Deciding whether to build green
I’m wondering if anyone can direct me to good discussions outlining the factors in deciding whether or not to build green. I purchased some property in zone 6b and am starting the design process. I was a carpenter for several years with a green building company and was on the crew of a passive house. I am, however, not wealthy by any means and I will be attempting to build this house for under 100k and without going into debt (I am ok with building the house quite small to meet this goal, I am thinking 500-750 sq ft at the moment).
I will be doing a large part of the construction myself for cost reasons, subbing out whatever I can afford. I have read a ton of articles on this site, and I was always under the impression that green building was sort of a given in cold climate zones in terms of comfort, high quality of building, and payback over time. With energy not being expensive in my area, i’m starting to wonder if the added costs are worth it.
Also, a wood stove is a must for me lifestyle wise (it just provides me great pleasure to have a fire in the house), and I plan on doing a lot of my heating with wood that I harvest.
It seems like there are some things that are somewhat no brainers – I can air seal the house really well without much added cost, and I can orient the house with some extra windows facing south, less or none on the north (my lot supports this possibility). Beyond that though, I have looked closely at all the various wall assemblies possible, and it seems that all will add significant time, complexities, and cost to the project.
How do I decide if they’re worth it? Can I build a sturdy, durable, “green”, airtight home that utilizes very basic and quickest construction methods without adding a lot of time and cost?
Thanks!
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Replies
Jacob,
Building green is not expensive especially if you are doing it yourslef. Lot of the actual cost of a home is not the walls/roof/insulation but interior and exterior finishes.
For example, when I was building my place, going from an R20 wall up to R32 added about $1k materials and 2 extra days. I spent more money and time finishing the interior staircase.
If you want simple/cheap/green pick a wall assembly that ends up within a standard thickness (6 9/16 or 7 1/2) that is build-able with box store materials and you can use standard windows and doors. I think for DIY, your best bet for a low cost wall is either 2x4 16" oc or 2x6 24" oc with Bonfiglioli strips ripped from ZipR and insulated with standard batts.
The extra cost in time and materials will pay off in a smaller HVAC and energy costs. You also get the benefit of a much more comfortable house, which alone is worth the extra cost.
You can save a lot of money, and do a sort of green reuse operation, by using reclaimed materials as much as possible. I’m a fan of exterior rigid foam for a number of reasons. You can often find reclaimed rigid foam available that you can use. Cost is less than new material, and you’re using something that would have otherwise been trash which is an added green plus. Exterior rigid foam is also very good for energy efficiency.
There are other areas you can save money. There is, for example, an entire industry built around recovering useable electrical equipment. While you’re probably best off buying a new circuit breaker panel, you can get used/reclaimed breakers cheaply and save some money there. It is possible to find other supplies this way, but for residential construction you don’t have a lot of savings in the little things (light switches, boxes, etc), and there isn’t much supply outside of the regular new-equipment channels. You may be able to get leftover “end cuts” of wire if you know some electricians.
There are other types of reclaimed building materials out there, but they don’t always save you money. Reclaimed wood, for example, is often sold as a premium product for people wanting the “distressed” look that has become popular.
I would advise you to be very careful during your design stage since there is a lot of money (and time) to be saved by doing a really good job of planning. You can minimize the number of cuts you have to make to framing lumber, for example, with careful consideration of room dimensions. Design walls to use full sheets of drywall to minimize cutting and finish work. Keep all your plumbing fixtures on a common wall or column so that you can share a single run of piping. Locate your electrical service (breaker panel) centrally to minimize wire lengths and installation labor. Be clever and creative, which is a common trait among many green builders looking to optimize their structures.
