I am in process of building a home in the Pacific Northwest. The house is designed to be heated almost entirely with passive solar heat. However, we would like to have supplemental heat just in case. It does occasionally get cold enough here to warrant it. I am trying to figure out what would be the most efficient option. The slab is already poured, so no radiant in there, but it's a traditional stick frame house otherwise. I am not interested in a forced air system, I'm looking for simple, flexible heating options. Thanks!

OK folks, don't shoot me for this:
This is not new, radical, or ecologically sound, but I would look at simple electric baseboard heaters.
If you need only an occasional assist for your passive solar, and don't want or need a forced air unit, these are a viable option. They are not that expensive to install, would not be that expensive to operate, require very little ongoing maintenance, and are mainstream enough to satisfy bankers and potential buyers in the resale market.

Good idea. the electrical costs could be offset by Photovoltaic panels.

Bob and Wes,

I like that combination.  That sounds like a winner.  Save money on the heating side and invest instead in photovoltaics.  Neat idea.  I think that combination will work very well in the Southeast where I practice.

Another simple option would be a vented, gas fired wall heater or gas stove. This would work ok if the house is well insulated and not too big. Not quite as simple as electric, but pretty bombproof.

You could also consider a pellet stove or wood stove for back up heat. The last two options require more user input and would not work for freeze protection if you were on vacation.
Another thought is a mini split air source heat pump. If it does not get too cold these can be quire efficient.

What do you pay per KWH for electricity? Do you have natural gas available? Are you going to use gas for cooking etc.? What is your estimated Heat load (worst case senario) durring the winter?
 These all affect the decision.

Cheers,
Eric

What's your anticipated peak heat load? I the lower the heat load, the less relevant the efficiency of the systems supporting that load become, and the amount that's reasonably spent on those systems fall. (Portable $50 oil-filled electric radiator space heaters might even be overkill for meeting the peak loads, and would be very flexible.)

Buying the PassiveHouse tools (http://www.passivehouse.us/passiveHouse/DesignTools.html) can make designing-in-the passive solar correctly & easily, making the break points between more glazing vs. better insulation more obvious.

If the heat load for the auxilliary heat is very big supporting or offsetting it with photovoltaics is likely to be more expensive than boosting the efficiency of the building envelope (and may not even fit on the roof).

Is geothermal an option? It can be kind of costly because it requires a lot of digging, but it works very well.

since this is a new house and assuming you'll get a airtight envelope you'll probably want to use an ERV/HRV for ventilation. than you can use an inline electric heater within the ERV/HRV circuit or use an water/air hear exchanger linked to your water heater within the same circuit.

as Dana said you need to know the heat load first and then you can calculate if any of the above methods can deliver enough heat for you. using this method the guys at passive house institute recommend that you not excede 50 degrees celsius for air temperature or the heat will burn dust particles.

good luck
Adi

If you can live in the house for a winter before deciding on auxiliary heat you'll come up with a much better answer. My plumber has no backup heat in his house, which claims it has never been colder than 62. I am putting in wood heat backup but I've reserved wall space for an oil-fired tankless boiler in case it's lots of wood.
The problem is calculating the net heat peak load, after adjusting for solar radiation and thermal mass. The imponderables include not merely cloud cover on any given day, but also how many gray days you get in a row. Building a well insulated tight house helps of course. But passive solar is not passive haus. An aggressive amount of glass is in itself a major source of heat loss. Casement windows seal better than than other opening systems. Research insulating window treatments -- builditsolar.com has a number of approaches -- and get those up right away.
More mass means more coasting power. The classic backup heat is a massive fireplace called a masonry heater. http://www.gimmeshelteronline.com/masonry/ It does double duty soaking up solar rays on bright days and wood heat on cloudy days.
Ruling out forced air, you'll also have distribution problems to solve. By spring you'll know where you need space heaters and in what size. Wall and ceiling mounts should be relatively easy to retrofit. Consider split mini heat pumps if the load warrants. With lots of mass in the house, you could run them during the day at optimal efficiency and then let the house coast overnight.
You'll be testing your family's tolerance in that first winter, but that factor may be the most important of all. The last time I talked to my plumber, he confessed that his wife carries around a ceramic heater. It's key to learn what your significant other would be packing.
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Todd,
I agree in part with the idea of running through a winter and then deciding what is needed. The down side is that the mortgage company may not be too happy with that arraignment and it is much harder to retrofit then to incorporate it in the first place. I would at a minimum, prewire for electric resistance heat and or install the linesets and controls for a split heat pump system and or chimney for a stove of some sort.

The heat distribution system may or may not be a problem if the house is small and well insulated, especially if it has an open floor plan. A reference and a good read that speaks to that point is:
 http://www.ornl.gov/sci/buildings/2010/Session%20PDFs/103_New.pdf
In my house a wood stove and a ceiling fan result in very even heat distribution throughout.

As far as masonry heaters go, they are awesome. However in the op’s case the slab is already done so unless the slab was built for it, you can’t just add all that weight. They are damn heavy in most cases.

How is the house build coming?

Cheers,
Eric

You'd think that scheduling subs would be easy in this economy, but nooo ... The best stay busy, and they tend to disappoint the owner/builder they'll never see again. But I see progress every week.

Posted By toddm on 10 Aug 2010 01:31 PM
If you can live in the house for a winter before deciding on auxiliary heat you'll come up with a much better answer. My plumber has no backup heat in his house, which claims it has never been colder than 62. I am putting in wood heat backup but I've reserved wall space for an oil-fired tankless boiler in case it's lots of wood.
....
You'll be testing your family's tolerance in that first winter, but that factor may be the most important of all. The last time I talked to my plumber, he confessed that his wife carries around a ceramic heater. It's key to learn what your significant other would be packing.
.

Toddm, do you know if it is possible to get a C.O. without a heat source? Perhaps a regional issue - but in south-central PA I think it may be required. I like your idea, if it is "allowed".

You do have a heat source: the sun. If you can show computer modeling to code officials that predicts a reasonable temperature range without HVAC, you've addressed safety and soundness if not comfort. My design should stay in a range of 55 to 85 without additional heating or cooling, for example. You may need to hire a professional energy planner to make your case.
Sad to say, passive solar is heading that direction anyway as IECC 2009, the new energy code, nudges home design further along toward windowless boxes. In theory, you can submit an energy plan in lieu of passing REScheck. Obviously you'd want to check first. I suspect you'd get a fair hearing. In a significant post-bust change, growth is good again in many areas that once used regulation to slow development.
I have auxiliary heat -- a wood stove boiler plumbed to a radiant slab -- and I passed REScheck (barely) under IECC 2006 so I don't have direct experience making these arguments.