"Green" Construction

Page 1 of 4  
In terms of "green" home construction, where do you get the most bang for your buck in terms of energy efficiency? Pointers to any online resources would also be appreciated.
Thanks.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
cellulose insulation. generally cheaper than fiberglass and much much better.
www.centralfiber.com

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Dec 11, 10:15 pm, "Steve Barker DLT"

Thanks Steve, I'll check it out.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sorry, styrofoam or equivalent is a better idea, in prefabricated panels or subassemblies, R-30 walls and R-50 roof. Try to catch This Old House somewhere---they are doing one of these buildings, although it is a ridiculously large monster.
My personal experience with peripheral-insulated slab construction makes me quite fond of it, although some people like basements. Does a nice job of air conditioning, and smoothes out rapid ups and downs of outside temp.
Also, some kind of heat pump.
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

..
Thanks, I'll try to check that out. Here in NC, we have a "healthy built home" certification that provides guidelines for defining their standards, and there is a whole section on insulation that calls for "rigid insulation", but the rest is greek to me.
"Rigid insulation installed as a thermal break at the slab edge (R5, 6" minimum, vertically installed)."
http://www.healthybuilthomes.org/docs/HBH_Statewide_Checklist.pdf
On the one hand, I should probably not micro-manage and just trust that the standards that are in place are good ones, but I'm just trying to define some "must haves" for homes that may not meet the HBH standards, and to address the variances within the standards.
For example, some certified homes have bamboo floors while others have concrete floors with radiant floor heat. All have heat pumps and dual- flush toilets and some solar-assisted heating.
Haven't seen any basements, but most houses in the South don't have basements.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sorry if you know this but..
Styrofoam is polystyrene and there are similar foams that are practically twice as good (eg polyisocyanurate).
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Dec 14, 4:56 pm, "Cwatters"

Yes I know it that's why I said or "equivalent", meaning rigid foam--- but ok, it isn't exactly equivalent. :-) I'm not sure what is used in prefab panels---it used to be mostly styrofoam, but I would specify isocyanurate if I were having a custom building.
I figure ta will do some research.
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

.
I am comparing two spec houses (not custom):
House1: solar-assisted hot water, isocyanurate insulation, "sustainable" oak flooring, low E windows, dual-flush toilets, hardi- board exterior and (surprisingly) a basement.
House2: solar-assisted hot water, blown cellulose insulation (which is touted as coming from recycled newspaper), stained concrete (radiant heated) and bamboo floors, dual-flush toilets, and hardi-board exterior. Basement is an optional upgrade.
House 2 is more expensive.
Yes, still doing research.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

...
I'm not sure what you mean by spec---are they built? If so, you can hardly have an optional basement ;-).
My inclination is to think about what would be an ideal---that is, go ahead and design a 'green dream house'---as a way to learn about the various factors and their relative merits and value to you. Builders are going to mix in 'features' just the way auto companies have options in packages, and it usually isn't worth the money.
I have researched blown-in cellulose as a retrofit, and the underlying problem is in the application---works fine as long as it is done very well, but you're not going to know up front. Since you are in a future tropical zone if AGW goes on, you should think about AC more than heating. That's why heat pump may be your best choice. Also what is R-value claimed and how do they justify it? Solar hot water is a great idea---wish I had it.
Stuff like bamboo floors doesn't sound like it matters that much really---is it supposed to be greener than oak or southern pine?
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

om...
It's optional on the ones that haven't been built yet. It's a neighborhood project.

House1 is heat pump and House2 has mini-split a/c (this house is actually ductless).

From House2 specs:
"All exterior walls, and interior walls to unheated spaces, will be insulated with blown cellulose R19. The ceiling/roof assembly will have 12” cellulose insulation R38. All wood-constructed first floors will have R19. All internal partitions around bathrooms, powder room, and Master Bedroom shall have R11 high-density batt sound insulation. All windows and door jambs will be sealed. The exterior walls are 7/16” ZIP System Panel with STORMEXTM water-resistive barrier."
Don't have the specs on House1.

Yeah, I'm trying to find out about reliability and maintenance costs etc. These systems have natgas backup.

