Advise re HVAC/Insulation for new construction project
We are buiilding a new home in Port St Lucie, FL. Delivery still more than a year out, but we need to make tons of ‘upgrade’ decisions fairly soon, and plunk down a sizable deposit on them well in advance. We are very undecided on what to let the contractor do, and what to do ourselves after-the-fact. Ther are serious pros and cons either way.
One of the decisions involves air conditioning, a major concern in this climate. The builder offers an upgrade to a dual comressor system, or whatever they call it, to the tune of some $4000. I see from my investigating the subjecdt that this will indeed lead to energy cost savings and probably prolong the life of the unit. But my thinking is: At an upfront cost of $4000, how much energy savings over and above the $4K will I REALLY realize?? I figure with $4000 still in my pocket, that’s a good start to a totally new system after 8-9 years, which is probably the max life span of AC units in this climate. Any thoughts on this subject from anyone?
Along the same lines, the builder offers an insulation upgrade from R19 to $30 for about $700. That sounds to me like a more reasonable and cost effective alternative to minimizing energy costs. Again, any thoughts?
Finally, in regards to the above insulation cost. Would I be better off letting the builder stick the standard R19 at no additional cost, then letter a third party add more to upgrade to R30 after-the-fact? Any pros or cons?
Thanks in advance.
Replies
close to 0% cahnce of ever finding a 3rd party to upgrade insualtion to R30 from R19 for $700 unless TIN:Y house. The GC $700 is close to cost of material only. (unless TINY hous0)
The HVAC? Go look at ecorenovator.com (for kicks if you are not a; DIY) on ultra low cost DIY options. HVAC opinions also.
re: insulation ... R-19 to R-30 ... for what? the walls? The ceiling?
A better consideration would be windows ... 1) consider orientation and 2) glass efficiency that includes both the U-value and the SHGC (solar heat gain coefficient). Windows can comprise 80% of heat loss/gain while only comprising 10% of the surface area. This can greatly affect the sizing of your cooling system. Poorly oriented (or protected) windows can be huge loads/relative sizes on A/C systems. You might cut your A/C system size in half with better window/glass choices ... and it will be much more comfortable as well.
Re: A/C - two compressors (2 stage) is superior to one. The stages are usually on/off. Most systems operate at a fraction of the time at peak/max load. This means that during the part load times, the unit cycles on/off frequently ... which wears the unit out faster. You might double the life of the unit with the dual compressors. Personally, I'd like to see compressors sized at 1/3 and 2/3 of the peak load. this optimizes the loads with the equipment. No idea if they offer this in residential applications. There may be modulating compressors that does a similar function.
I'd find out the local code requirements (assuming an energy code exists). If no code requirements ... default to the Intl Energy Conservation Code (IECC) ... to get performance minimums for both windows & A/C. Any builder worth his salt should be at or better than IECC. This is the time for advance planning and care.
An air conditioner is typically shot from corrosion after 10 years in coastal Florida so you'd have to save your original $4,000.00 plus another $2,000.00 or so in interest for a total of $6,000.00. I doubt if that is going to happen. Go for the insulation or spend the $6,000.00 on using closed cell foam to make a sealed attic which will save you money and make the house more comfortable.
Since you're building new your windows and doors will all have to be impact resistant and insulated. Sadly you'll probably never recover the added cost of the window insulation but you have no choice in the matter.