Q&A Spotlight

In Search of the Most Energy-Efficient Windows

Posted on July 26, 2010 by Scott Gibson

It seems like a very long time ago, doesn't it, that windows were considered simple building components? As long as they opened and closed and let in sunlight most of us were content. We know now that windows are anything but simple. They're an essential part of an energy efficient building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials.; they must simultaneously admit sunlight (and a certain amount of solar energy — but not too much), minimize heat loss or gain, prevent drafts, and last a generation or two.

Are Tankless Water Heaters Really Green?

Posted on July 19, 2010 by Scott Gibson

Tankless water heaters have one advantage over conventional storage units: no standby losses. Instead of keeping water hot around the clock, regardless of whether it's actually needed, tankless units heat water only when a tap or an appliance is turned on. By rights, this should mean lower energy consumption, a decidedly green advantage.

Bathroom Walls, Mold, Vapor Barriers, and Building Codes–Where's the Love?

Posted on July 8, 2010 by Scott Gibson

Josh, a builder in Columbus, Ohio, has been hired to add a bathroom in the attic of an existing house. Although he had hoped to use cellulose insulationThermal insulation made from recycled newspaper or other wastepaper; often treated with borates for fire and insect protection. in exterior walls, the homeowner's budget allowed fiberglass batts. Josh was counting on the kraft paper facing on the insulation to serve as a vapor retarder, but to his surprise the building inspector insists the paper be removed before the insulation is installed.

What gives? And will the inspector's decision increase the risk of moisture problems in the bathroom, surely one of the most humid rooms in the house?

Can Exterior Foam Insulation Cause Mold and Moisture Problems?

Posted on June 23, 2010 by Scott Gibson

Many builders add one or more layers of rigid foam insulation to the outside of a house to lower heat losses. Rigid insulation has an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of up to 6.5 per inch, but it also can be an effective vapor retarder.

Ed Welch touched off an extended discussion in the Green Building Advisor's Q&A section when he asked whether the foam would trap moisture inside walls, creating mold as well as the potential for structural decay.

How Can I Make Old Windows More Energy Efficient?

Posted on May 15, 2010 by Daniel Morrison

Q I want to increase the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. of the single-pane windows in my 44-year-old house in New Hampshire. I am considering using movable window insulation. Is this insulation good for limiting excess heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. in summer? The windows also fogTo fog a room or building is to use a fog machine during a blower door test, revealing locations of air leaks where the fog escapes. The fogging material is usually a glycol-based solution, completely non-toxic. up easily. Will inner storm windows prevent the fogging and provide more R-value? Can you suggest other alternatives?
-Patrick Clary, Dover, N. H.

How Did Water Damage this Brick Basement?

Posted on March 30, 2010 by Rob Wotzak

In a recent discussion from our Q&A forum, Chris Ermides tries to determine what caused severe deterioration of a brick column in the basement of his Victorian home. Chris knows that his basement could use some moisture remediation, but he is puzzled that none of the nearby brick walls have similar signs of decay. Fortunately, the chimney that the column once supported is long gone, and the load of the adjacent beams rests comfortably on lally columns, but Chris is still determined to solve this mystery.

What’s the Most Cost-Effective Way to Bring Fresh Air into a Tight House?

Posted on February 20, 2010 by Martin Holladay

Our Question of the Week focuses on a query from “DC,” a Texas reader who wants to know which residential ventilation system will provide the “most bang for the buck.”

DC knows that a tight home requires a mechanical ventilation system to provide fresh air. But how does one choose among the bewildering array of options? And are there any performance advantages to expensive ventilation systems?

Does Spray Foam Insulation Off-Gas Poisonous Fumes?

Posted on February 17, 2010 by Daniel Morrison

Spray-foam insulation has become a weapon of choice for many builders and homeowners trying to build tight, energy efficient houses. And with its long list of attributes, that's no wonder. It fills tiny cracks and fissures in walls and roofs to form an effective air seal. The high R-values of closed-cell foam pack a lot of punch in a small space, and closed-cell versions can block the movement of moisture into wall and roof cavities. Expensive as it may be, it's at the top of its class.

Will Solar Panel Mounts Cause Roof Leaks?

Posted on February 4, 2010 by Daniel Morrison

Our latest Question of the Week comes from a homeowner in New Jersey. Monica is uncertain of the best way to insulate the roof of a new second-story addition on her Cape Cod home. She wonders whether it's wise to insulate directly under the roof sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. — especially since the mounting system for her photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. array requires 54 holes to be drilled in her asphalt shingle roof.

Can a Kitchen Downdraft Fan Be Connected To an HRV?

Posted on January 21, 2010 by Daniel Morrison

Powerful kitchen exhaust fans do a good job of removing cooking odors and smoke. They also have the potential to depressurize a house, causing water heaters to backdraft and pulling ashes out of the fireplace and onto the hearth.

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