Thanks for asking. Here's a, hopefully not too long winded, rundown of results so far!

We moved into the house in April, the wife & I and two dogs. Generated body heat isn't near as great as when we were working in the house. Because of the overhang I have above the living room windows, and because the front porch shades the dining room windows, the summer time solar gain is less than it was during the spring. Heat gain picks up late in the day when the sun is more directly shining at the windows. The AC usually kicks in during the afternoon. Since the Daikin has a variable speed compressor and a variable speed condenser fan in cooling mode it moves out of the house only the amount of heat required to keep the temp constant. The indoor temp doesn't move up and down very much at all, maybe 3 to 4° at most. Much of the time, even when the outdoor temp gets into the low 90's, the air coming off the condenser was hardly any warmer than the outdoor air, and the fan was running at low speed! Note that the Daikin circulates air constantly, not just during cooling/heating times.

Interestingly, when we've been gone for a couple of days, the house will be at about 74° with the controller set at 75°. After we've been home for a couple of hours the temp will rise to about 75°, without touching the controller. All I can figure is our body heat causes the rise and it takes a little more rise to cause the controller to increase the cooling rate. Then the temp stays pretty close to 75° unless the heat gain picks up fast.

One thing I learned fairly soon after we moved in, is the Daikin remote temp sensor on the hallway wall just above the Daikin controller, and the Honeywell thermostat which I have wired into the ERV to control the Econo cool mode, are sensitive to the temperature of the wall! The air temp in the hallway would swing up and down upwards of 4° either way from what the sensor and thermostat were sensing. Subsequently, in both heat and cool mode the Daikin and the ERV weren't responding anywhere nearly as quickly as they needed to for room temp changes! Right now the Honewell is mounted about 1/2" off the wall, and the Daikin temp sensor is hanging loose from the box and a couple of inches away from the wall. Now the system responds to the air temp changes much better. Because the ERV feeds fresh air directly into the Daikin air handler return duct we installed their optional remote temp sensor in the hallway. Normally the air handler senses the return air temp with an in-unit sensor and uses that temp, compared to the controller set point, to control the rate of cooling or heating. The fresh air from the ERV causes the return air temp to not be a reliable indicator of the room air temp.

Another interesting phenomenom, to me anyway, is the living room air can be at 75 or 76°, but it feels downright uncomfortably cool when I'm lying in the recliner under a ceiling fan running at low speed! I'm sure that's because the room air temp is quite uniform from floor to ceiling since the air handler is running all the time, and the supply registers are in the floor and the return grills are in the ceiling. No 85° air at the 13' peak of the ceiling in this house!!

I have the ERV connected to the Honewell thermostat so that when the outdoor air is in the 60's, or cooler, and the indoor air is above the cooling set point, the heat exchange wheel turns off. That's on the 1st stage cooling set point. The second stage set point will put the ERV into 'boost' mode, meaning it runs full speed. There's also a thermostat in the incoming air to keep from going into boost mode unless the incoming air is 70 or cooler. I have the cooling set point at 73°, 2° cooler than the Daikin set point. What this does is cools the house down to 73 using cool outdoor air, if the outdoor air is below 70. This actually is the case during much of the summer here, 95 day time, 60 night time.

My garage is ICF with Icynene on the underside of the roof. On cool nights if I crack open the overhead doors and open a window the garage will cool down nearly to the cool night air temp. If it's closed up all day with outdoor temps into the upper 90's, the temp will climb about 5 to 6° is all. I'm considering installing a thermostatically controlled ventilation fan in the garage to cool it down every night whenever possible. Talk about nice to work in during a hot day, 90 outside, 70 inside! Even having a door open it doesn't heat up real fast in there. I have a 9000 Btuh wall unit in the garage. It will cool the garage down rather nicely. The garage was over 80 at 2:30 this afternoon so I turned the air on. It's now 5:50 PM. The temp is 76 and outside it's 97.

Our May 20 to June 19 power bill shows 1838 Kwh used, but that's for everything, cooling, cooking, heated shower walls, and hot water (I take long showers!). Money wise it's more than I was hoping for, but then I was looking at heating and cooling only when I was planning this house.

Right now it's 97 outside, 75 inside, and the AC is running comfortably blowing fairly warm air from the condenser.

I hope this has been a little bit informative, and not just a bunch of dribble!

Here's another thing to keep in mind...  When using a air-to-air heatpump, AC in the spring and fall should be very cheap because the units will be operating more efficiently.  The inside to outiside temperature difference is working to your benefit... so the electric bills shouldn't be nearly as bad as your AC running in the summer.

