Q&A Spotlight

Is This Insulation Too Good To Be True?

Posted on June 22, 2015 by Scott Gibson

Jan Verschuren has a nicely roofed older house, and a problem to go with it. Cedar shingles have been installed over skip 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. , making for a roof that's not only historically correct but one that allows air to circulate freely beneath the roof deck. Verschuren's next objective is to insulate between the 2x4 rafters, and here's where he has run into a snag.

How to Insulate a Foundation

Posted on June 8, 2015 by Scott Gibson

About to start a new house in Climate Zone 5, Nicholas C is working out the details of how to insulate the basement slab and foundation walls. There is more than one type of rigid foam insulation he could use, and it could be applied on either the inside or outside of the foundation.

For a couple of reasons, he's planning on 2 inches of extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) beneath the slab rather than expanded polystyrene (EPSExpanded polystyrene. Type of rigid foam insulation that, unlike extruded polystyrene (XPS), does not contain ozone-depleting HCFCs. EPS frequently has a high recycled content. Its vapor permeability is higher and its R-value lower than XPS insulation. EPS insulation is classified by type: Type I is lowest in density and strength and Type X is highest.). The XPS would perform better in a wet environment, Nicholas says, and Owens-Corning, one insulation manufacturer, claims it no longer uses a "bad" blowing agent.

Does This Roof Need a Vapor Retarder?

Posted on May 25, 2015 by Scott Gibson

David Amenhauser is buying a home near Boston, Massachusetts, that's apparently still under construction, but far enough along to have the roof framed and insulated.

Heating and Cooling in North Dakota

Posted on May 11, 2015 by Scott Gibson

Adam Emter is building a new house in North Dakota, a Climate Zone 7 location with some 9,500 heating degree days a year, and temperatures that fluctuate from 30 below zero in the winter to a humid 90 degrees during the summer.

"My family and I plan on living here for many decades," Emter writes in a Q&A post at GreenBuildingAdvisor, "so I'm very focused on building an efficient and comfortable house. I am also trying to keep a reasonable budget and simple design."

Is a Ground-Source Heat Pump My Best Bet?

Posted on April 27, 2015 by Scott Gibson

Cathleen Dalmeida is budgeting for a heating and cooling system as part of an energy retrofit and is wondering whether a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. is part of her future. An obvious question: How much do they cost?

"Is there a general rule of thumb for pricing of a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. and air-to-water heat pump for a medium sized installation?" she asks in a Q&A post at Green Building Advisor.

Where is This Water Coming From?

Posted on April 13, 2015 by Scott Gibson

Writing from Climate Zone 6, GBAGreenBuildingAdvisor.com reader David Metzger is looking for some advice about his standing-seam metal roof. More to the point, why is there water dripping from the soffit when the winter's accumulation of snow and ice starts to melt?

How Would You Insulate My New House?

Posted on March 30, 2015 by Scott Gibson

Nik Fiorito is grappling with the same issues every owner/builder eventually confronts: What's the best way of insulating a new house? Only in Fiorito's case, it gets a little more complicated.

First, he's building in Climate Zone 7, forty minutes north of the U.S.-Canadian border, on a hilltop where the temperature averaged 3 below zero F (-19.6 degrees C.) this past February. He's also considering a fully off-grid 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. (PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.) system plus a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. for both heat and domestic hot water.

Does a Fireplace Belong in a Green Home?

Posted on March 16, 2015 by Scott Gibson

Clara Kim and her husband are nearly finished planning their new custom home. Only a few details remain before they can seek construction bids. But one of the remaining loose ends has major energy implications.

Can Solar Electricity Trump a Ductless Minisplit?

Posted on March 2, 2015 by Scott Gibson

Ven Sonata's query is simple: If the falling cost of installing a 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. (PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.) system has killed off the viability of solar hot water systems, as GBA senior editor Martin Holladay believes, does it also represent a threat to the beloved ductless minisplit for heating and cooling?

Why Is It So Humid In Here?

Posted on February 16, 2015 by Scott Gibson

From the sound of it, Andy Chappell-Dick has left no stone unturned in his quest to keep the air inside his house comfortably dry.

His extremely tight new house in northern Ohio (Climate Zone 5) is built with structural insulated panels, and heated and cooled with a pair of ductless minisplit heat pumps. For ventilation, Chappell-Dick has a Venmar Kubix heat-recovery ventilator(HRV). Balanced ventilation system in which most of the heat from outgoing exhaust air is transferred to incoming fresh air via an air-to-air heat exchanger; a similar device, an energy-recovery ventilator, also transfers water vapor. HRVs recover 50% to 80% of the heat in exhausted air. In hot climates, the function is reversed so that the cooler inside air reduces the temperature of the incoming hot air. that pulls exhaust air from two small bathrooms and supplies fresh air to two upstairs bedrooms with a flow rate of between 40 and 80 cubic feet per minute (cfm).

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