This is not technical, but opinions after living with radiant floors for several years: One thing to remember is that we must adapt to a difference in how we think about heating. With F/A, wood, radiators, etc. we have a tendency to look at the outside thermometer registering cold, and then turn up the inside thermostat. Or maybe we walk by a window and feel cold seeping in -- and turn up the thermostat to compensate. That's often habit, but the habit is based on the fact that most houses are/were poorly insulated and often let cold or drafts into the living area -- so if it's cold outside our subconscious says oooh, it's gonna get cold in here, turn up the heat. You almost have to live with radiant flooring to really realize that one just doesn't need to play with the thermostat. If your house is well-insulated (and to an amazing extent even if it's not well-insulated) you set the thermostat for the temperature at which you are comfortable, regardless of what's going outside and you leave it there. And another thing which is rarely addressed is the fact that many (most?) people set the radiant flooring to 75 and are on the warm side of comfortable regardless of whether or not it's frigid outside. No matter what your source of heat, it takes less energy [and less $] for 75 than for 80°. Yes, if the cat stands in an open door peering out at a snowstorm there will be frigid draft coming in... no matter whether you have F/A or radiant. The difference is that F/A will have to warm up that cold air with more not-very-warm air and meanwhile you have both cold and F/A warm air blowing around you. Brrrr. With radiant, you have --and keep-- warm feet which physiologically makes you feel warm because the temperature of the floor has not changed. Yes, the open door's cold air is mixing with the warm air but it isn't blowing onto you to make you feel cold. Talking about vacations -- or a length of time away from home -- should take into consideration that radiant flooring does not make any ultra-high demands on its system. Radiant is meant to *maintain* an even temperature, not jerk it up with a blast of heat like other heating methods. So it makes sense to turn off a furnace while you aren't home because a furnace requires a blast of heat to warm the volume of air; long blasts for lots of warmth and short blasts when there isn't much difference between ambiant and desired air temps. Unless you are going to be gone for lots longer than it takes to cool-off followed by heating-up the radiant flooring, it does not make sense to change its temperature. Modern houses with radiant flooring are almost always considerably better insulated than their F/A counterparts, and it takes days not hours to cool off. And last, there are often comments about the length of time it takes to "warm up the house" with radiant heat. Especially if one lives in an area with a great variety of temperatures. Ah, excuse me, but if I'm comfortable at 75° what difference does it make what the temperature is outside??? If the house is highly insulated and draft-free it makes very little difference whether it's 10° or 50° outside. In my area outside temperatures with daily 40-degree variations are common for weeks at a time, regardless of season. Okay, not so common in the summer, but we don't need heated houses in August. On the rare occasion that it gets umcomfortably warm inside, I open the window. Low-tech but effective. Oh yeah, in July and August I turn on the A/C, not so low-tech, but effective. The point is, 75 is 75 is 75 and if your feet are happy at 75 it doesn't matter what temperature the outside air is. A 'warm house' is a side-effect of radiant because its main purpose is keep you comfortable, that is, maintaining your comfort with an even temperature.

how many sq. feet is this home going to be? Sounds more like a palace.

Chisue, I'd say 4K is probably not a bad bid. It is more expensive to retrofit than to install originally and it isn't quite as simple as just running some pipe under your existing floor. I don't see that the value of a 5K home in your neighborhood has much of impact on the conversation. From experience, the cost difference in many home retrofits and repairs in a high value RE value area, in the range you mention, and another in a low cost area, is not that much except when transportation costs of materials is at issue. In fact some services and inputs are more expensive in our lower home value area than in our higher value area, simply because more local trades that do higher end type installs are available and competing for work. From our experience we have to often hire someone from the nearby city --45 miles away -- to do the work and that does come at an up charge, understandably. There is also the fact that smaller jobs also cost proportionately more than larger jobs anywhere. It might help if you don't put down the trades as simpletons. If don't like the bid or can't afford that price, why don't you just go hire someone off the streets to install the tubing, direct the job yourself and just ask a master plumber to make a call to hook it up. LOL. Be sure to pull the correct building permit if ine is required -- it often is for additions to mechanical and plumbing systems.

Agreed Bry, that's a great point. In renovation or replacement comparison situations when a household is consistently using the baseline allowance, using the next tier rate up would be more accurate. It's also tough figuring out how much of the minimum monthly gas fee to include. I would guess the water heater may account for ~50% of usage so more accurate water heater gas costs would be somewhere near $302. Much tougher figuring the added comfort and space conditioning benefits of a HPWH and if the gas combustion appliance is naturally vented, there is probably added moisture and potentially health costs involved. For new construction, not knowing specific situations I think average kwh rates are where to start, and it's only the most energy intensive homes that would recover new infrastructure costs. Those outliers might be wise to improve the design. An energy rater would be helpful for plan specific comparisons. Mr. Fudd's Tier 2 kicks in at 202 kwh, lower than baseline allowances I saw digging around on the PG&E site. It must be an energy intensive area because most Tier 2 levels I saw were higher. This suggests the averages I linked to are close. Most tier talk for PG&E (serving a third of CA households according to this page) is about to be irrelevant as they are transitioning to Time Of Use rates for everyone. This makes sense for the increasingly renewable electric grid. For example, it will encourage electric vehicle owners to charge during off-peak hours and will keep electric water heating costs competitive with gas, even for replacement situations and even in places of high electric/ low gas rates. This requires the effort of putting a timing control device on a tank water heater, something those with basic electrical skills could DIY. Tying this back to topic, new construction skipping air-conditioning could use electric resistance (or heat pump) radiant floor heating during off-peak hours. The floor mass releases heat during on-peak hours of the day and an efficient envelope would keep it in. No combustion inside home necessary and cost effective if done right. A guy is doing it off-grid in Saskatchewan so it might be easy in CA. Here's a link to the controller he built for the PV to electric resistance radiant floor (or battery) interface.