Thought my home was tight?

[kkmcewen]

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?

[Shophound]

You may have had a power failure.

[tipsrfine]

Different climates call for different answers, and every lot / home design changes what is cost effective.

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.

What are you doing for air changes?

[paul42]

What are you doing for air changes?

six inch duct from outside to the return of the air handler.
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.

[energy_rater_La]

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.

and Lynn:
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....

[motoguy128]

It's either the tightest home in Texas or your pulling my leg, 2 tons isn't gonna do much on 4000 sq ft, much less in Dallas

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.

[Shophound]

Sorry, I just like to deflate the ego a little of those that gloat how low their electrical use is.

I don't think Paul is gloating much, just stating facts arising from the extra care he took planning and building his home.

He also hasn't said much about energy consumption. He's said a great deal about how well his supposedly undersized system keeps his house comfortable.

We tend to get overly hung up on energy costs, IMO. Comfort drives energy costs. If people aren't comfortable, they'll run their HVAC into the ground to get comfortable, and faint when the high bills come since they can never meet their goal.

Paul has an advantage over many of us. Should the electrical grid drop power to his house in the dead of winter or on a 110 degree day like we had yesterday, he's not immediately in a world of hurt. Unless he has a backup generator, he could probably coast through the cold or heat until power can be restored without a great deal of discomfort.

What Paul has, over and above low energy cost, is a house that is truly a shelter in more ways than one. Not only will it keep him dry, it keeps him warm and cool easily. I also suspect he does not live in a cave. When you begin to understand what makes buildings that are difficult and costly to heat and cool be that way, you begin to realize it's not always what folks want to blame for being the culprit. And sometimes it's a combination of the obvious and less obvious. That is why energy audits can have value, but if I had my way they'd be called "comfort audits", because low bills are just one source of comfort. Peace of mind that your house won't freeze you to death or kill you via heat stroke is another form of comfort.

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.

As one who participated in earth-sheltered housing concepts in my younger days, there are good and bad examples of this concept, as is true with anything. If you want an example of an early prototype berm home that was light and airy, check this one out:



This house was designed by Frank Lloyd Wright and built in the 1940's. Some would say it's a bit heavy on glass, and on cloudy winter days that might be an issue, but think about when this house was made, and what could be done with current technology.

[udarrell]

I have the next thing to a free lunch.

Two very low cost half-ton room A/Cs in a1937 farm home that I didn't have to do anything with to get extremely low electric bills.

If I had central installed that new furnace indoor blower (.5-hp; high spd; 7-amps @115-volts 805-watts.) would use as much or more wattage than either the 1st floor or 2nd floor A/C uses. The window A/C on the 2nd floor doesn't get used much;usually only a short while before I hit the sack.

The floor fan for the room A/C doesn't use but little juice on low or medium.

Well, that's if you're running 3-Ton of cooling; I'd probably be running 1.5 or two Ton so I could us a 3-Ton indoor coil for lower pressure-drop resistance operating in the heating mode.

[pstu]

I don't think Paul is anything but genuine with his claims. While it is capable of generating envy, it is better to learn from how he built. His house represents a benchmark we can shoot for when we have the opportunity (if we ever do).

When one builds new construction there is opportunity to do a lot better than the majority of houses. Much of the benefit is making sure of old fashioned craftsmanship, which seems to be a big factor in airtightness. My parents built in North Dallas in 1961 and actually got a large basement under the living area. I figure craftsmanship was fine because built by a relative and they acted as a mother-hen figure during the process. The AC was in a utility closet and the duct runs minimal although they passed thru an attic. Single pane windows were used and somehow I doubt there was much insulation in that year. With a white asbestos shingle roof the electric bills were supernaturally low. 2000 sqft living space, that classic 500 sqft/ton, and electric usage somewhere around 1200 KWH in summer months.


So yes, with benefit of modern knowledge and products I believe Paul can do what he says.

Hope this helps -- Pstu

[motoguy128]

I don't think Paul is anything but genuine with his claims. While it is capable of generating envy, it is better to learn from how he built. His house represents a benchmark we can shoot for when we have the opportunity (if we ever do).

