Help me cool down my house

[CoarsegoldKid]

I live in Central California at an elevation of 1500 feet with hot dry summers. My AC cooling electrical bill is very high for the 78-degree thermostat setting. I have only myself to blame for buying this 2004 era poorly designed house. I should have studied construction technology and architecture with an option in passive solar cooling instead of health science. Certainly the county engineers that approved the site and plans didn’t have a clue. Building codes only go so far in mandating requirements. God forbid they would mandate to save energy without added costs. And the builder and speculator didn’t think of the errors of such a design and placement. Be that as it may I have a nice house that was built with the wrong orientation to the sun. It’s too late to change that now. You see the house was designed with ten-foot overhangs 30 feet long placed on the front west and rear east sides of the house to provide shade I suspect during the mid day. The south side of the house has two small bedroom windows and north side of the house has one small bedroom window. All the rest of the windows are on the, you guessed it, east and west sides. There are two skylights over the living room. Except the morning and late afternoon sun heats the walls beyond my ability to withstand the burn when touched. This heat migrates through the walls and into the house. Duh!

Under the over hanged areas on the east and west side’s it gets might hot during the day. During the day the air beyond the overhangs is hotter than under but as the day progresses into evening the hot air under the overhang is trapped and doesn’t escape away from the house and it becomes considerably hotter than the air beyond the overhang. North and south sides are cool. Eventually by 2 or 3 in the morning air temp has stabilized and the east and west windows can be opened for cool air. However I’m asleep at the time. There are four passive gable vents on the house and thin runs of eve vents; even the overhang areas have eve vents. The attic insulation stops short of the overhang areas. No whole house fans.

 

I would like to open the house to the cool air but without enough window area north and south there is limited flow I suspect to be of use. The east and west windows will only let in hot air, remember it’s trapped under the overhang.

 

Now for a solution I am seeking the advice of this forum. Maybe one or several of you have solved this on your house or someone else’s home or you may be a contractor that knows just what to do and are willing to advise.

 

I have not tried any of my own ideas yet. My first thought was to cut open and screen very large vents into the overhang’s attic space to give the trapped hot air someplace to go upward as it is not going outward like a novice would think. If that didn’t help my second thought was to install a whole house or gable vent fan in the vent hole made in the first thought. The fan could draw overhang area’s hot air into the attic space. I don’t know if the gable vents are of sufficient size to use fans. The thinking here is get the hot air away from the house walls and eventually start drawing cool air into the overhang area and subsequently into the attic space where the gable vents will expel the hot air. My third thought was to install a whole house fan in the normal way inside the house. The thinking here is if I open the north and south windows with the whole house fan the cool air will come in through the windows, flow through the house drawn by the fan up into the attic and out the gables goes the attic’s hot air. There must be some physical dynamics of hot and cool air involved here that I’m not familiar with but I seem to remember that hot flows to cold. I have also thought of venting from under the overhang to above the roof line in some yet to be known fashion as a method of allowing hot air to escape above the house. I lean toward using the second and third thoughts in conjunction but the gable vents may need to be larger or add roof line gable vents high in the attic. It also gets cold in the winter so I would hate to have more venting than needed in winter only to watch the expensive heated air escape. Your thoughts?

 

[notacop]

I have some of the same issues as you with an old house. Fortunately I can open doors and windows to the afternoon breeze but it dies down in the evening and we are left with 90 degrees in the house and lowering temps outside.

The best bet is the whole house fan. It will definitely move some air. You just have to wait until the outside is cooler than in to be of any use.

There has been recent use of barn roof structures in the desert that canopys the whole structure to provide shade. with a 6 foot opening between the residence roof and the metal roof of the cover air can move freely and kep you cooler. They left enough overhang to allow for the seasonal sun movement.

[Mike]

Well, it sounds like you're going to be fighting the inherent design flaws in attempting any fix. I have a few thoughts, though:

 

-First, you need to plant some large and relatively fast-growing deciduous trees, at least on the south and west exposures. I know California weather can fight landscapers, but if you have to irrigate (perhaps a drip-irrigation system?), it will be worth it. Trees can provide a temperature decrease on the order of 20-30 degrees farenheit, so they should be an integral part of your plan.

 

-If I correctly understand your thoughts on venting the hot air under the overhangs into your attic, I doubt if that will help. Mother Nature has a virtually limitless supply of heat and I would guess that this could possibly just contribute to heat in your attic, which would further add to your heat problem. If the accumulation of hot air under the overhangs is contributing to your problems, a better alternative might be to install some outdoor ceiling fans in the overhangs to encourage some air movement. The part of this plan that I do like is to increase the flow of air through the attic. That, in combination with added insulation, will reduce the transference of the attic's superheated air to your living space. It will also help you in the heating season.

