New construction: Where to spend the money?
mpg9999
| Posted in General Questions on
My wife and I may be building a home soon. We are on a tight budget, so I’m wondering what’s going to give us the biggest bang for the buck.
A few facts:
– We are in zone 4A
– Crawl space foundation
– The house will either be a roughly 2,600 sq. ft. one-story (plus bonus room over garage), or a roughly 3,000 sq. ft. two-story. These are the minimum square footage requirements set by the HOA.
So, any advice on where we should spend more money to increase efficiency would be appreciated. An enclosed crawl space is pretty high on my list right now.
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Replies
Michael,
Since you haven't asked a specific question -- only a general one -- I'm guessing that you are just beginning to think about green construction and energy efficiency. Probably the best place for you to begin learning about these topics is with this article: Green Building for Beginners.
Since you came to GBA, you probably already know you are screwed if you've already bought the lot. The easiest way to build an energy efficient house is to build it a lot smaller than 2600-3000 square feet.
If you haven't done so already, carefully scrutinize all of the HOA rules. You may be limited to certain finishes, prohibited from a PV array on the roof, or simply required to build a house that's ugly as well as expensive. HOA rules can run the cost up and also limit your options.
I'm early in the design process myself. Best advice I can give is to find a good architect. I'd be leery of using the developer's designer, since clearly energy efficiency is not at the top of the list.
Question everything. Why a crawl space?
Since everything in a new building project starts with a set of plans, do spend some time finding a Designer or Architect that is EXPERIENCED in high-performing houses. Ask for their credentials and how many house they've designed have been CERTIFIED under any major green building program. It is my experience in general, to find a huge difference with homes that have gone through a rigorous third party verification and certification process. Don’t be bashful to ask for references and talk to their clients about the good and the not so good. Ask what their expectations were and if they were met.
I often get calls from folks having problems with their homes, and almost every time, they acknowledge their lack of research for the right Designer or Architect. Make sure you follow exactly the same process looking for a Builder.
I find today folks spending more time researching for a car, boat or sports equipment than they spend looking for the right people to design and build their home.
One thing to keep in mind in any NEW construction is that the price of grid-tied photovoltaic solar will become VERY cheap over then next 3-5 years (cheap enough that the Sanford Bernstein investment banker foresee a potential for broader energy price deflation setting in by 2025-2030: http://reneweconomy.com.au/2014/solars-dramatic-cost-fall-heralds-energy-price-deflation-76250 ). By 2020 the installed price for 5000-10,000 watt systems is likely to be under a buck a watt (compared to $8/watt in 2008, $5/watt in 2012, and under $4/watt in Q4 2013- $2/watt in 2013 in well developed markets like Germany.)
At a buck a watt it absolutely doesn't need a subsidy- the cost of it's output over a 20 year analysis is below today's grid wholesale price in most of the US, and WELL below fixed-rate residential retail, which means it's bankable- lenders would see it as a very low-risk investment, and for the homeowner it's a no-brainer investment. Even in crummier solar areas in the US a peak watt delivers at least 1kwh/year. If your retail power costs 12 cents/kwh, that buck-a-watt solar pays 12% per year after taxes. If you're paying more like 20 cents (like I am), it's 20% return after taxes.
When designing the house pay attention to your roof lines/pitches/orientation so that you don't cut yourself out of heavily discounted site-sourced power on your side of the meter. Think of it as a photon-farm, where every south facing square foot of roof yields 10 kwh per year. That acreage has value, but only if it's pointed at the sun, and doesn't get shaded by the shadow of dormers/chimneys, etc..
If the HOA has special rules about rooftop solar not being visible from the street you may have to get creative, but it's still do-able.
Build less if your budget is tight pretty simple. You have choices to make. What do you two want. It's not up to GBA participants. Building a custom home, first you chose a HOA area, fhen you chose the sqft. To me you might have just used up your whole budget with your first two decisions.
What is left to choose?
What is the budget left and where do you want to spend it?
aj
Thank you all for the responses. I should have included a bit more in my initial question, so let me do that now.
For reasons I won't get into, this particular lot is the only place we would be able to build, and it is located where we want to live. A smaller house or different neighborhood is not an option. The builder will be my father-in-law. He will build for us at cost. So the lot (and thus square footage) and the builder are already set in stone.
I probably should have posed my question like this. Lets assume you are building a home in zone 4A. You start out with plans that are just meet code. For insulation I believe it's R13 in the walls, R50 in the attic. What would you change if you had an extra 5,000 dollars? An extra 10k or 15k?
I know I can get up in the attic with some caulk and seal things up before the insulation goes in. That's just about free except for my time.
Should I do more than R50 in the attic? If so it's not that hard. The walls are another story. R-13 is code. I think the highest for fiberglass batts I've seen that will fit in a 2x4 wall is R-15. Then there is rigid foam on the outside (or ZIP R Sheathing), spray foam, or 2x6 exterior walls for more room for fiberglass. Is wall insulation something I should concentrate on if I'm on a budget, or would my money be better spent elsewhere?
Michael,
The most important step you can take is to perform a blower door test before the walls are closed up, and to schedule time for blower-door-directed air sealing work at that time.
If you still have money in your budget after that work has been paid for, you might take a close look at your glazing specifications -- you can learn a lot about glazing options here on the GBA website -- and you might consider installing a layer of exterior rigid foam on your walls to address thermal bridging through your studs.
Air sealing is the cheapest possible performance enhancement on a bang per buck basis. Some of it is best done as it's going up (eg, the bead of caulk under the bottom plate of the studwall, or between doubled-up top plates), but finding and fixing the errors of omission & commission is far cheaper before the insulation & gypsum go up.
Going more than R50 would be a waste if you're sticking with R13 2x4 wall construction- the insulation money would be better applied toward an inch or more of EPS on the exterior. In a zone 4 climate even 2" of EPS isn't insane, and you end up with a wall that is exactly as thick as 2x6 framed construction, but a whole-wall-R (with the thermal bridging of the framing accounted for) of about R18, compared to R13-R14 for 2x6 w/R20 walls. EPS sheathing runs about 10-cents per square foot per R, so figure on 40 cents a square foot for 1", 80 cents/ft^2 for 2".
The performance difference beween R13 and R15 is small- smaller than the mere R-value numbers imply. At a typical 25% framing fraction (about where you end up when the studs are 16" o.c.) a vinyl sided OSB-sheathed R13 studwall comes in at about R9.5 whole-wall after thermal bridging. Bumping the cavity insulation to R15 raises that to R10.1, and increase of only R0.6. But with the exteior foam approach the foam-R is not being thermally bridged by the framing, and you get the full-R. Even 1/4" of EPS (or 1/4" fan-fold XPS siding underlayment) on the exterior outperforms the difference between R13 cavity fill and R15 cavity fill, but you need at least 3/4" to be able to skip the interior vapor retarder to enhance drying capacity. But there is still a long term fuel-cost rationale for 2" (R8.4, for 1.5lb density "Type-II" EPS), and an even greater rationale for the enhanced resilience you get with 2" rather than a bare-bones 3/4".
If you design your roof lines with enough unobstructed south facing pitch to accommodate 5000-10,000 watts of PV, in less than 10 years it'll cost a buck a watt or less to install. (It's over 3x that right now in most of the US, but cheaper every year.) The cost today for designing the accommodation is small, but if you don't do it now, you may inadvertently close the window on the opportunity. In states where it is subsidized, if you can get your out of pocket costs (after tax rebates and other incentives) down to $1.50/watt or less, it may be worth doing right now. (In some parts of MA & CT that's a realistic proposition right now.)