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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

Good design and practice involve controlling the wetting of building assemblies from both the exterior and interior and different climates require different approaches. Ideally, building assemblies would always be built with dry materials under dry conditions, and would never get wet from imperfect design, poor workmanship or occupants. Unfortunately, these conditions do not exist.

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

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
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...
Recommended Freeze-Thaw Risk Assessment StepsBuilding Science Corporation has worked with project teams on a wide variety of masonry retrofits, from houses to large buildings, including historical...
Published Articles
J. Wilkinson, D. De Rose, B. Sullivan, John Straube

Evaluating the risks associated with insulating exterior masonry walls from the interior on a three-story school constructed in Toronto, Ontario in the late 1950s. Reprinted with permission from Journal of Building Enclosure Design, Summer 2009, pages 11-17.

Cold
Freeze-Thaw Risk: Site Visit Back to Recommended Freeze-Thaw Risk Assessment Steps Inspection by a building scientist can often identify existing moisture problems (due to rainwater, rising damp...
Freeze-Thaw Risk: Site Load AssessmentBack to Recommended Freeze-Thaw Risk Assessment StepsMost of the moisture that masonry walls must deal with comes from wind-driven rain. Unfortunately, the...
Freeze-Thaw Risk: Repair/Retrofit, Maintain and Monitor Back to Recommended Freeze-Thaw Risk Assessment Steps Each retrofit project is unique: the building’s features and historical...
Freeze-Thaw Risk: Prototype Monitoring Back to Recommended Freeze-Thaw Risk Assessment Steps In some cases, the risk of adding interior insulation is still not clear enough even after materials...
Freeze-Thaw Risk: Material Testing Back to Recommended Freeze-Thaw Risk Assessment Steps In many projects, the risk is not clear from inspection alone. Material testing is the next step in...
Freeze-Thaw Risk: Hygrothermal Modeling Back to Recommended Freeze-Thaw Risk Assessment Steps There are cases where hygrothermal modeling is simply unnecessary. For example, materials testing may...
Conference Papers
Kohta Ueno

A circa 1917 construction mass masonry building located on a Boston-area university campus was retrofitted with interior polyurethane spray foam insulation. Sensors were installed in the retrofitted walls to measure temperature and moisture conditions within the assembly; interior and exterior boundary conditions were also monitored. Hygrothermal simulations were run on the original and retrofitted assemblies using measured site environmental data, both to assess durability risks, and for comparison with the measured data. Durability risks examined included potential for freeze-thaw damage and interstitial condensation. The effect of thermal bridging through structural elements was also examined.

Conference Papers
Kohta Ueno

There is a large existing stock of uninsulated mass masonry buildings: their uninsulated walls result in poor energy performance, which is commonly addressed with the retrofit of interior insulation. Some durability issues associated with interior insulation have been or are being addressed, such as interstitial condensation and freeze-thaw damage issues. However, another durability risk is the hygrothermal behavior of moisture-sensitive wood beams embedded in the load-bearing masonry. Interior insulation reduces the beam end temperatures, reduces available drying potential, and results in higher relative humidity conditions in the beam pocket: all of these factors pose a greater risk to durability.

Conference Papers
John Straube

The influence of vapor barriers on the hygrothermal performance of wall and roof systems is a function of exterior climate, interior climate, solar absorptance, rainwater absorption, and the vapor and thermal resistance of all of the layers in the system. In many practical situations, a low-permeance vapor barrier will not improve hygrothermal performance and may in fact increase the likelihood of damaging condensation or trap moisture in the system. This paper examines the role of vapor barriers on hygrothermal performance with the aid of simple and transparent diffusion calculations supported by measurements from full-scale natural exposure monitoring.

Conference Papers
John Straube, Christopher Schumacher, Peter Mensinga

This paper is from the proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 in Clearwater, Florida. This paper summarizes some of the limitations of the various approaches to assessing the freeze-thaw resistance of brick masonry units and presents a detailed methodology for using frost dilatometry to determine the critical degree of saturation of brick material. Test results are presented for bricks from several historical load-bearing masonry. Recommendations are made for applying this approach together with hygrothermal model in the design of retrofit insulation projects.

Conference Papers
John Straube

This paper describes a fully instrumented large-scale mock-up completed in a southern Ontario private school to allow direct comparisons between insulated and non-insulated walls with a focus on the evaluation of freeze-thaw and corrosion risks. Climate conditions and wall temperature, relative humidity and moisture content are compared and discussed. Climate conditions (wetting and temperature) over the monitoring period were less severe than average. As a result, measured values were used to refine computer models to simulate wall performance under more severe climate conditions.

Cold
Conference Papers
John Straube, Christopher Schumacher

This paper examines methods of using hygrothermal models, primarily WUFI, to assess the impact of energy efficient enclosure upgrades on the durability of historical buildings. Means of producing and choosing input data for the hygrothermal simulation are discussed. Methods for using the hourly results from the simulations to generate a corrosion index and a freeze-thaw count are developed. An example wall is used to demonstrate the type of output that can be expected and how this can be used in making retrofit design decisions.

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