House temperature reduced from 93 to 83 degrees

[framistan]

I wanted to get my house cooler in the summer, so I installed two roof-turbines.

I monitored temperatures in the attic... 140 degrees... and house temperatures stayed at about 93 degrees (without AC)...  The roof turbines had almost ZERO effect!  so I placed a BOXFAN under one roof turbine... still only made a couple degrees difference! So i cut some big holes in my SOFFIT to let cooler air in... but it still didnt make much difference in ACTUAL MEASURED temperature up in the

attic. Most people place a turbine up there or two and feel good about it... but actual temperature measurements might make you rethink it!  Finally, i bought some cheap 1/4 inch thick styrofoam in the fold-out sheets. it costed about 200 bucks to

cover the whole attic CEILING as pictured here. I had to do the belly-crawl up there

for a couple days... but NOW my attic is down to about 115 degrees! and the house seems to stay no higher than 83 degrees with air conditioning OFF!  After many months of measurements and experiments,  i believe the summer house temperature is a result of ATTIC OVERHEATING plus AVERAGE outside temperatures (day vs night). I was surprised to realize the OUTSIDE temperature at night gets pretty low, even in summer... about 70 degrees commonly here in St. Louis.  But the daytime temperature can get up in the 90's. making the average about 80.  But if you ATTIC is 140 degrees then your home will not be 80..... it will be about 90!  so, I wanted to post this to help others who may want to reduce their homes overheating in summer. This method worked for me... but once you get attic temperatures down to about 115 degrees, then further attic cooling is not much effect due to the AVERAGE day/night temperatures tend to keep the house at about 80 to 83 degrees. We have found that

83 degrees is about the upper limit of comfort without running the air conditioner.

We have not used airconditioning much at all this summer since i did this to the attic !!!

The effect of the insulation makes the heat rise up and out through the roof turbine, and pulls cooler air in through the soffit vents i cut open.  Here's a picture of the finished attic with insulation attached to ceiling.  I used cheap poker chips as large washers so the screws wont pull through the thin styrofoam. Any gaps in the edges of the styrofoam must be tight for best effectiveness.

[David HK]

This is very interesting.

Can you expand on what your house walls are made out of and how they can be heat insulated to reinforce the thermal roof insulation so that you can keep your lower rooms cooler in summer and nicely warm in winter.

David in HK

[framistan]

My house walls are just standard frame construction insulated walls. house built in

about 1973.  My attic you can see has minimum insulation only covering the rafters about six inches deep.  The picture at bottom shows one of the wood panels i used to crawl around on up there.  I dont claim this helps WINTER heating temperatures.  But it did help keep summer temperatures down. I forgot to mention it... but sheets of card-board would also probably work, and might even work BETTER!  because i read somewhere that cardboard has double the insulation value of the 1/4 inch styrofoam. however, cardboard is not waterproof and looks "tacky." I plan on adding more attic

blow-in-insulation before winter. FRAMISTAN

[GeeMac]

The main purpose of attic vents is to prevent moisture build up from condensation in the winter time, which could lead to damaged wood and insulation, rot, and mildew or mold, and to relieve extreme heat build up in the summer. Without proper ventilation in the summer, the air temperature in an attic can easily exceed 100°F (38°C), which causes a home's central air conditioning to run harder than necessary to cool the home as well as causing damage to the wood, roofing, and other building materials over time. So, I hope you have not sealed the area.

[SeanR]

Another thing to consider is the roofing material. If you have asphalt shingles the added insulation just under the ceiling is not a goot idea because the heat in the shingles has nowhere to go so they will get even hotter in summer. This wil reduce their life dramatically. If you look at a roof, shingles on the sun exposed side usually get much more damage quicker.

But if you have other roofing material then my comments are useless.

Best for asphalt shingles is lots of ventilation in the attic and lots of insulation between the attic and the room below.

