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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.

Research Reports
Joseph Lstiburek, Terry Brennan, Nathan Yost

This article briefly repeats some of the information in the other mold articles but also includes information on how to prevent mold in residential structures. Mold requires water. No water, no mold. Mold is the result of a water problem. Fix the water problem, clean up the mold and you have fixed the mold problem. For more information, see Popular Topics/Homeowner Resources.

Research Reports
Joseph Lstiburek, Terry Brennan, Nathan Yost

The purpose of this document is to assist builders with the decisions regarding what to do and how to do it when mold is found in specific locations. This article provides both general guidelines for mold remediation as well as specific guidelines for the typical locations where mold is most often found in houses. For more information, see Popular Topics/Homeowner Resources.

Research Reports
Joseph Lstiburek, Terry Brennan, Nathan Yost

Mold testing procedures were not developed to determine whether a home is “safe” or “healthy” or “clean." Although this article is titled "Mold Testing" it actually tells you why testing for mold is usually not needed. For more information, see Popular Topics/Homeowner Resources.

Research Reports
Joseph Lstiburek, Terry Brennan, Nathan Yost

Too much mold can affect the health of you and your family. In addition, mold can damage or destroy building materials such as wood or gypsum board in our homes. This article answers your questions about mold, what it is, where it grows, how it spreads, how it can be prevented. For more information, see Popular Topics/Homeowner Resources.

Research Reports
Joseph Lstiburek

Builders for many years have put mechanical equipment and ducts in non-living spaces such as crawlspaces and attics primarily to save valuable floor space. Be that as it may (there are lots of good reasons for having this equipment in conditioned spaces, GIVEN proper attention to ventilation and pressurization issues), it makes perfect sense to condition these areas, for a variety of energy, moisture and durability reasons.

Research Reports
Joseph Lstiburek

What relative humidity should I have in my home? Seems like a simple enough question. However, the answer can sometimes be difficult to understand.

Research Reports
Joseph Lstiburek

Unvented roof systems can be safely used in many different climates. In cold climates, insulating sheathing must be added exterior to the roof sheathing to prevent condensation on the underside of the roof sheathing.

Research Reports
Joseph Lstiburek

Wood moves. Drywall does not move. Interesting problem. The more you attach drywall to wood, the more cracks you have. Easy, attach the drywall to less wood, and, in a way, that allows the wood to move.

Research Reports
Joseph Lstiburek

The primary function of a housewrap or building paper is rain penetration control. It is not air infiltration despite what the manufacturers say. The energy aspects of housewraps are vastly overstated. They have been embraced by builders for this function as can be evidenced by their market penetration. Yet their critical role in building durability is under appreciated and not marketed. It has been a triumph of marketing over physics.

Research Reports
Joseph Lstiburek

The manufacturers of housewraps have for years promoted the fantasy that water vapor in wall assemblies only moves one way – from the inside out. So, therefore, walls should be designed to “breathe” outwards. So, therefore, you should buy a highly vapor permeable housewrap. So, therefore, you should buy “our product.” But housewraps are not a “magic wonder material” that should be used everywhere without thought. Like all materials, you have to pick your spots.

Research Reports
Joseph Lstiburek

Brick is a reservoir cladding, meaning that it absorbs and stores water (rain) when it becomes wet. In some homes, with brick veneer cladding systems, mold contamination has occurred within exterior wall cavities. In some homes, wood decay at bottom plates has also occurred.

Research Reports
Joseph Lstiburek

This is a concise overview of the principles and steps to follow when dealing with water from the foundation to the roof.

Research Reports
Armin Rudd

This report provides transfer grille sizing information excerpted from “BA-0006: Discussion of the Use of Transfer Grilles to Facilitate Air Flow in Central Return Systems.” The goal is to prevent pressurization of individual bedrooms when door is closed.

Research Reports
Joseph Lstiburek

Most of us are not aware of just how differently these two barriers work in building assemblies. This article makes the differences as clear as the polyethylene film that should (or more likely should NOT) be in your walls.

Research Reports
Building Science Corporation
Masonry walls are generally highly durable. However, when masonry walls are too wet during freezing spells, freeze-thaw damage can occur. This issue has particular relevance for energy efficiency...
Thermal Metric Test Wall Construction and Installation The Thermal Metric (TM) research project uses a novel hot box apparatus to investigate multiple factors that contribute to thermal performance...
This report provides a summary of the Thermal Metric Project and results of Reference Wall testing. The Thermal Metric Project is a multi-year collaborative research project headed by Building...
The Thermal Metric Hot Box Apparatus For the purposes of the Thermal Metric (TM) research project a novel double-guarded hot box apparatus was designed and constructed (Figure 1). The apparatus is...
Research Reports
Building Science Corporation
The Thermal Metric (TM) project was initiated in 2007 to support good design and construction practices by improving the way thermal performance is measured. Ultimately, the project goal is to...
Vancouver Test Hut Phases I-III Wall AssembliesThe Vancouver Test Hut is a 900 square foot field testing facility located in Coquitlam, BC, on the rooftop of the two story commercial office building...

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