I recommend having a load calculation performed, then proceed.

Without knowing the details of your home, I would hazard a guess that you will need two systems - one upstairs and one downstairs. Get a heat gain and loss done for the equipment size necessary for you build and location. Brand is unimportant, just make sure it's installed competently.

Is it too cold for heat pumps there?

What is your criteria for best system? You will get different answers depending on your needs.

Do you have access to natural gas? That would be the most economical fuel for heating.

what are your fuel choice availability and their cost?

IMO

We have Natural Gas at the lot line and hydro rate start around $0.1287 per kWh

I assume your winters are long and cold, and the summers are mild. If that is the case then a natural gas furnace or boiler would work best. A furnace could be integrated with a split system with an AC condenser. For more money you could install a boiler with baseboard radiators, or possible floor radiant heating with a separate duct work for cooling.

Do you know what is the natural gas rate?

I grew up in a house with a natural gas-fueled boiler with baseboard radiators. It's such even, comfortable heat.

It is a complicated rate system but overall Natural Gas is very economical. Winters are mild with average winter temperatures of 5 degrees Celsius with periods of - 5 to 10 degrees Celsius, Summer are around 20 degrees Celsius with a few weeks fo high 20's.

Sounds like two heat pumps would match your needs. I'm assuming it is fully ducted. Heating and cooling in one. All electric. Maybe some solar panels?

Nat gas furnaces or boilers. With the slab concrete lower level you could add radiant boiler fed radiant heat. I think those that are recommending heat pumps are off base.

i would recommend 2 separate systems or at very least one system with zoning controls.

IMO

I live in Creston BC I have a gas boiler with baseboard rads and I love the even heat we get but in a new build I would have done under floor radiant heat. This is a question that should have beed addressed before starting your build and your architect should have had that conversation with you So do that now. There are a lot of heat pumps where I live and people love them because they handle both heating and cooling.

Thank you everyone for your comments. I appreciate the feedback. In the design it was planed for a High Efficiency Forced Air Natural Gas Furnace.The builder is now suggesting a Heat Pump with an HRV and or ERV.

My concern is with the later is that the lower level may not be warm enough in the winter months.

an accident waiting to happen...if you want comfort on lower level slab, then radiant boiler heat is the way to go....heat pumps for lower level slab, nothing but a joke and disappointment. You are being poorly advised. Sorry...

IMO

Are you planning to have A/C at all? Need it? Don't know your climate but from the sounds of it A/C is secondary consideration. Consider ceiling fans and smaller split a/c units in the rooms where most needed.

mini splits seem to be an expensive solution and questionable use for best dollar resources where AC is most likely a secondary concern to heating...you know your cooling needs for the cooling season...weigh options, costs, and use...

IMO

I agree about boiler heat we have it in our house in Creston as mentioned but we should really have AC we are looking at installing something this year . Our basement is so nice with that heat.

I disagree with a lot of the comments here. High efficiency heat pumps matched with efficient design and construction is the overwhelming direction of healthy, high performance homes. Skipping gas appliances is easier than ever with new construction, even in very cold climates.

Hire a third party to do a Manual J load calc and assemble a competent team to help with the details. Insisting on Energy Star is a great way to ensure a minimum level of performance.

Totally disagree with above post both from OP's location and comfort and operational cost standpoint.

IMO

For the OP: from the climate description, my question remains whether A/C is needed at all, but I don't know your needs and how that 'to high 20s' feels (i.e. humidity amongst other things). To me if gas was available, that would be my first choice.

For the brief period of time in the summer when we do get warm, I believe that we can manage without AC. The house is situated on the ocean where there is usually a breeze off the water.

If you don't need A/C, it makes the choice a lot easier. Me, I'd prefer gas-fired radiant heat (radiators or heated floors). For those short hot periods, I find moving air makes a big difference in comfort - whether from a natural breeze (windows) or ceiling fans.

My 2 story house was built in 1940 with a boiler and cast iron radiators for heat, and no A/C. We later added A/C in the attic, so we how have a gas boiler with radiant in the winter, and A/C to provide cooling in the summer. I am in climate zone 4 with moderate to high humidity in the summer.

Cold air is heavier and goes down easily, so the attic-mounted A/C works well to cool both floors. The cast iron radiators and boiler provide very even heat in the winter, with only about a 1 degree temperature variation between the two floors. It wouldn't make sense for a new build to buy two systems, but it is definitely a very comfortable heating and cooling combination.

Bruce

In your case, I’d recommend either a gas furnace with forced
air or a gas boiler with radiators or in-floor radiant, depending on what you
prefer. If you chose the furnace, then I would recommend a central
air-conditioner or mini splits depending on how much air-conditioning you felt
you needed, if any.

If you chose the gas boiler hydronic system, I’d recommend
cast iron radiators or in-floor radiant, configured to require the lowest
possible boiler temperature for greatest possible efficiency and select mini or
multi-splits for air-conditioning where/if needed.

If you don’t like gas, then it’s something all electric.

IMPO

SR

Hello @Jeff W, As a technician with well-known air conditioning contractors in Houston, I suggest you first perform the load calculation; after that, decide accordingly.

If you want the desired comfort level within your space, kindly follow my suggestion before anything else; you will indeed have the best possible outcomes.

Never select the heating and cooling system just by word of mouth as it's a matter of HVAC system design. So, be objective.