[Greenbuilding] House renovation question #1 - HVAC

[Chris Green]

Ava Kuo wrote:
> 1)  Our house <snip> is not insulated, though we do have relatively new
> double pane wndows.
>   
>   Should I just put in a
> good high efficiency furnace and A/C unit, improve the attic ventilation,
> forget about the 2nd zone, and save my money?
My 2 cents worth:
I think you should spend the money to insulate the building instead of 
buying a second furnace. Having two furnaces would be a bit like having 
two engines in your car. They will be working against each other, and 
neither will perform at their highest level of efficiency. .
Since you're in a location with high heat and high humidity, try to 
install a mineral fiber insulation (like Roxul ) or blown -in-cellulose 
( such as Cocoon ) instead of various fiberglass batt insulation.
You can buy an awful lot of insulation for the price of a decent HVAC 
system. With good insulation, you can then opt for a smaller HVAC unit 
and better ducting design and installation which in turn can create 
local heating and cooling zones.

A geosource heating/ cooling system will be a bit more costly up front, 
but once installed, they only use a small amount of electricity to 
operate the pumps and fans: the average monthly cost is turning out to 
be in the $38-$65 per month range in my area for this type of system. 
The variation in costs comes mostly from houses being different sizes, 
and some from the different living habits the occupants have.

Depending on how your building is oriented on its' lot, it may even be 
possible to redesign the building to make better use of solar heating, 
along with improved air flows and shading to provide cooling, and 
minimize your overall energy use. Ideally, the building should have the 
long axis on an east-west line, and the south side facing slightly east 
of south.

Those are some general comments: for more, you should have a local 
consultant who can actually walk around the site and make recommendations.

Cheers,

Chris Green.