Musings of an Energy Nerd

A Researcher Looks at Insulated Roof Assemblies

Posted on July 22, 2016 by Martin Holladay, GBA Advisor

Kohta Ueno knows a lot about insulated roofs. As a researcher and engineer at Building Science Corporation in Westford, Massachusetts, Ueno has seen plenty of well-designed roofs, as well as plenty of rotten 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. . For a building science researcher like Ueno, rotten sheathing isn’t a disaster; it’s data.

Comparing the Properties of Insulation Materials

Posted on July 15, 2016 by Martin Holladay, GBA Advisor

We’ve all seen tables that list the R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. per inch for a variety of insulation types. These tables are handy, of course, but because old information is endlessly republished, in some cases long after the old information becomes obsolete, the tables are often flawed. Most authors make little effort to update these tables in light of the latest information from researchers.

Construction in Cambodia

Posted on July 8, 2016 by Martin Holladay, GBA Advisor

A few weeks ago, I accompanied my wife Karyn, who is a pediatrician, on a three-week trip to Cambodia. She volunteered her services at the Angkor Children's Hospital in Siem Reap, in response to a request from hospital administrators. The hospital invited her to Cambodia to provide two weeks of specialized medical training for the hospital staff.

Lucky me: I got to tag along.

Siem Reap is a bustling town in northwest Cambodia, only a few miles away from the world-famous temples of Angkor Wat.

Can Rural Living Be As Green As Urban Living?

Posted on July 1, 2016 by Martin Holladay, GBA Advisor

Rural residents are surrounded by greenery and breathe fresh air. Urban residents are surrounded by concrete and breathe polluted air.

On the other hand, rural residents live in wasteful single-family homes and depend on private cars for transportation. Urban residents live in efficient apartments and use public transportation.

So which lifestyle is greener? According to most analysts, urban living is better for the planet than rural living. But a few aspects of the question remain unsettled.

Resilient Food Supply Systems

Posted on June 24, 2016 by Martin Holladay, GBA Advisor

GBAGreenBuildingAdvisor.com has published a lot of articles about resilience — for example, articles pointing out that well-insulated buildings with low levels of air leakage are more resilient than code-minimum buildings. In other words, in the event of a disruption to energy supplies, such a building can ride out a cold spell — even one lasting for weeks — without risking frozen pipes.

A few GBA bloggers, including Alex Wilson and Tristan Roberts, advise anyone concerned about resilience to consider where their food will come from during an emergency.

Remodeling Contractors Talk About Energy Retrofits

Posted on June 17, 2016 by Martin Holladay, GBA Advisor

One of the liveliest sessions at this year's NESEANorth East Sustainable Energy Association. A regional membership organization promoting sustainable energy solutions. NESEA is committed to advancing three core elements: sustainable solutions, proven results and cutting-edge development in the field. States included in this region stretch from Maine to Maryland. www.nesea.org-sponsored conference (BuildingEnergy 16) in Boston was a panel discussion featuring four remodeling contractors. These energy-conscious New England builders talked about the challenges they face as they try to incorporate energy improvements into remodeling projects.

Nailbase Panels for Walls

Posted on June 10, 2016 by Martin Holladay, GBA Advisor

These days, lots of builders are installing a continuous layer of rigid foam on the exterior side of their 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. . The usual approach is to sheathe the wall with OSB or plywood, and then to install one or more layers of rigid foam outboard of the sheathing.

Some builders are beginning to simplify this process by switching to nailbase panels — rigid foam panels with a layer of OSB or plywood glued to one side. Since nailbase panels provide sheathing and foam insulation in a single panel, they should (in theory) simplify the construction process.

Thermal Drift of Polyiso and XPS

Posted on June 3, 2016 by Martin Holladay, GBA Advisor

Most insulation materials have an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. lower than R-5.6 per inch. As David Yarbrough, a nationally known insulation expert, explains, “At 75°F, the theoretical maximum R-value of a product is 5.6 per inch. That represents the maximum R-value if there is no convection and no radiation — it represents the pure conductivity of air. That’s as high as you can go unless you are talking about a product that incorporates encapsulated gas, or a vacuum, or nano-scale powders.”

How Much Insulation is Too Much?

Posted on May 27, 2016 by Martin Holladay, GBA Advisor

To reduce future energy bills, some builders are willing to include above-code levels of insulation. Each additional inch of insulation saves energy — but with each additional inch, the savings per inch diminishes. At some point, the cost of adding more insulation because hard to justify.

How to Order Windows

Posted on May 20, 2016 by Martin Holladay, GBA Advisor

Anyone who needs to choose windows for a new home has a lot of decisions to make. In this article, I’ll try to provide an overview of some of the factors to keep in mind when ordering windows.

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