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climates

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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.

Building America Reports
Rosie Osser, Phil Kerrigan

Project Home Again is a development in New Orleans, Louisiana, created to provide new homes to victims of Hurricane Katrina. BSC acted as a consultant for the project, advocating design strategies for durability, flood resistance, occupant comfort, and low energy use while maintaining cost effectiveness. These techniques include the use of high density spray foam insulation, LowE glazing, and supplemental dehumidification to maintain comfortable humidity levels without unnecessary cooling. Stringent airtightness goals were achieved by the project, helping to meet the Builder’s Challenge targets set by Project Home Again. Floor plans, enclosures, and heating, ventilation, and air conditioning attributes are quite similar among different homes in the project.

Hot-Humid
Building America Reports
Armin Rudd

This guideline pertains to design and application guidance for combination space and tankless domestic hot water (DHW) heating systems (combination systems) used in residential buildings, based on field evaluation, testing, and industry meetings. As residential building enclosure improvements continue to drive heating loads down, using the same water heating equipment for both space heating and domestic water heating becomes attractive from an initial cost and space-saving perspective. This topic is applicable to single- and multifamily residential buildings, both new and retrofitted. In order to be assured of meeting the Building America savings goals, and the persistence of those savings after installation, continued sharing of lab and field testing results is needed.

Building America Reports
Ken Neuhauser

This project examines implementation of advanced retrofit measures in the context of a large-scale weatherization program and the archetypal Chicago, Illinois, brick bungalow. In response to the apparent weatherization program limitations with respect to homes with masonry bearing wall construction, this research project examines two distinct strategies for insulating and air sealing the top of houses. One strategy applies best practice air sealing methods and a standard insulation method to the attic floor. The other strategy creates an unvented roof assembly using materials and methods typically available to weatherization contractors.

Cold
Building America Reports
Peter Baker

The use of exterior insulation is an effective means to increase the overall thermal resistance of wall assemblies that also has other advantages of improved water management and often increased air tightness of the building. However, the engineering basis and support for this work has not been conducted, resulting in obstacles for building official and building code acceptance. Additionally, the water management and integration of window systems, door systems, decks, balconies, and roof-wall intersections have not been adequately developed. This research project developed baseline engineering analysis to support the installation of thick layers of exterior insulation (2” to 8”) on existing masonry walls and wood framed walls and as well as relevant water management details.

Building America Reports
Peter Baker

There is a significant push for energy performance upgrades to existing homes. An important target is often the windows. Old single-glazed windows have such low thermal resistance that their effect on the overall thermal resistance of the walls can be staggering. Improving the performance of the window stock is therefore central to the goal of reducing the energy consumption of the existing building stock. This measure guideline provides information and guidance about rehabilitating, retrofitting, and replacing wood window assemblies in residential construction. It is intended primarily to help contractors and homeowners understand the options for safely improving the performance of their wood windows.

Building America Reports
Honorata Loomis, Kohta Ueno, Randy Van Straaten

Building Science Corporation (BSC) has been working with Byggmeister, a partner on the Building America (BA) team, on retrofit projects under the BA program. Byggmeister is a local design-build firm that specializes in energy efficient retrofits and new construction. The Byggmeister multifamily test home located in Jamaica Plain, Massachusetts (Jamaica Plain or J.P. Three-Family) is a three-story brick row house. The test home is examined with the goal of producing a case study that could be applied to similar New England homes. Basic areas of research that this report is expected to contribute include finding the combination of measures that are feasible, affordable, and suitable for this type of construction and acceptable to homeowners.

Cold
Building America Reports
Ken Neuhauser

Through discussion of five case studies (test homes), this project evaluates strategies to elevate the performance of existing homes to a level commensurate with best-in-class implementation of high performance new construction homes. The test homes featured in this research activity participated in Deep Energy Retrofit (DER) Pilot Program sponsored by the electric and gas utility National Grid in Massachusetts and Rhode Island. Retrofit strategies are evaluated for impact on durability and indoor air quality in addition to energy performance.

Cold
Building America Reports
Christopher Schumacher

Historically, weatherization programs have required that cellulose insulation materials be dense-packed to a minimum installed density of 3.5 pcf. This density limit was, in part, required to realize beneficial reductions in air leakage. The Building Performance Institute (BPI) currently has under development two standards that will set requirements for the airflow resistance of insulations used in retrofit cavity (i.e. dense-pack) installations and define acceptable test methods to measure the airflow resistance of insulation materials used in dense-pack applications. An experimental apparatus and test method were developed for the purpose of measuring the airflow resistance of dense-packed fiber insulation installed as a retrofit to empty wood-frame wall cavities.

Building America Reports
Kohta Ueno, Joseph Lstiburek

Basements can account for up to one quarter of the typical energy consumption in a house. Therefore, insulating foundations is a critical measure for achieving high performance buildings. However, many foundations are damp (either due to bulk water or capillary “wicking” of moisture) or of a type of construction that is not easy or straightforward to insulate (such as rubble foundations). Damp foundation repair methods can be “leveraged” to provide energy efficiency benefits. An example of this “hybrid” approach is spray foam insulation, which can be an effective means of liquid phase water control (leaking basement), vapor phase water control (diffusion and air leakage transported condensation) as well as an effective insulation.

