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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, Jonathan Smegal

This paper documents the experimental methodology, details, and results and discusses how this information can be applied to modeling drained wall systems. Practical applications and research questions arising from the work are presented. Drainage is widely accepted as one of the most effective measures for reducing moisture damage due to rain penetration. Although drainage is effective, some water is always retained in the drainage space, either as droplets on the surface or absorbed and adsorbed to materials lining the drainage space. Previous ASHRAE-sponsored research has shown that ventilation behind the cladding can remove significant amounts of this retained moisture.

Research Reports
John Straube

This document summarizes the theory behind thermal insulation and building system heat flow control metrics and presents a literature review of selected research into this area. As the building industry strives to reduce energy consumption for environmental and economic reasons, building enclosures with high thermal performance, reliably and affordably installed in the field are required. The R-value was developed over 50 years ago to provide users and specifiers of insulation with and easy-to-compare, repeatable measure of insulation performance. The strength of the R-value is that it is simple to measure, easy to communicate, and widely accepted.

Research Reports
Armin Rudd

Concentrations of 54 volatile organic compounds (VOCs) and ventilation rates were measured in four new manufactured houses over 2-to-9.5 months following installation and in seven new site-built houses 1-to-2 months after completion. The houses were in four projects located in hot-humid and mixed-humid climates. They were finished and operational, but unoccupied. Several of the site-built houses had ventilation rates below the ASHRAE recommended value. Generally, the ratios of emission rates at the low and high ventilation rates decreased with decreasing compound volatility. Changes in VOC emission rates in the manufactured houses varied by compound. Only several compounds showed a consistent decrease in emission rate over this period.

Mixed-HumidHot-Humid
Research Reports
Joseph Lstiburek, Betsy Pettit, Armin Rudd

This paper reviews current ventilation codes and standards for residential buildings in Europe and North America. It also examines the literature related to these standards such as occupant surveys of attitudes and behavior related to ventilation, and research papers that form the technical basis of the ventilation requirements in the standards. The major findings from the literature are that ventilation is increasingly becoming recognized as an important component of a healthy dwelling, that the ventilation standards tend to cluster around common values for recommended ventilation rates, and that surveys of occupants showed that people generally think that ventilation is important, but that their understanding of the ventilation systems in their houses is low.

Research Reports
Joseph Lstiburek

The purpose of this research program was to determine the impact resistance performance of advanced framed wall systems with insulating sheathing as the primary sheathing from wind blown debris. With no standards available for testing wall assemblies, a window industry standard ASTM E1886-05 and E1996-05 Missile Level D, Wind Zone 1 and Wind Zone 2 Enhanced Protection and Wind Zone 3 Basic Protection Standard was used as a starting point for the research. The testing results indicate that high performance wall assemblies provide equivalent or even better impact performance then standard wall assemblies.

Research Reports
Joseph Lstiburek

A performance review of residential assemblies in the central Florida (Orlando) area during the three hurricanes in August and September 2004. The specific focus of the review is on the water management details associated with stucco claddings. Two types of stucco claddings were reviewed: "traditional three coat hard coat stucco" and "cementitious decorative finishes." Both are renderings applied to substrates and the fundamental physics apply to both equally.

Hot-Humid
Research Reports
Joseph Lstiburek

Two seemingly innocuous requirements for building enclosure assemblies bedevil builders and designers almost endlessly: keep water vapor out, let the water vapor out if it gets in. It gets complicated because, sometimes, the best strategies to keep water vapor out also trap water vapor in.

Research Reports
Joseph Lstiburek

Just about everyone in the building industry can be guilty of using building terms loosely, and a prime example is with attics, roof assemblies. You can vent single components, you can vent assemblies, and you can vent spaces. But doing one is not the same as doing the others.

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
Rob deKieffer

Construction practices have improved and the HVAC systems need to improve with them. The deKieffer Bypass relieves air pressure in rooms without compromising sound or light transmission.

Research Reports
Joseph Lstiburek

This report presents a 3D window installation sequence with detailed step-by-step instructions on how to effectively install a window using building paper as the drainage plane. These details were published in Water Management Guide; Building Science Press, 2006.

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

Air barriers are systems of materials used to control airflow in building enclosures. They typically completely enclose the air within a building. The physical properties which distinguish air barriers from other materials are the ability to resist air flow and air pressure.

Research Reports
Building Science Corporation

A concise explanation of how a high performance HVAC system works in a high performance home. How can I be saving energy, money, and wear and tear on my equipment if it seems as though my system is running a lot more than systems in other homes?

Research Reports
Building Science Corporation

When constructing unvented roofs with asphalt shingles in hot humid climates, a vapor barrier must be installed between the asphalt shingles and the roof deck. Asphalt shingles store water from dew (condensation due to night sky cooling) and rain. Asphalt shingles are a reservoir for water and behave similarly to traditional wood shingles and cedar shakes in that regard. With traditional wood shingle and cedar shake roofs, a receptor for this moisture is typically provided. This receptor is an air space that can be accomplished in a variety of ways.

Research Reports
Armin Rudd

The simplest, most effective, and most economical way to introduce fresh air in homes with central forced air systems is to use the central fan to pull in and distribute a controlled amount of outside air. The central fan integrated supply ventilation approach depends on two patented processes: fan cycling and ventilation damper cycling.

Research Reports
Andrew Äsk

"Buildings leak water and air, which is normal and unavoidable. Therefore, designers should not fixate on preventing leakage, i.e. making buildings “airtight.” Because even if all cracks were sealed, buildings have doors and windows. How much leakage is acceptable? The author suggests as a modest goal that buildings should leak no more than the air that must be introduced for acceptable indoor air quality.

Research Reports
Kohta Ueno

This article was written to tie together and summarize the various papers on unvented conditioned cathedralized attics found on our website. We realize that there is a wealth of information, and much of it too detailed to understand or digest in a single sitting. Furthermore, building officials might not have the time available to carefully examine the many documents on the page; this is meant to summarize the main arguments, and provide pointers to where detailed information and measured data can be found.

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