IMO there is not enough info but what is it you want from us ? Your architect is who you should be getting this info from and with no other info from you impossible to answer.

Since you won't have ducts for heat, how do you plan to address air conditioning?

Where is the house located? Will this house be built on a slab or will it have a basement or crawl space? Will this by a hydronic system? What fuel will be used? I assume you will want cooling and if so duct work will be installed.

My first advice is to select your floor coverings and see if they can be used with radiant floor heating. Talk to a flooring expert who is knowledgeable about radiant floor heating. My other advice is for a house two big you should plan at least an upper and lower floor zone. The nice thing about radiant heating is you can have multiple zones.

Radiant floor heating is the most expensive to install. I also think it is the most expensive to operate since it is not practical to set back the temperature. You really have to make sure you are in love with radiant heating and can't live with anything else.

Yeah, search this forum on radiant floor heat .

There are literally dozens and more threads on the subject.

Get it! We had it in last build, large home, and we did it all though out the first floor. Fall becomes chilly and that's when I set it to 72* and never touched it again. Ours was self regulating. It doesn't heat the air, as I am sure you know; it heats the furniture. Toasty all winter (north east). To accommodate A/C, we used those ducts upstairs for forced hot air heat, as well.

All I know is my builder sent the floor plans to CA and it was there a detailed blueprint was designed on how to lay the heating system. He didn't trust anyone to lay the floor via plan, so he did it himself.

Which leads me to another important matter. You don't mention what material you are using for flooring. There may be a disclaimer voiding warranties using radiant heat.