Need opinions/help modifying 20x30 plans to 20x40 with a Cupola along middle

[flsupraguy]

Hello everyone,

I am in Florida and wanting to build a 20x40 with a Cupola down the middle of the home. My objective is to keep the house as cool as possible. Basically, I am trying to copy this house for the most part http://www.finehomebuilding.com/PDF/Free/021165096.pdf

Please let me know what you think. I just purchased home designer 8 as well.

Thanks.

[John Raabe]

Shading the house with porches on the sunny side will help with reducing solar load. Siting properly for breezes and planning casement, slider or double hung windows so that cross ventilation is maximized will also help. These are inexpensive cooling techniques for almost any climate where cooling is needed.

As designed, the Universal Cottage attic is insulated in the floor and the attic itself can then be vented at gable and ridge to keep attic air temps down. If you want to do a full cathedral roof with a venting windowed ridge (cupola) you would want to explore either special trusses or ridge beams (one under each side of the cupola) and single rafters where the insulation is placed (probably 2x12, perhaps with an inch or two of interior foam board added). You might then want to have the main social spaces on the 2nd floor since this will now have the higher ceilings and more open feel.

Whether or not that amount of customization is actually cost-effective - from an energy point of view - depends on the climate. If just increasing airflow through the house will be all the cooling needed for most days (ie: in Hawaii), then passive cooling makes good sense and is all you will normally need. If however, on most cooling days the outside temps are too high or humid for comfort, then it doesn't matter how much fresh air is pulled through the house, the AC will be on (and working over time too cool all the extra air!)

In that case you do much the same as you would in a cold climate; insulate the shell, control airflow, and actively condition the interior climate.