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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
John Straube

The research reported in this paper is aimed at increasing the understanding of the hygrothermal performance of interior basement insulation systems by a combination of field monitoring of four assemblies and one-dimensional computer modeling. The work described here is part of a Canada Mortgage and Housing Corporation (CMHC) sponsored research program to determine the significance or insignificance of potential moisture problems due to an impermeable polyethylene layer in above- and below-grade walls (Wilkinson et al. 2007).

Cold
Research Reports
Joseph Lstiburek

Exposure to sunlight (ultraviolet radiation) and moisture are the major factors affecting the durability of paint coatings and the durability of the substrate. Ultraviolet radiation, moisture and heat can each lead to the breakdown of the resin in painted surfaces which binds (holds) the pigment to the substrate surface.

Research Reports
Joseph Lstiburek

Exterior insulation and finishing systems (EIFS) are inherently defective and unfit of use as an exterior cladding system where moisture sensitive components are used without a provision for drainage or in locations and assemblies without adequate drying. Exterior insulation and finishing systems (EIFS) are inherently defective and unfit to use as an exterior cladding system where moisture sensitive components are used without a provision for drainage or in locations and assemblies without adequate drying.

Hot-Dry/Mixed-Dry
Research Reports
Joseph Lstiburek

Roofs can be designed and constructed to be either vented or unvented in any hygrothermal zone. Air barrier systems are typically the most common approach, however, air pressure control approaches are becoming more common especially in cases involving remedial work on existing structures. Vapor diffusion should be considered as a secondary moisture transport mechanism when designing and building roofs. Specific vapor retarders are often unnecessary if appropriate air movement control is provided or if control of condensing surface temperatures is provided.

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

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
Building Science Corporation
The Vancouver-area “leaky condo crisis” began to surface in the 1980s. An unusually large number of moisture-related problems, not only in condos but also in most building types, prompted extensive...
Published Articles
John Straube

One-third of the energy you buy probably leaks through holes in your house. Reprinted with permission from Fine Homebuilding, October/November 2012, pages 45-49.

Published Articles
John Straube, Christopher Schumacher, Jonathan Smegal, M. Jablonka

Adhered veneers, in which masonry units are directly attached to a substrate via mortar and ties without a drainage or ventilation gap, have become a very popular finish in residential and light commercial construction. Reprinted with permission from Journal of Building Enclosure Design, Summer 2009, pages 31-35.

Published Articles
Joseph Lstiburek

Today’s houses make it easier for mold to find the food and water it needs to thrive. The cure is a quick cleanup and smarter choices in materials. Reprinted with permission from Fine Homebuilding, December 2006/January 2007, pages 70-75.

Published Articles
Joseph Lstiburek

Outdoor air is added to a building via a controlled ventilation system. What isn't controlled is the air change created by wind effects, stack effects and pressure effects caused by the operation of the HVAC system. The following article was published in ASHRAE Journal, April, 2002, pages 18-21. Reprinted with permission.

Hot-Humid
Published Articles
Joseph Lstiburek

How water gets into a structure, why it doesn't leave, and how these architectural flaws become HVAC headaches. This two-part article was first published in HPAC Engineering, December 2001 and January 2002.

Published Articles
Betsy Pettit, John Snell

Here we explore issues unique to Veterans Era Housing and present three cases where moisture problems were successfully addressed. Originally published in Home Energy November/December 2001, pages 33-37. For more information about mold in homes go to Popular Topics/Homeowner Resources.

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