 

-In addition to the planting of trees, is there any way to add lattice work or some other material to reduce the amount of sunlight impacting the surfaces under your overhangs? Again, live plants have a huge effect in reducing temperatures, and some vines growing through the lattice would not only screen the sunlight, they would contribute to a temperature reduction through evaporative cooling.

 

-I'd say "yes" to a whole-house fan, the idea being to draw cool air in from the outside during the evening. You mention your recollection that "hot air flows to cold." That's not exactly right. Hot air is lighter and less dense than cold air and tends to rise. If you were to open a door between a cold room and a warm room, the cold air would tend to rush into the warmer room, attempting to displace the less dense hot air. In order to maximize cooling, you need to work with this principle in mind. A whole house fan will draw out the hot air, which will be concentrated in the upper levels of your rooms (and perhaps more importantly, in your attic), and permit what cool air can be introduced to replace it. Also, when thinking of air flow, remember the cooling effect of air moving across your skin. The whole house fan can help in this regard by encouraging air movement, but you will feel more immediate relief from ceiling fans or portable room fans.

 

-Finally, the idea that your interior walls are so hot that you can't keep your hands in contact with them suggests to me that your builder may have scrimped on insulation in the walls. There are a lot of ways to address this, but you should get someone out to your home to do an assessment. If the walls are not insulated or under-insulated, blown-in cellulose insulation could make a huge difference.

 

Good luck!

[Firefight911]

Joe,

 

As you know, our house is not large or with the specific problems as yours but, we have a sun facing wall that you can feel the heat through by late afternoon.

 

Our solution, which cut our cooling costs by a full 1/3, was to add a whole house fan. Our difference is that we went with a TAMARACK fan. It is not loud, intrusive, etc. at all. Jamie and I sleep with it on many nights.

 

I still get a kick out of turning it on and watching/feeling the temps drop in the house when we kick it on.

 

My bet is that it would first draw the air from the overhangs to clear the hot trapped stuff. Secondly, you would draw the cooler surrounding air to replace it. Depending on your ability to draw/evacuate will dictate how quick it takes. We are using the 1000 cfm and it is very quick. There are multiple volume units to choose from and they have the flexibility to be installed both horizontally and vertically so you could even put one in a wall, etc. Their design allows them to drop into 16 and 24 on center beams/studs.

 

Wiring is simple and switching is via remote which does not require line of sight. Our unit is at the top if the stairs and we can operate it from the living room while watching TV.

 

One of several options.

[Aluminum_Butt]

Finally, the idea that your interior walls are so hot that you can't keep your hands in contact with them suggests to me that your builder may have scrimped on insulation in the walls. There are a lot of ways to address this, but you should get someone out to your home to do an assessment. If the walls are not insulated or under-insulated, blown-in cellulose insulation could make a huge difference.

 

+1 on this. I lived in Wildomar, CA for a time - Inland Empire - very hot in the summer. The stucco walls got hot on the outside, and there was obviously some impact on the inside, but nothing like what you describe.

 

I also like the idea of a whole house fan. It can likely be put on either a timer or a thermostat to address the time-of-day issues.

 

I'd consult with a couple of HVAC contractors in the area, and see what kind of answers you get from there. The advice and recommendations should be free.

[CoarsegoldKid]

Let me nip an idea that I must have created: The interior walls are not hot to the touch. It's the east and west exterior walls that are very hot and they conduct the heat to the interior. The walls are supposed to have R13 or so and the attic space R38. I can't remove material to check the walls to check insulation R value. In the attic the insulation just barely rises above the 6 inch joists so it's likely less than the stated certificate.

[tallman]

More insulation, where possible, create shade where possible, add ridge vents (if applicable to your part of the world, gable fans will move some air, whole house will move you out of Kansas.

Ceiling fans to maove air on the porch or inside will make a difference in how it feels with the moving air.

We had a sunroom that was not insulated and we are just finishing a renovation with wall insulation, sheetrock, insulation in ceiling and new sheetrock.

Probably a 10-20% gain in efficiency overnight.

The room used to be very hot, even with shades down and now, is cooler than it was with shades up.

Good luck.

[mrduck]

Joe, try some fruitless mulberry trees on the south and west sides. They grow fast, plenty of shade, lotsa leafs to deal with in the winter! I put a 3 foot deep, 6 inch pipe down by the base of the trees with a bubbler head hooked to the sprinkler system to keep them watered.

