The most recent blogs at Green Building Advisor

Cold-Weather Performance of Polyisocyanurate

Posted on September 4, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

The ability of insulation products to resist the flow of heat changes with temperature. Most insulation products — including fiberglass batts, 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.), and 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.) — perform better at low temperatures than high temperatures. At lower temperatures, there is less conductionMovement of heat through a material as kinetic energy is transferred from molecule to molecule; the handle of an iron skillet on the stove gets hot due to heat conduction. R-value is a measure of resistance to conductive heat flow., less convection, and less radiation — so insulation materials usually work better than they do at warmer temperatures.

Retrofits versus Reductions

Posted on September 3, 2015 by Marc Rosenbaum in Green Building Blog

Anyone who is contemplating a deep energy retrofit has to consider multiple approaches and techniques for taking the diverse building stock we have and transforming it — from the standpoint not just of energy use, but also comfort, health and safety, and durability — because so much of our building stock is plagued with deficiencies. Retrofits fix the issues with the building — and saving energy almost ends up as a desirable byproduct.

Ten Essential Steps to a Pretty Good House

Posted on September 2, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

My friends up in Maine came up with the concept of the Pretty Good House a few years ago, and I love the idea! Not everyone can or wants to build a LEED Platinum, Living Building Challenge, Passive House. But a lot of architects, builders, and home buyers would like to design, build, and live in houses that are better than the barely legal, code-minimum houses that populate the market.

Ventilation for Your Tight House — Part 1

Posted on September 1, 2015 by Christopher Briley in Green Architects' Lounge

In this episode we are assuming that you are preparing to design or build a super-tight house and you're interested in the best way to provide fresh air for its occupants.

In the old days, you'd just “let the house breathe” [shudder]. But those days are long gone. A healthy house leaks, while an energy-efficient house controls how it leaks — and this episode is all about the latter.

Do Ductless Minisplits Work With Every Floor Plan?

Posted on August 31, 2015 by Scott Gibson in Q&A Spotlight

Clay Whitenack, planning a new home in central Kentucky, had assumed that 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. would be a "no-brainer" for heating and cooling. Then he began reading about minisplit air-source heat pumps, and suddenly the situation didn't seem so simple.

He's intrigued with the possibilities for minisplits, but he's not certain he'll have a floor plan that would be compatible with this type of system, he writes in Q&A post 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.

Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!