getting closer to the "getting plans done" stage, so I'm getting really excited.  We are very fortunate that on our lot, the natural placement of the house is with the back wall almost due south.  I want to maximize our passive solar gains because of this.  From what I've read, it sounds like it will make the most sense to have essentially as many windows as we can along the back (something we wanted anyway - we have a nice view), overhangs to control the summer vs. winter sun, and probably higher solar gain/higher u value windows on the back, with lower u-value windows on the front (north side).  Sound right?

here's my question - the house will have a basement, which means the first floor (where most of the windows will be) will be wood - not much thermal mass.  How big of an issue is this?  The way I understand it, we will probably experience plenty of heat during the day, but there won't be much 'stored' to radiate out at night.  Add to that, the higher u-value windows, we'll probably lose plenty of what we gained during the day.

I don't see this as a huge issue, but want some feedback.  Am I on the right track?

Jerkylips, You are on the right track, but I would not give up the u-value on the back windows. Depending on what you want as far as style of windows you will be able to have low u-value with high SHGC. I sell a window from North Star Windows that is a triple pane with krypton and has a u-value of 0.18 and SHGC of 0.47. This is very good for the price that I can get. This is a link to the ratings on triple pane. http://www.northstarwindows.com/html/tech_pdf/SL_EnergyRatingsUSA_07.pdf

It is difficult to say without knowing where you are. In feeble sunshine in the far north, you'd want low mass; in bright sun in New Mexico, you'd want high mass. If it isn't clear cut, it is easier to live with too much mass than too little. In south central pa, where I am building, the average radiant energy passing through my 275sf of south facing windows in Dec amounts to 11k btu/hr according to free UCLA software called Climate Consultant. But the normal range is up 25k btu/hr, and the brightest Dec day on record at the Harrisburg NWS would have poured 48k btu/hr through them. Either would create major overheating.There is no substitute for doing this analysis of your weather. http://www.energy-design-tools.aud.ucla.edu/
A concrete first floor isn't out of the question. You could use an ICF form like Lite Deck, or panels made of autoclaved aerated concrete, or a gypcrete overlayment topped with ceramic tile. You can also add mass with a masonry heater http://builditsolar.com/Projects/BioFuel/biofuels.htm#Wood or special walls. http://builditsolar.com/Projects/SpaceHeating/Space_Heating.htm
Knowing your local weather is also important for choosing windows. Skipping Low E gave me a SHGC of 0.60, which I need in gray pa. I'll add a radiant barrier in insulating roman blinds instead.

We're in NE Wisconsin - probably not too far off from PA, maybe a little colder?

I gave some thought to concrete, but I also want something that's comfortable to live with.  We're doing hardwood throughout our house - no carpet.  I think wood over concrete may be a little hard.  We had a lot of tile in our last house & there was a significant difference between the wood & the tile in terms of comfort.

Jerky,
I am working with an inventor that has come up with a solution for your exact situation. Thermal mass windows!!! The windows being developed by Hunter Douglas the window shade company have thermal mass contained within the window. Triple pane exterior with a 1" thick layer of glass and gel that stores the suns energy in the gel mass. The concept isn't new he has been developing them for 5-6years and is ready for production. I used his previous version on a house I built here in MA last year. The previous ones had water filled blocks inside the window that stored the heat, but cost made them impractical. I did a whole series of videos showing the performance on my you tube account.
http://www.youtube.com/user/eebuilder http://www.youtube.com/watch?v=qdUGDAqyagU
The videos were before anyone moved in the house, but just last Friday 12/18/09 I called the home owner to find out how they were doing. Last Friday's high temp here in MA was 29F with an overnight low of 10F. The windows last Friday at 4:30pm were 91F. These windows contained 3,000 lbs of water so the BTU"s stored in them on that one day was about 60,000 BTU's at the end of the day. The interior of the house was 71.5F without heat. While the windows are not in production at this time, I can get them as a prototype installation. The windows are fixed units and measure 2'x7' and have a shading mechanism built into them. The cost per window is $1,000 , from his research and testing each window will contribute 1,300,000 BTU's to the house annually here in MA probably not much different than in PA. This approach eliminates the need for thermal mass in the floor. They were also used on this years BAC/Tufts solar decathlon house and impressed the judges. The idea was born from the Trombe wall concept but the ability to see out your windows is pretty important to most people. If your interested get in touch with me and I can arrange for you to come and see the windows for yourself. The inventor is anxious to get some installed and build a market for the product. It is costing him more than $1,000 a window to build them but once up to production speed this is his target pricing. They also take at least 12 weeks to get at this point.

Tom Pittsley
[email protected]
www.eebt.org

My brother has enough south facing glass in a non passive solar house in Belgium Wis that he complains about afternoon heat buildup. That doesn't mean you'll have comfort issues, but I'd sure want to scope it out. The UCLA software gives you a choice of weather data from Milwaukee, Manitowoc, Green Bay or Sturgeon Bay.

Also Menominee in the UP.

thanks for the replies. I don't think we can do the thermal mass windows. I've talked my wife into quite a few things already, I don't think that one would fly... ;) I will definitely check out that UCLA site. I had a feeling that we would get plenty of heat during the day. I'd rather have too much heat in the winter -that's pretty easily managed (open a window, turn off your furnace, etc.) I think we just need to find the right combination of specs for the windows. thanks!

Jerky we also have a good southern exposure and do notice solar gain, not that we have had much sun lately, but when we do it noticeable warms up on the south side of the house. We have mostly tile on the main floor that warms up nicely and holds the heat a bit. If I know it's going to be sunny I will turn the furnace down a degree or two in the am so the solar won't overheat the house. If I forgot or it was unexpectedly sunny I flip on the furnace fan to move the warmer air to the other spaces in the house, that seems to work out pretty well.

toddm that is all the location that the software gives? They are all on the lake that is no help to us located west of there.

Heed has weather data for 19 locations in WI: http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=4_north_and_central_america_wmo_region_4/country=1_usa/cname=USA You pick the nearest point when you install the software. The programs then automatically adjust everything for where you are.
If you are merely curious what passive solar could put through your windows, here is a pdf with lookup tables for eau claire, lacrosse, green bay, madison and Milwaukee http://www.nrel.gov/docs/legosti/old/7904.pdf