Attic insulation

[lgtech]

I have an attic fan and love it. Here in NH, we only need A/C for about 10-20 days out of the year. Larryrose11 has it right... running it at night can really cool down the house if the outside temp is cool enough. I still like a direct breeze so I installed a couple of ceiling fans, too. One other thing... when you close the windows the next morning after running the attic fan, be sure to pull the window shades if you are in a sunny area. That radiation/solar heating can really add back the heat into your cooled space.

Lgtech

[RH77]

Apologies for the delayed response -- one would thing an AC adapter would last longer than a year, but Dell laptop designers had other ideas

Originally Posted by lgtech

I have an attic fan and love it. Here in NH, we only need A/C for about 10-20 days out of the year. Larryrose11 has it right... running it at night can really cool down the house if the outside temp is cool enough. I still like a direct breeze so I installed a couple of ceiling fans, too. One other thing... when you close the windows the next morning after running the attic fan, be sure to pull the window shades if you are in a sunny area. That radiation/solar heating can really add back the heat into your cooled space.

Here's the concern...Allergies. I open things up only to take-on allergens and humidity. I put the high-performance (lower-flow) filter on the blower to test the symptom-response. From a previous post, I re-wired the blower to run at full-speed instead of Medium-Low as it was, so cooling performance is up to par. It has just been too hot lately in the KC heat. I know, the solution would be Zyrtec and open windows at night, but I end up in a fog with the meds, so that's out. Overnight/sleep-time is the critical period of taking-on the allergens, so open windows at night is tough. I have a new (stand alone) HEPA Air Purifier on order -- the other one took 10+ years of constant operation and is giving it up. More on the new model soon...

I'm constantly opening and closing the blinds to use sunlight instead of lamps, then closure to prevent the "not-so-green House" effect in the afternoon/evening.

Originally Posted by larryrose11

Yes, these can be bennifical at cooling the attic, but generally, where the heat is coming in (summer)is where the heat is leaving (Winter), so a good sealing job (See above posts) is always in order. Also pay attention to the attic hatch. Think of it like a door. It my house, it was just a piece of plywood. I reinforced it with 2*4, heavily insulated it (I love foam board.) and put EPDM foam strip on both surfaces, the hatch and the ledge it sits on when in place. It seals nice.

The closet access and bedroom remains sealed and unused in the Winter. Still, a decent seal job would bode well for the colder months.

If you have ducts running through the attic area, they need to be well insulated and sealed at the beginning and end. PILE cellulose insulation on top of the ducts. Make walls out of cardboard to hold the loose fill in place. If the ducts are metal, then I know that there are leaks along the path. Where they join are obvious problems. You can find the leaks by turning on the furnace blower, and with a stick of incense and a flashlight shining on the smoke. If the smoke moves at all while you slowly move the incense stick along the surface of the duct, then you found a leak. Seal up the duct leaks with aluminum tape, NOT duct tape. AL tape rocks!

I really need to get up there and perform a full inspection and assess the need for sealing. It's definitely on the short-list of priority items. The house is a 2004/5-build model -- my biggest complaint is the HVAC system (the sub-contractor frankly stinks and the equipment is less-than-ideal to put it politely).

leave 1 return open in the basement, but no supply's open in the basement.

The return is a challenge. There are 2 outlets that are sealed-off, but there is no dedicated return chute in the basement. Question: would a small hole in the return duct offer the proper air draw? The question becomes what size, and would it require a runner...

Great discussion!

RH77

[larryrose11]

Rh77,
Congrats on your house! Did you have any input during the build? If so, what were your upgrades?
In general, builders want to do the minimum required (code) unless otherwise specified, especially on the energy / air quality side.

One more thing about home sealing: The house / foundation interface. In my house while in process of finishing my basement, I got up there to take a look. BIG gaps. I vacuumed and sealed this interface w/ GreatStuff. The basement temp went up 7 degrees! A 1/8 of an inch gap in a 1000 ft sq basement is the same as 1.31 sq foot hole!!!! This solution worked, but during the latest remodel, I had the polyurethane foam installer just back fill these areas, because there were more leaks than I could find, and this was a cheap solution given he was already here, and how much a pain in the ass it is to work there.

ON HVAC: the installer wants things to go in quick, so the compromise is air leaks in the system. This may seem like not such a big deal, but it is. As I said, an built to code home will have about 30-50% of the air leak out of the ducts. Half of the air not arriving or coming from its intended location, so some areas get too much (heat or cold) and other areas don't get enough. This is especially true on the joist covered return ducts. They are usually horrible: Big gaps, wire penetrations and just missing material. The supply and return ducts need to be sealed at every junction. This is easy in a ranch, not so much in other styles. Still, you should do this wherever you have access.

On solar gain: If you are more concerned about cooling than heating, or you live in a climate that is cloudy all winter, like here in south east MI, window films on your south and especially west facing windows are an option. They are cheap and effective, DIY solution. Google Solar Window Films.
This is available at home depot:
Gila Film Products : Residential Window Film - for your Home and Office - Reduce Heat Glare and Fading while Lowering Energy Costs
a better product:
3M™ Residential Window Films

[bryn]

don't forget windows.
windows are terrible heat loss. even the best on the market right now are just over 3R.
we have curtains made from a fabric from Warm Windows , the manufacturer claims 7R.
it makes a huge difference.
there is a bigger return fixing the really bad areas first.

[aerohead]

Originally Posted by Daox

To go along with adding the soffit vents I'm looking at adding some insulation to the attic of the house. It currently has 6" of fiberglass insualtion which is supposidly around an R-19. The recommended R value for my area (Wisconsin) is R-49! So, I was thinking of blowing in some cellulose on top of the fiberglass to boost it up to R-49. However, I'm also wondering if it would be worthwhile to go a bit higher than R-49? Does anyone have any info that compares added insulation to energy savings?