When one builds new construction there is opportunity to do a lot better than the majority of houses. Much of the benefit is making sure of old fashioned craftsmanship, which seems to be a big factor in airtightness. My parents built in North Dallas in 1961 and actually got a large basement under the living area. I figure craftsmanship was fine because built by a relative and they acted as a mother-hen figure during the process. The AC was in a utility closet and the duct runs minimal although they passed thru an attic. Single pane windows were used and somehow I doubt there was much insulation in that year. With a white asbestos shingle roof the electric bills were supernaturally low. 2000 sqft living space, that classic 500 sqft/ton, and electric usage somewhere around 1200 KWH in summer months.


So yes, with benefit of modern knowledge and products I believe Paul can do what he says.

Hope this helps -- Pstu

I'm not saying his claims are inaccurate. Only that again, there is no free lunch and I think you should be mindful of the associated costs.

I am however a very strong proponent of investing in infrastructure of a home rather than on cosmetic elements or simple square footage. I praise Paul for that. He inevitably could have built a larger or "fancier" home rather than invest in insualtion and advanced building techniques.

I would however, love to see a revisal of classical arcitectural styles rather than the seemingly cookie cutter neo-eclectic house style that covers the current landscape. There just no warmth or personality to them much kike many of the cars and trucks we buy.

Could you imagine someone buying a lot an putting up a real Foursquare, Craftsmen, Queen Anne or Italianate?

Look at this one. Like many newer homes thre's at least 3 different styles cobbled together. Is it a colonial, greek revival... hey, it even has a little Queen Anne tossed in there for good measure. http://0.tqn.com/d/architecture/1/0/...ion-010030.jpg

[Shophound]

Look at this one. Like many newer homes thre's at least 3 different styles cobbled together. Is it a colonial, greek revival... hey, it even has a little Queen Anne tossed in there for good measure. http://0.tqn.com/d/architecture/1/0/...ion-010030.jpg

That house looks like it was designed by a committee. Or a first year architectural drafting student. Or a clip-art mashup. Or all of the above.

Part of the problem with today's housing stock is the styling and construction. People want the lofty ceilings (why people like to feel insignificant in their own homes escapes me, but maybe tall ceilings don't have that effect on everyone), which increases interior air volume and can aggravate stack/reverse stack effect. Little thought is given as to how the mechanical systems can best accomodate the architecture. Rather, the architecture (if you can call it that) comes first and the mechanicals must merely be shoehorned in as an afterthought.

HVAC does not have curb appeal. But it will make or break a house. Same goes for the envelope. Most people don't pull up to a house for sale and say, "Wow! Check out the 2" exterior foam insulation sheathing and a sealed attic foamed at the roof deck with a standing seam roof! Where do I sign??" Rather, "Oh, look at those cabinets! And the lofty ceilings! Granite countertops! Bonus room! Where do I sign??"

Aesthetics obviously play an important role toward enjoying a house. However, my opinion is that for far too long aesthetics has run roughshod over other equally vital matters that one should consider when buying or building a house. As energy costs go up it's likely these other tangibles/intangibles will become more marketable. Until then, looks like granite countertops will keep trumping sealed attics and ducts in conditioned space.

[Timber]

Hey Paul42 , how bout some pics...

[motoguy128]

I think it's been mentioned before that the expectations of most homeowners for HVAC are ver,y very low. What I consider ot be a noisy, drafty unbalanced system. Is "normal" to most buyers. "For many it's does it heat and cool? OK good enough." Or at least good enough until it's near design temp and it's not keeping up due to poor ductwork and leaks and they get a $300+ utility bill.

I think there could be a market for ultraefficient homeseems like it remains a niche market for custom designed homes. Most of the ones I see are built on large properties in rural areas. That's where most of the geothermal properties units get installed.

[paul42]

My wife is a very private person and has told me to never post pictures of our house on the internet. She is very proud to show it to friends and family, but not to the world.

The insulation cost was not all that high. There is about $1,500 invested in cellulose, and approximately $2,600 in poly iso foam board. 4x8 sheets 2" thick were around $.45 a board foot when I got them.