Building America Reports
Rosie Osser, Ken Neuhauser, Kohta Ueno

Building Science Corporation seeks to further the energy efficiency market for cold climate, New England area retrofits by supporting projects based on solid building science fundamentals and verified implementation. The utility company National Grid engaged BSC as a partner to develop guidelines for its Deep Energy Retrofit Pilot Program. In addition to guideline development, BSC has acted as a consultant for these projects and others following similar retrofit strategies. Costs of each project are presented, with an attempt to isolate the costs of measures specific to DERs and not regular home maintenance and aesthetic upgrades. Finally, occupant feedback from the retrofits is discussed to determine overall satisfaction with the retrofit efforts. For more information about retrofits, see Popular Topics/High R-value Retrofits.

Cold
Building America Reports
Ken Neuhauser, Daniel Bergey, Rosie Osser

This project examines a large scale renovation project within a 500 unit, 1960’s era subsidized urban housing community. The development comprises low-rise and mid-rise structures both of which exhibit exposed concrete frames with uninsulated masonry infill walls. The renovation project has a particular focus on indoor environmental quality and energy performance. The nature of occupied rehabilitation necessarily limited the scope of work implemented within apartment units. This research focuses on the airflow control and window replacement measures implemented as part of the renovations to the low-rise apartment buildings.

Cold
Building America Reports
John Straube, Kohta Ueno, Christopher Schumacher

Load-bearing masonry buildings are a significant portion of the existing building stock. Given the Building America goals of reducing home energy use by 30%-50% (compared to 2009 energy codes for new homes and pre-retrofit energy use for existing homes), insulation and air sealing of mass masonry walls will need to be a component of this work if mass masonry residential buildings are to be addressed.

Building America Reports
Kohta Ueno, Joseph Lstiburek

Successfully executing strategies to control bulk water for foundations is critical for building durability, indoor air quality, and creating acceptable conditions and/or living spaces within the foundation space. Although the energy impacts of properly done bulk water control are small to insignificant, it should be considered a base requirement for any high performance house. In addition, measures such as basement insulation are predicated on properly managed foundation bulk water.

Building America Reports
Armin Rudd

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. The main focus for this research project is the integration of a combination space and domestic hot water heating system (“combi system”) with a high-efficiency air source heat pump to optimize efficiency and comfort.

Building America Reports
Armin Rudd

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. The main focus for this research project is on the AAON heat pump system with digital scroll compressor and modulating hot-gas condenser reheat installed in the GreenCraft Builders prototype house in Lewisville, TX.

Hot-Humid
Building America Reports
John Straube, Aaron Grin

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. The goal of this research is to find optimally designed, cost effective roof insulation systems that can be included with other enclosure details to help reduce whole house energy use by 70%. This report will compare a variety of roof insulating strategies and present their advantages and disadvantages according to several comparison criteria.

Building America Reports
John Straube

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. Many concerns, including the rising cost of energy, climate change concerns, and demands for increased comfort, have led to the desire for increased insulation levels in many new and existing buildings. Building codes and green building codes are being changed to require higher levels of thermal insulation both for residential and commercial construction. This report will review, and summarize the current state of understanding and research into enclosures with higher thermal resistance, so-called “High-R Enclosures.” Recommendations are provided for further research. For more information see Popular Topics/Foundations and Slabs and Popular Topics/High R-Value Walls.

Building America Reports
Joseph Lstiburek, Aaron Grin

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. This report investigates the implementation of advanced framing in both production and prototype built homes built in a variety of climate regions across the USA. The current industry standard wall is being replaced by a 2×6 frame at 24-inch centers with single top plates, two-stud corners, no jack studs, no cripples and single headers (and in many cases no headers at all). Advanced framing can save energy, greenhouse gas emissions, and money if properly implemented. To maximize cost savings and energy savings for the homeowner, the builder financial savings are best shifted to implementing more energy saving measures.

Building America Reports
Jonathan Smegal, John Straube

The following report is an excerpt from the 2010 Building Science Corporation Industry Team Building America Annual Report. Many concerns, including the rising cost of energy, climate change concerns, and demands for increased comfort, have led to the desire for increased insulation levels in many new and existing buildings. Building codes are improving to require higher levels of thermal control than ever before for new construction. This report considers a number of promising foundation and basement insulation strategies that can meet the requirement for better thermal control in colder climates while enhancing moisture control, health, and comfort. For more information see Popular Topics/Foundations and Slabs.

Building America Reports
John Straube

This paper describes a hygrothermal modeling study, including all of the US climate zones, a range of interior humidity levels and numerous arrangements and types of insulation. The results showed that so long as airtightness is provided, and wintertime humidity is controlled, numerous unvented solutions using either or both spray foam (open and closed cell) and fibrous insulation (cellulose and mineral fiber) can be successful. Climate, the solar properties and exposure of the roofing, the air and vapor permeance of the insulation(s) and interior humidity are the most important factors to be considered in the design of moisture-safe unvented roof systems. For more information about roofs, see Popular Topics/Unvented Roof/Attic.

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