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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.

Building America Reports
Building Science Corporation

This report summarizes indoor temperature and humidity data that have been collected from houses by the Building Science Consortium of the US Department of Energy Building America Program. Data were collected at 43 houses from May 2000 through February 2005. The houses are located in various southern cities, including Houston, Austin, Dallas, Jacksonville, Fort Meyers, Orlando, and Oklahoma City. Most sites were located in the hot, humid gulf coast region. The data collected from the test homes were analyzed to understand when and for how long high humidity occurred in these homes. The analysis also evaluated how closely high humidity and the need for dehumidification corresponded to cooling operation.

Hot-Humid
Building America Reports
Armin Rudd

High performance space conditioning and control systems that match the high performance of Building America enclosures are necessary to meet performance targets of DOE residential research program. Conditioning systems with integrated mechanical ventilation and year-around temperature and humidity control are necessary. The most significant climate-specific need is for system-integrated dehumidification for humidity control without overcooling the space. Cost-effective dehumidification without overcooling will enable continued and further reduction of sensible loads (including high-performance glazing) that would otherwise exacerbate humidity control problems in humid climates.

Mixed-HumidHot-Humid
Building America Reports
Armin Rudd, Kohta Ueno, Joseph Lstiburek

Twenty homes were tested and monitored in the hot-humid climate of Houston, Texas, to evaluate the humidity control performance and operating cost of six different integrated dehumidification and ventilation systems that could be applied by production homebuilders. Results showed that energy efficiency measures, combined with controlled mechanical ventilation, change the sensible and latent cooling load fractions such that supplemental dehumidification, in addition to that provided by the central cooling system, is required to maintain indoor relative humidity below 60% throughout the year.

Hot-Humid
Building America Reports
Armin Rudd

This is one of eleven projects from the full report of Building Science Consortium’s research efforts for 2004. The research program is aimed towards advanced building systems that have the potential to reduce residential building energy use by 50-60%. It is based on evaluation of market trends, industry partner needs, and initial results from our team’s system engineering research program. A total of eleven individual research projects were detailed in this report. This project report explores the development of more cost-effective, integrated supplemental dehumidification systems.

Building America Reports
Building Science Corporation

SNAPSHOT stands for Short, Non-destructive Approach to Provide Significant House Operation Thresholds. It is a test form used in the Building America program to ascertain house performance and specifications.

Building America Reports
Building Science Corporation

SNAPSHOT stands for Short, Non-destructive Approach to Provide Significant House Operation Thresholds. It is a test form used in the Building America program to ascertain house performance and specifications. This technique incorporates the field characterization of critical parameters, for indoor environment, thermal comfort, air delivery and distribution systems as well as their interaction with the building envelope. The data collected will then be used as direct inputs to energy prediction tools, such as REM/Design or DOE-2. The major parts of the testing include building envelope leakage, duct leakage test, and differential pressurization of zones. Also, the form provides a place to collect information on mechanical equipment and ventilation systems.

Building America Reports
Building Science Corporation

Using four Building Science Consortium Building America community-scale projects, this paper investigates the nature, strength, and durability of connections between high performance dwellings and developments. There are few inherent or natural links between the two (particularly in the production home setting); the connections must be either imposed (by government entities) or created in the marketplace. Because communities often involve two very distinct players—the developer and the builders—and the project often spans up to 10 years, it is challenging to develop and sustain either an imposed or marketed system with strong and meaningful links between high performance homes and neighborhoods.

ColdHot-Dry/Mixed-Dry
Building America Reports
Building Science Corporation

Not all low-e glass is created equal with regard to color filtering. Some low-e glass is remarkably close to #1-clear glass. Others filter out substantial portions of red and/or blue light, creating color distortion of transmitted. The lesson learned here is similar to the one manufacturers of compact fluorescent lights (CFLs) have learned: high performance is not just about energy—it’s about achieving energy savings without sacrificing other aspects of performance, such as color rendering.

Building America Reports
Joseph Lstiburek

Conditioned crawlspaces perform better than vented crawlspaces in terms of safety, health, comfort, durability and energy consumption. Conditioned crawlspaces also do not cost more to construct than vented crawlspaces. Despite that, there is not a significant trend towards the construction of conditioned crawlspaces. The model codes do not allow the construction of “unvented” crawlspaces – except in very limited circumstances, but they do allow the construction of “conditioned” crawlspaces. The distinction is important and necessary. Four conditioned crawlspaces were constructed and monitored over a 12-month period. The data is presented and used to support the current code requirements for the construction of conditioned crawlspaces.

Building America Reports
Building Science Corporation

Heat loss through uninsulated basement walls can account for up to one-third of the heat loss from an average home. Installing insulation on basement walls is often inexpensive, easy to accomplish and frequently combined with “finishing the basement.” Unfortunately, basement walls are often damp or are only dry on the surface because of evaporation of water into the basement air. Installing wood framing or fiberglass batts directly against basement walls subsequently leads to mold growth and decay of the wood due to fungal growth. Insulating basement walls can be safely accomplished by assessing the moisture conditions of these walls and applying some basic "building science" to the design process.