Sean

[framistan]

I have added MORE ventilation!  The 2 roof turbines and several soffit vents. Both areas of the attic are ventilated. the "upper" area above the styrofoam vents out the turbines.. and the "lower" area below the styrofoam vents out the same 2 vents

as it always has.  That is a good suggestion that i forgot to mention about ventilation, thank you. however attic temperatures at my house were EASILY 140 degrees every day the sun shined. Now, the 140 degrees is ABOVE the styrofoam. It didnt seem to make the temperature any hotter, just pushed it UP away from my ceilings and OUT the roof turbines.  So i don't think it will hurt the life expectancy of the roof shingles.  I took many many measurements with remote-wired probes.  If your attic temperature is 115 degrees or lower, it is probably not a problem.

Here is a diagram to help a little.

[GeeMac]

It looks, to me, as if moisture might accumulate in the attic area below the styrofoam. Ask a certified home builder what he thinks of your idea. Check the area a few times to see if there is dampness on the overhead styrofoam and check again when it gets cooler. If dampness does accumulate you will need a vent hole(s) in the styrofoam too. You do not want moister to get into your ceiling joists.

[framistan]

Your comment is a good lesson to me and anyone planning to build anything.  It is good to do lots of thinking and research before starting any project.  There are LOTS of things to consider before starting construction!  Is the idea waterproof... is it fireproof... is it against housing standards... is it tacky looking... will it affect airport landings...?? etc etc...  In my idea... I do not want anyone to build something that would cause moisture problems in their house.  So be sure you have done your research before building YOUR attic like mine.  My house has a vent

on both ends that still serve the UNDERNEATH section of the styrofoam. The styrofoam has been up there two summers and one winter and i have gone up there several times to do tightening up of the gaps and other wiring things.  There is no moisture building up anywhere.... but thank you for your comment as it will be a warning for anyone else contemplating this project for their house.  Here is a picture of the vent on my attic to show what i have.  FRAMISTAN

[spinningmagnets]

Whenever there is housing constrction nearby, I can often find fairly good sized pieces of flakeboard (OSB) in the trash bins. I save them up as they are useful. One of the things I did on my last houe is to nail down a roughly 3' platform around the attic entry hole, and also a walkway down the center.

I like your idea and it makes sense. I had installed a thermostaically-controlled fan on one of the attic end vents ($65). It was powered by an on/off switch I put by the attic entrance. When it was hot enough to need A/C, I would turn it on, and the thermostat would kick it on when the attic was 100F.

I wanted two of them (two end vents) and it was just dumb luck the first one was installed over the house instead of the garage. After subtracting my winter electrical baseload, I calculated I was saving about 30% of my A/C bill during about 5 months a year.

I moved, but my plan was to also install a "whole house" fan ($260). Its a slow moving quiet multi-balde 3' fan thats installed in the center of your house in the ceiling. Of course you don't run it at the same time as A/c, but it reduces the amount of time the A/C is needed. It pulls air from the house and pushes it up into the center of the attic. The air exits the attic where-ever it can. I was also going to install two of the solar-PV powered electric "chef-hat" turbine vents.

Shading the OUTSIDE of windows has also made a noticeable difference. I think your "insulation forming ducting between the rafters" idea is great and well worth the effort and cost.

[zeusmorg]

 There are several ways to reduce attic temperatures, the easiest and most effective is to get rid of your black shingles and put on white or at least a light color shingle.

 My house cooling scheme incorporates 2 peak vents, a ridge vent across the entire width of the roof, and about 15 2"dia soffit vents.

 Also I use night ambient outside temperatures to cool the house down. I have 2 filtered vents in existing windows in the basement (filters for reducing dirt and dust) then I have a whole house attic fan that pulls air up from the basement throughout the entire house. This scheme works quite well, as I only have 1 small window A/C unit and i doubt it has been run 40 hours total this summer.

 The addition of the roof peak vent really improved the ventilation to the prior side peak vents only.

 I really do not think insulating near the roof itself a very good idea, as it can cause problems in a lot of climates. The ideal location for additional insulation is on and over your ceiling rafters. Any buildup of heat at the roof itself can cause warping in the summer, and condensation in the winter.

 I have R 60+ in my attic on the ceiling rafters, and even at 120 F in the attic (which mine never gets) very little of that heat would radiate downwards through that much insulation.

 I've also never thought much of turbine style ventilators a good solar chimney or peak vent system would be much more effective.