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climates

Very Cold - A very cold climate is defined as a region with approximately 9,000 heating degree days or greater (65°F basis) or greater and less than 12,600 heating degree days (65°F basis).

Cold - A cold climate is defined as a region with approximately 5,400 heating degree days (65°F basis) or greater and less than approximately 9,000 heating degree days (65°F basis).

Mixed-Humid - A mixed-humid and warm-humid climate is defined as a region that receives more than 20 inches of annual precipitation with approximately 4,500 cooling degree days (50°F basis) or greater and less than approximately 6,300 cooling degree days (50°F basis) and less than approximately 5,400 heating degree days (65°F basis) and where the average monthly outdoor temperature drops below 45°F during the winter months.

Hot-Humid - A hot-humid climate is defined as a region that receives more than 20 inches of annual precipitation with approximately 6,300 cooling degree days (50°F basis) or greater and where the monthly average outdoor temperature remains above 45°F throughout the year. This definition characterizes a region that is similar to the ASHRAE definition of hot-humid climates where one or both of the following occur:

  • a 67°F r higher wet bulb temperature for 3,000 or more hours during the warmest six consecutive months of the year; or
  • a 73°F or higher wet bulb temperature for 1,500 or more hours during the warmest six consecutive months of the year.

Hot-Dry/Mixed-Dry - A hot-dry climate is defined as region that receives less than 20 inches of annual precipitation with approximately 6,300 cooling degree days (50°F basis)or greater and where the monthly average outdoor temperature remains above 45°F throughout the year.

A warm-dry and mixed-dry climate is defined as a region that receives less than 20 inches of annual precipitation with approximately 4,500 cooling degree days (50°F basis) or greater and less than approximately 6,300 cooling degree days (50°F basis) and less than approximately 5,400 heating degree days (65°F basis) and where the average monthly outdoor temperature drops below 45°F during the winter months.

Marine - A marine climate meets is defined as a region where all of the following occur:

  • a mean temperature of the coldest month between 27°F and 65°F;
  • a mean temperature of the warmest month below 72°F;
  • at least four months with mean temperatures over 50°F; and
  • a dry season in the summer, the month with the heaviest precipitation in the cold season has at least three times as much precipitation as the month with the least precipitation.

information

Building Science Insights are short discussions on a particular topic of general interest. They are intended to highlight one or more building science principles. The discussion is informal and sometimes irreverent but never irrelevant.

Building Science Digests provide building professionals from different disciplinary backgrounds with concise overview of important building science topics. Digests explain the theory behind each topic and then translate this theory into practical information.

Published Articles aare a selected set of articles written by BSC personnel and published in professional and trade magazines that address building science topics. For example, our work has appeared in Fine Homebuilding, Home Energy, ASHRAE's High Performance Buildings, The Journal of Building Enclosure Design and The Journal of Building Physics. We thank these publications for their gracious permission to republish.

Conference Papers are peer-reviewed papers published in conference proceedings.

Research Reports are technical reports written for researchers but accessible to design professionals and builders. These reports typically provide an in-depth study of a particular topic or describe the results of a research project. They are often peer reviewed and also provide support for advice given in our Building Science Digests.

Building America Reports are technical reports funded by the U.S. Department of Energy (DOE) Building America research program.

Designs That Work are residential Case Studies and House Plans developed by BSC to be appropriate for residential construction in specific climate zones. Case Studies provide a summary of results for homes built in partnership with BSC’s Building America team. The case study typically includes enclosure and mechanical details, testing performed, builder profile, and unique project highlights. House Plans are fully integrated construction drawing sets that include floor plans, framing plans and wall framing elevations, exterior elevations, building and wall sections, and mechanical and electrical plans.

Enclosures That Work are Building Profiles and High R-Value Assemblies developed by BSC to be appropriate for residential construction in specific climate zones. Building Profiles are residential building cross sections that include enclosure and mechanical design recommendations. Most profiles also include field expertise notes, material compatibility analysis, and climate challenges. High R-Value Assemblies are summaries of the results of BSC's ongoing High R-Value Enclosure research — a study that BSC has undertaken for the U.S. Department of Energy (DOE) Building America research program to identify and evaluate residential assemblies that cost-effectively provide 50 percent improvement in thermal resistance.

Guides and Manuals are "how-to" documents, giving advice and instructions on specific building techniques and methods. Longer guides and manuals include background information to help facilitate a strong understanding of the building science behind the hands-on advice. This section also contains two quick, easy-to-read series. The IRC FAQ series answers common questions about the building science approach to specific building tasks (for example, insulating a basement). The READ THIS: Before... series offers guidelines and recommendations for everyday situations such as moving into a new home or deciding to renovate.

Information Sheets are short, descriptive overviews of basic building science topics and are useful both as an introduction to building science and as a handy reference that can be easily printed for use in the field, in a design meeting, or at the building permit counter. Through illustrations, photographs, and straightforward explanations, each Information Sheet covers the essential aspects of a single topic. Common, avoidable mistakes are also examined in the What's Wrong with this Project? and What's Wrong with this Practice? mini-series.

