Thought I would post a link of how our ICF construction housee turned out. I was to have been around 3300 sq. ft. but it grew to almost 5,000 sq. ft.
Anyone with questions feel free to ask. I learned alot at my cost, maybe I could share from my mistakes and you could save some of your money.
http://community.webshots.com/user/jonrjen
Jon
GORGEOUS!!
What did you use for roof insulation? I like the thought of a ICF wall with some timberframe trusses in the great room and probably a SIP or similiar panel on the roof.
Thank you,
The roof is your basic plywood sheeting covered with a layer of composite underlayment (thick tar paper, vapor barrier) then covered with a no exposed screw UL listed metal roof. The use of the metal roof equated to an insurance savings of 40% had composite shingles.
We used the spray in foam insulation in the attic space, sprayed between and above the ceiling joist. The house has 24" overhang with soffet vents to keep air circulation in the attic space fresh.
When building an ICF house and spraying foam insulation in the attic on the ceiling joist, you are basically building and sealing the house with the same principal as how a foam ice chest is deigned. The house is designed and built so tight, that we have an exhaust ventilation system that is set so when someone turns on the exhaust fan in one of the bathrooms the system pulls air from all of the rooms with exhaust vents. We placed vents in all of the baths, kitchen, laundry room and rear foyer. The system is also on a timer, where it turns itself on a couple of times a day for 6 minutes just to recalculate the interior air. Exhaust vent switches in all of the rooms are timer style switches so that vents never get turned on and then forgotten to be turned off.
I hope this explaination helps and not confuses you
I am immensely interested in this. I am starting construction on a 3600 sq' house next year, and we are looking at Structural Insulated Panel or ICF construction.
How 'bout the top five lessons learned doing ICF.
That would be a great help
Your home is amazing! I'm curious what the two gray boxes in the back are? Air conditioning?
I am sorry, it has been quite a while since I have visited this board, if there are any questions I may help you with please either post them here or Email me at jonrjen@aol.com
INteresting house. Did you consider an ERV or HRV? What sort of heat and air system did ou install?
My original design called for 3 geothermal units but with Lennox's recent 19+ SEER air to air heatpumps with gas fired backups I elliminated 2 of the ground sourced units and it was a wash. Kept one geo unit (WaterFurnace brand) to service the hydronic heating of the central core spaces and master suite.
[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]
"I'm not from your planet, monkey boy!"
OK, what is ERV and HRV?
The a/c unit was custom made. It is a combination of a design where the cooling unit is in a separate tower. When the a/c comes on, water is pumped to the top of the cooling unit and rains down. This drops the ambient temperature of the outside unit by about 25 degrees prior to the actual cooling of the air.
All of the duct work for the heat and air is run under the house and is vented through floor registers. The entire underside of the house is used as a very large return vent system, there for the entire underside of the house is also conditioned air. By having the duct work run in conditioned air space we experience no heat or cooling loss such as some people would experience using the old standard method of ducting air exchange. For example: a number of houses in the south would have an a/c unit which would cool the outside air, then disperse it into the house through duct work run through the attic. So you are taking outside hot air, cooling it down, running it through the attic where the temp. is somewhere around 135 degrees. You loose a lot of the coolness due the excess heat in the attic robbing the coolness of your conditioned air. With our set up the outside unit cools the air, and brings it into an environment where the duct work is the same temp. as the house..............little or no loss of temp variation.
As for the heat. We have a constant flow hot water system. In line with the loop of the hot water line is a grid of copper pipes close together. In the winter we set the thermostat and a blower will blow across this grid and the heat from the pipe is what warms the house. A pretty basic hydronic heating system. This also keeps plenty of humidity in the house during the winter and allows us to set the temp lower than what it would be set without the humidity in a dry air heated house.
I had looked originally at doing Geothermal units, but was told the only thing I would gain would be bragging rights to say I had Geothermal. With the construction of the ICF, the added insulation, the metal roof and having no earth contact with any flooring surface of the house which would result in interior thermal transfer, the geothermal would have been wasted money with no point of recouping the dollars invested.
jonrjen, I think you will want to know about ERV/HRV. Something you might want to consider for retrofit.
ERV is Energy Recovery Ventilator and HRV is Heat Recovery Ventilator. The one adresses sensible heat only and the other also addresses latent heat. I can't say which would be best for you as I don't know where you are or your climate other than you must have a relativley low typical relative humidity as reflected by your HVAC design. My situation makes the selection a wash so I chose the simpler version which does not address humidity.
Here is what it does... You have a ballanced dual air handler with two separate air paths where the air in the two paths never comingle (in the system.) One "circuit" of the unit exhausts stale air from the residence and the other brings in fresh air from outside. The two air streams are passed through an air to air heat exchanger. This allows you, in summer, to recover the "cool" you paid for as the incoming outside air is cooled by the exhausting air. Similarly in winter when you have paid to heat the inside air, that heat is transfered to the incoming cool outside air. These units are very cost effective as they save more costs in heating and cooling than they cost to run. Breakeven times are good but $ isn't the only consideration. You need fresh air to breathe.
