Your effeots should be giving satisfactory results so there must be somthing unusual about the structure. Lack of radiant barrier ? The tile roof needs good attic air circulation to prevent tile acting as heated ballast after sunset. Is there ample vent area to alow full cfm of whole house fan to escape attic?

Thanks for your reply, klem1.

The attic has multiple adequate vents, according to the whole house fan installer and also a licensed very competent hvac guy said plenty for the wh fan. He thought an attic fan running during the day would be helpful, but do they really do much?

Would a radiant barrier help? That is another thing I considered, but wondered if it would make the home too cold in winter--it is good now in winter, didn't want to exchange one problem for another...

Here are some simple principals to keep in mind as you go about it.
Since heat rises an open window 2' from floor on windward and/or shaded side plus a window opening at 6' from floor on other side of room will cool better than window openings at same height on both sides. In the latter case,warm air will stratify near ceiling while cool air enters and exits. In the first arrangement,cool air enters near floor pushing warm air residing near ceiling out higher opening. The same principle was responsible for the improvment you noticed when the skylight opened at highest point in room. All that is by convection. When solar heats the intire structure, interior is heated by conduction,lower floor heat migrates upward by combination of convection and conduction ,adding to existing heat on secound floor. The seound floor also gains heat by conduction from attic. Windows exposed to sun alow air in room to be solar heated.
Awnings are far better than window film or reflective/insulated blinds. A compermize can be struck by extending flat awnings outward only enough to shade South facing windows. Sun will come through window when it moves closer to South horizion during winter.
I suggest measuring square inches of attic vents to compare with that required by fan mfgr to varify what you were told. Attic vents MUST NOT BE COVERED WITH CONVENTIONAL WINDOW SCREEN. 1/4 inch or larger hardware cloth is ideal. With whf running have one person stand in doorway of hotest room while another partly closes door(s) of ooler room(s). Does air flowing from hot room increase? If so,adjust doors acordingly.
Radiant barrier is difficult to add on roof and impossible to add to walls in existing structures.
Let us know if that helps.

You can not move enough air in a typical attic to keep heat out of your living space. That is not to say that attic venting needs to be carefully considered with the local climate in view. Much of the heat gain is from re-radiation of heat absorbed by roof sheathing, conducted or radiated to the roof deck and then radiated to the attic floor. You need lots of insulation to prevent the heat gain in such a system.

Is the whole house fan in an upstairs hallway? If you want the upstairs to cool fastest, you need to open windows there. If that does not work, I think that the fan is not big enough.

As for the hot windows. Low-E glass would seem like a good idea. Have you considered having an energy rater look at your house?

klem1 and ionized, thank you for your thoughts and suggestions, they are helpful and educational.

I suggest measuring square inches of attic vents to compare with that required by fan mfgr to varify what you were told.

Will do.

Attic vents MUST NOT BE COVERED WITH CONVENTIONAL WINDOW SCREEN. They are 1/4" hardware cloth covers. This is the building code in this area.

With whf running have one person stand in doorway of hotest room while another partly closes door(s) of ooler room(s). Does air flowing from hot room increase? If so,adjust doors acordingly.
Yes, it develops a good flow from the hottest room. We will adjust the doors--it should help. Thank you for that suggestion.

That is not to say that attic venting needs to be carefully considered with the local climate in view An architect suggested adding vents at the top of the walls, at the apex of the walls--something we'll look into.

I understand the heat that is in the attic space--the wh fan has improved that somewhat--I'm looking for a couple or three degrees more relief--wondering if window awnings is going to get me there. Heat does come through the windows as well--one can feel it. Awnings would be less expensive than new windows--the windows are doubled paned and in excellent shape--too soon to replace them.

Have you considered having an energy rater look at your house? Yes, I would like to, but they all seem to be selling something--what ever they are selling seems to be the solution. How does one find an independent that does that for a fee and not try to sell me something?

