so you second story is smaller than the first story, based on size of systems. my advice is not hvac realated but house problems. being in the same type climate as you (louisiana) we have this complaint often. think about this.. this second story is surrounded by hot attic air. between the ceiling and roof, between floors and on the sides where the interior walls are shared by attic. if it is 100 degrees outside, then your attic is 130 to 140 degrees. (see southface institute air sealing factsheets, building science hot humid climate builder's guides) while there isn't much you can do at the roof/ceiling that is economically feisable, you can stop the heat gain through the walls, and the air leakage. if you look at these attic walls from inside the attic you'll prolly see insulation bats..(hopefully well fitted into stud bays!) while this helps, the air movement through this insulation reduces the efficiency of the insulation. the key is to stop the air movement and reflect the heat back into the attic. the best way to achieve this is to use foam/foil faced sheathing boards. they are easy to work with, cut with a razor knife and attach with buttoncap nails. install the sheathing board with foil facing into attic space, in a continous manner to the bottom of the wall, nail well and seal seams in foil board with foil faced tape. this will stop air movement and the foil will act as a radaint barrier and reflect heat out of walls. Caulking at top of wall and bottom to stop air movement. while builders seal the sole plates on first floor walls, they seldom do the same on second floor, this will effectively seal these areas from the attic. to stop the air movement between floors takes more time and effort. the same foil board should be cut to fit between ceiling joists of first floor, caulked to seal to joists and connected to foil boards installed on walls. if you look at the fact sheets on southface's site it will show you in pictures what I am trying to exlplain in words. another option which is easier, but much more expensive is open cell foam (again climate specific type of foam) installed on roof rafters to make an unvented attic..building science site has quite a bit of unvented attic info. however...to make a good seal the foam must be installed correctly. I have personally done the types of install with the foil board and reduced the air infiltration to second story to acceptable rates. Testing homes with a blower door has shown this to be common leakage areas that have a huge effect on the comfort of these upstairs and bonus rooms that are surrounded by attic temps. your options 1, 2 and 3 solar vent fan...no no no..these create negative pressures making house leakage worse, and duct leakage worse. radaint barrier..will help, but the wall area will still be leaky and radaint barrier will not lower attic temps enough to achieve level of comfort in second story. portable a/c & dehumidifier...no to the a/c but possibly for the dehumdifier..I like dehumidifiers. however they won't be of much benefit when only used for short periods of time. it takes time to lower RH and to maintain RH below 50%, dehumidifier use will be constant. best of luck

Big question---what does your spouse think of the idea?? If he's open to it then explore the possibilities. Consider how you could use the house. As a close by "get away" it offers a big yard, small pool, and lake access. Great things for a family with 3 boys. It wouldn't be too far away if you did have a kids ball game to attend. Owing it would allow for the option of you parents relocating and living in it, or perhaps just staying there part of the time. Or, you might find after living in it part time that you like it so much you want to move into it as is or do a sensitive addition. Or, you might find that after owning it for a while that 2 houses are a pia and decide to sell it! You could do any, or all, of those things while you owned it. But you can't if you don't own it. So should you rush to buy it? NO. Like any real estate purchase look hard before you leap. We had our 2d home inspected BEFORE we bid on it. That gave us a good idea of what was needed and how much repairs/renovation would cost (of course there were many surprise problems) and if we really wanted to pursue it. I checked county records re sales prices, taxes, easements, etc of it and surrounding homes. We talked to the neighbors. We also looked at at least 6 other places after discovering this one to make sure it was a good choice and value. We went from my husbands long declared "I'd never own a second home" to his "Honey, what would you think of buying a house on a small lake and oh, by the way I paddled by one for sale today" to buying it in less than 2 weeks. Now it has been 2 years (and lots of renovation) and every time we are out there (frequently as it's only an hour drive)I comment on how glad I am we bought it. Besides the lake, I love its bright contemporary feel as opposed to our traditional in town home. The lake house better reflects me and makes me happy so I understand your falling in love with such a neat mcm home. In summary, if after you both think it through and are interested, look carefully, come up with an estimate of repair/remodel costs (x1.5 to be realistic!), figure out how much you are willing to pay/market value considering those costs then go for it. If you can't get it for a realistic price walk away. If the condition turns out to be too deteriorated--walk away. Either you'll get another opportunity when no one else buys it or you can console yourself by thinking about all the negatives/ impracticalities/second yard to keep up/ etc. that you missed. Let us know the outcome. PS- If you don't buy it you should suggest they list it on the mcm website Lottaliving.com to help it find an appreciative owner.

In my old house they had run a very long HVAC duct over to the master bathroom, and then split it so that it also heated the large walk-in MBR closet. It always provided marginal heat and A/C, which was not what we wanted for the master bathroom. I finally went up in the attic and ran a completely new duct for the master BR closet and bathroom. I upsized the duct size by 2", put a bigger register in the bathroom, and also switched from flexible plastic insulated ducting to metal ducting wrapped in insulation. All the junctions in the metal ducting were screwed together and taped with HVAC tape. This change made a very noticeable difference in the air flow, and fixed our marginal heat/AC. Bruce

Load shedding/demand management is not a new idea. It's certainly an appropriate strategy when user demand for electricity exceeds transmission capability--irrespective of the cost of electricity or what state you happen to live in. Whether it's appropriate for a particular user to volunteer to participate in a load shedding program requires them to weigh a number of factors including their lifestyle and health needs and the performance of their particular home. Bumping a temperature setpoint up or down in a well-insulated home, for example, will have different implications than a poorly insulated one. Shedding the hot water heating load will have different implications for a large family or a single person and for a system which has a large versus a small tank. As for me, I'd rather have the set-point of my air conditioner raised a couple of degrees than the alternatives if the alternatives are a loss of a power grid or rolling blackouts. But, that's a personal choice.