Thanks all!

My husband and I would love to keep windows open at night, and we live in a “safe” area (or so we like to believe), but there’s another member of our household who has extreme security anxiety so...most windows will be closed for now. His idea was to install a ceiling vent in each bedroom to draw warm air up and out. Maybe not such a crazy idea, especially since we are not fond of nighttime AC?

The insulation has yet to be ordered, so perhaps we still have time to tone it down somewhat. I do like the idea of sound insulation though!

Have you considered ceiling fans in bedrooms?

Remember you need to provide replacement air for any that is exhausted from the house. Any exhaust will need to be sized such that it can make a difference.

Virgil Carter, yes we have prepared for ceiling fans in each bedroom.

PPF, well my definition of “warm“ is probably quite different than yours since you are in AZ, but let’s just say it is almost always too warm for this middle age lady! seriously though, nighttime temps are usually somewhere between mid 50s and mid 60s. I know I should not complain!

Mittens you can work with the security anxiety. Do you have an alarm system? If you don't, you should get one. We are in what would be considered an extremely safe area and break-ins at all times of day are getting more common. They used to care if people were home, but they are becoming more bold.

With an alarm you can set the perimeter alarm with the windows open, by placing a second sensor in the open window position. Just make the opening narrow enough that a person trying to break in would need to open the window wider and thereby breaking the sensor contact and causing the alarm to go off.

You anxious person should be able to accept that compromise? You can now keep windows open and still know if someone tries to break in. I would still strongly suggest you look into a whole house fan. So CA weather is truly the best climate for them.

Your home needs to be designed and constructed to work as a system. There is more to this than simply meeting code-required insulation R-values and more to conditioning the interior living space than opening and closing windows, running fans or turning the air conditioner on or off for occupant comfort. Invest in design professionals who know what works in your climate zone and what doesn't and you'll have a healthier, more energy-efficient, and more sustainable home.

@chispa, thx, whole house fan was installed with new HVAC system last month and security system is being bid on now. :) Alas, anxiety always seems to find a new worry to thrive on.

@Charles Ross Homes, we presumed our architect knew all this stuff ( and I'm not saying he doesn't), but after telling me yesterday that interior wall insulation was required, now he said no it is not required (I think he just misread my original message). That's why I'm wondering if we should do cut down on the amount of insulation in interior walls to let things breathe a bit more?

I don't know what else we can do this late in the game besides roof vents over the limited attic space (only one bedroom has attic space). Our town has a very tough design board to get through, so you can't go changing plans without a long process. Maybe a huge layer of tin foil over the roof? lol

Radiant barrier on top of the inside ceiling, if you can’t place it under the shingles, will make a MASSIVE difference. The interior insulation won’t hold heat, and will not restrict “breathing”, but it’s strictly your call.

I'll look into it! Insulation starting Wednesday, so...!

We've been designing and building dwellings for thousands of years, but the "science" part of "building science" is relatively new. In my experience, most residential architects--and for that matter, most builders-- know very little about building science nor plumbing, electrical, or mechanical systems beyond prescriptive code requirements.

I recommend you get your home design reviewed by a building science consultant or a HERS rater familiar with best practices for your climate zone.

To be sure, you want to design wall assemblies that can dry out when they get wet, but you don't want a home designed to "breathe." You want a home that's designed to keep the outside environment on the outside and which provides proper control of the indoor environment.

In CA radiant barriers are effective. I've been using them since 2003 with noticeable reductions in heat gain and never looked back. The last energy code update had us sometimes installing an additional layer of insulation against the bottom of the roof deck in addition to the ceiling in order to keep attic HVAC systems cooler. The roof deck insulation negates the radiant barrier, but is more effective.

At night the heat your home gained continues to heat the home even from the attic. Verify this for yourself by feeling the warm ceiling after a hot day.

Attic fan(s), whole house fans and/or possibly running your AC on "vent" without the expensive compressor/cooling running, with a make up air/outside air exchanger could provide the effect of "leaving the windows open" without the security issues. Installed several client requested whole house fans this year in new builds but now realize most don't have the will to operate them properly & effectively so will be researching a more automated solution.

Beefing up West facing walls is a good idea.

