Please be nice to the new guy

We're considering building a new home, 1900-2000sf, 1.5 story w/ full basement.  Just for reference, we're at the stage where we think we know what we want, and are about to engage an architect.  We have several questions:

How important is it the the architect have ICF experience?
We haven't settled on ICF, we may go 2x6 stick.  From everything I've read, the cost delta is about 5%+ for ICF.  is this real?  Or, is it potentially higher?
We don't want to pay the architect twice, once for an ICF design and again for a stick design, just to get competitive bids.  Does anyone have a suggestion on how to resolve the cost issues w/ ICF construction prior to committing to the design?

What else should we be considering?  We're in SE IN, and the house will be on a substantial piece of land.  Energy efficiency is a priority, but it needs to realistically fund itself.

Thanks for any advice.

-Slice

I'm sure there are some architects who could give you a good ICF design their first time around, but if you want to make sure you should seek one out with a proven ICF history.

Many architects aren't working as much as they might like so you might try negotiating if you find one whose designs interest you. Negotiate a flat rate plan where they would do a limited concept design with some basic plans that you can shop around to potential ICF contractors. If you can't get comfortable with a ICF contractor and a price that way, then the architect can do the final plans with more conventional construction. The architect might not make the hourly they would like, but at least they would have a project and you would be able to have some options.

I think the best way to resolve the ICF cost delta is to get an experienced and efficient ICF contractor.

You should consider passive solar principles in the design of your home. Much of it shouldn't cost anything extra and you should be able to get a 15% or 20% efficiency boost.

Posted By HomeSlice on 26 Mar 2012 01:48 AM

Please be nice to the new guy

We're considering building a new home, 1900-2000sf, 1.5 story w/ full basement.  Just for reference, we're at the stage where we think we know what we want, and are about to engage an architect.  We have several questions:

How important is it the the architect have ICF experience?
We haven't settled on ICF, we may go 2x6 stick.  From everything I've read, the cost delta is about 5%+ for ICF.  is this real?  Or, is it potentially higher?
We don't want to pay the architect twice, once for an ICF design and again for a stick design, just to get competitive bids.  Does anyone have a suggestion on how to resolve the cost issues w/ ICF construction prior to committing to the design?

What else should we be considering?  We're in SE IN, and the house will be on a substantial piece of land.  Energy efficiency is a priority, but it needs to realistically fund itself.

Thanks for any advice.

-Slice

It would be better to employ an architect who is familiar with ICF. You don't want an architect learning ICF on your project and on your dime.

Cost wise, that will depend on ICF contractors you find in your area. Best cost/bang for buck build would be 2x6 wood frame, 5" of blown in cellulose, 2" of EPS on exterior, you should see a R-20 or R-24 after calculating thermal bridging. If you are looking for strength, air tightness, and better safety (fire, wind, tornado), along with a true R-23, then ICF is the way to go.

I would get BOTH bids, one for ICF and one for wood. Get multiples bids and shop around.

If energy is #1 priority, I would definitely shoot for a R-60 for the attic/roof. Insulate the basement walls and foundation. Research passive solar and utilize high SHGC windows on the south side of the home.

Being in Indiana, you are on the edge of tornado alley. ICF would be the better choice but if you want super energy efficient walls, a staggered wood wall with 8" - 10" of cellulose and 2" + of EPS on the exterior walls would be the best.

Prices are highly dependent on local conditions and individual effort. GCs and subs will discount to get work in what is surely the worst housing economy since 1973, but it won't be the first quote you hear. The premium you pay for ICF could large or small depending on how competitive that corner of construction is in your area. I'd start by researching the local ICF market. Readymix companies can point you to distributors who can point you to contractors. Distributors can also give you names of architects and engineers. If has been my experience that engineers are quicker to try new materials than architects. I found a great engineer and had him do my plans (with a weird system that isn't ICF.) You'd want an architect or designer if you have livability questions or you want a unique design. Good luck.

Posted By HomeSlice on 26 Mar 2012 01:48 AM

Please be nice to the new guy

We're considering building a new home, 1900-2000sf, 1.5 story w/ full basement.  Just for reference, we're at the stage where we think we know what we want, and are about to engage an architect.  We have several questions:

How important is it the the architect have ICF experience?
We haven't settled on ICF, we may go 2x6 stick.  From everything I've read, the cost delta is about 5%+ for ICF.  is this real?  Or, is it potentially higher?
We don't want to pay the architect twice, once for an ICF design and again for a stick design, just to get competitive bids.  Does anyone have a suggestion on how to resolve the cost issues w/ ICF construction prior to committing to the design?

