I am building a 3,400 s.f. house, plus basement of 2,250, for my family of 5. This is our "forever house" and is located in Pasadena, CA. I'm the owner/builder. After 3 years of wrangling/haggling with the City over what we can build, we finally have the go-ahead to proceed. (If you've ever wondered why there's so little building innovation in CA, look no further than the "enlightened" folk who run these City Building Departments!!!) Anyway . . .

The envelope of the house will be SIP, basement is ICF, windows all high-efficiency dual glazed. Walls have R Value of 32, roof: 52. So, very tight when it needs to be. Plenty of operable windows for passive cooling. Poured floors in basement and main floor with be in-floor radiant heat; upstairs heat will be Warm Board or equiv.

I would like to use as little air conditioning as possible. I am intrigued by Earth Tubes. I've been in contact with Rehau. At $5,800 for the residential kit, it's not inexpensive. You get 180' of tube, plus the inlet, connectors, etc. But, I'll have the ground open down to 11' anyway for the basement and footings. And I'll be doing the labor. I was thinking that I'd circle the foundation about 3' out with the tubes and terminate it in the return air plenum of the HVAC that will service the main floor (about 1,800 s.f. area). 180' is likely too small for the volume of the house, but it's all I can spend. My question is this: if the Rehau system is too small does it make any sense to do it all? Is some free cooling and fresh air better than none? COMMENTS?

The solar chimney is the other idea I'd like to implement. The staircase is one big shaft from basement floor to roof. It's in the middle of the house where the heat will naturally rise, anyway. I'd like to put a cupola or or set of clerestory windows at the top of the staircase. However, because of a really stupid City restriction, we can't do that. Because it's a SIP slab roof there's no attic. Question: should I use a solar powered attic vent to exhaust the heat out of the house? Again, because of the SIP roof, there's no attic. We'd have to frame-out the vent like a small skylight. I'd have to install a register to close the aperture in cold months to not let cold air in.

Will a solar attic vent be effective? Are there other options for drawing the heat up and out?

Thanks for your input!

Here are some things that strike me about your plans.

1. First of all, is there really any "cold air" to be found in LA? I mean, I never found heating to be a big problem there.
2. I'm really a fan of solar chimneys, but I'm not sure I would want to encourage untreated Pasadena air to ventilate my home.
3. Wouldn't all the money spent on radiant floors and what not, best be spent on PV panels and solar hot water?
4. What about water conservation measures like reuse of gray water, etc?
5. Are SIPS the right choice? Think about traditional CA architecture....heavy walls, adobe, sun shading, etc....

SIPs may not be the right choice. ICF might be better. Or a hybrid of ICF all the way up from basement through 1st floor and SIPs on the 2nd floor. SIP roof.

As for climate, Pasadena gets chilly (I'm from the Northern Plains so I reserve "COLD" for real cold). It's not that unusual to have a night time temps in the high 30s. My wife has lived in a house with in-floor heat. She really wants it, as she's always cold. I have installed in-floor radiant in 6 projects. It's EASY. Since we're pouring floors anyway we'll be lashing on the PEX.

Gray Water: stupid City won't allow it, but I'm going to make it grey water ready. Same goes for Rain Water harvesting. Not allowed. Isn't that dumb? They don't even let Cal Tech do it, which infuriates my friends at Cal Tech.

And yes, I'll be using solar hot water. It'll be Solar Ready. We'll see what's left in the initial budget, but solar will happen.

What issue does Pasadena have with a cupola or clerestory?

ICF and SIPS roof sounds interesting. The ICF would help shut out the sounds of the city.

As long as you are looking into a tight home, I would do whatever might be necessary to improve the quality of the air you are moving inside.

Gray Water: stupid City won't allow it, but I'm going to make it grey water ready. Same goes for Rain Water harvesting. Not allowed. Isn't that dumb?

Have you looked into it?

It's not specifically the cupola or clerestory that's the City's issue. It has to do with height. We can not exceed 18' inside the house. Our Planner insists that a stair tread is a floor! She has measured the bottom-most tread that's on-axis with the ceiling way above (the stair case is all in one big vertical shaft). It's 18' + So . . . we have to drop a ceiling at the very top to get below 18'. As I said, the City is moronic.

Grey Water. I'm looking at a system from Boulder. Water Legacy.

Have you considered building the basement, walls, floors and roof with Structural Concrete Insulated Panels (SCIPs)?  I mention this because Tridipanel should be available in your area.

We can not exceed 18' inside the house.

Eighteen feet should be enough to get some good flow going Make sure that upper window is in an area open to the rest of the house and that it is not exposed to a prevailing wind which would tend to create backpressure on it. An awning window with a motorized opener makes a good stack vent. It doesn't have to be very big.

I mean, have you looked into the Pasadena regulations on grey water and rain catchment?

How do they handle moisture issue in earth tubes? Is there enough air moving through them that it isn't an issue? I supposed the air is drier in your area than other parts of the country. I'll have a lot setup that would make it easy for earth tube install as well, but I think the moisture is the problem in cooling in my area.

I see a problem.

Your wife does not like to be cold. To make a solar chimney a viable part of the equation you need to have something to temper the cool air. We cool down our house at night to keep it cool during the day. Mornings can be quite nippy and some people would not be happy.

If you can make the stairwell out of mass( concrete ) you cool it down during the night and then use it to absorb the excess heat during the day. It would need to behave doors that you can close so as to contain the cool. If it is all concrete and insulated from the rest of the building this would work. There are several ways to control the ventilation. Fans, windows, doors, tubes in the concrete running from top to bottom.

Thomas,

Make sure to use a radiant roof. I would consider triple pane windows, small additional cost, 1/2 the cool loss, and 40% quieter.

Most cities will allow grey water as long as it is separate from kitchen sink and toilet. Most of the easy to reuse water is shower and clothes washing related. If it is an issue you can install a bypass valve in that line allowing you to turn on the system. How are you planning on using the grey water?

If you contact me I can explain ways to DIY earth tubes at a lower cost as well. http://www.zehtalk.com/ or
(360) 567-6681

Brian