Most electric power,many fuel suppliers and a few government agencies perform free energy audits. One can get variable benifits from such audits depending on how well the inspector understands their work. The audits seldom address passive cooling and heating but instead look at ways to reduce energy consumption..
Your comment about additional vents at top of wall prompts me to ask where vents are located. While any vent of any size helps,placment is very important. Exhust/exit vents perform best when located at higest point of attic (gable) and are greatly inhanced by interance/intake vents located at lowest point( soffits ). Soffit vents arn't nessary for whf but are very benificial to passive venting. You can easliy test benifit of awnings by temporarly shading a window that recieves direct sun. Shade blocks solar heating of glass which you feel when you touch it. The solar heated glass heats room air by convection. Regular double panes do a good job blocking conduction and convection heat movment. What I'm saying here is why I reccomended extenting awnings only far enough to shade window in summer but alow sunlight to fall on glass during winter.

For an energy rater, try resent.us. I honestly don't know what their standard is for selling solutions, but by contacting some of them, you might find some that do only energy ratings. I hope that energy_rater-la will chime in on that. When you call them, do an interview on the phone with a brief description of your concerns and see how they respond. Their job is to identify the low-hanging fruit to pick to keep your home comfortable for less energy consumption.

Since your windows are good, but no Low-E, consider window films if awnings are not an option.

An adequate whole house fan will do double duty in cooling off the house and the attic after the outdoor temp starts to decrease, but it can't help in the attic when it is not running, you have to make sure the attic as good enough passive venting for the daytime. As I mentioned, even that can't eliminate most of the heat gain from the roof because of the radiation.

I'd put awnings first.
beat the heat before it gets into the house,
is your best savings.
besides, with dual paned windows, you
can't use window film.

for instance, I have bananna trees planted on west
side of my house.
by mid July when heat in afternoon is getting strong
the trees are tall enough to block the bulk of the sun.
come august/september..windows are fully shaded.

solar plantings can save you $$, if you have room,
time & want to do so.

I agree with Ionized about www.resnet.us
but interview the raters in your area.
pick the one who best understands your
situation.
I also have issue with raters/auditors selling
products. but have come to the understanding that
I often recommend things that the homeowner either
can't do, or can't find anyone to do.
thus I get into the energy retrofits...

audits from utilities will offer at best 15% savings
of overall utility cost. to save more..hire an independent.
don't forget that utilities are in biz to make $$.
in existing homes 40-50% savings isn't uncommon
if all reccomendations are followed.

and to answer your how does summer heat get
into a home? radiation, convection & conduction.
air leakage, heat gain, cooling loss.
making the house tight, sealing ductwork so
that all cooled air gets into the space where
you live..those are money savers.

best of luck.

Thanks all for your valuable information--a lot to absorb and think about. I am going to check resnet, thanks for that recommendation.

I'd put awnings first.
beat the heat before it gets into the house,
is your best savings.

In my readings I read that stopping the heat before it gets into the house via the windows is helpful, that is why I was looking at awnings. That and adding more air venting to the attic seemed like the best "bang for the buck". We do not have soffit vents in the eaves because we do not have eaves on the home--due to building code--no eaves allowed in this neighborhood due to wildfire safety requirements.

The hvac guy we had to look at an issue with our A/C said the ducts were very well sealed and in good shape. I think the home is pretty well sealed because it sure holds in heat!

I did an experiment this summer stringing a pieces of big-box solar shade temporarily over the outside of one of the windows on the west side, and it brought down the temperature in that room about 2 degrees--though the rest of the upstairs heated up due to the other windows and of course whatever the heat factor of the attic space does. Awnings might work even better.

I also read that after a certain point there is no use adding more insulation to the attic, more and more and more is not better. We are well over code requirements (not that building code is necessarily adequate) on insulation.

Here the utilities are for-profit (supposedly regulated) so they partner with "energy savings" companies for more profit, not to actually help customers reduced energy use. Our energy bills are not that bad because we have a photovoltaic system, what I am really interested in is being comfortable on summer nights and A/C cools the house down but it feels so stuffy with all the windows closed. I would rather have the upstairs windows open and get fresh air, which is actually cool at night--we just can't get enough of it into the upstairs fast enough--yet.

Thanks again for your very helpful and informative comments, energy_rater_la, ionized, and klem1. I really appreciate it.