What else should we be considering?  We're in SE IN, and the house will be on a substantial piece of land.  Energy efficiency is a priority, but it needs to realistically fund itself.

Thanks for any advice.

-Slice

For any energy efficiency issue to "fund itself" depends on what you actually mean by that.  Putting more cash into building envelope in the right ways can be cost-neutral to some degree when balanced against the costs of the now down-sized mechanical systems needed to support the heating & cooling loads, and that's before looking at the net-present-value (NPV) of future after-tax savings on heating & cooling loads.  If you're looking at energy savings only, over merely a 5-10 year period you can't even make a financial case for insulating to code-minimum. But with high-R houses you're buying more than just energy savings, you're buying comfort.

The single most cost-effective efficiency upgrade on any new construction comes in air-sealing.  It's not too tough in new construction to get the air leakage of the house well under 2 air exchanges per hour at 50 pascals (ACH/50) when it's BY DESIGN, rather than retrofitting after test when the house is nearly done.  ICF and SIP technology is inherently tighter (and therefore easier to seal) than stick built, but neither is guaranteed without both a planned continuous primary air-barrier connecting all 6 sides of the cube, and followed meticulously during construction, and verified/rectified when the shell is completely up with windows & doors installed, but not the interior finish.  Stick built can be made as-tight. Most PassiveHouse designs are timber framed, and are required to be under 0.6ACH/50 for certification. The Canadian R-2000 spec is 1.5ACH/50, and has proven to be quite buildable when designed in from the sub-slab vapor-barrier up and over the roof & back.

ICF's insulation is EPS foam, which comes at something of premium relative to some other materials, so going high-R (R30+)may not have an economic rationale when looking strictly at the NPV of future energy costs and savings, but it probably does at R20-22.  As others pointed out, with a low-thermal-mass 2x6 stick-built with blown or sprayed cellulose plus  2-3" of exterior iso (or 3-4" of EPS) you'd hit the mid to high-20s handily for less money, and comparable or better thermal performance to a thermally massive R20-R22 ICF, assuming equivalent air-tightness.  (For rough whole-wall estimations,  the cellulose 2x6 is ~R13-R14 by itself, so add the R value of the exterior foam to it, eg: 2" of iso is R12, so R13+ R12= R25.  Add another inch of iso and you're at R30, but that may be getting to a level beyond "funding itself" on strictly an energy savings basis.)

A rough guide to your whole-wall (all thermal bridging factored in) targets can be found in table 2 on p10 of this document.  SE IN is in US climate-zone 4, so you're looking at:

     R25 wall/R60roof/R15 basement wall/R7.5 under the basement slab.

There are minimalist ICFs in the R16 range that would get you there, but 1" of XPS with a 2x4 batt-insulated studwall on the interior of the foundation could get you there as cheaply, but that would leave a heat leak through the foundation wall to ground via the footing.  Better to go with ICF even if you stick-build the rest, and align the studwall such that the sheathing foam is 1/4" out from the exterior EPS of the ICF to fully thermally break the foundation sill, yet have the drain-plane outside the foundation's EPS.)  You can use 2" of EPS or 1.5" of XPS under the slab and hit those levels, but it's important that the slab edges are thermally-broken between the foundation wall, so butting the sub-slab foam up to the interior ICF foam and floating the slab tends to work pretty well.

