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Putting the Duct Back in Ductless Mini-Splits

Posted October 3, 2013 4:15 PM by Scott Gibson and Peter Yost
Related Categories: BuildingGreen's Top Stories

A would-be HVAC designer wonders if a ductless mini-split head can be hidden in a closet and connected to conventional ductwork.

This post by Scott Gibson first appeared on Green Building Advisor.

A ductless minisplit head isn't everyone's cup of tea, at least not aesthetically. One reader wonders if he can still get the benefits of a ductless system if he hides the head and makes his own ducts. (Photo: Fujitsu)A ductless minisplit head isn't everyone's cup of tea, at least not aesthetically. One reader wonders if he can still get the benefits of a ductless system if he hides the head and makes his own ducts. (Photo: Fujitsu)A ductless mini-split head isn't everyone's cup of tea, at least not aesthetically. One reader wonders if he can still get the benefits of a ductless system if he hides the head and makes his own ducts.

Ductless mini-splits have a lot going for them. These high-performance air-source heat pumps operate efficiently in much lower temperatures than standard heat pumps, and they don't suffer the same energy losses due to leaky ducts. A tight, well-insulated house may need only one or two wall-mounted heads to maintain comfort, summer and winter.

It's the "wall-mounted" part, however, that not everyone warms up to. As is the case with Jerry Liebler's wife, as Jerry introduced in a recent Q&A post at Green Building Advisor.

Liebler is convinced a Mitsubishi Hyper Heating system would meet his heating and cooling needs. But his wife “dislikes the looks of mini-split indoor units." Liebler's proposed solution is to place the head in a closet along with a small air handler and an outlet duct through the floor.

"A 'shelf' would run horizontally around the mini-split and the outlet duct of the air handler," he writes. "With the closet door closed there would, in effect, be a 'plenum' above the shelf, pressurized by the air handler."

Liebler thinks the air handler's motor would overcome the friction losses of the ductwork. Ducts through the closet floor would be connected to conventional ducts to distribute heated or cooled air.

"Has anyone done something similar?" he asks. "See any problems?"

That's the topic for this Q&A Spotlight.

WUFI Without Worries: Doing More Good than Harm with Hygrothermal Modeling

Posted October 1, 2013 11:26 AM by Peter Yost
Related Categories: BuildingGreen's Top Stories

Using WUFI for educational purposes? No worries! Predicting performance is trickier, though. (Photo: Evil Erin. License: CC BY 2.0.)Using WUFI for educational purposes? No worries! Predicting performance is trickier, though. (Photo: Evil Erin. License: CC BY 2.0.)WUFI doesn’t kill buildings. Poor design, specification, and workmanship kill buildings.

Last year, BuildingGreen made a modeling software program one of our Top-10 Green Building Products for the first time—the WUFI hygrothermal modeling software from Fraunhofer IBP and Oak Ridge National Laboratory (see “Using WUFI to Prevent Moisture Problems,” an EBN building science primer). We did this because managing moisture as intensely as we manage energy is key to building durability and indoor air quality (IAQ).

But after taking the two-day WUFI training and working with WUFI PRO 5.2 for a while, I began worrying about just how much I might be misusing or abusing this powerful and complex modeling tool.

I thought it made sense to reduce that worry by taking Building Science Corporation’s Advanced WUFI one-day workshop. I would like to tell you that today I am less worried about myself and other dilettante users of WUFI—but frankly, I am now more worried than ever.

That’s because, as with any modeling software, getting something wrong in WUFI can lead to wasted materials and money. It’s one thing to use more energy than you expected, though, and quite another to have your building quietly rotting from the inside out. Getting something wrong hygrothermally can be devastating in terms of overall building durability.

Is PVC Banned in LEED v4?

Posted August 27, 2013 12:32 PM by Tristan Roberts and Paula Melton
Related Categories: BuildingGreen Talks LEED, BuildingGreen's Top Stories

Is LEED v4 leading architects to arbitrarily avoid PVC, to the detriment of their projects? The Vinyl Institute says it is. We check the facts. Would PVC-containing products like these carpet tiles from InterfaceFLOR be banned under LEED v4? The short answer is "no." | Photo – InterfaceFLORWould PVC-containing products like these carpet tiles from InterfaceFLOR be banned under LEED v4? The short answer is "no." Photo – InterfaceFLOR


The vinyl industry has been vocally opposed to the new LEED v4 MR credits, even going so far as to characterize MRc4 Option 2 as a ban on PVC. The Vinyl Insitute, which represents PVC polymer makers, warned BuildingGreen in an email that LEED v4 “can actually lead architects and designers to make bad decisions in order to secure credits so they can market their buildings.”