 

Also, is the humidity low enough for an evaporative cooler there where your at? Cheap to run and can be ducted into your exsting AC ducts. I have both AC and swamp cooler, only use AC when humid out.

 

Lotsa ceiling fans, gotta keep the air moving!

 

Living here in the desert, we learned some tricks for staying cool!

 

 

Good Luck

[azkaisr]

The Duck speaks of truth if you can get an EVAP

 

They are worthy devices

[Dennis Andress]

Evap cooling is awesome! Until monsoon season when humidity rises. Up Dux along with a cooler are incredible.

 

But, there is a better way ..... ( Camarillo weather )

 

 

[Twisties]

Joe,

 

We have used a multi-pronged approach. Strategic planting of trees and shrubs to provide summer shade and allow winter sun. Added insulation in the attic. Added ridge and eave vents to vent the attic. Built trellis to shade part of house and ran a grape vine over it (your overhangs sound like they do this). Changed to double pane high e wood framed windows from old single pane aluminum framed originals. More windows that open now too.

 

I don't know what trees for your area are, but I will say there may trade offs between fast growing and slower. Around here at least most of our fast growing options are those that tend to lose branches... not what you want right up by the house. Also, you'll want to be careful about roots interfering with drains, septic or your foundation.

 

I'm convinced from what you say that the insulation as installed was not as advertised. Our house is much older, so not sure how much of that applies to you guys.

 

Best wishes,

 

Jan

[SteveB]

Evap cooling is awesome! Until monsoon season when humidity rises. Up Dux along with a cooler are incredible.

 

But, there is a better way ..... ( Camarillo weather )

 

 

 

Dennis, that was just mean!

[SageRider]

Joe,

...Our solution, which cut our cooling costs by a full 1/3, was to add a whole house fan. Our difference is that we went with a TAMARACK fan. It is not loud, intrusive, etc. at all. Jamie and I sleep with it on many nights.

 

I still get a kick out of turning it on and watching/feeling the temps drop in the house when we kick it on....

We have one of these units in our house also. Not as quickly effective as a full blown whole house fan, but as with Phil, we just turn ours on and run it all night (or until I'm freezing...).

 

The whole house fan concept has two plusses. It brings cooler air from outside in, and blows the inside air into the attic, which cools the attic also.

 

We also have a couple of gable fans in the attic that are temperature controlled. Our attic gets hot enough (even during winter when it is 40 degrees max outside) to trigger these fans set at 110 degrees. We shut off power to the fans in winter to preserve this warmth...

 

The gable fans allow the air conditioner to shut down for the day at least 1 to 2 hours earlier than no gable fans.

Turning the Tamtech fan on while the gable fans are still turning really pulls a lot of air through the house!

[FrankT]

Here are my recommendations based on your posts:

 

1. Add vast quantities of attic insulation. From what you've said, you do not have enuf. I did this and it made a big difference. Just as we humans lose the most heat/cooling out the tops of our heads, so do our houses through the ceiling.

2. As others have suggested, plant trees for shade although this takes a while for them to grow.

3. Install an attic fan, this can be either gable or roof mounted. Mine operates via a thermostat. This may require additional gable vents for proper air flow.

4. Install also a whole house fan. Mine is manually controlled and I do not turn it on unless the attic fan has turned off and there is sufficient temperature difference between the house interior and outside to effect cooling.

[SteveB]

Your temps over the next 10 days are similar to ours here in Murrieta. We have moved since you came down for the tech day so we are no longer on top of the hill. That house was miserable in the summer and we dreaded the electric bill every month. Remember we work at home so we try to stay reasonably comfortable.

 

The new house stays pretty cool downstairs for most of the day without the use of the A/C. Unfortunately the front of the house faces WSW and the upstairs office can get toasty. We figured out shortly after moving in May that we should have chosen a different room for the office. The first thing we did was install solar film on the double pane windows to reduce the heat gain. We did 7 windows with the solar film and the leaded glass on and beside the front door with security film for $600 if memory serves. I truly believe we have recovered our money by reducing the A/C to very rare occasions this summer. Now that we are in August we have just installed a small (6500 BTU) window unit in the office. It hangs on the side of the house nestled into the palm tree so it disappears pretty well. Rated annual cost for the window A/C unit is $54 so we should be able to recover the $140 cost this month by not needing to run the old inefficient whole house unit.

 

One of the reasons we bought this house was the trees around the property. They make a big difference. Trees are an investment that won’t help this month or probably next year however they can help tremendously. Beware of quick growing trash trees (mulberry). Consider installing a GreenScreen with a deciduous vine to allow summer shade on the side of the house while allowing the winter sun to shine through. +1 on the whole house fan to take advantage of the cooler evening temps.