At R20+ whole-wall values, the windows tend to dominate the heat gains/losses of the walls.  Take the passive solar design aspects seriously, since this can be a HUGE net gain or loss on annual heating costs.  In general, fixed non-operable windows are the most air-tight, and should be used where ever you don't actually need or want operable windows.  Casement & awning windows are inherently tighter than single/double-hungs and sliders, and offer more egress area per square foot of glazing.  Since every square foot of U0.25 window is an R4 hole in your otherwise high-R wall- a code-min U0.34 window is an R3 hole, even worse! Unless it's oriented for intentional solar gain, when in doubt, go smaller.  It doesn't take a huge expanse of window to provide decent daylighting.  West facing window need to be minimized (or even done away with) to avoid high PM summertime solar gains raising and extending the peak air conditioning loads.  East facing windows, similar story, but not quite as bad. North facing windows don't have those issues, and tend to do a better job of shadow-free daylighting, so when there's a west vs. north wall window decision for daylighting and required egress, go north!   South facing windows can be larger, higher-U, as long as they have higher solar gain characteristics.  In heating dominated climates larger is generally better, since the solar heat gained outmatches the higher loss of a higher-U window, but this needs to be optimized with the thermal mass of the house to not end up overheating in summer.  If you're careful in your window selection & sizing, smaller/tighter/fewer windows can offset the cost of lower U values for the WNE sides, and less expensive larger windows on the south side can be a net boost.

There is currently a DOE program subsidizing U0.20 (R5) windows and low-E storms, which may or may not work for you, but something to keep in mind.

To optimize & compare designs for energy efficiency, the DOE has a pretty-good freebie downloadable tool called BeOpt, which does a pretty good job of predicting energy use, and is quite handy to play with when trying to decide what upgrades are or are not self-funding.

In a high-R home the cost of mechanical systems can be dramatically smaller too. With relatively open floor plans it's pretty easy to both heat and cool a 2000' house in your neighborhood at high efficiency with ductless air source heat pump technology (mini-split/multi-split), which is usually as cheap or cheaper operating costs as with condensing gas furnaces. Even in retrofits it's often possible to get the heat load at outside design temp down to 30,000BTU/hr or even 20,000BTU/hr, at which point these systems can be a slam-dunk.  A 2-3-zone multi-split in that size range is usually under $8K, installed. A 2-ton (24,000BTU) single zone runs ~$5-5.5K.  And since it both heats & cools at high efficiency, you're not designing & building two separate systems. There is at least one air to hydronic (pumped hot water) version currently available in the US (Daikin  Altherma), but it's more money, and requires low-temperature panel radiators or radiant floor to get the best efficiency out of it.

Posted By Dana1 on 26 Mar 2012 06:39 PM

At R20+ whole-wall values, the windows tend to dominate the heat gains/losses of the walls.  Take the passive solar design aspects seriously, since this can be a HUGE net gain or loss on annual heating costs.  In general, fixed non-operable windows are the most air-tight, and should be used where ever you don't actually need or want operable windows.  Casement & awning windows are inherently tighter than single/double-hungs and sliders, and offer more egress area per square foot of glazing.  Since every square foot of U0.25 window is an R4 hole in your otherwise high-R wall- a code-min U0.34 window is an R3 hole, even worse! Unless it's oriented for intentional solar gain, when in doubt, go smaller.  It doesn't take a huge expanse of window to provide decent daylighting.  West facing window need to be minimized (or even done away with) to avoid high PM summertime solar gains raising and extending the peak air conditioning loads.  East facing windows, similar story, but not quite as bad. North facing windows don't have those issues, and tend to do a better job of shadow-free daylighting, so when there's a west vs. north wall window decision for daylighting and required egress, go north!   South facing windows can be larger, higher-U, as long as they have higher solar gain characteristics.  In heating dominated climates larger is generally better, since the solar heat gained outmatches the higher loss of a higher-U window, but this needs to be optimized with the thermal mass of the house to not end up overheating in summer.  If you're careful in your window selection & sizing, smaller/tighter/fewer windows can offset the cost of lower U values for the WNE sides, and less expensive larger windows on the south side can be a net boost.

Dana -

I think one can have their cake and eat it too with new technology windows like Intus which have a U-Value of 0.11 - 0.14 (R-9 or R-7 Value). In addition, the pricing on these windows is actually less than windows that have poorer energy values. Sometimes the R-3 windows cost double to what a high-energy efficient R-9 window costs. It takes some research and thinking and looking outside of the box, or the "big-box" store windows.

For every .01 drop in U-Value = 3% increase in energy efficiency and subsequent energy loss


On my home design I have the following:

South  = 13 windows
North = 3 windows
East = 2 windows
West = 3 windows (1 of which is completely shaded at all times of the year)


Would a north facing window during peak summer solstice get any direct sunlight?