Bill
As a DIY it's hard to be the price/performance of using reclaimed roofing polyiso on the exterior. A 2x4/R15 wall with 3" of continuous reclaimed roofing polyiso on the exterior (~R17) substantially beats the performance of an IRC code min 2x6/R20 + R5 c.i wall at the same wall thickness. I can get 3" reclaimed polysio in near-perfect shape almost any day of the week in my area for between $15-25/sheet (4' x 8' ). There are a few reclaimers who will ship to almost anywhere in the US, the biggest of which is Nationwide Foam (nationwidefoam.com) with distribution depots in most regions of the lower 48.
The "whole-wall R" of a 2x4/R15 + R17 c.i wall is north of R25 after thermal bridging (even after derating the polyiso for temperature), with the R-values of the other layers added in, and with a simple roof design it may be possible to hit Net Zero Energy in zone 6B with a PV array that fits comfortably on the roof.
For shadow free daylighting a modest amount of north facing window makes a lot of sense. A lot of south facing glass can introduce substantial glare and overheat the place on bright winter days even when it's -10F outside. The side to watch out for is west facing glass, which isn't easily shaded in summer with overhangs, and potentially delivering a hot punch of afternoon solar gain after the house has been soaking up the heat all day. This is far more of an issue than north facing glass- it can double your peak cooling load if you're not careful.
For windows, an argon filled double low-E double pane with an SGHC of 0.5 or higher on the south and north sides makes a lot of sense- it's considerably cheaper than triple panes of similar performance. In a zone 6B climate there will be days during cold snaps when condensation will form on the windows, temporarily undoing the benefit of the secondary low-E coating on the interior face of the window, but keeping the indoor relative humidity low during those periods can mitigate against that. For west & east facing windows a low SHGC double-low-E double pane keeps the harder to manage summertime gains at bay.
Multiple window vendors have these types of glass under proprietary trade but you have to almost waterboard the sales-droids to get the right information out of them. Specifying that it be equivalent to Cardinal LoE 180 + i89 insulated glass units for the high-gain windows, and LoE366 + i89 for the low gain sides might get some of them to do their homework. With argon fill both will run about U0.20 at center glass, but the high gain windows would have about twice the gain of the low-gain windows.
Something to keep in mind when specifying different glass on different sides: Make the low gain and high gain windows different sizes than one another- that way it takes a truly creative idiot to install them on the wrong side. :-)
Download a copy of BeOpt for tweaking the design performance.
Jacob,
Cheap energy can often mean dirty energy. Wyoming and West Virginia have some of the lowest energy costs in the country but they are also using a lot of coal. I think it is worth it from an environmental perspective to build a 'green' home. But, I think you are already down that path!
A 700 square foot, reasonably insulated/tight home will already use very little energy.
If you want to take it a step further, here are my thoughts for a super cheap- R-40 wall:
Outside in:
1x board siding (reverse board and batten)
tyvek housewrap
2x4 24" O.C. stud wall filled with HD fiberglass batts
3.5" gap will with (horizontal) HD fiberglass batts
6 mil poly (taped)
2x4 wall 16" O.C., filled with HD fiberglass batts (metal bracing as needed, per wind)
drywall or tongue and groove pine
Roof:
site built trusses with blown in cellulose.
Floor/Foundation:
Raft slab over reclaimed foam.
Polished concrete for floor prevents need for expensive joists and flooring material.
>"Cheap energy can often mean dirty energy. Wyoming and West Virginia have some of the lowest energy costs in the country but they are also using a lot of coal."
They burn a lot of coal in Montana too, but wind in that region is so cheap it's rendering many of existing coal plants uneconomic, sending the remaining utility shareholders owning a stake in the Colstrip plant looking for legislative & regulatory relief (on the backs of the Montana ratepayers) to keep it from folding entirely after the major Washington state share holder Puget Sound Energy goes 100% renewable. Montana Senate Bill 278 is an attempt at a regulatory end run to stick the ratepayers for the bill even after the large Colstrip powerplant closes, which it is destined to do.