 

[rgl]

We have a very similar climate (Folsom) and having lived in 4 different houses battling this issue, here is what I have learned (mostly the hard way):

 

Once the sun hits it, it's too late, so obviously trees will help (eventually), but so will sunscreens, awnings and anything else you can do to KEEP THE SUN OFF ANY GLASS.

 

It's not the air that heats the walls but the sun.

 

Get the heat out of the attic, with vents or attic fans. Pick large diameter fans that turn slower (they are quieter). Don't fight the natural breeze, and make sure you have plenty of openings for replacement air to be pulled in. Contractors are not good at this, and always seem to block them somehow. If you have an asphalt roof, it will make it last longer.

 

Make sure your AC is working OK. Maybe you have a loose duct or trouble at the compressor. An HVAC tech can check this easily if your bill is not in line with your neighbors.

 

Venting the overhang on the west side should help too, but probably not necessary on the East.

 

Cover or shade the skylights, which are basically solar collectors!

 

A whole house fan is definitely going to help assuming you would sleep with the windows open, and it cools down soon enough that you can open up before bed. I've found the best ones have belt drives and more blades (6 is great), they have 2 speeds (not a rheostat) and mostly you leave it on low, with the right windows open to direct enough air where you want it.

 

http://www.trianglefans.com/wholehouse.html

 

Hard to add insulation to the walls but you can easily check the attic and blow more in for a few hundred dollars.

 

Loose the fridge in the garage or at least clean the coils!

 

Vent showers if no bath fan to remove humidity.

 

Good luck, and be happy that we don't have the heating bills that some do!

[brennaman]

We had the same problem with our house. We had an A/C specialist come out and do a complete check of our house. They pressurize your house, and find any leaks, (windows, walls, outlets...) They are also able to check the amount of air loss in your duct work in the house. We were losing over half of our air conditioning in the duct work itself. Also in our attic, the runs off of the main trunk were too small. They also used a thermal camera to see which walls had insufficiant insulation in them. There are way's to reinsulate your outside walls without taking off your sheetrock in the house. They found that my soffet vents were to small, and too few. After I opened them up my attic dropped about 15 deg. I am also in the process of installing some aluminum type insulation on my rafters in the attic for a radiant barrier. They came up with quite a few things we could do, too many to list, that helped quite a bit. Last year with these 95 deg. 70% humidity, my son's room upstairs would be about 88 deg. With all that I have done, which cost about $600, it is a comfortable 73 deg. I think you can find someone in your area at the energystar.gov website. The state of MO gives me the $500 back that the inspection cost if I show receipts for the work that they suggest. We are pretty happy. Good luck. Phil

[Shaman97]

Alot of good suggestions; let me add a few:

 

Insulation is important, but remember that insulation slows the transmission of heat (and cold) through it - it doesn't stop it. If your attic space is hot, and that's guaranteed, the insulation is soaking up alot of heat during the day, and radiating it into your house during the evening. This is where a quiet thermostatically controlled attic fan comes in - it gets rid of the hot air that is being built up in your attic. Better yet, lay down some Radiant Barrier after putting in a few more inches of insulation.

 

Use the whole house fan in the evenings and early mornings to bring cool air into the house via windows, and perhaps a storm door.

 

For both the attic fan and whole house fan solutions, make sure you have enough ventilation (roof vents, soffitt vents) to get the hot air in the attic out quickly.

 

If you can get the house inspection done cheaply - the one that uses the house pressurization to check for leaks - you'll be $$$ ahead.

 

Have your HVAC system checked. Have the coils cleaned, pressure checked, and the ductwork inspected.

 

Grow the deciduous trees as others have suggested.

 

Ceiling fans in every room - they're great for evaporative cooling while you're in the room; turn off when you leave.

 

Swamp coolers are good, but you may have to have the ductwork reworked to gain the best benefit from it as a first stage of cooling - put the money elsewhere first.

 

Anything you can do passively is better than everything you do mechanically.

 

[CoarsegoldKid]

Everyone including Dennis has offered good ideas many of which I have pondered. I wish I had not misplaced my camera because pictures of the overhang would have gone well with my description of the problem.

Trees, yes. The best trees to grow here are oaks. They take precious little water but grow slowly. I'd like more trees to shade the house however we live in a fire prone area and trees up close are a no no. In fact Farmers Ins dropped me because of the trees I have. We are growing water thirsty Redwoods as fast as we can on the west(front) side but I think it will be 10 years before they even shade the ground in front of the house. On the south side some shade would be welcomed. A pergola would do it. Growing anything there would be next to impossible as even the weeds don't like that dirt. In the meantime on the to do list is shade foil on the south bedroom windows receiving direct sun and maybe even 75% shade cloth over the outside of those windows like I did the skylights which made a difference in the living room.