An actuary joke: Hearing a series of loud thumps next door, Bill stuck his head in Jim's office to see his fellow actuary clutching his chest and tripping repeatedly over his wastebasket. "Jim!," Bill cried. "Heart attack," Jim gasped. " As you know, the odds of surviving a fall are much better."

The other punch line is this. Even in Tornado Alley, stretching from Texas to Kansas and sporting the highest incidence of tornadoes in the world, if one staked out a specific spot, one would wait on average 1,400 years for a tornado to pass over it. TT Fujita, who developed the tornado severity scale, spent 30 years of part-time storm chasing before he finally saw one. Frustrated the University of Chicago professor marched down to the DMV and got the vanity plate: TT 0000. http://www.sky-fire.tv/index.cgi/tornadoes.html
Nor is clear that your wood roof wouldn't go flying, along with your photo albums and perhaps you, given a strong enough storm or indifferent attachment to ICF walls.

Lbear: While a U0.11 window is far better than a code-min window, it's still more than 2x the heat loss per square foot of wall area.  But if a U0.12 Intus can be had for the same money as a U0.25 window from another vendor, you can double the glazed area if you wanted to take in the view or get higher levels of daylighting. (Unfortunately there are no Intus dealers anywhere near SE IN.)  Price/performance is always an issue, and cutting the glazed area 25% is usually cheaper than reducing the U value by 25%.  But sometimes the view or enhanced visibility is worth it.

The point is to have a conscious rationale relative to EVERY window in the place. Sometimes the western view might be deemed "worth it", in which case a low-E very low solar gain low-U value window would be in order even if it costs a bit more, whereas a south facing window in the same room may want to be something completely different.  You don't have to live in the dark to have a high-efficiency building envelope, but sizing & typing the windows for fullest function is a process with both financial and efficiency gains.

At SE IN ~ 38-39 degrees north latitude only for at most an hour or so at sunrise and sunset in the few weeks surrounding the summer solstice would there be any direct light falling on north facing windows, and it would be at such an oblique angle that nearly all of the light is reflected rather than transmitted, (a function of the difference in refractive indices of air vs. glass), so the solar gains would be negligible independent of window type.  This is related to why the solar gain on south facing windows isn't super-terrible in summer:  The mid-day sun is high enough in summer that the preponderance of the light is reflected, not transmitted.  Designing in overhangs to limit the summertime sunlight falling on south facing windows is often advised, but not always necessary.   

In WhiteHorse Yukon or Fairbanks AK you'd get some real solar gains from north facing windows in summer,  but it's not as if those gains would be unwelcome in those climates the way it would be in IN.  (Fairbanks experiences over 100 heating degree-days in both June and July, and fewer than 100 cooling degree days annually. Most Alaskan coastal zone towns have ZERO annual cooling degree days.)

BTW: In any new construction it's useful to think ahead. Orienting the roof pitches for optimal photovoltaic panel output is a low cost consideration up front, but expensive or impossible to do later. PV prices have CRASHED over the past 3-4 years, and the economics of PV will become compelling at some point in the next decade or so (they're already compelling where state & local subsidies are in play.)  While this would increase the sensible cooling loads slightly if PV isn't installed at time of construction, with R60-R75 attic floor the impact on energy use is miniscule.

Orienting the roof pitches for optimal photovoltaic panel output is a low cost consideration up front, but expensive or impossible to do later.

Are you talking about the cases where your proposed pitch is greater than optimal? Is the big issue aesthetics, because the cost of standoffs to elevate the PV panel pitch is relatively small, isn't it?

Posted By ICFHybrid on 28 Mar 2012 09:43 AM

Orienting the roof pitches for optimal photovoltaic panel output is a low cost consideration up front, but expensive or impossible to do later.

Are you talking about the cases where your proposed pitch is greater than optimal? Is the big issue aesthetics, because the cost of standoffs to elevate the PV panel pitch is relatively small, isn't it?

No- it's primarily the orientation, of a large section of roof within 45 degrees of due south that's key. Optimizing the pitch for the latitude is only a secondary issue.  Whether the pitch of that roof is 4:12 or 12:12 makes remarkably little difference (low single-digit percentages) in annual uptake if facing due south, but if the pitch is facing east or west the roof pitch has to be much lower to lessen the hit, and no matter what it's a fairly substantial reduction. 

