GWhittleAL,

You may not have to use sheetrock in the attic over steel SIPS if you use metal conduit for the electrical lines.  ACTechpanels.com have been used for walls and ceiling without sheetrock in areas subject to the code.

Thanks...

Here is a photoshop modifed approximation of what the house will look like.  I created this image by modifying the house that inspired me.  The interior floorplan is more modern and quite different than this original house, but the exterior look will be similar to this.

Hello,

I saw that you are about to build an ICF house. Energy efficient and sustainable talking, i would recommend you to built the entire house with ICF walls and an insulated inclined concrete roof system, so you full house is energy efficient and hurricane proof.

Regards,

The front of the house will face north.  I intend to have window wells in the north basement wall heavily shaded by landscape plants.

The belvedere should act like a solar chimney and cause hot air to rise and exit the open cupola.  I will mount a weather vane on top of the cupola to identify prevailing wind directions.  This way I can only open the windows that will encourage airflow out of the house.  With all other windows and doors in the house closed, the replacement air should be pulled into the basement through the much cooler north side window wells.  The air entering these windows will go through a HEPA filter before entering living space.  The basement room this air enters will likely be equipped with an energy efficient dehumidifier.  [I hope they will someday commercialize the solar recharged dessicant dehumidifying water fall used in the University of Maryland's Solar Home.  Such a dessicant waterfall would be ideal for this room.]

I am hoping that with cool air entering the basement and hot air rising that it will not only passively cool my house but also help passively dehumidify my house as well.  Antebellum architects relied on this solar chimney effect to passively cool and dry southern homes.  The rising and exiting hot air holds more moisture than the entering cooler air.  The net effect was supposed to be a reduction in indoor humidity as compared to outside.

The house has an open airflow path along the center of the house from the north main stairwell through to the south and all the way up to the cupola.

During the winter, I can close off the doors separating the north part of the house from the south part of the house on the 1st and 2nd floors, and allow the solar heated south side air to rise to the attic and the north side cooler air to fall down to the basement, creating a natural convective air flow through the house to more evenly "passively" distribute the passive solar heat gathered in the solarium.

The primary daytime living spaces are in the well daylit and passively winter heated south side of the house.  The northern rooms are rarely used special guest rooms (dining room, parlor, and foyer, and the sleeping areas of bedrooms.  The west wall of the house is buffered with a garage, laundry, mud room, pantry, and with one of the master closets.  The north and east walls of the house are buffered with wrap-around porches.  And the south wall is buffered with a screened in porch in the summer which becomes a glassed in solarium in the winter.  The 2nd floor screened porch should make a very comfortable, "traditional southern" summer sleeping porch as well.

I want an extremely tight and energy efficient envelope with an ERV system with humidity controls.  If the energy calcs show I need supplemental "active conditioning," I will be very careful not to oversize my HVAC unit(s).  Ideally, the house will behave like a large scale PassivHaus and the ERV system can have supplemental heating and cooling built into it, with no additional need for a full-scale HVAC, but maybe I'm dreaming...

I don't plan on cooling the basement, but merely dehumidfying the air.  The north wall of the basement where the window wells will draw in air for the solar chimney (when the cupola is open), will be an empty basement storage room, where I hope to add the dehumidifier and any required HVAC eqipment.  When all the windows are closed, doors can be strategically closed and opened to cause the cool northside air to drop into this "conditioning chamber" for dehumidification prior to recirculating across to the southside of the basement and then rising back through the house in the planned, natural convective air flow. 

If I have to have an active HVAC system with forced air that is separate from the ERV, then I am considering having the cold air returns dump into this basement conditioning and utility room for dehumidification prior to entering the HVAC for cooling and forced air recirculation through the house. 50% of the energy cost of cooling a home in Alabama is dehumidifying the air.  There are cheaper ways to dehumidify air than using an HVAC compressor to do it!  Additionally, if the humidity is controlled separately, the frequency of HVAC cooling becomes less critical to the health of the home.

I am considering putting radiant pex flooring in the south end of the basement slab and out in the pool patio slab as well (eventually I will add a retractable pool enclosure which will increase my winter solarium effect).  I will pre-plumb the pipes and possibly add the manifolds and SHW heaters for the radiant floor system later.  This radiant floor heat in the basement can help further drive the convection cycle of hot air through the home when the house is closed tightly. 

Note: I will have to carefully ensure the comfort of the theater room without over-heating the air and thereby disrupting the natural convective flow.  The theater room's radiant floor defintely needs to be zoned so that I can carefully control the temperature of this room to prevent the convection cycle from stagnating or reversing back up into the foyer.  When the basement north window wells are opened as replacement air for the "solar chimney," the theater room will also be the first room to circulate exterior air brought in to passively cool the house.  Will the theater get too cold in moderate weather months, when the cool air is being pulled in by the solar chimney in order to flush heat from other parts of the house??? 

Thinking about this, the basement theater room will likely be the hardest to keep passively comfortable.  The south side attic bedrooms may also have a tendency to passively over heat.  I think I can keep most of the rest of the house passively comfortable.

The ERVs will suck air from the bathrooms, pre-condition the replacement air with the energy from the exiting air, and blow that air into the nearby bedroom closets to then circulate into the bedrooms and out to the center hall of the house.  The replacement air for the bathrooms will be sucked from the center hall of the house.  With a bathroom adjacent to every "closed" room in the house, and jumper ducts from each "closed" room to the center halls, there will be no room in the envelope of the house subject to stagnant air, nor any unconditioned space.