I recently bought a small two story second home in a SoCal coastal area that's 20 years old and has a stucco exterior. Even on mild days (which is to say, most days) the west walls get quite warm to the touch. Warmer than the ceiling. That heat and also that from a reasonably well ventilated attic radiates into the interior for hours and hours and unless there's a steady breeze blowing throughout the evening, closing the windows means the inside temperature will increase. I've found there's no substitute at such times for using the AC to remove the heat.

There's a school of thought that attic fans aren't a good thing to have. The louvered opening between the house and the ceiling usually doesn't seal tightly and so provides an ingress path for air from the attic to the house. Think of turning on a bathroom fan or a kitchen exhaust fan in the summer or winter and having that air come in. If the louver can provide a tight seal when not in use, different story.

@Jeffrey R. Grenz, General Contractor, thanks much! And good to hear from a fellow Californian in a summer hot spot. :)

Our place is a 2,200 sq foot single story, and we opened up most of the ceilings while remodeling, so the only dedicated attic space is above one 12x14' bedroom, two small bathrooms, a couple of hallways and a walk-in closet. New HVAC already installed, and insulation and drywall to start this Wednesday. Wish I'd thought of radiant barrier earlier, but that's where we are. Is it too late? And any idea what cost we should expect if we can arrange it?

Here's a visual of main living space if it helps somehow (there is now HVAC flexible duct traveling along the space above sliding glass door on right).

Also, I always thought a "whole house fan" was the same thing as setting our HVAC to "fan only" (no cooling or heating). Another thing we should have thought of, I guess! Thanks again for your input (everyone else, too).

@Charles Ross Homes, I definitely want our house to "breathe" as much as possible. I'm such a fresh-air fanatic that I actually hesitated quite a bit on insulating the house (since it had zero insulation previously and we lived there for 20 years). I don't mind putting on an extra fleece in the winter, but I hated the extra heat in the summer.

And yes, we need more building science! So much conflicting (and poorly written) info out there in Internetland....

You’re not over insulating anything. If anything, you are under insulting. R-13? Really? That’s code minimum in a warm

area. You can do so much better than the lowest level allowable.

Spend a couple of weeks reading here. https://www.buildingscience.com/documents/building-science-insights-newsletters/bsi-026-they-all-laughed

Most likely your attic heat was radiating into the home at night before if it didn't have insulation.

If your vaulted ceilings are also the roof, there is little attic to vent, so ask your builder or architect if a whole house fan or powered attic vent would be effective. If the roof is new, it typically will have some mandated reflectivity that will help.

Likely the architect controls the energy calcs and related design, so start there.

CA energy guidelines are good, but designed to work with the AC (and/or heat) on.

Attic fans, whole house fans and the AC fan without the compressor cooling on use a fraction of the AC cooling.

@Jeffrey R. Grenz, General Contractor, yes, at night it definitely felt we were being baked from above! Also from the west-facing walls. Granted, my son and I seem extra sensitive to heat. My DH and the cat barely noticed, lol. And the roof was finished yesterday, so I'm guessing we are too late, alas. :(

@GreenDesigns, I'll add that to my reading list. We had zero insulation in the house for 20 years and survived, so, to me, installing R-13 in the walls and R-30 in the ceilings sounds like we're about to be wrapped in a double winter coat! :)

@Mittens Cat,

It sounds like your definition of a house "breathing" is what you get when you have a leaky house due to poor insulation and air sealing. It's difficult to control the indoor environment in a leaky house. A better approach is to build the home tight and installed a controlled ventilation system which provides fresh air make up to the home and maintains the ability to control air quality. Depending on your climate, you may wish to consider an ERV or HRV for that purpose.

I'm in the camp that believes whole house and attic vent fans are generally not a good idea, but I'll qualify that by saying my experience is limited to a mixed-humid climate. In a mixed-humid climate a whole house vent fan can depressurize a home and can pull moist air and soil gasses from the crawl space into living areas and even stud cavities. Plus, you lose the ability to control indoor air quality for example, the ability to filter dust and pollens and control humidity. I recommend you consult with a building science consultant or HERS rater; they'll know what best practices are for your climate zone.

I think you could place a radiant barrier before Installing the drywall on the ceiling, under the insulation. Anyone know for sure?

