Image Credit: Image #1: Midwest Construction
More Musings of an Energy Nerd
Houses are changing. Anyone buying a new home in 2018 expects the home to be quite different from one built in 1918, of course.
What “new features” is the typical buyer of a new home seeking out? It depends. Some buyers are looking for a foyer with a 20-foot ceiling and a master bathroom with a big Jacuzzi. Others, including the typical GBA reader, are looking for low energy bills and superior indoor air quality.
A beautiful house from 1918 probably included a large coal bin in the cellar. These days, coal bins are obsolete. If you want your new home to be green, then you probably realize that many of the must-have features of decades past are as obsolete as a coal bin.
Features you do not need
Some of the features listed below were normal (or even desirable) in a house built a few decades ago. In a green home? Not so much.
A vented crawl space. Unless you live in an unusually dry climate, a vented crawl space is usually damp and nasty, especially during the summer. There is no longer any justification for building this type of foundation. Instead, build on a slab foundation or a basement foundation. If you insist on a having a crawl space — and I’m not sure why you would — make sure that it is an unvented conditioned crawl space.
For more information, see Building an Unvented Crawl Space.
Bay windows. Most bay windows leak a lot of air. Moreover, the unglazed portions of a typical bay window often have very little insulation. (If you look at the horizontal ledge that a typical bay window sits on, you’ll realize that this cantilevered platform is too thin to contain much insulation.)
A well-insulated house has as few bump-outs…
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28 Comments
Unvented Crawlspace
Hello Martin. I just built an unvented crawlspace. Despite your words of advice against crawlspaces in general, it was quite a bit less expensive than a basement and the grade/soil conditions were such that it seemed to me the logical choice. My questions is about installing a floor register in the floor above to allow air to flow between the living area and the sealed crawl space below. Could that be considered a fire hazard by a building inspector?
Why a crawl space?
Sean: I understand why no basement, but why a crawl space? What do you see as the advantage of a crawl space over a slab?
Response to Sean Bromiley (Comment #1)
Sean,
As I noted in my article, Building an Unvented Crawl Space, installing a grille in the floor above a crawl space is a code requirement. The requirement is found in Section R408.3 of the International Residential Code. That said, your local code requirements may vary.
Since the grille is required by code, it's hard to imagine that it creates any fire safety risk. I have never heard of any code official objecting to such a grille.
Response to Stephen Sheehy (Comment #2)
Stephen,
One advantage of a crawl space over a slab is that a crawl space can be easier (and sometimes cheaper) to install on a sloping site than a slab. That said, I think that the disadvantages of crawl spaces are serious enough to justify the upcharge to a slab (if the slab costs more) or a basement.
Crawlspaces
Another advantage of having a house on a crawlspace is adaptability. Renovations or repairs are a lot easier in house with a trussed roof and crawlspace, than they are in houses with slabs (or finished basements), and stick-framed roofs.
Closed Breezeway
I'm in the beginning steps of designing a house and we are planning on building a detached garage but with a closed unconditioned breezeway that functions as a mudroom. I was planning on finishing the exterior wall of the house with all of the insulation and air sealing used on other exterior walls before constructing the breezeway. I'm also planning using an exterior door for the entry between the breezeway/mudroom and the house. Any thoughts on if this would be sufficient to address the air quality issues associated with an attached garage? Or should I replan and just go with an open breezeway?
Response to Tyson Godfrey (Comment #5)
Tyson,
Like many design issues, the issue you raise is a judgment call. If you have an enclosed breezeway between your house and your garage, the breezeway lessens the chance that fumes from the garage will cause air quality issues in the house. An open breezeway is better, but may not be necessary.
The decision hinges in part on (a) whether members of your family are particularly concerned with indoor air quality issues, for medical or other reasons, and (b) the likelihood that you will store paint, gasoline, and chemicals in your garage.
Great List -but have Sliding Glass doors evolved?
Great List! Was surprised to see wood stoves on here but it makes sense.
Some "Lift and Slide" Sliding glass doors market themselves as being less prone to air leakage. I wonder how true this is? Anybody getting low ACH numbers with lift and slides?
Response to Rick Evans
Rick,
You're right -- lift-and-slide doors are less prone to air leakage than old-fashioned sliding glass doors. They're mentioned in one of my articles (All About Doors).
I'll edit this article to include a mention of lift-and-slide doors. Thanks.
Patio Doors
Huh. I never even thought about sliding patio doors as a problem.
I knew reading the list that I would be caught in the "sin" of having a natural gas range, but I figured that would be the only one. Never even thought about the doors. Sadly, too late to change now.
Response to Stephen G
Stephen,
The advice I've given isn't intended to make you feel bad. Enjoy your patio doors. No house is perfect, and life is too short to worry about a little infiltration here and there.
Floor Register in unvented crawlspace
Martin - thanks for commenting on the required floor grill in an unvented crawler. It’s interesting that the code allows for it but also requires areas like that be blocked off with plywood or drywall or something to slow the spread of fire between floors. I suppose I’ll just put a grill about the size of a forced air heat register in the floor and call it good.
Response to Sean Bromiley
Sean,
Almost every two-story house in the U.S. has an open stairway connecting the first floor with the second floor -- which seems a much more significant air path between floors than a small floor grille. So I think you are misinterpreting the code.
Sean
Code provisions requiring fire-stops and blocking are to stop the spread of flames between concealed-spaces, not within the living area. The idea being they don't want fire that gets into the structure to have a hidden path between the floors, walls and roof. I suppose a case could be made that a hole in the floor above the crawlspace that was under a wall, and connected to a wall grill might meet this definition.
Ok good point.
Ok good point.