I am considering installing a direct fresh air replacement supply line (with its own HEPA filter) positioned next to the powerful kitchen downdraft fan mounted in the island in order to prevent it from causing negative pressure on the nearby fireplace.  With the downdraft fan pulling high volumes of air out of the kitchen, this outdoor "fresh," but unconditioned air should mostly be sucked back out of the house to limit energy losses.  To limit the use of the powerful downdraft fan just to usage while cooking, I am also considering installing a seperate lower volume ceiling vent fan to purge remaining IAQ issues from the kitchen after the cooking is over and additional humidity is not being actively added to the room.  This secondary ceiling vent would be operated with a timer so as to limit "wasting" conditioned air.

Likewise, I want a humidistat controlled ventiallation fan that is separate from the ERV in the most commonly used shower enclosures to limit the amount of humidity that is released into the envelope of my home.

The other principle source of IAQ problems is the laundry room.  Ideally, the laundry room should be in the garage outside of the conditioned envelope.  However, my wife and most other comfort obsessed homeowners prefer doing their laundry from a laundry room conveniently within the conditioned envelope.  So, I've designed a compomise.  I'm building a tightly sealed laundry closet inside my laundry room, with an air intake from outside to provide make-up air for the dryer exhaust, so that I won't be wasting conditioned air.  We have energy star, very efficient front loading washer and dryers. 

But I'm also considering the possibility of building a "drying closet" (at least once solar recharged dessicant systems get commercially available and affordable).  As dry as an efficient front loading washer gets clothes, they can be hung afterwards on a clothesline and they actually dry quite quickly...  But noone wants to go outside to hang a clothesline, and quite frankly my neighborhood restrictions "ban" clotheslines.  But what if the clothes are hung up damp inside a drying closet with a dessicant dehumidifier and a basic fan to circulate air.  Presumably, within a few hours the hung clothes would be dry and ready to take to the bedroom closet without the higher energy expense of a drier.  [I'm thinking ahead to when I convert my house to a grid-tied but net Zero-Energy Home [ZEH].]

I also hope to design a fresh air intake into the basement conditioning room to replenish the lost air from showers, the kitchen, and possibly losses from the laundry room; this intake will be designed to always maintain positive pressure in the home.  I'm thinking that a pressure monitor could be the "switch" to turn the fan on...  Pressure tends to stratify in a closed house with the highest pressure in the attic, and the lowest pressure in the basement.  If sustained negative pressure were to occur, it would generally be measured in the basement.  I want the fresh air intake into the basmeent conditioning room to kick on automatically when the measured pressure drops below a pre-set...  This would keep  the house always under positive pressure and would also actively assist the desired air flow when the solar chimney is in use...    

One last thing about interior air flow...  I also intend to install a whole house attic fan in the cupola, to help actively flush the house with cool evening air (when the solar chimney effect doesn't work as well)...  I want a hygrometer measuring the outdoor and indoor humidity levels, mounted next to the attic fan switch so that it isn't turned on in unfavorable conditions.  [Note: flushing with cool evening air is only a good idea if it is also not high humidity air!  Otherwise, the energy consumed to dehumidify the air back to desired levels may be greater than the energy that would have been consumed to merely cool the house.]

The whole house envelope (walls, slab, roof, doors, and windows) will be carefully engineered and selected as investments in energy efficiency. 

For energy efficiency and as preparation for becoming a ZEH (or at least near ZEH) home, I want to use all energy star appliances and the most energy efficient ones I can afford.  A conduction electric cooktop will be used to limit unnecessary heat from escaping into the home during cooking.  Likewise, the microwave will be sized as a primary cooking oven because it releases less heat than a wall oven.  I will still have a full sized oven for occasional use, but will get the rapid cooking version.

I will have solar water heaters for domestic hot water use, as well as for radiant slab heating in the basement.  If I end up with an active HVAC system, it will likely only be for a short period of supplemental cooling use each year.  I will strongly consider a geothermal heat pump (but with our other energy efficiency investments, the opportunity for a payback on a geothermal heat pump becomes significantly lower...), if I can make the numbers work.  With the reduced loading requirements from the tight envelope and from a properly deisgned ERV with humidity controls (hopefully resulting in PassivHaus performance levels), the smaller sized HVAC requirements (if any are actually needed) may still make the heat pump cost affordable.  We shall see...  If I have a geothermal heat pump, I will also consider a heat recovery unit tied into the hot water system.

Eventually, I will add PV panels which will make sense as panel costs go down with volume and with technology advancements, and as utility rates increase with rising energy demand.  The day will come, and probably not to far down the road, that PV will be a financial no brainer, even in Alabama.  In preparation, I am pre-wiring for PV, and I intend to install a 16" standing seam metal roof at an 8:12 slope for quick and easy addition of PV panels in the future.  I can either go with roll and stick PV sheets in the troughs, or I can simply clamp higher capacity panels directly to the standing seams.  I will design the roof to handle PV panel loads and SHW loads as potentially needed.

Depending upon budget constraints, I am considering adding earth tubes from the basement conditioning room to the heavily shaded ravine or creek areas.  With the long distance from my house to the ravine, the air should further cool and somewhat dehumidify before entering the house.  Additionally, with the steep slope, the moisture should naturally condensate, drain, and keep the tubes clean and healthy.  They could be easily flushed and disinfected regularly when in use.  If budget doesn't permit at the time of construction, this is something I can add later with minimal disruption and relatively minimal additional costs using trenchless pipe installation methods.  With the earthtubes further enhancing the passive cooling and passive dehumidification, PERHAPS an active system beyond the ERV and dehumidification won't be needed.  At any rate, on the few "unbarably hot" weeks a year, if the thermal mass and ERV system can't keep the house sufficiently comfortable, the basement would still be comfortable with only dehumidification.

The upshot is, this house will be capable of "passive survivability" with relevative comfort, regardless of public utility failures. 

I've got lots more thoughts on this, but I'm out of time for now.

I'd love to here some constructive criticism regarding my theories and how to improve my plans to achieve my goals.