Doax,as you probably know,your heat transfer coefficient is the reciprocal of your R-factor.It's kinda like the drag coefficient,as in this case,for your ceiling.So the lower the number,the less drag(on your pocketbook).Going from R-19 to R-49 shifts your U-value (like Cd) from 0.0526,to 0.0204.-------------------------- Say on a hot summer day,and the attic was at 110-degrees,and you were trying to keep the house at 78-degrees inside,then the heat transfer you have now would be your delta-T ( 110-78 degrees) times your U-value(0.0526),times the area of the ceiling.So say for 1000 square-feet,you'd have [ 32 (degrees) times 0.0526,times 1000 (square-feet) = 1683 Btu/hour entering the house through the ceiling/per 1000 square feet.-------------------------------------- If you go up there and blow the cellulose,and get the R-factor up to 49,for the same design conditions,your new cooling load would drop to 1030 Btu/hour,for each 1000 ft.Almost a 39% load reduction at the ceiling.--------------------------------------- You could throw in some numbers for the winter and calculate your heating load as the ceiling loses your precious heat.Say at 30-degrees in the attic,and trying to maintain 68-degrees as recommended by utility companies,adding the insulation would save you 1225 Btu/hr.

[Daox]

Thanks Phil, that is great info!

[aerohead]

Hope it helps!

[RH77]

Originally Posted by larryrose11

Rh77,
Congrats on your house! Did you have any input during the build? If so, what were your upgrades?
In general, builders want to do the minimum required (code) unless otherwise specified, especially on the energy / air quality side.

Thanks! (Of course there's a story ) I owned a small starter townhome at the time, got married, and needed something bigger. We looked a long time and found a lot of overpriced junk or inefficient floorplans. My Wife's best friend (since elementary school) and her husband bought in a new neighborhood and kept noting that one house down the street sat empty, 80% complete, identical floorplan to theirs. It was probably 6 months. We took a "self-guided tour" at first and after the long search, the start ended up at the finish. The trick, we knew how much to offer (a bit more on lumber prices) and got a great deal Think "Colonial" floorplan with a modern exterior (plus a 3rd "mini-garage" to work on projects).

To answer the question, we got to pick the carpet and dishwasher. Everything else was already in-process or complete. The plus, was not having to deal with the build process, but we didn't get to choose the HVAC equipment (which I'm pretty particular about).

To shorten the story, we moved in, and...

1. The HVAC wasn't wired at the 'stat
2. Summer #1: Freeze-up and failure of the A/C -- low freon level (blamed as not having been charged properly).
3. Summer #2: Froze-up again (when my folks visit from Ohio and it's 100F out). Turns out they failed to seal the system and it was leaking the whole time.
4. Summer #3: Re-wired the blower to full-speed on A/C since it ran constantly on "low", but "hi" in the Winter. Ute bills much lower now.
5. Then, lightning took out the A/C compressor's capacitor (cheapy GE item). Service call and the whole bit.

On an HVAC forum, I'm told that the A/C unit SEER rating is barely enough to handle the square footage. Plus, the backup gas burner (heat-pump primary) is a real fuel hog. If I had the cash, I'd rip out the works and start it right.

One more thing about home sealing: The house / foundation interface. In my house while in process of finishing my basement, I got up there to take a look.

Good idea -- that may be the next step this fall. There's just fiberglass insulation stuffed in there and you can really feel the air in the colder months.

ON HVAC: the installer wants things to go in quick, so the compromise is air leaks in the system.

From what I can see, I'm actually pretty impressed with the actual ductwork. Things are sealed well in the basement (with sector shut-offs to direct air where it's needed). The downfall is the air return. You can see (and hear) the main return duct suck inward in a loud metallic pop when the blower engages. I have unused rooms closed-off and the whole works. Not sure what the deal is there. Most of the design is inside-wall air return. Some return vents don't have a speck of dust, so it's just poor flow design.

On solar gain: If you are more concerned about cooling than heating, or you live in a climate that is cloudy all winter, like here in south east MI, window films on your south and especially west facing windows are an option. They are cheap and effective, DIY solution. Google Solar Window Films.

Our friends with the same house has the tinting and has a big difference. We just need to do it -- again asset allocation.

Thanks for the ideas -- my "honey-do" list needs a new notepad

Originally Posted by bryn

don't forget windows.
windows are terrible heat loss. even the best on the market right now are just over 3R.
we have curtains made from a fabric from Warm Windows , the manufacturer claims 7R.
it makes a huge difference.
there is a bigger return fixing the really bad areas first.

We have blinds, but I'm concerned about drapes and dust collection for allergies. We both suffer from indoor allergens. Good suggestion, though!

RH77

[jonr]

A couple of points.

1) I recommend that anyone with only fiberglass bats in the attic blow some cellulose over it. Fiberglass suffers from ducting - ie, channels that allow air to move.

2) Do not seal up the attic. It needs to breath - that's why they have soffit vents, ridge vents, etc.

[larryrose11]

jonr,
Perhaps I mis spoke: When I said seal up the attic, what I meant is to seal the living space from the attic space, not seal up the soffits and such. Yes, attic space needs to breathe. But it is important to seal the living space from the non-living space
Air Seal and Insulate with ENERGY STAR : ENERGY STAR

On cellulose, your comment is why I said seal up the attic from the house. Cellulose doesn't seal up air movement until it is packed dense, about 2.5 lb / cu ft which you can't achieve with just loose fill, gravity settled, hence the emphasis on the GreatStuff foam.