Mini split cost
I love my minisplit system but, at current prices, it's still a little more expensive to operate than NG here in Michigan. But speaking of the big beast in the basement, have you seen this thing from Dettson.
http://www.dettson.com/products/chinook-compact/
I was introduced to it at a great conference Habitat puts on here. I haven't ever worked with one but I feel like it's the only gas furnace I would consider personally, especially the Zender style duct system (watch the video). Anyone have experience or opinions to share?
Response to Andy Kosick
Andy,
Last week, I heard John Straube give a presentation at a conference in Burlington, Vermont. Straube mentioned the Dettson Chinook 15,000 Btu/h furnace, saying something along the lines of, "After begging furnace manufacturers for years to make a right-sized furnace, one is finally available."
The furnace is manufactured a short drive from my house:
Dettson Industries Inc.
3400 Boulevard Industriel
Sherbrooke, Quebec J1L 1V8
Canada
Tel: 819-346-8493 / 800-567-2733
Dettson
I gave serious consideration to using a Dettson system in my home near Flint, MI. From a technical standpoint, it seemed superior to what I ended up with. Business concerns stopped me from using one. No local contractors have any experience with it. I would have had to procure it myself and then have a local contractor install it based on written instructions. The HVAC contractor already hated me for making them learn how to install an ERV.
Stay tuned
I'm in the process of writing an article about the Dettson Chinook furnace. I had an extended conversation with one of the company's engineers this morning, and the article should be published on GBA soon.
Wasted floor area
The best way to make a house green is to reduce its size. So, anything that wastes floor space should go. You mentioned the big master bath with the Jacuzzi and the double height foyer.
Walk in closets are my favorite space waster. The area in the middle of the closet is only used when you are picking out or hanging your clothes. On the other hand, having one long closet along one wall of the master bedroom makes better use of that space.
En suite bathrooms are another wasted space. But I think I'm tilting at a windmill there.
Response to David Baerg
I have to disagree about walk in closets. At the expense of the small walkway between hanging spaces they offer vastly more efficient storage space, allowing easy access to upper walls etc. Wall length reach in closets take up valuable wall space and impede secondary furnishing of a compact bedroom. Plus, if you live in a tornado or hurricane prone area they provide a vastly more comfortable storm shelter than a bathroom. For smaller bedrooms with lesser storage needs we have planned compact corner closets which provide excellent flexibility in use while taking hardly any wall space.
Crawl spaces
Martin Holladay is an inestimably valuable source of information and good sense about all things green in building but I am afraid he betrays his regional bias in his ongoing campaign against crawl spaces. Many millions of Americans live in places where basements are impractical, and those of us whose business includes extending the useful life of older buildings groan when confronted with the inflexibility of a slab foundation. All well and good if a home is well planned from the get go but we all know that so many are not, and sadly this includes many of the 'green' home plans posted here on GBA for review. Particularly if you live south of the Mason Dixon line where access to stable subsurface soil temperatures is your friend, properly detailed encapsulated crawl spaces are one of the most important green tech construction advances of the last two decades.
Response to James Morgan
James,
Believe it or not, when the backhoe comes to your site to dig your crawl space foundation, you can ask the backhoe operator to dig just a few feet deeper to create a basement. This switch from a crawl space to a basement is possible at 90% of all sites where crawl spaces are installed, even though builders in North Carolina mysteriously insist that it's impossible to dig any deeper.
You'll pay a little more for a basement than a crawl space -- but a better house costs more than a not-so-good house.
And if the budget is tight, a dry slab beats a damp crawl space.
All of that said, I am being maligned. In the article on this page, while I did express my opinion that either a basement foundation or a slab is preferable to a crawl space, I didn't say that a crawl space won't work. I simply advised readers to avoid vented crawl spaces. I also advised any readers who are planning to build a crawl space to make sure that the crawl space is unvented.
Crawlspaces
Ah - the wicked Mr Holladay is back with his nefarious campaign to malign crawlspaces.
Basements necessitate deeper excavations, our code demands engineered reinforcement for their taller concrete walls, they yield poor living-spacesand take away space on the floor above for stairs, are more prone to water infiltration, even when unfinished are more difficult to renovate or alter as their services run under the slab not through the middle as they do in crawlspaces, are more expensive to construct and more difficult on rocky terrain, require that the drains leave the building at a much lower elevation often necessitating sumps or pumping, make teenagers who spend time in them anti-social and facilitate drug abuse.
Long live (unvented) crawlspaces.
Response to Malcolm Taylor
Malcolm,
Because of the tell-tale odor, you have to go outdoors to smoke pot. Basements are for teenage sex, not teenage drug use.
Martin
I stand corrected
wood stove for backup
Catching up on GBA blogs I missed over the past month, I read both that wood stoves are the best option for getting through a long power outage , and that they are on Martin's list of things I don't need. I had already been having trouble deciding whether to put one in the spot I reserved for it. Now my indecision has been amplified.
Response to Charlie Sullivan
Charlie,
Yes, you've identified an inconsistency in the green building community. We have a love-hate relationship with wood stoves.
This inconsistency is a result of the big divide in our community. In an article I wrote about this big divide, "Low-Road Buildings Are Homeowner-Friendly," I identified the two sides (using exaggeration and caricature) as the hippies and the Passivhaus builders.
If you're a hippie, you're happy with your wood stove (and you're feeling smug when your house is warm during a power outage). If you are the owner of a brand-new Passivhaus, however, you might be angry with your builder if you can't light your $10,000 European wood stove without first cracking a window.
GBA tries to give advice to everybody -- to the builder of a new Passivhaus, who wants happy clients (and will therefore try to steer their clients away from a wood stove), as well as to the rugged rural resident who wants to be able to feel independent when the power goes out (and who is flexible enough to crack a window when necessary).
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