Moving around in my attic is a real exercise for contortionists. I tried. So gable fans and extra attic insulation will surely be done by contractors. I know what company did the insulation. Maybe I'll call them out to give it a look see what is needed and when they tell me it's not R38 I'll pull out the certificate they issued.

 

I may be able to install the whole house fan myself so it's on the to do list. Summer is not the time to go up into the attic. But I think I might be able to wire up a cheaper whole house fan in the outside overhang using existing light wiring, don't think I'll hear it if it's outside, and it could force the hot air out of the attic through the existing gable vents with somewhat cooler air from the outside. Also on the list will be to take out an east window in a bedroom and move it to the north side in the same bedroom.

[ESokoloff]

Lots of good tips already.

 

What is the color of the exterior wall(s)?

Lighter will reflect the most sun/heat.

[onmyrt]

Lighter will reflect the most sun/heat.

 

If you use Google Maps in Satellite mode to view homes in the Phoenix area,

you'll notice that many of the roofs are either white, or very lightly colored.

 

I've read that just having white roof shingles can lower the summertime temperature in your attic by up to 70 degrees!

 

That has got to translate to lower energy costs.

 

[Knifemaker]

has anyone run a proper heat load calculation on your house? No matter what you do if your AC unit is not properly matched with your heat load calculation the AC unit will never shut down and properly cool if the the unit is not sized correctly.

[Lynn]

I do have one idea (in addition to all the other ideas folks have for you). Since you have said it is going to be a while before your trees get big enough to help, can you hang some kind of shades from your overhangs to block the sun and keep it from getting so darned hot under there in the first place? Some of that probably depends on how windy it gets there and how your eaves are placed.

 

I can say that we have this type of shades on our porch that we put down most of the day to keep it cool(er), and then open them up when it gets dark. I am thinking of the inexpensive outdoor types of roll-up shades like these:

 

http://windowdesigner.com/vinylbamboorollupshades.html

 

It makes a huge difference in the back side of our house to not let the porch get miserably hot in the first place, rather than trying to cool it down after it is already too warm for comfort.

 

 

[CoarsegoldKid]

No heat load commisioned by me. But the AC is running according to all that I've read on the subject. Walls are gray. Roof is black. Wrong I know but the roof is also 4 years old so I won't replace it but I might apply a reflective coating that I've seen for this purpose. I'm afraid of the look though.

I've also put roll up shades as an experiment. They cool the walls a bit but the western sun is brutal. Shades were purchased at Lowes and the mechanism is poor and the wind has damaged the west side to the point where rolling up at night is a chore. I stopped using the east side roll ups figuring I was trapping the heat with them in favor of a different shade that does not go floor to eve and frankly there is no difference between the temperatures on the east or west.

 

[eddd]

I read through the responses rather quickly, so forgive me if someone already mentioned this: radiant barriers.

 

Two years ago I had a new home built. Since I was starting from scratch, I was able to design the home to get maximum value from the energy used. I'm all electric, and my bill is always WAY below anyone else, due in large part to my radiant barrier. While the radiant barrier I used is not practical for your house, there are several types that could be used in your situation. I'd suggest a google search and contacting local suppliers. (some types are dyi).

 

Let me know if you need more information.

[Shaman97]

No heat load commisioned by me. But the AC is running according to all that I've read on the subject. Walls are gray. Roof is black. Wrong I know but the roof is also 4 years old so I won't replace it but I might apply a reflective coating that I've seen for this purpose. I'm afraid of the look though.

I've also put roll up shades as an experiment. They cool the walls a bit but the western sun is brutal. Shades were purchased at Lowes and the mechanism is poor and the wind has damaged the west side to the point where rolling up at night is a chore. I stopped using the east side roll ups figuring I was trapping the heat with them in favor of a different shade that does not go floor to eve and frankly there is no difference between the temperatures on the east or west.

 

Take a look at Sun Shade screening. You can do it yourself, and it's alot better than having to go out every day to raise/lower the shades.

 

Phifer is the largest manufacturer of the stuff that I know about. Not very cheap, but it is DIY and effective.

[ESokoloff]

...the AC is running according to all that I've read on the subject.

 

So you have about a 20* split across the evaporater coil?

 

If you have a split system (half outdoors & the other half indoors) then when the compressor is running, the vapor line (the big/insulated one) is cold & sweatting?

 

These do not prve that the unit is operating properly but they can give you an indication the al is Ok or not.