Forests destroyed by mountain pine beetles can be made into valuable engineered wood products.


The mountain pine beetle has killed millions of acres of forest across the western U.S., including most of the western slope of Rocky Mountain National Park.
Photo Credit: USDA Forest Service

Balancing our need for timber along with the other environmental and financial benefits of forests has always been a challenge, especially in areas where forests and wildlife are integral to local communities.

On the western slopes of Colorado’s Rocky Mountain National Park, the trees are an integral part of the hiking experience, yet the trees along the trails that I used to run are now all dead and brown or gray as far as the eye can see, killed by the mountain pine beetle.

Green Globes May Be an ANSI Standard At Last

Posted June 7, 2013 10:40 AM by Paula Melton
Related Categories: BuildingGreen's Top Stories

The latest version of Green Globes for New Construction focuses on novel ways to measure energy performance, but details are hard to come by.

Portland VA medical centerThis Veterans Administration hospital in Portland, Oregon, achieved three Green Globes out of a possible four. Photo: GBIThere seems to be a lot to like about the new Green Globes for New Construction, which was apparently launched earlier this week.

I say “seems to” and “apparently” because, despite repeated requests, I have not been allowed to view the rating system myself or to interview anyone involved in its creation.

As you read the summary below, be aware that the Green Building Initiative (GBI) has not released any public-comment drafts or the final rating system to the public—opting instead to release only media alerts and a document it is calling a “white paper” (PDF—more on this document below).

Fancy schmancy ANSI

The most significant change to this version of Green Globes appears to be that it’s based on GBI/ANSI 01–2010—a green building standard developed through the ANSI consensus process.

GBI has been touting its “true consensus process” for years to compare Green Globes favorably with LEED. If you’ve been paying attention to the political wrangling around LEED and Green Globes over the past couple of years, you may be surprised to hear that Green Globes isn’t already an ANSI standard, but until now the ANSI standard developed by GBI and the Green Globes tool itself have been two different animals.

The Hidden Beltway Lobbyists Who Shape Green Building Policy

Posted May 15, 2013 1:31 PM by Paula Melton
Related Categories: BuildingGreen's Top Stories

Poison pill pushed by illegal lobbyists, or exciting, bipartisan energy bill that could change everything? It could be up to you.

Strategic Advocacy Solutions Green GlobesMeet the "strategic advocate" behind Green Globes. The president of this organization is also Green Buidling Initiative's vice president for federal outreach—and claims she doesn't need to register as a lobbyist. Screen capture from SAS website.We’ve been keeping an eye on the sweeping Energy Savings and Industrial Competitiveness Act (PDF), introduced by Senators Jeanne Shaheen (D–NH) and Rob Portman (R–Ohio).

The common-sense bill, likely to come to the Senate floor any day now, enjoys broad support across the political spectrum. It would boost the national model energy code for both homes and commercial buildings, support commercial retrofits with financing help, and develop training programs for green building jobs.

Earth Measure—A Stone Product That’s Green from Start to Finish

Posted May 14, 2013 2:13 PM by Brent Ehrlich
Related Categories: BuildingGreen's Top Stories

Turning waste into a unique architectural product, Coldspring and Jason F. McLennan have teamed up on a new dimensional stone product.

photo of linear series coldspringPhoto: ColdspringAs the founder and CEO of the International Living Future Institute and its influential Living Building Challenge, Declare product database, and Living Future unConference, Jason F. McLennan has been busy setting a high bar for “green.” Now the former BNIM architect has crossed over into product design, as he is set to announce tomorrow the launch of a unique line of sustainable dimension stone products called Earth Measure, in a collaboration with Coldspring, one of the nation’s largest natural stone providers.

In a world in which green products are defined by recycled content and low VOCs, natural stone has arguably gotten short shrift, as we noted recently in Environmental Building News, in Stone, The Original Green Building Material. Stone is simply cut from the earth and processed., It emits no VOCs or hazardous airborne pollutants, it is water-resistant, will outlive most buildings, and can be reused after the structure is no longer usable. How can you build on that pedigree?

How about turning the relatively small amount of quarry waste produced by stone manufacturers into a valuable product? While working with Coldspring as a consultant, McLennan recognized that the offcuts from stone processing still had value beyond landscaping and aggregate, and with Cold Spring’s corporate goal of creating zero waste from processing, a partnership was born.