@User, thanks, I presume it'd be a whole lot easier to put the radiant barrier in first, before the ceiling gets stuffed with R-30 fiberglass batts. I also read it's important to leave a gap of some sort between and insulation and radiant barrier. Wondering how that can happen when there's so little room up there as it is. @Charles Ross Homes, I contacted a couple of HERS raters, hoping they aren't too busy! :-o

In a hot climate if the insulation is in the attic floor, the best location for a radiant barrier is on the bottom face of the roof sheathing.

The term “breathe” in regard to a building envelope generally refers to interior water vapor escaping through the envelope.
Introducing fresh air to the building is referred to as ventilation.

Reflective radiant barriers must have one side unobstructed to be effective. It cannot be in a "sandwich". The bottom side of the roof when insulation is well below at the ceiling works best; however, newer CA requirements need an increase that is usually obtained by adding insulation to the roof as well as the ceiling, rendering the reflective barrier useless as it creates a "sandwich" .

Its one or the other.

@Jeffrey R. Grenz, General Contractor, thanks for the expertise!

It seems there's so little room for anything up there as it is. Maybe an umbrella over the whole house would be the best option at this point...neighbors would love that. :)

No, you don't install a radiant barrier at the attic ceiling level--either under or over insulation. It works at the underside of the roof sheathing to reduce the amount of heat radiated into the attic space. You can still install a radiant barrier if there is room to maneuver and install foil faced insulation between the rafters. Here's a link to additional information:

https://www.energy.gov/energysaver/weatherize/insulation/radiant-barriers

@Charles Ross Homes thanks, i needed that very piece of info!

Thanks Charles. I know deck is preferred, but we also install on the floor around here...so I wasn‘t sure. It looks like mittens can install a radiant barrier directly on the exposed decking? I assume using a perforated type.

Radiant barriers should be installed under the roof sheathing for best results. Radiant barrier sheathings are available, and they have a good track record. A radiant barrier can be retrofit between the rafters, but it is discontinuous at the rafters and it's pain to install after the fact.

I would avoid use of a radiant barrier on an attic floor (above the insulated ceiling in living area) because it's effectiveness is reduced if dust accumulates on the radiant surface (which is highly probable) and because there can be a potential for condensation in the space between the radiant barrier and insulated ceiling below. Unintended consequences are why professional input in the design phase is so important.

Couple points I think have been missed....we have ceiling exhaust fans...if they are big enough... they are very noisy ...(still better than a.c.....but loud)...and leaving the windows open all day is nice but it lets the heat in...to avoid a.c.the house should be kept closed during the day...to keep it cool...in the evenings you turn on the exhaust fans and open a few windows or doors to pull the cool fresh air into the house...if this doesn’t suit your lifestyle needs then you will have to rely on the a.c. ...

@btydrvn thanks. I'd guess we'd run the ceiling exhaust fan during waking hours, probably in the afternoon up to bedtime, to suck out much of the heat in the attic. Hopefully there are improved fans, much like our recently installed whisper-quiet bathroom fans!

Re letting heat in through windows, not sure where you are, but here in coastal SoCal we have pretty steady ocean breezes....cool ocean breezes, so leaving windows open is our free AC. :) The exception to this is during the infamous Santa Ana wind conditions, where the wind blows in from the east, bringing all the hot, dry desert air with it (which makes some people, myself included, very edgy!). Fortunately that only happens a couple weeks per year.

To be honest, most of my neighbors would laughing at my angst over the cooling issue. Only about 10% of people in our town have AC because we're on the Pacific Ocean. But I installed it anyway, mainly for those Santa Ana days.

paint your roof white.

https://www.builditsolar.com/Projects/Cooling/FSECRoofPaperSummary.htm

oh, and keep windows closed during the day.

D E, neither of the white configurations in your link is a white painted roof. One is white metal, which uses a powder coating solution, much tougher than paint, the other is white tiles, where the color is through the tiles. Since white paint would rapidly weather and fail, and since it can’t be applied to shingles anyway, what was the point?

Funny, we were semi-joking yesterday about painting the roof silver.

The architect originally designed the house with a metal roof, but we nixed it to save $. Plus, I was concerned that a house topped by metal might make sound insulation worse, not better. We ended up just keeping the basic black composition tiles, and the final roof patching was completed last week (racing to prepare for inspection).

We are looking into solar panels and/or tiles, though. Perhaps they help somewhat?

