The most recent blogs at Green Building Advisor

Domestic Hot Water: No Perfect Solution

Posted on May 13, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Some questions are easier to answer than others. For example, there is a fairly straightforward answer to, “How should I insulate the floor of my unconditioned attic?” — namely, “With a deep layer of cellulose.” (There’s more to say on the topic, of course — but even a full answer isn’t very complicated.)

There is no easy answer, however, to, “How should I heat my domestic hot water?” Every type of water heating technology is flawed; every solution involves compromise.

Many factors affect the decision about what type of water heater to choose, including:

Testing Air Leakage in Multifamily Buildings

Posted on May 12, 2016 by Sean Maxwell in Guest Blogs

In a previous article, I explained why it's important to prevent air leaks between individual apartments in multifamily buildings — a type of air sealing known as "compartmentalization." With my compartmentalization rant over, let me tell you how we can change our building codes to find a solution to the problem of leaky apartments, and why you should support a change to the language of the International Energy Conservation Code.

The World Needs Sustainable Forestry

Posted on May 11, 2016 by Joshua Axelrod in Guest Blogs

The Forest Stewardship Council (FSCForest Stewardship Council. An independent, nonprofit organization that promotes responsible forest management through the use of a third-party certification process. FSC certification includes a chain-of-custody requirement that tracks sustainability of wood products from growth to end use.), the world’s leading independent certifier of sustainably managed forests, is facing increasingly vitriolic attacks from various industry trade groups and players in Canada, who argue that the FSC’s policies — specifically their move toward requiring protection of threatened intact forest landscapes — will cause them to lose access to significant wood volumes they need to maintain their current operations.

CarMic House: No, We Are Not Crazy

Posted on May 10, 2016 by Carri Beer and Michael Hindle in Guest Blogs

Editor's note: Carri Beer and Michael Hindle are renovating this 1954 house in Catonsville, Maryland. Hindle is a Certified Passive HouseA 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. Consultant and owner of Passive to Positive. Beer is a registered architect who has been practicing sustainable architecture for 18 years. She is an associate principal with Brennan+Company Architects. The couple's first post about the project, Rebuilding a Mid-Century Dinosaur, was published on March 2.

How to Attach a Thick Layer of Exterior Insulation

Posted on May 9, 2016 by Scott Gibson in Q&A Spotlight

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.

These Superinsulated Homes Were Delivered By Truck

Posted on May 6, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Last fall, Dartmouth College realized that it needed to build four new single-family homes, pronto. Beginning this summer, the homes will be occupied by the “house professors” assigned to new “house communities” — the term that Dartmouth uses to describe the college’s dormitory clusters.

The LEED Pilot for Wood

Posted on May 5, 2016 by Stuart Kaplow in Guest Blogs

The U.S. Green Building Council is to be applauded for the release last week of the new pilot credit, MRpc102 – Legal Wood.

There may be no single subject matter more discussed with over the 15-year history of LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. than forest product certification. And that this new pilot credit continues the discussion is positive.

But make no mistake: this new alternative compliance path credit does not alter the existing LEED credit, NC v4 MRc3, that mandates: "Wood products must be certified by the Forest Stewardship Council(FSC) Nonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest. or USGBCUnited States Green Building Council (USGBC). Organization devoted to promoting and certifying green buildings. USGBC created the LEED rating systems.-approved equivalent."

The Water Efficiency Rating Score (WERS)

Posted on May 4, 2016 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

The Green Builder Coalition has been working hard on their Water Efficiency Rating Score — the WERS — for homes. The inaugural WERS training happened in Santa Fe, New Mexico, in March. I was in that class, and I learned a lot.

The program has been in development for the past couple of years. Now it's ready for prime time.

When Will Rooftop Solar Be Cheaper Than the Grid?

Posted on May 3, 2016 by Joshua Rhodes in Guest Blogs

The National Renewable Energy Laboratory said recently that rooftop solar panels have the potential to generate nearly 40% of electricity in the U.S. But what about the cost of going solar?

Many people ask when the cost of producing power from 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.) panels will be equal to or less than buying from the grid — a point called “grid parity.” Reaching grid parity could accelerate solar adoption.

But in asking the question, they often compare apples to oranges and forget that the answer varies from place to place and from one type of installation to another.

Are New Homes Getting Better?

Posted on April 29, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

A subset of North American builders has been interested in a high-performance homes for at least 40 years. You could call these people green builders, progressive builders, or energy-conscious builders; whatever you call them, they’ve been around for a while.

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