Oriented due south the "ideal" roof pitch for maximizing annual uptake a ~40-degree latitude location would be ~25-30degrees, or about a  6 or 7:12 pitch, but even a 4:12 pitch is less than a 5% hit, as does 12:12. But facing it due-east or west you'd be into double-digit percentage lower performace at any pitch angle. Standing them off the roof for a better angle just isn't done as much these days except for VERY low angle roofs or if the pitch is oriented well off-axis.  Parallel to the roof deck is the current norm, which usually works pretty well from an aesthetic point of view.

Posted By Dana1 on 27 Mar 2012 05:21 PM

At SE IN ~ 38-39 degrees north latitude only for at most an hour or so at sunrise and sunset in the few weeks surrounding the summer solstice would there be any direct light falling on north facing windows, and it would be at such an oblique angle that nearly all of the light is reflected rather than transmitted, (a function of the difference in refractive indices of air vs. glass), so the solar gains would be negligible independent of window type.  This is related to why the solar gain on south facing windows isn't super-terrible in summer:  The mid-day sun is high enough in summer that the preponderance of the light is reflected, not transmitted.  Designing in overhangs to limit the summertime sunlight falling on south facing windows is often advised, but not always necessary.   

I would be curious to know if the future home would theoretically be "overheating" today. It  is 75F (high) with a 45F (low). With high SHGC windows and the suns angle still being at the half way point (equinoxes), would my home start overheating with 75F high temps today?

You have to design for the seasonal averages, not the 1% anomalies, so it could easily be an overheating day.

Any house theoretically has a cooling load when the average outdoor temp is above ~65F, but when solar gains are added in that binned-hourly crossover temp comes earlier. With a high of 75F and a low of 45F the binned hourly average temp for the day is about 60F, and the thermal mass of the house averages it out, but it's still below the heating/cooling balance point for most houses, but not much lower.

The passive solar BTUs input for the day could easily exceed the very low daily heat load at that average temp if you have a lot of south facing high-gain glass, so yes, it's an overheating day, but in even a low-mass house it's not necessarily an UNCOMFORTABLE overheating day- the thermal mass of the house soaks it up during the day, lets it go overnight. If it gets too warm in the PM (or in the sunniest rooms) you can always open the windows, eh? The bigger the high-gain glass to thermal mass ratio, the more likely it is you'll hit the uncomfortable level on days like that, so before going more than ~7% of the floor area in high-gain window area on the south side rooms (old school rule of thumb) it's important to do the math on the available thermal mass in those rooms. Concrete & ceramic floors count for a lot, going with 1" gypsum on the walls counts too. The greater the thermal mass, the more solar gain you can actually utilize rather than throwing it out the open windows.

Thanks so much for the feedback! I'm sorry for the late response, but I did something that resulted in my account getting locked...

The house will be oriented with the front facing just west of due south by about 10-15*, both SOuth and north sides will be covered by a porch.

By "self funding", I meant cost neutral. For example, the payment of an increase in capital cost of $10K @ 4%/360mos is roughly $48/month, so we would want that $10K upgrade to save as close to that amount as possible.

Posted By Lbear on 26 Mar 2012 03:21 AM

If energy is #1 priority, Research passive solar and utilize high SHGC windows on the south side of the home.

Would it be smart thing to do in Florida? I guess it all depends on climate zone and I would assume lower SHGC on the south side of the house in Florida would be more effective. Am I right?

Thank you

Posted By Karapet on 21 Sep 2012 08:36 PM


Would it be smart thing to do in Florida? I guess it all depends on climate zone and I would assume lower SHGC on the south side of the house in Florida would be more effective. Am I right?

Thank you

Florida it is a cooling dominated climate. South Florida has a tropical climate, while north Florida is a humid subtropical climate. I would go with a LOW SHGC (<0.30) on the south side of the home, in addition to the west and east windows. You can run the numbers through DOE but placing high SHGC windows on a Florida home is not a good idea. Even with large roof overhangs the potential to overheat in spring and fall equinox is very probable. The potential gain in winter heat will surely be overshadowed by the higher cooling loads you will experience.

Even northern Florida (Tallahassee) can see daytime highs in the 70s and 80s during December and January. With a high SHGC on the south side you would definitely overheat your home.