Generally, I believe bamboo is considered to be more "sustainable" since it can be replenished more easily and more quickly, and it's easier to harvest, and the oak in this case is FSC-certified.
I agree, it's not one of the more critical considerations, although I currently have bamboo flooring and, irrespective of any environmental benefit, I simply like the appearance better than oak.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

Ooops, they gave me some wrong information. Turns out it's open cell foam in the roof and fiberglass in the walls.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I don't want to get into one of those philosophical definition things with you ta,;-) but I don't think R19, which is the legal requirement, can justifiably be called 'green'. Seriously, you should refine the question somewhat.
If the goal is to reduce energy consumption and associated consequences, then the thermal balance of the structure is the big deal. R30 walls and R50 roof will keep you cool in the summer and warm in (what you guys call) winter. Thermal mass, orientation of the structure, shading and working shutters, and so on, will also make a real difference. The *type* of insulation is irrelevant, as long as it functions properly over the (long) life of a well constructed building.
There is such a thing as a 'really' green house, but it's not likely to be found in one of those developments---although maybe the construction and environmental group people can give some counterexamples.
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well, as I hinted at earlier, I wouldn't know an R19 or R50 from a B52 or an F18, so I'm just going by the "Healthy Home Built" standards that exist in NC. These are the standards that are used to define what is minimally "green".

Hey, we have "skiing" in NC and everything.
http://www.skinorthcarolina.com /

Well, the NC Healthy Built Home standard is probably just a minimum requirement for marketing purposes, but there is still some merit to the standards. At minimum, these standards ensure the homes are "greener" than your average home, if not ideally "greenest", by whatever standards those might be.
Obviously price is a major consideration too. If I was going to build a custom home that was maximally "green", then I presumably could afford to do all kinds of things.
I realize these "green" developments don't represent the ideal, and that there is probably some marketing fluff in there, but that's kinda what I'm trying to sort out . . . whether the "green" features are actually worth the premium.
You apparently believe that the features I listed are not enough to make it "really greann". So then what would you consider to be a "really green house"?

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK, I see the problem. Are you saying that these HHB standards are *not* a requirement? I thought they were part of the state building code. Your first step is to sort out what's what; I thought most codes already specified R-value, for example, as a result of the last energy crisis. So if someone is claiming that baseline as a marketing feature, I would stay far away from that builder.
-tg

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

NC has a green homebuilder certification program called "NC Healthy Built Homes", which establishes "green" standards that, in many cases, go beyond the normal state requirements, or have additional, more stringent requirements (but again, not being a builder or engineer, I really don't know what the differences are in some cases, such as insulation):
"The NC HealthyBuilt Homes Program provides a certificate for homes meeting "green home guidelines" built by residential builders who practice sustainable, high performance building strategies making the home a comfortable, healthy and affordable place that reduces energy and water usage, promotes renewable energy use and helps protect the land where the home is built.
In a HealthyBuilt Home, building materials and processes are selected to reduce pollution and the waste of natural resources during the manufacturing and construction phases and throughout the life of the home. The builder is encouraged to provide homeowner education about the high performance features of the home and provide local resources for "green" living."
The standards list everything from insulation to water usage to landscaping to indoor air quality and so on. The standards are listed here:
http://healthybuilthomes.org/docs/HBH_Statewide_Checklist.pdf
So I am comparing two homes built by two different builders, both of which are "NC Healthy Built Home" certified, but each has varying implementations of the standards. In comparing the two, I'm trying to discern which features provide the "most bang for your buck", as I stated originally.
IOW, I'm trying to separate the fluff from the real "green" stuff.
You have pointed out that the R19 requirements are not really that green at all. So I'm curious as to what other features you think are required in order for something to be considered "green".
Thanks.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Ok I checked your state site and you apparently *don't* have a statewide mandatory code for 1 and 2 family dwellings.
I think that using minimal non-renewable energy is the goal, and you end up somewhere along that spectrum. The 'features' I listed above tend to make you much more comfortable while using less energy---much less if you do all of them; probably half as much as the house you are talking about.
Using less water is nice as well, but that isn't very difficult or costly---we have a very expensive toilet and a very cheap one, and they both use the minimal amount of water and work fine. Next step is composting (waterless) type, and that ain't happening. Likewise, low flow showerheads and faucets and so on are all out there and just as cheap as anything else---probably because here we do have state codes that require their installation.
So I would classify most other things as fluff, and I would question lines in the spec that say "doors and windows will be sealed", since that is just standard construction anywhere. In fact, I think I will add long-lasting quality construction that doesn't require constant maintenance and replacement to my 'green' requirement; one house every 100 years is much greener than one every 50. And that's another reason that factory-built structures are a better deal.
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Which features were those? Is that what you're referring to?

