The most recent blogs at Green Building Advisor

Hygrothermal Software Sometimes Yields False Results

Posted on August 28, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Building designers and researchers have begun to realize that computer modeling programs, including WUFI, sometimes falsely predict that certain common wall assemblies — wall assemblies that have been used successfully for years — should be failing. (WUFI is a so-called “hygrothermal” modeling program — that is, a program that calculates heat and moisture flows through building assemblies. For more information on WUFI, see “WUFI IS Driving Me Crazy.”)

Yet experienced builders know that these wall assemblies aren’t failing. So what’s going on?

Cold and Old Standards — And Opportunities for Greater Building Efficiency

Posted on August 27, 2015 by Ruth Greenspan and Tripp Shealy in Guest Blogs

Last Monday, scientists in the journal Nature Climate Change answered a nagging concern of practically everyone we know: why are offices and buildings so ridiculously over-air conditioned? The article reports the design of office buildings incorporates a decades-old formula, a significant part of which is based on the metabolic rates of the average man.

The Best Way to Keep Your Attic Cooler is to Change Your Roof Color

Posted on August 26, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

The most contentious issue I’ve written about since I started blogging isn’t bad Manual Js. Nor is it endorsing government intervention by raising efficiency standards or improving energy codes. Incredibly, it’s not even whether or not naked people need building science. Nope.

Net-Zero Cities Aren’t Possible, You Say?

Posted on August 25, 2015 by Jonathan Rowe in Guest Blogs

From an environmental perspective, cities are already responsible for the majority of the planet’s energy consumption and greenhouse gas emissions. To meaningfully battle climate change and stay within our carbon budget, getting things right at the urban scale is critical.

Sustainability, Scandinavian Style

Posted on August 24, 2015 by Paul Eldrenkamp in Guest Blogs

This past October I was in Sweden and Denmark with four colleagues from the Northeast Sustainable Energy Association (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. We were on a study tour of sustainable design and green building practices in Scandinavia, a trip inspired by a similar tour we did of Upper Austria and Saxony four years ago. My traveling companions were architects Chris Benedict and Tom Hartman, engineer Andy Shapiro, and energy analyst and graduate student Heather Nolen.

Can Unvented Roof Assemblies Be Insulated With Fiberglass?

Posted on August 21, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Experts usually advise builders that you can’t install fiberglass insulation directly against the underside of 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. . If you want to install fiberglass between your rafters, you have two basic choices: either include a ventilation channel between the top of the fiberglass insulation and the underside of the roof sheathing, or install enough rigid foam above the roof sheathing to keep the roof sheathing above the dew point during the winter. These rules were developed to prevent damp roof sheathing.

Meeting the Airtightness Challenge

Posted on August 20, 2015 by Mike Steffen in Guest Blogs

This is Part 5 of a blog series describing construction of the Orchards at Orenco project in Oregon. The first installment was titled The Largest Passivhaus Building in the U.S.

How to Move Air Quietly Through a Duct System

Posted on August 19, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

At my first Building Science Summer Camp in 2011, David Hill gave a great presentation on some of the big problems with duct systems. (In case you weren’t reading this blog back then, I got myself invited with my 2010 article called I Don't Need No Stinkin' Building Science Summer Camp.)

Drawing Lessons from Ancient Roots

Posted on August 18, 2015 by Sam Hagerman in Guest Blogs

From the beginning of time, the most common building materials have been the most common materials in the immediate environment. This of course means that early buildings were built of dirt, a material that is plentiful, cheap, and malleable.

Many of the oldest buildings in the world are made of rammed earth (compacted dirt). And this type of building continues to be a common and viable construction methodology in many places of the world.

How to Finish a Third Floor

Posted on August 17, 2015 by Scott Gibson in Q&A Spotlight

Joe Watson lives in a three-story 1993 house in Richmond, Virgina, with a walkup attic, part of which he'd like to turn into living space. The question is how.

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