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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.

Published Articles
Armin Rudd

By creating a path for air to move, structural vents are supposed to prevent the buildup of moisture in an attic. This article was first published in Builder Magazine, January 2006.

Published Articles
Joseph Lstiburek

Smarter strategies can save money, speed construction, improve energy efficiency, and cut down on jobsite waste. Reprinted with permission from Fine Homebuilding, October/November 2005, pages 50-55.

Published Articles
Armin Rudd

This article reports on field experience of unvented cathedralized (UC) attics in the U.S. Traditionally, in some regions of the country, slab on grade construction is a preferred mode of construction. Mechanical equipment for air conditioning and distribution ducts are usually located in the attic spaces to conserve space. Conventional construction involves providing insulation on the floor of the attic and venting the attic space to the outside leading to  loss in efficiency in operation of the equipment and through duct leakage. Insulating the attic roof itself and blocking of ventilation to the outside transfers the air and thermal energy controls from the boundary with the living space to the plane of the roof. The air distribution systems now fall within conditioned space, which increases their efficiency, durability, and maintainability. This article was first published in the Journal of Building Physics, Vol. 29, October 2005.

Published Articles
Betsy Pettit

Think $50 per square foot and $50 a month for utilities are unattainable? Government-sponsored research proves otherwise. Reprinted with permission from Fine Homebuilding, June/July 2005, pages 56-61.

Cold
Published Articles
Joseph Lstiburek

Top ten blunders that rot your house, waste your money, and make you sick. Reprinted with permission from Fine Homebuilding Magazine, April/May 2004, pages 52-56. 

Published Articles
Joseph Lstiburek

Brick veneers are essentially transparent to water. Wood clapboards, fiber cement siding, and vinyl siding also leak, each in its own special way. In the real world all claddings leak sooner or later. They always have, and they always will. When your cladding leaks, neither caulking nor sealants will keep water out of your building. So if all claddings leak, and all sealants and caulks fail, how can we keep buildings dry? By creating a water management system beneath the cladding: a continuous drainage plane with integrated flashings and weep holes, with an air space between the cladding and the drainage plane where water can flow. Reprinted from The Journal of Light Construction, March 2003.

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

When designing a building’s envelope and its interaction with the mechanical system, temperature, humidity, rain, and the interior climate often are ignored. The focus for the building may be more on aesthetics and cost than on performance. This article was first published in ASHRAE Journal, February 2002, pages 36-41. Reprinted with permission.

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.

Published Articles
Betsy Pettit, John Snell

Multifamily public and low-income housing have particular problems when it comes to moisture and air pollutants. In this first of a two-part series, we look at one particular type of multifamily construction: midrise housing. Originally published in Home Energy September/October 2001, pages 24-28. For more information about mold in homes, see Popular Topics/Homeowner Resources.

Published Articles
Armin Rudd, Joseph Lstiburek

A multi-zone, single-gas, tracer gas decay measurement technique was used to test the ventilation systems of a single-story, slab-on-grade 1350 sq. ft. house in Las Vegas, Nevada, and a two-story, 3192 sq. ft. house with basement in Minneapolis, Minnesota. Some of the systems were independent of the central air distribution system, while others were integrated with it. In general, results showed that all ventilation systems benefitted from periodic operation of the central fan, giving excellent uniformity of ventilation air distribution. System without central fan recirculation showed poor ventilation air distribution for closed rooms where there was no ventilation system duct. This article was first published in ASHRAE Transactions 2000, Vol. 106, Part 2. Reprinted with permission.

Project Home Again is the first and the largest development of new homes in Louisiana to be Builders Challenge certified. This article was first published in Home Energy Magazine, September/October...
Hot-Humid
Joseph Lstiburek
The reason we have lots of Greek symbols associated with statistics is that the ancient Greeks had figured out a lot of statistics and other sciences, including means and medians. Statistics really...
Information Sheets
This article addresses the issue of undercutting bedroom doors to provide return airflow from bedrooms resulting in risks such as insufficient airflow, pressure imbalance, energy-inefficient loss of...
Information Sheets
This article addresses the issue of unsealed conditioning equipment and ducts located outside the conditioned space in a vented attic, unconditioned crawlspace or basement resulting in risks such as...
Information Sheets
This article addresses the issue of unsealed wall stud cavities used as a return air plenum located in a wall between a garage and living space resulting in risks such as indoor air quality issues...
Information Sheets
This article addresses the issue of unsealed wall stud cavities or panned floor joists used as a return air plenum resulting in risks such as indoor air quality issues due to negatively pressurized...
Information Sheets
This article addresses the issue of extra framing used unnecessarily around window openings resulting in extra costs of both time and materials that could potentially be avoided. Corrective measures...

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