Since white paint would rapidly weather and fail, and since it can’t be applied to shingles anyway, what was the point?

why do you assume paint would weather and fail? there are coatings that are specified for shingle roofs.

Ive also seen data with lime washed roofs(bright white) with no degradation after several years.

1) Because paint is a sacrificial coating.

2) Painting shingles invalidates any warranty, and can lead to very serious issues with the underlying deck.

3) Limewash is also a sacrificial coating and would not work on a asphalt shingle, as it’s designed to be absorbed by the surface. Surprisingly, to some, shingles are designed to shed water.

Mittens, solar panels would reduce heat absorption by the shaded roof below. They would also do a nice job of powering the a/c.

Mittens...with your added info I see we have different situations..our exhaust fans draw air directly from our home..yours will be cooling the attic only..so sound is probably not an issue for you...it may be possible to install a thermostat in your attic to automatically turn on the fan when the heat reaches a certain temperature...the open windows during the day will work perfectly and the a.c. will probably only be needed in the evenings...to cool off the house for comfortable sleeping as needed...does it cool off in the evenings where you are?...we live near the pacific coast in the mountains and spend the winters own your way....it is perfect weather in the desert in the winter...

Coastal SoCal where only 10% of neighbors have AC?
Sounds like where I live. We don’t need it, and couldn’t afford it in any event. Our gas and electric bills now run $500/mo on avg and we do use heater in winter (not my choice, wish we didn’t). Friends who do use AC near us, farther inland, report costs upwards of $1100+/mo. And going up, as you might know.
I would not have installed the AC. I’d work on security and venting, whole house fan if it makes sense, and solar to help pay for anything you do use.

@btydrvn, months ago, my GC spoke of a fan with attached thermostat--thanks for the reminder; I'll ask him today.

@Mrs. S, yeah, I feel kinda guilty about the AC, especially since we're 1.5 miles from the ocean. But we only use it in extreme cases, maybe 8-10 days a year? I've had heat stroke twice and am much more sensitive to heat now because of it. I usually stick with cold drinks, wet washcloth around my neck and portable fans, but just having the AC "just in case" there helps bring down my heat anxiety.

Really hoping to do solar panels at some point!

3)" Limewash is also a sacrificial coating and would not work on a asphalt shingle, as it’s designed to be absorbed by the surface. Surprisingly, to some, shingles are designed to shed water"

sorry but I can tell you have not used limewash and are assuming based on false theory.

I have limewashed a roof and it works quite well. It also reduced my electric bill by almost half since my ducts are in the attic.

as far as paint, I have no experience there but I know there are paints that are advertised safe for using on asphalt.

anyone interested in the benefits of limewashing a roof in a hot climate should read these

https://www.builditsolar.com/Projects/Cooling/MobyDickRoof/MobyDickWhiteRoof.htm

https://www.builditsolar.com/Projects/Cooling/WhiteRoofExperiment/WhiteRoof.htm

https://www.builditsolar.com/Projects/Cooling/MobyDickRoof/TheWhitenessoftheWhale.pdf

Guilt around a/c use is of course common in CA but kind of silly. I have a relative - somewhat inland but at elevation - who don't really use their a/c as much as I would like when I visit. The one pickier about a/c use drives a F-250 truck. So whatever environmental motivation is a bit suspect. Mostly, he is disgusted at spending $.50 a kwh - which I kind of understand.

A/C use is so easily covered by solar that it is a minor issue compared to driving a gas car let alone a SUV or truck. Last time I was in CA, people still drive SUVs ... almost as much as anywhere else.

In general, attic based powered fans are a bad idea. Now - semi-arid may change that. In the SE, the negative pressure created in the attic increases infiltration by depressurizing the house. Usually the insulation values in the attic and the tendency for heat to go up, really minimizes the downside of hot attic temps. Does not make them go away of course but a radiant barrier is a much cheaper and more effective thing to do.

You need adequate ventilation - much more than worrying about insulation.

Note: In case anyone misconstrued my meaning, I didn't intend that anyone (or even me!) should feel "guilty" about installing or using A/C... ...the only guilt I would feel is that I overspent $$ out of our budget. If I had A/C, I'm sure I'd run it, and then have regrets when I saw the bill.