https://www.greentechmedia.com/articles/read/coal-montana-bill-colstrip-south-dakota-utility
https://billingsgazette.com/news/state-and-regional/govt-and-politics/republican-save-colstrip-bill-still-in-play/article_4c0e3fce-9595-5b63-bfe6-6e262952fe68.html
https://www.utilitydive.com/news/wyoming-passes-coal-support-bill-in-spate-of-western-action-to-save-ailing/549753/
Whether Colstrip closes or not, the cost of the renewable energy replacing it is cheaper than keeping coal plants open. But the putting the cost of paying for the guaranteed to be stranded coal fired asset on the ratepayers rather than the shareholders in the investor owned utilities seems a dubious move at best. It feels a lot like the "privatize profit, socialize risk" model of American capitalism.
>”Wyoming and West Virginia have some of the lowest energy costs in the country but they are also using a lot of coal.”
The lowest electric rates in the country are usually in the Pacific Northwest, and the reason is the large amount of hydropower out there. My Regular company has lost buisness (large datacenter clients) before because we can’t compete with their electric rates. Electricity is far and away the largest cost in my industry. Six figure monthly electric bills are common — we’re on track to hit $300,000/month later this year.
I’ll be surprised if any large utility goes all renewable (wind/solar, in this case, since hydroelectric seems to be forgotten). The energy density just isn’t high enough in most cases. Solar can be a big electric offset on residential projects, but it doesn’t make sense on industrial facilities since they simply don’t have sufficient land for the solar panels, especially in northern latitudes. Solar makes the most sense in the southwest. I’m not a big fan of windpower because I like the open spaces and the wind turbines in many ways ruin them. I know a number of people in Appalachia who hate the noise from the things. Off shore wind though, I think can be used to augment utilities where it’s practical.
The only truely large-scale electric users I’m aware of that are using unconventional power sources are using fuel cells, generally fueled by natural gas. The overall conversion efficiency of these fuel cells can be very high, but the cost is too, unfortunately.
Bill
If this will be a do it yourself project without much government approval/inspection, I say think outside the box and build a straw bale house and clay plaster the wall. Spend your money on an elevated concrete pad and a roof trusses with heels and wide overhangs.
Walta
One of the things I like about this website is how broad and deep the discussion and expertise is within the GBA community. The breadth and depth of what qualifies as "green" is a double-edge sword: how do I prioritize global vs local environmental impact; how do I rank energy efficiency, water efficiency, environmental footprint of different materials, building durability?
At the start of any building project, it's a useful exercise to prioritize all of these aspects of "green" because later in the process, you can tie yourself in knots over new issues that arise as you go.
Peter
That is a tall question. The labor increase in high insulation levels is mainly the walls, exterior foam w/ rainscreen is probably the way to go. Others have said it, you can get used polyiso for super cheap. The best deal I got on the whole house was, 3" thick, $10 a sheet - 80 sheets - for $800 delivered and help unloading. They even still had the washers on them so I had a way to hold them on the wall until I got the furring strips / rain screen installed.
In a cold climate you've got to highly insulate and go air tight, it is probably even more important when heating with wood. You can heat with 1 or 2 cords a winter, that way processing and collecting wood is not so back breaking. I installed a wood cookstove in our house, it works well and I really was buying into the resiliency of it being multifunctional at the time. I think a stove like a 'blaze king' would be even better, and the key here is you want a stove with a catalyst so that you can get a uniform heat output over a long period of time. I think if had gone that route we would probably easily burn under a cord a winter and not have much a temperature swing. Most of the winter we would be getting 30-40 hour burn times, which is insane when you think about it.
You could definitely build a highly insulated very durable house up to around 1500 sq/ft for around 100k. That is what I've done, and we spared no expense on things like standing seam roof, clear pine clapboard siding, all cherry interior cabinetry, trim, staircase, ash flooring upstairs, secondary heat source is a ductless minisplit which is a wonderful pairing with the woodstove.
Good luck to you, it's a hell of a ride. No one will know how much work it is but you.