This is relatively important in a "TIGHT" residence such as ICF can produce. A design goal in residences should be that when you slam an entry door that it makes your ears pop. Yet with a tight house (low infiltration) where do you get your fresh air? With all the modern materials we use there are loads of chemicals outgassing into the house. Formaldehyde is but one. This continues for years. What about radon in your area? Even if you had no sources of indoor polution.. no candles, no perfume, air freshener, pilot lights... zip, zilch, nada... the occupants still need fresh air.
A good tight house is energy efficient but can easily be a "sick" house. You need to purposely engineer a solution to a fresh air supply. This is more important than fenestration/daylighting but often gets much less consideration.
I have exhaust grills above the Jacuzzi tub, above the commode cubicle, in the shower, and in the walk-in closets. These are connected toghther and go to the HRV. Neither the master bath nor the walk-in closets have air delivery ducts but depend on conditioned air being drawn into their volumes as stale air is exhausted. The fresh air, tempered by passing through the air to air heat exchanger, is delivered to the great room where it has access to one of the main return air grills where it can find its way back to the master bath and closets after mixing with the air in the master suite and essentially providing fresh air to the whole house. (The master bedroom does have supply and return ducts.)
I'm not implying you need a design like mine, just sharing my design with you. I will say that there is a good chance that you could use an ERV or HRV to good advantage. Amen to running the ducts in conditioned spaces. This is another design goal of the cognoscenti. I vae epitomized that in my shop where the uninsulated ducts are run inside the room being conditioned. Due to design conisiderations/difficulties some of our ducts are not in fulling conditioined spaces. I used interior soffits in some rooms as duct chases but ended up with some ducts in the attic. Some under insulated roof but in some instances above ceiling insulation. We used only rigid metal ducts to reduce leaks (now and later) and insulated the heck out of them where they are not in conditioned spaces.
I sure appreciate your comments regarding geo and bragging rights at the club. My original design called for three geo units but we ended up with one geo unit and two 19.2 SEER air to air units. Breakeven on the geo is 20 years or approximately the life expectancy of the system compared to the new Lenox units with 410A refrigerant. I retained the one WaterFurnace brand geo unit as it can make hot air or hot water or both at the same time (or cold air) and much of the home has either hydronic heat in the slab or ceiling.
During the shoulder seasons it is easy to have temperature under or over shoot since the thermal time constant of the slabs is so large. We have two thermostats in the effected zones, one to control the slab and one for forced air heat. In the spring and fall we'll turn the slab down some so that it remains comfortably warm but does not supply all the heat, making up the difference with warm air. Then when some afternoon gets realy warm the air control thermostat will shut off the warm air so you don't overheat. Without this capability, in-slab hydronic heat is not well suited for our climate. The hydronic ceilings have a much faster response and don't present much of a problem as regards thermal overshoot when a warm day comes along after a cold period.
Some folks design their hydronic system just for floor warming (comfort level) and not for heating the house. We chose hydronic ceiling for our master bedroom since we wanted plush carpets and plush carpets have too high of an R-Value to allow efficient in-slab hydronic heat, especially from a geo unit as water temps are lower than say a gas fired boiler. Our two air to air heatpumps both have propane fired furnaces as their air handlers with a outdoor thermostat that selects gas heat or hetpump depending on its set point. This setpoint is selected based on cost of propane vs electricity, the efficiency of the furnace vs heatpump etc. Had we been moved in last winter, 38F was the breakeven temperature above which the heat pump would run.
The geo unit of course needs no backup as it is "mining" heat out of 62F dirt irrespective of the air temp.
I can appreciate how easy your place will be to heat and cool as our master suite wing (bedroom, walk-in closets, bathroom, and sitting room) is all ICF construction with a PanelDeck ceiling. PanelDeck is a horizontal analog to ICF.
I'm going to stop here befor I need chapter titles and a table of contents but feel free to ask any questioins or point out and mistakes.
[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]
"I'm not from your planet, monkey boy!"
We are located just south of Dallas, TX.
The house does have a whole house ventilation system installed. It can be either run by a timer which is mounted on the fan housing or turned on via wall timers in the house. All of the bath rooms, kitchen areas and laundry room has ceiling return vents and timers. If someone were to go into a bathroom and turn on the vent (all of which are timer switches) the fan which is mounted in the attic pulls air not only from the room in which the timer was turned on but also the vents through out the entire house. This pulls in fresh air through a vent mounted under the house where it becomes conditioned air. It is basically routed through as return air through the system.
You are diffidently correct with your statement about CFI being tight and needing fresh ventilation. It is very easy to make the house too tight, which can result in problems.
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