Tools You Need for Building Science

RED Calc Pro is Ready for You.
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Do Your Work Like a Pro!
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RED Calc Free

Free building science calculation tools used by building professionals around the world. RED Cal tools are the gold standard of building science calculation aids!

RED Calc Pro

Save time, reduce mistakes, use your smartphone, auto-save to RED Cloud, save and print reports, include work orders, organize your work with folders, work offline. Work smarter.

Who Uses RED Tools?

Wx Assistance (WAP)

  • Energy auditors
  • Inspectors
  • QC inspectors
  • Monitors
  • Crew leaders
  • Subcontractors
  • Trainers

Home Performance

  • Contractors
  • Energy auditors
  • Ventilation designers
  • Inspectors
  • QC inspectors
  • Program designers


  • Energy auditors
  • Inspectors
  • QC inspectors
  • Subcontractors
  • Trainers

Code Enforcement, etc.

  • CEOs
  • Home builders
  • Research analysts
  • Engineers
  • Building science instructors
  • Homeowners

RED Calc Free Tools

RED Calc Pro


  • Mobile friendly
  • Works on major browsers
  • Tools based on consensus codes and standards
  • Autosave to RED Cloud
  • Fully functional offline mode
  • Advanced error reporting
  • Auto-repair characteristics
  • Customizable reports (PDF)
  • Locking for data protection
  • Custom tool and folder templates
  • Math-on-the-fly calculator for inputs
  • Collapsing/expanding tool sections
  • Popup help (click any label)
  • Step-control for input values
  • Notes feature for folders and tools
  • Choice of U.S and metric units
  • Markdown-enabled report forms
  • Detailed results info
  • Multi-tab/window syncing
  • Available by monthly or annual subscription, individuals or teams
RED Calc Pro is the #1 set of Building Diagnostics tools for energy and building analysts. Give it a try today!
RED Calc Pro home screen
Home screen and main menu
Folder, tools, and menu
Folder, tools, and tool menu
Tool-selection menu
Section of ASHRAE 62.2-2016 tool
Math on-the-fly highlighted
ASHRAE 62.2-2016 tool with menu
ASHRAE 62.2-2016 tool on smartphone
Popup Help, a feature of all tools
Customized tool report
Notes tool report

Major Study Shows ASHRAE 62.2 Ventilation Works!

A significant research report published in April of this year by the National Center for Healthy Housing (NCHH) found that subsidized multifamily housing with ASHRAE 62.2-compliant ventilation had better indoor air quality than housing without 62.2-compliant ventilation. This important research states: “Levels of four of the five indoor contaminants improved substantially with [continuous] mechanical ventilation.”

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Core Sampling Cellulose Insulation Density

It is often useful to be able to determine the installed density of dense-pack cellulose in a wall. Because the installer must work without the benefit of viewing the coverage or density, core sampling was devised many years ago to measure these important metrics. If the density is too low, the R-value and air leakage degrade. If the density is too high, insulation and labor are wasted.

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Better Sleep Leads to Sweeter Building Science Dreams

Sleep is vital to our health, including our immunity from disease, heart function, and even reproductive vitality. A bad night’s sleep might contribute to poor performance at work and a sour emotional state the next day. It is difficult to assign a cost to a bad night’s rest, but I think most of us agree that it’s a cost we would rather avoid.

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