Retrofit full heat/ac system in 60's modern
We're looking at another house renovation & rec'd great advice from the board last time we renovated.
The new project is an architecturally significant modern house (1962) in the NE--post and beam, large window walls--like the Eichler houses in CA. No attic (cathedral ceilings, original flat built-up roof w. parapets). Ballpark the house is about 3800 sf, single story, roughly in the shape of a 'T'. Windows & sliders are all single pane commercial aluminum. I have no idea about wall insulation, or whether there is any insulation in the room deck. The uphill half of the house will need a new roof (top of "T"), & could have insulation added when a new (likely membrane) roof is done.
Construction is over a vented crawl space.
Existing system is a two furnace gas hot air system delivered almost exclusively through floor registers. The smaller furnace feeds the master bedroom/office (top of the 'T'); larger furnace feeds the large open LR/DR/Kitchen as well as the kids' bedrooms. I suspect the zoning was design driven--it looks as if the crawl spaces are isolated by foundation walls. Uninsulated duct work is all through an uninsulated crawl space. Currently the house has no air conditioning system. The existing main furnace is on its last legs (dreaded blower bearing knock by the sound of it...)
We would like to bring the house HVAC systems up to modern standards, add A/C while also generally improve the energy consumption footprint.
I'm a big fan of underfloor water systems, but 2 problems--existing wide plank hardwood floors (that may be salvageable), & you would create a bigger problem as to how to add A/C.
So assuming that you try to work with what's there....
1. How hard would it be (or how efficient is it) to add air conditioning to an existing system as described? (eg no ceiling drops & very difficult to install in roof slab--also you don't want to detract from design)
2. Should the underfloor joists be insulated?
[There are also moisture problems in the house--first contractor has recommended a vapor barrier be installed and a "rat slab" be poured. (I'm inclined to deal with perimeter drainage first...)]
3. Should/can the duct work have insulation retrofitted? Is this wildly expensive? (most of the crawl space is 4' or less...)
Other Improvements may include:
-Window replacement (for all except the clerestory windows that "knife" into the under-roof deck.
Where to begin? Or what is the recommended sequencing to get my arms around the problems???
Radiant floring is do-able
If the ductwork needs to come out anyway, Put radiant up under the flooring then insulate the joist bays. Reuse the registers with new insulated ductwork. Maybe Hi-velocity will be needed.