Because of the variable speed compressor in the Daikin vs a fixed speed compressor in the typical American heat pump, the efficiency differences are probably not as great during seasonal temp swings. In cooling mode the Daikin efficiency increases on the order of 15% when outdoor temp drops from 90 to 50 w/ the indoor at 75°. In heating mode its efficiency increases about 20% when outdoor temp rises from 20 to 50° with the indoor at 70. These are from the published engineering data from Daikin and for a connected indoor unit capacity load equal to 100% of the outdoor unit capacity. They publish figures for indoor loads of 50% to 130% of the outdoor unit capacity.

Another aspect of my system I just last night became fully aware of is the thermal storage of my crawl space. Since I use the crawl space as the supply plenum the rat slab and building structure get cooled to under 70 with the system in cooling mode. What I just observed is the living space temp continues to drop in the late evening even after the controller has turned cooling mode off. Because the air handler is running constantly the house air continues to circulate through the cool crawl space and continues to drop in temp. Right now at 11:15 PM it's 70° outside, the controller is set at 75°, AC has turned off, and the house temp in the hallway is 73°.

dmaceld,

These websites might be of interest:

www.ourcoolhouse.com and http://www.welserver.com/index.htm

They have a nice webpage that shows some of their greenbuilding thoughts, and are all about energy monitoring.

cheers.

dmaceld,
I noticed in your last post you mentioned using your crawl space as a supply plenum.
Tell me a little more about that and how that works for you.

Will do in a few days when I get back from making a motorcycle trip on some North Idaho roads.

It's working great so far. Haven't been through a winter season yet so don't know yet if it'll work as planned, although it should.

Because the ICF walls go from footing to roof the perimeter is sealed, naturally! I put 2" foil covered rigid insulation on the top and sides of the perimeter footing. The entire crawl is covered with poly with the poly draped over all the interior footings. I then put 3/4" blue board over the entire crawl and covered it with about 2" of concrete. So far, in A/C mode, there has undoubtedly been very little heat exchange with the earth below as the crawl space temp varies from about 64° to 74°. I believe the slab is acting as a cool thermal storage as the house temp continues to drop after the A/C unit has shut off.

I used the Daikin 36,000 Btuh duct mounted ceiling unit in the crawl. I have three short runs of ducts, about 6' to 15' long, to direct the air flow toward the thee ends of 'T' of the living room & bedroom floor plan. Floor registers are located around the perimeter the same as if it were a ducted system. The one variation is that the register must, by IRC, have an 'ash pan' hanging under it. This is to catch dust, cigarette butts, who knows what all, and keep them from spreading around the crawl space. I think it's a code requirement will very little, if any, real benefit.

Along with using the crawl for the supply I'm using the attic for the return. I have return grills in the ceiling scattered around the perimeter of the house. There's one large duct from the attic down do the air handler in the crawl. The fresh air duct from the ERV feeds into the return duct.

Because of all the supply registers and return grills, and the fact the air handler fan runs continuously, there are no drafts anywhere in the house and the whole house is at a pretty uniform temperature. The one exception will most likely be that the living room and dining room will be somewhat warmer during spring and fall from solar gain. But this would occur with a ducted system also.

The only comfort issue I've identified so far is the floor temp. The floor temp is near the same temp as the air in the crawl space so during cooling mode it is uncomfortably cool to bare feet. But I believe we may be getting the benefit of radiant cooling from the floor.

Everything should work pretty much the opposite during winter heating. I'm hoping that the floor will be somewhat warm so that I will have a quasi radiant heated floor. But what little heating experience I had this past late winter and spring showed the floor didn't get much above the room temp. But that could be because I relied on my pellet stove for most of the heat back then.

One thing I concluded fairly soon after we moved in is thermostat set back isn't a great idea. The mass of the entire structure, including exterior walls, interior walls, floors, furniture, appliances, tile walls and floor, and the crawl space concrete creates a tremendous amount of thermal inertia. The house air is circulating around or past almost all of it. Coupled with a heat pump that is putting out air only a few degrees above or below the set point there was a severe time lag in raising or lowering the temperature of the entire structure. I also found out that the thermostats are sensitive to wall temperature, to the extent they weren't responding quickly to air temp changes.

Sorry if I've bored you with more info than you wanted. Ask away if there's anything more you want to know.

dmaceld,
Not boring at all. Just the opposite. Please keep us updated. I am very interested to see how the system works over the winter.

I wonder if it would be possible to reverse the flow for the a/c, using the attic as supply plenum and crawlspace as the return?  Then return to your original setup for heating purposes.  Very interesting concept.

You have a valid concern, but something occured to me. You said you are concerned about the heat from 4 workers, lights and tools, etc. When your house is done, will there be workers and tools buzzing around creating heat? I know firsthand how much heat just one of those lights can create when doing construction. I would imagine that other than maybe an occassional workout on the treadmill or random house project that heat source would go away would it not? Just a thought.