Big Ladder Software

Unmet Hours

IBPSA-USA and Big Ladder Software are pleased to announce a new, free online community resource called Unmet Hours, a question-and-answer (Q+A) website for building energy modelers.

What is a question-and-answer website? It’s a new type of resource that has emerged from the programming world as an alternative to mailing lists or forums. But it’s super simple. You ask a question. Other modelers answer it. The best answer gets voted to the top. Or you can search on your topic and you might find that your question has already been asked and answered. And it’s always good to give back to the community (while showing off your expertise and earning good “karma”) by helping other modelers with their questions.

At Unmet Hours, you can ask questions about any modeling topic or software tool. Numerous experts are standing by, eager to help, and ready to answer your questions–big or small.

Unmet Hours is a resource for the building energy modeling community, built by the community. We are counting on your support and participation to continue its success.

Unmet Hours was developed by Big Ladder Software with the generous support and collaboration of IBPSA-USA.


Further Reading



Unmet Hours offers many capabilities that make it a powerful resource for the building energy modeling community:

  • Each individual question is kept together with its answers on one web page that can be easily referenced with a unique URL.
  • Answers are peer reviewed and voted on by the community to reach a consensus on which ones are most likely to be helpful or “correct”.
  • Questions are easily searchable on the website. All content is indexed by Google and other search engines.
  • Questions are tagged with category labels such as ‘infiltration’, ‘daylighting’, or ‘energyplus’ making it easy to find topics of interest.
  • Questions can be tagged across multiple categories for cross-cutting problems, for example, ‘ashrae-90.1’, ‘hvac’, and ‘energyplus’.
  • Tags or individual questions can be “followed” to receive email updates when there is new or changed content. You control your email update preferences.
  • Comments are used to discuss or make suggestions about a question or answer without distracting from the main content.
  • All content is actively moderated and curated by the community. Questions and answers can be revised at any time to be clearer and more helpful, or to be updated as new information becomes available. It’s a living knowledge base.
  • And it all works conveniently in the web browser on your smartphone!


Unmet Hours was originally developed with the generous support and collaboration of the founding sponsor, the USA affiliate of the International Building Performance Simulation Association (IBPSA-USA). This project was developed based upon funding from the Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the US Department of Energy.