It is an unusual house.
Originally Posted by Gus-Herb94
The house is on a slope. The top floor is the living quarters and is 2,300 sq. ft.. The bottom floor is storage and mechanical with no windows and only one exterior door.
The bottom floor is all above ground with the exception of the east end which faces the fill under the garage. The bottom floor is the same size as the top floor, but due to the slope of the ground, the ceiling is only 6' at the east end, so I call it 1,700 sq. ft. So, I have at least 4,000 sq. ft. of conditioned space, all above ground.
All of the duct work is in the bottom floor and feeds wall stacks with vents about a foot below the 10 foot ceilings in the top floor.
The house has 3 foot eves and large porches which shade all of the windows on the north & south. The east is shaded by the garage. The west has 3 small windows tucked up under the eves. They have very low e glass and don't get any sun until after 6. The rest of the windows in the house don't see any sun at all during the summer.
The attic has R49 insulation. The walls have 2" of polyiso foam board between the sheathing and the brick, all sealed with aluminum foil tape. I spent a lot of effort air sealing the house while in construction. I sealed the outlets, sealed the top plates, added gaskets behind the drywall, and spent a few hours in the attic with a foam gun before the insulation was blown in. On the walls, between the polyiso foam and the sheathing is a peel & stick roofing membrane that is completely air & water tight.
I heat & cool at least 4,000 sq. ft. with one 2 ton heat pump in north central Texas.
I live in Sherman Texas....Just north of Dallas.
Originally Posted by lynn comstock
Paul, do you actively condition what you might call your "basement"? (North Texas homes typically do not have basements, so your house is indeed unusual). IOW are there supplies and returns in the lower level?
Originally Posted by paul42
With your ducts out of an attic and in conditioned space, and with the type of envelope construction you outline above, I don't think you're trying to pull one over on us. Placing insulation outboard of exterior sheathing, and sealing it, is one of the smartest things one can do with RNC, along with no ducts in the attic and an airtight barrier between house and a ventilated attic.
Were I doing it, however, I'd forgo the "basement" for slab-on-grade and foam the roof deck, along with a low emissivity standing seam metal roof. Radiant barrier on top, insulation directly underneath. Ducts in attic like normal, but the heat gain issue is minimal, since the attic is sealed and insulated. Kill the winter stack effect, kill the radiant gain in summer and reverse stack effect. But that's just my preference.
Of course, sounds like you built into the side of one of our rare hillside lots here in Cowtown.
paul42's history on this site is well documented with a registration date of 2001. Many of his postings had to do with construction issues as the home was being built. The sizing of his system was the center of much discussion at the time and he has been able to provide updated info on the performance of is comfort system(s) that supports his decisions during the construction period. No legs are being pulled.
Paul should start a thread about his homes performance for the benefit of the people who come to this site on advice on the building of thier new homes. Way to go Paul!!!
There is one supply and one return in the basement. The majority of the cooling comes from the uninsulated metal duct work that is located in the lower level. The heat pump water heater in the lower level provides year round dehumidification.
Originally Posted by Shophound
The slab on grade was not an option with this lot, too much slope, several huge live oaks we just had to keep - and they are still doing quite well.
I strongly considered making the attic part of conditioned space, but it just was not cost effective for this lot and house layout. My wife & I really wanted a standing seam metal roof, but the cost was astronomical. My wife is in love with the idea of a rain water collection system and a standing seam roof would have been ideal. Sadly, the dollars were just not there.
Different climates call for different answers, and every lot / home design changes what is cost effective.
Originally Posted by tipsrfine
For this part of the country, the secrets are
put the air handler & duct work in conditioned space
shade the windows in the summer
Make the house air tight.
There are many ways to achieve it, but those 3 things are critical for an energy efficient house in my part of the country.
Noticed something new this afternoon. When I got home my outside unit was not on. The thermostat was set at 77 and the temp showed 79. The infinity thermostat show call for cooling, but ac showed off. The fan was running. The unit did come on in about three minutes. It is 111 today and the unit is running non stop. Does the system shut down for certain conditions. I looked at the last 10....and it showed nothing?
You may have had a power failure.
What are you doing for air changes?
Originally Posted by paul42
six inch duct from outside to the return of the air handler.
Originally Posted by tipsrfine
I've thought about adding an in-line fan and a CO2 controlled switch, but haven't got there yet.
Before my CO2 monitor died, it said I was doing ok as long as we didn't have lots of company, then it was marginal - sometimes as high as 1,600 ppm.
Paul's house with 2 tons is not impossible. just right sizing
better building practices and a LOT of air sealing.
OP..your post title is thought my home was tight...correct?
was it tested for air leakage..were ducts tested for air leakage?
most people think thier homes are tight..but you don't know
unless you test. that would be my advice to you as to where
to start. there are a lot of energy raters in Texas, you should
invest in an audit.
Tell us more about the home construction. Is it subterranian? Do you have windows and doors? How are they constructed? Do you have the recommended ACH? Do you have an ERV or HRV?
you really crack me up with that droll sense of humor. thanks for the laugh!
subterranian..do you have windows and doors...LOL!
as the cajuns here would say...me la! (not how it is spelled but how it is pronounced.)
but they also say coullion which means crazy but is pronounced ku yon..go figgure....
Originally Posted by Texas-Tech
Oh, it's possible, but the he pluncked down at least an extra $25k in insulation when he built his home... and probably doesn't have a lot of whole lot of windows... or those windows were mighty expensive as well. SO let's see, increased construction costs of $30k, so with a 30 year loan and interest that's what, $150/month extra?
I have a 3200swft home that requires around 4-1/2 tons of cooling, if I cut my cooling and heating bills by 70%, I'd still only be saving around $140/month. And I'd probably have to give up 1/2 of my 42 windows to do it.
Sorry, I just like to deflate the ego a little of those that gloat how low their electrical use is. There's no free lunch. You cna live in a berm home and have very low bills and low constructon costs, but then you have to live in a berm home... a cave.
Nope...no free lunch. Goethermal for example is great, but you have to drop 5 figures to drill the wells.