I also have about $200 worth of spray foam invested, another $50 in duct sealant for all the outlet boxes, around $100 in aluminium foil tape, and around $40 in the foam tape they use to insulate between the foundation and the footer (I also used that for the drywall gasket). I paid some of the younger framers to come in on their Saturdays's off to install the foam board. That cost me around $300. There is also a couple of hundred hours of my own time invested.

I still have the window quote on my computer. The total cost for the windows was $3,685. The windows total 226 sq. ft. all on the top floor, which as I have said before is 2,300 sq. ft. We have 10 foot tall ceilings on the top floor. The windows are vinyl, either casement or fixed to cut down on infilltration.

We skipped the granite counter tops and went with a formica that we both like. We bought pre-finished hardwood flooring and I installed that myself. I also installed all the metal duct work in the walls, and did the porch floors and railings. I was working a full time job at the time and it was a very busy year. Christmas day, I was installing flooring and my wife brought me out a P&B sandwich for my Christmas dinner.

I just finished building the bookcase for the hallway, all oak with 15 barrister doors, etc... I'm working on the office furniture now, the wife found some cherry lumber on sale so I can build bedroom furniture, and we plan on adding a hidden passage with a stairwell down to the basement. My wife says I am very handy to have around.

[paul42]

I used HVAC calc to figure out the size of the heat pump that I needed.
Total heat gain
6,076 Infiltration
4,929 Walls
2,650 People
2,124 Windows
1,464 Ceiling
1,265 Doors
1,200 Misc

16,084 Sensible
3,624 Latent
19,708 total

[lynn comstock]

I used HVAC calc to figure out the size of the heat pump that I needed.
Total heat gain
6,076 Infiltration This seems extremely high at 30 to 37.5% of total (super sealed and ducts inside.)
4,929 Walls This seems high. Was the correct insulation value chosen?
2,650 People I usually figure 300 btu per person.
2,124 Windows
1,464 Ceiling
1,265 Doors Door load almost as much as ceiling load?
1,200 Misc

16,084 Sensible
3,624 Latent
19,708 total

If your design temp is 95°F or less and calculations are correct, a 2 ton will do it. It is possible that the duct losses are calculated as a part of infiltration. I don't know. In any event, a 2 ton DOES do it.

[paul42]

If your design temp is 95°F or less and calculations are correct, a 2 ton will do it. It is possible that the duct losses are calculated as a part of infiltration. I don't know. In any event, a 2 ton DOES do it.

Because the ducts are inside the conditioned space, there are no duct losses.
Hvac-Calc has limited options for infiltration values and wall insulation. I chose the closest match I could come up with.
At R49, the ceiling is very well insulated - Hvac-Calc also did not consider the radiant barrier sheathing.
- we have 4 exterior doors.

The design temperature is 100. 2 tons works up to at least 110, it is running constantly at that temperature.

[lynn comstock]

I don't think that this is your doing, but a limitation and flaw in the basic Hvac-Calc program.

The infiltration calculation was greatly exagerated by Hvac-Calc for the infiltration and wall constuction. If you have 3 bedrooms, Manual J would figure 4 people at 300 each for 1200 btus (less than half of the 2650 calculated). In Yuma the Manual J door load at 110°F OD design would be 15.5btu/sq ft *4 doors * 20 sq ft/door = 1240 btu. It would be about 900 btus at 100°F OD design (1240*25/35 assuming 75°F ID design). My 226 sq ft window load in manual J for all shaded dual pane low e (regular) is more than double yours: Manual J 4520 btu vs. 2124 btu in Hvac-Calc.

I wonder if other pros have compared the Hvac-Calc calculations to Manual J. This is the only time I have had a comparison. I did loads manually for years but now use RightSuite Universal by Wrightsoft which is ACCA certified for accuracy to Manual J.

[hershfieldtwo]

Lacking a knowledgeable party during design, construction, and investigations of facades is risky, and was proven many times to lead to substantial short and long term losses for building owners. Thanks for all the knowledge you have shared


hershfieldtwo building envelope