Q&A Spotlight

Tweaking Plans for a Minisplit System

Posted on August 15, 2016 by Scott Gibson

A GBAGreenBuildingAdvisor.com reader by the name of Green Heron has recommendations in hand from an HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractor for heating and cooling a Climate Zone 2 house currently undergoing renovations. But he's not sure whether the recommendations make sense.

The contractor has proposed a four-zone system using a mix of ductless and ducted minisplits, Green Heron explains in a post in GBA's Q&A Forum. A single 3-ton compressor would run the four indoor heads — two ducted units installed in the attic, and ductless units in both the kitchen and the living room.

How to Vent a Dryer

Posted on August 1, 2016 by Scott Gibson

The exhaust from a conventional clothes dryer is full of moisture and lint, and the best place to vent it is directly outside. Matt Culik knows this, but his particular situation makes him wonder whether there are circumstances when this rule might be broken.

Culik will soon be moving into a new house, and the intended laundry room does not have a vent connection for a clothes dryer. Coincidentally, he is planning to replace an old electric hot water heater with a heat-pump water heaterAn appliance that uses an air-source heat pump to heat domestic hot water. Most heat-pump water heaters include an insulated tank equipped with an electric resistance element to provide backup heat whenever hot water demand exceeds the capacity of the heat pump. Since heat-pump water heaters extract heat from the air, they lower the temperature and humidity of the room in which they are installed. , and this has given him an idea.

Mounting Baseboard Heaters Unconventionally

Posted on July 18, 2016 by Scott Gibson

Writing from Detroit, a Climate Zone 6 locale, Marlena Crows poses this question: Must electric baseboard heaters necessarily be installed at floor level, or can they be mounted higher on the wall and get an assist for heat distribution from a ceiling fan?

Will This Roof Design Have Problems?

Posted on July 4, 2016 by Scott Gibson

Planning a new house in Climate Zone 6, Chad Kotlarz is reviewing his architect's plans for the roof — and discovers he has a few misgivings.

The unvented roof will be framed with 2x12 rafters, sheathed with plywood and capped with standing-seam metal roofing. Closed-cell spray foam will insulate the rafter bays, and the interior of the cathedral ceiling will be finished with gypsum drywall. An exposed truss with a collar tie provides structural support.

Making the Best PEX Connections

Posted on June 20, 2016 by Scott Gibson

Building his “forever house,” Dean Sandbo is mulling what type of tubing to use for his plumbing supply lines. He has narrowed the choice to one of two types of cross-linked polyethylene (PEXCross-linked polyethylene. Specialized type of polyethylene plastic that is strengthened by chemical bonds formed in addition to the usual bonds in the polymerization process. PEX is used primarily as tubing for hot- and cold-water distribution and radiant-floor heating.): PEX-A or PEX-B.

Key issues, Sandbo notes in his Q&A post at GBA, are how long the tubing will last, and whether there are safety concerns — that is, will the PEX tubing leach chemicals into his drinking water?

"I am on a well," he writes. "Any input as to the longevity and safety of these two different types of pipes?"

Solving a Roof Dilemma

Posted on June 6, 2016 by Scott Gibson

Joe B is building what he hopes will be a PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates.-certified home in Port Washington, New York, a town on the north shore of Long Island in Climate Zone 4. The house is well underway, but Joe worries about the potential for trouble in a very complex roof design.

Installing a Concrete Slab the Right Way

Posted on May 23, 2016 by Scott Gibson

As part of a remodel of his San Francisco area home, Torsten Budesheim is converting the 700-square-foot lower level into living space. An existing slab has been removed, and Budesheim has removed a few inches of material to increase the finished ceiling height. Now, he's nearly read to place a new 5-inch-thick slab that will include tubing for radiant heat.

How to Attach a Thick Layer of Exterior Insulation

Posted on May 9, 2016 by Scott Gibson

Adding a layer of insulation to the outside of a house, over the wall 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. , makes all kinds of sense from an energy perspective. But the thicker the layer, the more challenging becomes the actual means of attaching it to the building.

In a post in the Q&A forum at Green Building Advisor, Burke Stoller shares some of his concerns, as well as a proposed solution. Stoller is working out the details for a 6-inch-thick layer of Roxul ComfortBoard mineral wool, consisting of two layers of 3-inch-thick panels, each 2 feet by 4 feet.

Do Earth Tubes Make Any Sense?

Posted on April 25, 2016 by Scott Gibson

Daniel McKinney is reaching four decades into the past for two important features of a new house he plans to build. Both notions were mostly discarded after early attempts at energy efficiency ledLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. builders in new directions, but McKinney thinks they may still have some merit.

Finding Insulation That’s Safe

Posted on April 11, 2016 by Scott Gibson

On top of all the other problems anyone building a new house is bound to encounter, Carolyn Farrow has a concern that outweighs all others: her daughter's health.

"Our toddler has a lot of chemical sensitivities and respiratory issues and insulation decisions are completely overwhelming me," she writes in a post at GBA's Q&A forum. "I can't find any contractors that I trust."

The allergist and pediatrician treating Farrow's daughter say she could react to virtually any type of insulation, and they are not comfortable making any specific recommendations.

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