Single pane of lexan? Will that be a problem for your overall R value?
Eddie
It is my opinion that "R'" values, like excitement and Cuban cigars, are vastly over-rated...
The design objective for the deadlights was to flood the Great Room with natural light each morning and evening....
The deadlights will have two layers of glazing with air in between...the r-value was not as big a consideration at the desire for the light...tho thermal gain via sunlight WAS considered....the August sunlight/shade survey I performed when I drew up the plan on Sketchup showed the deadlights that face the porch will be shaded from about 10 AM on, while the kitchen deadlights will begin to recieve direct sun at about 4:30...I have a retractable (motorized) solar screen planned for the kitchen windows...so far the survey is spot-on for predicting the shade times...
Overall the house is NOT designed to employ the latest "sealed house" technology...I feel strongly that the current crop of "sick houses" and moldy remediation nightmares are the fault of too little air movement in the structure in an attempt to wring every possible "R" out of it....my house is intentionally VERY loose...
I will pay a few more $$$ over the life of the structure in the form of BTU's rather than spend it up front in the form of "tight" technologies...
....the walls and roof are vented full length from ground to peak thru the "ribs" to allow passage of air outside the insulation envelope to keep moisture from collecting...
...passive cooling of the occupants is provided by a thicker slab coupled directly to the earth (vapor barrier without insulation) which so far has maintained an August average temperature of 80f, masonry flooring (stained concrete) rather than insulative wood or laminate allows the floor to act as a "thermal flywheel" moderating temperatures day and night...
...high ceilings throughout the house to allow warmer air to rise above occupants head level, (there is no attic...the roof line is the ceiling line), a "whole house" vent fan set at the peak can be used to eject hot air on extreme days or pull cool air in through the screened windows and doors during more clement periods, all rooms peaks are vented to allow passage of hot air to the vent fan...
....wall and ceiling cavities allow ample room for insulation (2x10 rafters and 2x6 walls) which will be good old fiberglass, the air infiltration barrier is planned on the inside of the insulated space to control drafts, rather than the classic "house wrap"....I WANT air to move thru the walls in a controlled fashion...
...AC will be provided by thru wall units to allow zoned cooling, heat will be added as needed by vent-free gas heaters provided in each bedroom, the bath and a gas / wood masonry stove in the Great Room...
...ceiling fans WILL NOT be used in the summer to provide airflow for cooling, this avoids mixing the stratified hot and cooler air and raising the average tempurature in the portion of the strata occupied by people, hot air rising to the peaks to be ejected from the space...during cool weather, ceiling fans WILL be used to prevent stratification and RAISING the average temperature in the occupied zone...
During the current heat of High Summer, the interior, tho uninsulated, is surprisingly cooler...
I'll let you know how the 20 year cost study works out...
T