I really don't follow as to where exactly I would gain this 50% more efficiency based on what I've said.
Re: insulation, going by this R Value Calculator (http:// www.jmhomeowner.com/betterliving/energyefficiency.asp), the R19 walls are rated "Good" with R21 being "Best" -- I really don't know how much difference it would make between R19 and R21 tbh). The ceiling R38 is rated "Good", "Better" and "Best" (R38 is the only value listed). The downstairs floors have radiant heating, but the upstairs floors are R19, which ranks below their R30 value of "Good" and R38 of "Best". But I'm not sure if the radiant floor heating in the downstairs would affect their insulation choice in the upstairs.

Right, I noticed some of the standards seem rather common sense.

Well, sure, but the question is how can I determine whether the house is of "quality construction".

Both of the homes I'm referring to are not "factory-built structures". These are small, private, locally owned builders that live in the neighborhood in which they are building these houses. We're not talking about huge tract developments where corporate builders like Pulte and such throw up 150 houses in 3 months and move on to the next hunk o' land. (I live in one of those houses now, and it is definitely not "quality construction", but the only way I came to discover that was by living here).
The one project has 12 single family homes and the other has a mix of duplexes and single families for a total of 15 units -- both are infill development projects in walkable communities right in town. We're talking low-volume, small-time local builders here.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I notice you're cross posting to several groups, I'm limiting my response to construction types..
Firstly, insulation is not generic. Dense packed cellulose, if that's what they're using for the walls, is much, much better than fiberglass. Fiberglass loses R-value as the temperature goes down. Cellulose does not. Dense cellulose minimizes air movement through walls, fiberglass does not. Cellulose "buffers" moisture (a good thing), fiberglass does not.
Second, there was a comment along the way about sealing windows and doors. This is NOT standard practice. Builders think it is, but every house I analyze has windows and doors installed the same way - they shove fiberglass in the opening between the framing and the door, thinking that will help the insulation in that space. It does nothing good. Proper sealing of the window or door involves filling the entire gap with a low-rise foam that insulate and air seals. If they are not installed completely air tight, you can install the most expensive window and it will perform little better than a cheap one. You also run the risk of wood rot as moist air works its way into or out of the house.
Third, R-19 vs. R-21 wall insulation. Again, the type of insulation makes a difference. Also, an R-whatever wall is not really that R- value. You could put insulation rated R-19 into a wall with 24" stud spacing and that wall will be better insulated than R-21 in 16" stud spacing. If it were an option, you should have whatever R-value in the wall plus use taped, insulated sheathing on the outside. This will give you the best overall R-value for the wall structure as it minimizes the "thermal bridging" at the wall studs". That is a very good bang for the buck as adding R-7 insulated sheathing could increase the overall R-value by about 50%. See: http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/97/970308.html for a very good discussion of these factors.
As others noted, in your climate, go with as much insulation in the attic as possible. You get a lot of heat and regardless of attic venting they put in, you're going to have a boiling hot attic. Pay extra for added attic insulation. R-50- R-60. Again, air sealing is a key part of the construction, especially in the attic. Before the insulation is installed, you need to make sure that all the holes between the house and the attic are sealed air tight. That means every electrical wire, pipe hole, etc. should be sealed. Also, if you have a choice - don't use recessed lights. They're one of the biggest holes into the attic that you can have. No matter the rating, I've not seen a recessed light that doesn't leak like crazy. Use surface mount or hanging lights. The fewer holes through the ceiling, the better. And any holes that are there, seal them up after the electrical work is done.
Light colored roofs make a difference in attic heating.
All the other basic stuff everybody says - front load washers save tons of water and get out more water so you need less drying. Smaller, over/under style fridges can be much more efficient than side by side models. A heat pump water heater (very few on the market) would be great in your climate and would reduce water heating energy use by 1/2. Heat pumps for the house are great in a tightly constructed house. And don't forget about an HRV or ERV, which is a necessity in a tight house (google it if you don't know what it is).
Good luck! -ted
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