Building America Reports
Building Science Corporation

Perhaps the single most challenging BSC performance for Building America production homebuilders is that all ducts and HVAC equipment must be within the conditioned space (this means no ducts in outside walls and no ducts or air handlers in garages, vented attics or vented crawlspaces). It’s an important and even driving element for each of the four case studies in this report. So, why all the heartache over this single design element? There are really two sources of the heartache—how important it is to locate all ducts and equipment in conditioned space and how hard it can be for homebuilders to achieve this.

Building America Reports
Armin Rudd, Joseph Lstiburek, Kohta Ueno

Twenty homes were tested and monitored in the hot-humid climate of Houston, Texas, to evaluate the humidity control performance and operating cost of six different integrated dehumidification and ventilation systems that could be applied by production homebuilders. Results showed that energy efficiency measures, combined with controlled mechanical ventilation, change the sensible and latent cooling load fractions such that supplemental dehumidification, in addition to that provided by the central cooling system, is required to maintain indoor relative humidity below 60% throughout the year.

Hot-Humid
Building America Reports
Building Science Corporation

It’s quite likely humid or hot or both in Houston, Texas. As a builder/buyer of high performance homes who naturally wants to deliver/buy a comfortable healthy home, just how do you most efficiently and cost-effectively cool and dehumidify inside air while maintaining sufficient introduction of outside air for ventilation? And perhaps most importantly, how do you condition for humidity when the season calls for neither heating nor cooling? These are two knotty, nasty questions with a bunch of potential answers, none of which have ever been systematically explored or compared….until now.

Hot-Humid
Building America Reports
Building Science Corporation

Combo systems use a gas water heater to provide domestic water and space heating. It’s pretty slick having one equipment set-up handle these two. You can save on floor space and equipment/ducting costs; and adding space heating demands to a properly sized tank water heater more fully employs its capacity, increasing its efficiency during the heating season. These systems can be first-cost effective when the upsized water heater plus the air handler coil (and any reduction of gas supply lines and venting that can be credited to the combo system) cost less than a furnace and water heater. Find out when its appropriate to use such a system and guidelines for doing it right.

Building America Reports
Building Science Corporation

PV systems have come a long way in the last two decades. While they may not work for all homes, residential installations are becoming a practical reality under more and more conditions. Here are the nitty-gritty details of photovoltaic systems. The details are meant to “de-mystify” both the technology and its economics.

Building America Reports
Building Science Corporation

Heat loss from basements accounts for a significant portion of the energy loss from a home. In many jurisdictions, basement insulation is a building code requirement. Cost usually determines the type of insulation system used. Unfortunately, safely insulating basement walls requires consideration of many factors in addition to reducing thermal conductivity across the foundation wall. Moisture dynamics must be considered in detail before insulating a basement wall. Materials used to insulate a basement wall must be selected based on their ability to control the flow of moisture and air as well as heat. Selecting the wrong type of insulation or placing it in the wrong wall assembly often leads to moisture accumulation with subsequent material deterioration and growth of mold.

Building America Reports
Steve Baczek, Peter Yost, Stephanie Finegan

Americans have been building homes with wood—shaping logs, joining timbers, nailing studs—for almost 400 years. Our current approach, stick framing, grew popular in the mid-1800’s (particularly in the rapidly growing “West”) because it took less skill, required simpler tools, and took fewer people than timber framing. We apparently really like waste haulers, too. The NAHB Research Center reports that the “typical” home generates about 3,500 pounds of wood waste during its construction, about half of which is solid sawn lumber. There are opportunities to use wood more efficiently at every stage of a home’s design and construction to save time, money, energy, and resources - you could call this optimum value engineering (OVE) from start to finish.

Building America Reports
Kohta Ueno

This is a report describing the test methodology and results for experiments run on two test houses at the Bonita Springs development in Fort Myers, FL. The goal was to determine the effect of attic ventilation in a hot-humid climate; previous work had shown that little to no benefit is derived from ventilation in terms of energy use, and that it is detrimental for moisture control. Two houses with identical orientations and plans were compared; one was ventilated at the typical 1:300 ratio, and the other had sealed vents. This work was conducted in order to move houses in hot-humid climates forward in technology in their building envelope and HVAC systems.

Hot-Humid
Building America Reports
Joseph Lstiburek

High performance building envelopes require controlled ventilation systems, sealed combustion appliances and allow the use of innovative air distribution systems. The optimum controlled ventilation system in all climate zones is a supply ventilation system that allows for filtration of outside supply air and the pressurization of building enclosures to exclude environmental contaminants. The high performance aspects of the building envelopes allow for the simplification of duct distribution systems. Advanced space conditioning involves the integration of a building’s heating, ventilating and air conditioning (HVAC) system with the building enclosure or building envelope.

Building America Reports
Armin Rudd

Forced air distribution ducts are often hard to seal. Air leakage in ducts makes it difficult to assure that the correct quantity of air is conveyed to or from the intended space. In order to reduce duct leakage and the overall cost of installing sealed ducts, central return ducts are preferable to distributed return ducts. Our cold-climate design calls for a central return on each conditioned floor, and a separate return for the master bedroom. In order to assure that the intended amount of supply air is delivered to each secondary room without over-pressurizing the room (< 3 Pa), air transfer grilles are specified. Transfer grilles represent a cost-effective alternative to individual return ducts if they are properly configured for air flow, privacy, and aesthetics.

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