The other thing about SoCal and A/C units is that they take up valuable real estate. Side yards here are often small, and the A/C units are obtrusive, and need maintenance as well. So, those are the reasons I'd skip it.

" Our gas and electric bills now run $500/mo on avg "

Really, and with no air conditiong? Sounds very odd to me. How much for each component? Where is the house located and how large is it?

" The other thing about SoCal and A/C units is that they take up valuable real estate. Side yards here are often small, and the A/C units are obtrusive, and need maintenance as well. . "

For houses with a flat roof, the condenser can be put on the roof. For narrow side yards, there are models shaped like a box fan, narrow with the fan mounted sideways that take up less than half the footprint of a conventional cube.

Do you know anything about air conditioning? It doesn't seem like it.

Carrier upright condenser, needs only 6 inches out from wall

" Guilt around a/c use is of course common in CA "

Seriously? This is of course BS, not the first time from you.

I'm a native of the state and have never encountered this attitude, not ever, not once. What is your "of course" information based on.

Family and friends that live there. I did live there for a time also and native also (Palo Alto). But big state for sure. Why so hostile? I have always lived in moderate (and fairly environmental, liberal) climes in CA. Since it is a big state, where do you live?

Also in Silicon Valley, a transplant from coastal SoCal in my 20s.

You seem to have a righteous, know-it-all approach to your comments that I think would come off better with a little humility. I've never ever heard any "guilt" about AC and in fact it's the opposite because summers seem to be getting warmer and in warmer coastal areas even up to Monterey Bay, humidity at and near beach areas on warm days s higher than it used to be. Still below East of the Rockies standards but higher than it's been.

AC in the Bay Area and warm coastal areas from here to the south has never been common. It's becoming so, now, being added to older homes everywhere and a standard for new construction. In the inland hot areas, it's been the norm for decades. I never lived in a house with AC and I think I'm fairly typical because I've added it to the two I own in the past few years.

But of course, you knew all that.

how much are you guys in california paying for electricity. mine here in north texas just went to 8.8c/ kwh .

If I were paying anywhere near what Im seeing in this thread my roof would be covered in solar panels.

Well, I really don't want to get into all the details of kw/hours. Why? Because I know very little about it! I just pay the bills! But here's an article about the high cost SDGE charges for their "tiers". This story says rates go to 48cents/kwh. I'm not going to research it. But I can vouch that with this many people living in one home, that cutting usage down to baseline (even before we had the pool) was never achieved, even without AC, and by the way, we are more coastal than the people in this story.

.

https://www.sandiegouniontribune.com/business/energy-green/sd-fi-sdge-highbills-20180913-story.html

In defense of the poster who mentioned Californians feel "guilty" about the non-greenness of using AC, yes I know a few people who say stuff like that. Sometimes on Nextdoor people say things like that.

We put in solar a couple years ago, so have some relief from high bills, but our solar doesn't cover the whole electricty bill. We have a home with 7 people living in it. Also a large pool and the pool filter takes a lot of juice.

Edited to add: in fact, the mayor of Los Angeles (not where I live) has famously said that he feels guilty running his air conditioner, a sound bite that is replayed over and over again on a certain local radio station. So there are plenty of folks who feel it's not green to run AC. (I wouldn't feel guilty, but then again, I haven't researched the environmental effects-- and I don't have AC).

I have homes both north and south with non-municipal system service. We've had Cal PUC mandated "baseline" pricing for some time with investor-owned utilities. With PG+E, the lowest tier, the "baseline", is around 22 cents for the first ~225 kwh used. The second tier is from there to 4 x that (~usage of 226 to 900) and is around 28 cents. Beyond 4 x is the penalty range, around 40 cents per kwh.

In SoCal, it's more like 25-40-50 cents.

The baseline amounts vary with location and slightly by utility. I've quoted coastal location, the hot inland areas get somewhat more.

Unfortunately, these prices hurt lower income people the most, though there are programs in place to provide lower income people with meaningful price discounts.

Part of what has driven prices higher has been the state mandate for all utilities to increase in stair step fashion with year targets the share of so-called "renewable" power sources, which around here means mostly large solar projects. Because of our weather, I expect in 10-15 years, in areas where it can be afforded, more houses than not will have solar panels. That will drive system electricity costs higher for those who don't because there will be less electricity sold through the systems.