the user gave.
Limits - what it will not do
- No EPD, GWP factor, R-value or design temperature is built in.
- EPD comparability (product category rules, functional unit, stages) is not checked; a warning shows when the stages differ.
- Conduction only: no air leakage, ventilation, solar or internal gains. Not a heating load for sizing equipment and not an energy-code compliance check (use DOE COMcheck or REScheck).
Who must review it
- Sustainability consultant or LCA practitioner: EPD comparability for the options compared
- Mechanical engineer: design conditions and any use of the conductive loss
Worked example
Inputs Option A 1,200 m² x 2.5 + 40 m³ x 300; Option B 1,200 m² x 1.8 + 40 m³ x 250; R 5.0/in x 3 in and R 3.7/in x 4 in, target R-20; walls 1,000 ft² U 0.05 and roof 2,000 ft² U 0.032 at 70 to 0 degF
Expected A 15,000, B 12,160 kg CO2e (A +2,840, +23.4%); R-15 and R-14.8, 4 in and 5.41 in for R-20; 3,500 + 4,480 = 7,980 Btu/h
Checked by an automated test on every change.
Sources
- Embodied carbon from Environmental Product Declarations (arithmetic) - Method sheet energy-carbon/1.0, read 2026-10-16
kg CO2e = quantity in the EPD declared unit x the EPD global warming potential per declared unit; options are compared on the lines entered. Every factor is entered by the user from a named EPD.
- EC3 - Embodied Carbon in Construction Calculator - Building Transparency, read 2026-10-16
Free, open-access embodied carbon calculator with a digitized EPD database. Use it to find an EPD and its declared GWP, or to run a full embodied-carbon assessment.
- 16 CFR Part 460 - Labeling and Advertising of Home Insulation (the FTC R-value Rule) - U.S. Federal Trade Commission (eCFR), read 2026-10-16
The federal rule under which home insulation R-values are tested and disclosed on labels and fact sheets. Read the R-value per inch from the product label or datasheet.
- ASHRAE Handbook - Fundamentals: Heat, Air, and Moisture Control in Building Assemblies - Fundamentals (thermal resistance of layers in series) - ASHRAE, read 2026-10-16
One-dimensional steady-state conduction: resistances of layers in series add, U = 1 / R total, and the temperature drop across each layer is in proportion to its share of R total.
- Steady-state conductive heat loss, Q = U x A x dT - Method sheet energy-carbon/1.0, read 2026-10-16
Heat flow through a surface = U-factor x area x indoor-outdoor temperature difference. 1 Btu/h = 1055.05585262 / 3600 W (NIST SP 811).
- ASHRAE Climatic Design Conditions (station viewer) - ASHRAE, read 2026-10-16
Station-by-station design temperatures. Enter the outdoor design temperature for the site with the station and percentile used.
- COMcheck - commercial energy code compliance - U.S. Department of Energy, Building Energy Codes Program, read 2026-10-16
The DOE web and desktop tool for demonstrating commercial building energy code compliance. Use it, not this screen, for compliance.
- REScheck - residential energy code compliance - U.S. Department of Energy, Building Energy Codes Program, read 2026-10-16
The DOE tool for demonstrating residential energy code compliance.
- NIST Special Publication 811 - Guide for the Use of the International System of Units (SI), Appendix B conversion factors - National Institute of Standards and Technology, read 2026-10-16
Exact factors: 1 in = 0.0254 m; 1 ft = 0.3048 m; 1 yd = 0.9144 m; 1 mi = 1609.344 m; 1 lb = 0.45359237 kg; 1 U.S. gallon = 231 in3 = 3.785411784 L; 1 Btu (IT) = 1055.05585262 J; t(degC) = (t(degF) - 32) / 1.8; T(K) = t(degC) + 273.15.