In BC and Ontario (and I believe other places too) the building code includes passive heat capture for drains for new builds. You can recover quite a bit of the heat for very little money.
For example, we didn’t insulate our concrete slab floor because our windows provide too much passive heat 10 months out of the year. We’re on the edge of the region where such insulation is recommended (thankfully, it is not required here - in the fall, we have to run the air conditioning when it is in the mid sixties outside! In the summer, we don’t need A/C until the upper seventies because of the angle of the sun and passive cooling from the slab).
Anyway, our hybrid hot water heat pump has a COP of two or three, and was a much cheaper upgrade than passive heat reclamation would have been.
Because we bought an efficient unit, it uses hardly any power (800kwh per year, so an average of 91 watts, or about $100/year, or charging my car from empty to full 24 times), so we’d be better off with some other upgrade on a thing that hasn’t hit diminishing returns.
For instance, we should have used bigger air ducts on our hvac system to improve the air handler’s efficiency.
We had been planning a highly insulated slab with exposed concrete floors, but your comments on having to run AC seems concerning if I am reading it right. We plan for awnings to keep sun off the windows in the high summer sun.
We went all electric in an area where PG&E outages are frequent. We have battery and solar, but during extended outages there usually isn’t any sun. Our solution is to get a propane tank and generator that can charge the battery. This is a complicated compatibility problem, so we should have put the generator in at the same time as the battery and solar.
Heat pumps are fine, but the contractor undersized the ducts. Run a system backpressure test yourself (get the service manual) before writing the final check for the install.
Permitting and insurance in California are maliciously bad.
If you want a graywater system, apply for the permit at the same time you start the project. Also, be prepared to pay $20-30K for “engineering” and permits, but only $1-5K for parts and installation. (Or look around more than we did for an ethical designer.)
Get the best possible insulation and if possible pay for plaster. We’ve had a few leaks, and plaster / rockwool is much more tolerant of water than drywall / fiberglass.
Pay for all the smarthome stuff, but insist on offline home assistant compatibility.
Wire multiple outdoor circuits (120v and 240, if possible) so you can charge a car, run a hot tub, run a pool pump, charge a lawnmower, etc, etc without thinking about circuit capacity. You won’t do those things, but they cost basically nothing now, and $10K or more later.
AFCI breakers are a scam (incompatible with appliances that contain motors or switches), so expect nuisance trips unless you replace them with GFCI post-inspection.
The fancier the lamp, the more compatibility and capacitor whine you will encounter. Our most trouble free lamps were under $100 at ikea. I know which ones cost 10x that, but meh.
Under no circumstances purchase doorknobs made by emtek, assa abloy or kwikset. (Two of those brands are $$$).
Keep a bottle of spray air on hand at all times because modern smoke detectors will go off at 2am and the only way to fix it (other than a hatchet) is by spraying off the sensors.
Whatever your plan is for a roof, get a nicer one.
Pick a general contractor that has put up lots of homes in your county.
https://www.vetrinawindows.com/styles/tilt-and-turn-windows
(I’ve never heard of that brand, but their webpage has a nice animation explaining the product.)
I am immediately on the side of the owner-builder, but then
> in the fall, we have to run the air conditioning when it is in the mid sixties outside!
what? building design has a lot of parts to it.. "big cement slab" and "some insulation" are not the only parts.. But good quality design and the parts to build it are expensive. There is an underlying theme of saving money to accomplish something otherwise not possible. I am sympathetic to that of course.. Something is not right about the design, but what bad manners to point it out first! Someone put a lot of effort into some upgrade and they likely cannot change the decisions they made, due to time and costs, etc.
good to hear the details and mostly supportive here -- green building has got to get better, starting yesterday IMHO
Of course, the excess sun means excess solar production when most people aren’t running heaters or A/C.
The expensive fix is to increase the amount the roof sticks out by a foot or so to block the sun for an additional month in fall and spring.
The cheap fix (what we are going for) is to put up curtains or blinds that let us manually tune the amount of passive heating we get from the sun.
Either fix would also reduce glare, but only the curtains let us tune the pre/post solstice passive heating. It is colder post-solstice for a given angle of sun, so extending the roof enough for November probably implies paying more for heat in Jan/Feb.