Building Science InsightsNewsletters
Joseph Lstiburek

Huh? Blasphemy. Yeah, well, in some assemblies, it is actually a pretty good idea. The most famous "double vapor barrier" of them all is a classic compact flat roof. Check out Figure 1. The roof membrane on the "top" is clearly a vapor barrier. In...
Building Science InsightsNewsletters
Joseph Lstiburek

A wall is supposed to keep the outside out and the inside in. That is the way things are supposed to work. Check out the “perfect wall” (Figure 1). We have our water control layer, our air control layer, our vapor control layer and our thermal...
Building Science InsightsNewsletters
Joseph Lstiburek

With the “perfect wall” we were here way back when (BSI-001: The Perfect Wall). The perfect wall has four control layers outside of the structure:a water control layeran air control layera vapor control layera thermal control layerThese are...
Building Science InsightsNewsletters
Joseph Lstiburek

Maybe not. For years I have said that dog won’t hunt1. I have come around. The engineer in me likes tools. I can’t help it – it is a genetic defect we engineers are born with. With therapy we engineers have learned that tools come with...
Building Science InsightsNewsletters
Joseph Lstiburek

Sometimes the obvious is not so obvious. And sometimes the not so obvious becomes obvious. For example installing leaky ductwork1 in a vented attic is a pretty dumb idea (Figure 1). It leads to negative pressures and high air change that...
Building Science InsightsNewsletters
Joseph Lstiburek

We have long wrapped our framed buildings with a “layer”. What we called it and what we make it out of has changed over time. And now the vapor permeance of it needs to be re-thought. How low can you go1? How high can you go? Does it...
Building Science InsightsNewsletters
Joseph Lstiburek

Vitruvius had it right 2,000 years ago: “…if a wall is in a state of dampness all over, construct a second thin wall a little way from it…at a distance suited to the circumstances…with vents to the open air…when the wall is brought up to the top,...
Building Science InsightsNewsletters
Joseph Lstiburek

Sometimes we make easy things hard. And sometimes we make hard things easy. With continuous insulation and punched openings both things are true.The physics is easy. A wall has to control water, air, vapor and heat. A window has to control water,...
Building Science InsightsNewsletters
Joseph Lstiburek

Things have evolved considerably since the Eisenhower and Diefenbaker years. Hutcheon2 taught us about air flow that decade but it took more than a half century to get it right. We needed air control. We needed an air control layer – an...
Building Science InsightsNewsletters
Joseph Lstiburek

For all that we know about roofs–which is a great deal–sometimes things can get confusing. I am more than partly to blame for that. I wrote a lot of the code language dealing with both vented and unvented roof assemblies. Yes, the language is...
Building Science InsightsNewsletters
Joseph Lstiburek

Personally, I think the most beautiful floors in the world are wood. I like the look. I like the feel. Even Greenies like wood floors because apparently wood grows on trees.1Wood floors have been around forever. You would think folks...
Building Science InsightsNewsletters
Joseph Lstiburek

So what does “net zero” mean anyway? And what is the difference from a “zero energy house”? A zero energy house is “off grid” and makes all the energy it needs on site using renewables. This is not easy to do and typically involves an ultra...
Cold
Building Science InsightsNewsletters
Joseph Lstiburek

"linings and warmth . . . "1How do you insulate uninsulated masonry buildings on the inside? Carefully. There I go again with the obvious. It is trickier to do it on the inside. But it is often less expensive than insulating them on the...
Building Science InsightsNewsletters
Joseph Lstiburek

Chicago is well known for a bunch of things—among them a baseball team that does not win, fabulous pizza1, and uninsulated masonry buildings. The Windy City2 does not want to be known for its uninsulated masonry building...
Building Science InsightsNewsletters
Joseph Lstiburek

Ballast is necessary in ships for stability, balance, trim and to otherwise keep them upright because the alternative is not pleasant. The amount of ballast necessary varies based on the type of ship and the amount of cargo if any. Legend has it...
Building Science InsightsNewsletters
Joseph Lstiburek

“What we’ve got here is failure to communicate . . .”1In what is turning out to be an unfortunate turn of phrase the terms “unvented attics” and “unvented roofs” have entered the lexicon. A lot of the blame for that goes to me and for...
Building Science InsightsNewsletters
Joseph Lstiburek

PrologueFolks sometimes ask me how do I know “that”? How could I possibly know that “that” would happen? I chuckle and answer “that’s because I have good judgment…and good judgment is based on experience...and experience is based on bad judgment…I...
Building Science InsightsNewsletters
Joseph Lstiburek

We live at the bottom of an ocean of air. Each of us is carrying around 14.7 pounds per square inch when at the beach in Miami1. We are powerful creatures indeed. Imagine carrying around 101,000 Pascal’s on that beach. Or 1,010 millibars...
Building Science InsightsNewsletters
Joseph Lstiburek

Putting ductwork outside is bad enough, but putting ductwork in an attic is even worse (Photograph 1). Attics are even hotter than outside during the summer and as cold as the outside in the winter. Of all of the places to put ductwork in I can’t...
Building Science InsightsNewsletters
Joseph Lstiburek

Life was simple when I grew up in Canada. Winters were long and cold, we had no air conditioning, walls dried to both the outside and the inside and the Toronto Maple Leafs would win Stanley Cups. That all changed when we started putting plastic on...

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