--------------------
-----------------------
I can only answer the very narrow question about the actual structures and their relative merits in terms of (non-renewable) energy efficiency. You clearly get points for walkable and infill, for example, but what are we comparing it to? The same problem exists when you talk about cost---are you going to be using coal-fired electricity with no carbon tax? Are you thinking of resale value in 10 years when energy costs may include what are now externalities? All too complicated for me.
But I would guess that, even in NC, the house you describe would use twice as much energy as the house I describe here:
1) R30 prefabricated wall panels and R50 prefabricated roof panels. 2) Heat pump 3) Slab foundation perimeter insulation only. 4) Interior walls 5/8 gypsum, tile floors where functional. 5) High efficiency lighting. 6) High efficiency windows with external shutters, skylights. 7) Structure orientation and shading non-random.
You get the most savings with 1, perhaps 30% or more of the heating and cooling. Each other thing contributes some percentage, and that depends on lifestyle to some degree---you might get a total more than 50%. I'm also not familiar with your climate, but as I said somewhere I am thinking that cooling is more important than heating. That would influence my choice, for example, about the radiant floor heat business. Those are getting popular now but I'm not convinced; I would like to see radiant heat that is in the ceiling of the downstairs and floor of the upstairs, for example, which would also serve for cooling.
I think the other stuff is fluff, as I said. Is cellulose 'greener' because it is recycled? I don't think so, really, because if it settles and loses R-value---which it probably will---you have a big tradeoff. What about the CO2 transport cost of bamboo v native lumber? And so on.
I know this may not help since you don't have the choice to build 'my' house and you might have different tastes. But you shouldn't just take the builders at their word, because the numbers get played with a lot. For example, the claim of R19 by itself is meaningless---it may refer only the insulating value of the 6" glass insulation, where a 4" wall with foam sheathing and insulated vinyl siding could be rated the same but yield better results.
I'm happy to try to give some guidance if you have specific questions.
-tg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've read mixed reviews (again, I'm very early on in my research and I am starting from basically point zero) so far of prefab walls. Most recently, I was reading this highly critical analysis:
http://www.jetsongreen.com/2008/09/prefab-is-not-t.html
Feel free to add your counter-arguments to theirs if you wish.
Secondly, regarding R-levels and insulation, I've talked to several insulation experts (i.e., people who are not in any way associated with the builders and who would actually be motivated to upsell me), and each of them basically said the same thing, which is that anything beyond the R19 walls and R38 roofs spec'ed by the builders would be overkill and not cost beneficial. For you people who have for some god- forsaken reason made the dubious decision to live in the Arctic zone, perhaps the R38 and R50 levels you mentioned might do some good, but I really don't know. ;-)
I also talked to a local Energy Star certifier, and he went as far as to say that the R-levels are not irrelevant, but a comparably minor consideration compared to the sealing of the house. The Healthy Built Home certification mandates that these homes are Energy Star certified as part of the process, so they would be sealed using the highest standards and inspected appropriately.
In either case, I am pursuing the question with another individual who certifies homes for energy efficiency.
On a side note, according to the individuals I spoke with, NC does have mandated residential building codes (R11 for floors, R13 for walls, R21 for roofs, if memory serves me right). In either case, the levels on the two homes I referred to exceed the minimum levels enforced by the State.
I really can't argue the comments made above; I'm just passing on the information. In any case, this is all very good because it makes a perfect launching pad for discussion/research on my part.

Check (on House1) ... mini-split a/c on House2

Check.
I don't think this is feasible with 2X6 framing, is it? Why tile floors over concrete?

Check. Energy Star certified.

Check on windows (Energy Star certified), don't think so on external shutters and skylights.

Both homes are roughly North/South facing. I don't know what "shading non-random" means.

That didn't seem to be the opinion of the folks I spoke with, none of whom are affiliated with the builders in any way, but I'll keep investigating this.

In Western NC, the average high temps in the dog days of summer are around 80 and the average low temps in Winter are around 30 (the skiing ain't that great, I'm sure). In fact, it's not uncommon at all to find houses that have no A/C at all.

Bamboo grows in NC and other parts of the States, but I'm not sure where these particular floors are coming from - something to investigate. The ones I currently have were manufactured in China, I'm pretty sure. The oak floors in House1 are FSC-certified, but I'd have to investigate their source of origin.

Well yes, why do you think I started the thread? ;-) I'm seeking out a number of different sources of information, as I always do.

Oy. Lots to learn.

Thanks for the feedback! Good information.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.