REScheck — The Complete Guide: IECC Energy-Code Compliance for Homes
REScheck is a free tool from the US Department of Energy, developed at PNNL, for checking homes against the IECC energy code. The method is simple: for each envelope assembly you calculate U×A, that is the heat-transfer coefficient times area, add them up and compare the total with the value the code allows. It covers single- and two-family houses and residential buildings up to three storeys, and works in the browser or as a Windows program.
REScheck
PNNL (US Department of Energy)
Checks home envelopes against the IECC energy code, with a simple UA calculation and a ready report.
Get it from the vendorWhat you get
- UA calculation — walls, roof, floor, windows and doors in one table.
- Comparison with the code — how far the envelope is better or worse than required.
- Swapping options — see at once how different insulation or glazing changes the result.
- Mandatory requirements — a checklist next to the calculation.
- Compliance report — a document ready for submission to US authorities.
A note for readers outside the US
REScheck is based on the US IECC and does not replace local requirements; in Israel, for example, building energy rating follows SI 5282. It is a good tool for understanding the logic of a UA calculation and for US projects. The Windows version only supports older IECC editions, so newer editions need the browser version.
Related tools
For commercial buildings — COMcheck. To calculate an accurate U-value for a wall detail or window frame — THERM and WINDOW.
COMcheck
PNNL (US Department of Energy)
Energy-code compliance checks for commercial buildings — envelope, lighting and mechanical systems — under IECC and ASHRAE 90.1.
Get it from the vendor
THERM
Lawrence Berkeley National Laboratory
2D heat transfer analysis of envelope sections — thermal bridges, U-value and condensation checks.
Get it from the vendor
WINDOW
Lawrence Berkeley National Laboratory
Thermal and optical properties of glazing systems — U-value, SHGC and visible transmittance.
Get it from the vendorEnergyPlus
US Department of Energy
Annual building energy simulation — envelope, HVAC, thermal comfort and daylight. The US DOE engine.
Get it from the vendorThe bottom line
REScheck is a simple, quick and free tool for checking a home envelope against the IECC, and a good lesson in thinking about heat loss.