This Week’s Un-News on GSA and LEED

Posted May 7, 2013 11:09 AM by Paula Melton
Related Categories: BuildingGreen's Top Stories

Cool your super-efficient jets, green building world. We still have no idea what GSA is going to do about LEED.

As GSA goes, so goes the federal government? Maybe...maybe not.
Photo Credit: Shalom Baranes Associates

It’s been a long and confusing year for people who track federal green building policies.

Between the military’s LEED battle and the loooong interagency review by the U.S. General Services Administration (GSA)—both of which are sure to be complicated by sequester and politics in ways we don’t yet understand—we’ve had newsroom motion sickness for months.

A Friday press release from the U.S. Green Building Council (USGBC), republished in Building Design + Construction and covered by Lloyd Alter at Treehugger, unfortunately hasn’t brought clarity to the conversation.

Whole-building LCA is about to get really big in LEED and elsewhere. It's a great tool, as long as you understand its limitations.

As part of its "Journey to Deep Green," international construction firm Skanska is tracking embodied carbon of the core-and-shell projects it builds for its real estate development arm. Rather than relying only on available LCA data, which are just estimates and averages, the group is tracking actual transportation miles of both materials and workers, measuring the amount of energy used for onsite equipment and lighting, and carefully calculating total waste generation and waste transport. That level of detail is not found in a typical LCA, and gathering the data is a lot of work.
Photo Credit: Skanska Commercial Development

Are you designing the world’s greenest building?

If so, have your model line up here with all the others that have laid claim to the title. That’s right: single-family homes to the left, everyone else to the right. Today we’re finally going to settle this!

As soon as the bell sounds, start entering all your building’s materials into this hand-held life-cycle assessment device. I hope you all remembered to bring your carefully tracked site-visit mileage and the spreadsheets showing carbon released from the soil during construction? Also your energy models and decommissioning plans? GO!

And the winner is…

OK, OK, this would never work: buildings are complex, and there are just too many variables and unknowns. Also, you could never fit all the “world’s greenest” building designs into one room.

Yet to hear some people talk about the hottest new sustainable design trend—life-cycle assessment, or LCA—you would think it was the one and only methodology we need to determine whether a building product or a whole building is sustainable.

That’s ridiculous, and we explore why—along with what LCA does really well—in this month’s EBN feature article, “Whole-Building Life-Cycle Assessment: Taking the Measure of a Green Building.”

Below are five things to keep in mind when using LCA in your practice.

7 Tips to Get More from Mini-Split Heat Pumps in Colder Climates

Posted April 4, 2013 11:40 AM by Peter Talmage
Related Categories: BuildingGreen's Top Stories

Air-to-air heat pumps are getting more popular as a primary heat source in colder climates. Here’s how to get the most from your system.

[Editor's Note: This guest post comes to us courtesy of Peter Talmage, P.E., an energy and design consultant and an instructor in the Renewable Energy & Energy Efficiency program at Greenfield Community College.]

I have heated my various homes with wood since 1975. It was always a love/hate relationship. The wood fuel was “free” off my land, but burning it was a very dirty business in many ways.

This Fujitsu 3/4-ton model 9RLS is in its third season as the primary heater for our 1,500 ft2 home in Northfield, Massachusetts. The interior unit is 18" off the floor, and certain creatures like that very much.
Photo Credit: Peter Talmage

Mini-splits in cold climates? Yes we can!

Three years ago, I installed a ¾-ton Fujitsu model air-source mini-split heat pump to heat my historic 1790 cape home here in Northfield, Massachusetts. It has been a great success.

During the winter of 2010–2011, the heater for my 1,500 ft2 home consumed 1,757 kWh from October 2010 to June 2011. For the warmer winter of 2011–2012, the usage was only 1,247 kWh from September 2011 to April 2012.

So far this winter, from October 2012, to March 23, 2013, the usage has been 1,501 kWh. I have a 5.4 kW PV array that supplies about 200% of my electrical consumption, including that of the heat pump, so the heating system is very “green.” I have since installed mini-splits in two other houses.

Below are my suggestions for successful house-heating with a mini-split—even in a cold, Northern New England climate like mine.

Recent Comments

7 Tips to Get More from Mini-Split Heat Pumps in Colder Climates

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Jo, part of what makes mini-splits particularly efficient is that they have motors that operate at partial loads, in contrast with conventional AC...

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