Ontario • ICF Homes • Heating Systems • 2026
The Best Heating System for an ICF Home in Ontario: What We’ve Learned After Building Hundreds of Them
Everyone asks about the heating system. And there’s no shortage of opinions — geothermal, air source heat pumps, forced air, in-floor radiant, “a bit of everything.” We’ve built enough ICF homes in Simcoe County to have a strong view on what works in this climate, what costs more than it should, and what keeps homeowners happiest ten years after move-in. This is the builder’s perspective: honest tradeoffs, real-world comfort, and the numbers that actually matter.
Before you pick equipment, pick… math.
In an ICF home, the envelope changes the game. Heat loss is lower, temperature swings are smaller, and “rule of thumb” sizing becomes the fastest way to buy the wrong system. Start here: why heat loss calculations come before any heating system decision.
Let me set expectations properly. This post is not a manufacturer shootout, and it’s not a government incentive brochure. It’s a practical comparison from a builder who’s designed and lived with these systems in real Ontario winters — Barrie, Midland, Tiny, Collingwood, and everything that gets blasted by Georgian Bay wind.
If you want the short answer up front: for most new ICF homes in Ontario, we recommend (and usually specify) a high-efficiency combination boiler feeding hydronic radiant floor heat. It’s comfortable, simple, serviceable, and the operating costs are consistently good — especially when the home is properly designed and not oversized.
If you skip the heat loss calculation and “pick a system,” you’ll still get heat… but you’ll also get short-cycling, weird comfort complaints, and money burned on equipment you didn’t need.
Why the Heating System Decision Is Different in an ICF Home
Start Here: ICF Changes the Numbers Before You Choose Anything
In a conventional wood-frame home, you can “get away with” a lot. The building leaks, the loads are higher, and an oversized furnace can brute-force its way through comfort problems. In an ICF home, you don’t have that same wiggle room — in a good way.
1) The envelope changes everything. A well-built ICF home typically has a lower heat loss than a code-minimum wood frame home of the same size. That changes equipment sizing, operating cost calculations, and the payback math on premium systems. If your heating load is already substantially lower before you pick equipment, some “high-upfront, high-efficiency” options don’t pencil out the same way. (Here’s a deeper look at envelope differences: how ICF envelope performance compares to wood frame in Ontario.)
2) Thermal mass changes how your home behaves. ICF homes warm up slower, cool down slower, and stay comfortable through short temperature swings in a way wood frame doesn’t. That matters because the best system for an ICF home is often the one that delivers steady, even heat, not “blast furnace for 10 minutes, then off.”
3) Right-sizing matters more than the brand name. The most important decision isn’t “boiler vs heat pump.” It’s designing around a real heat loss calculation — room by room if you’re doing radiant zones. An oversized system in a tight ICF envelope is wasteful, noisy, and often less comfortable.
The Options on the Table
What You’re Actually Choosing Between for a New ICF Build in Ontario
In the real world, most Ontario ICF builds come down to four families of solutions:
- High-efficiency combination boiler + hydronic radiant floor heat (natural gas or propane). One wall-hung unit does both space heating and domestic hot water.
- Air source heat pump (electric). Very efficient in moderate weather, less so in deep cold. Rebates can be significant.
- Ground source heat pump (geothermal) (electric). Best cold-weather consistency. Highest upfront cost.
- Forced air systems (gas furnace or ducted heat pump). Lowest upfront cost, fastest install, but typically the worst “match” for how ICF comfort works.
If you have special priorities (maximum carbon reduction, all-electric goals, or a lot that’s perfect for geothermal), we design for that too — but we don’t pretend every system is equal in Ontario winters.
What We Use and Why
The System We Specify in Most of Our ICF Builds — and the Reasoning Behind It
The system we put in most often is simple to explain: a high-efficiency wall-hung combination boiler (natural gas where available, propane where it isn’t), feeding hydronic radiant floor heat through manifolds and PEX loops. The same unit also provides on-demand domestic hot water.
The combination boiler piece: Modern combi boilers are compact, efficient (often 95%+), and proven. They don’t need a big hot water tank taking up mechanical room space, and they don’t waste money keeping a tank hot 24/7. When you want hot water, you get it. When you don’t, you’re not paying standby losses.
How the radiant system works: Warm water moves from the boiler to a manifold, then out to PEX loops in the floor. Each zone can have its own thermostat. Instead of blowing hot air out of vents, the entire floor becomes a gentle heat source — quiet, even, and comfortable. No duct noise. No “my feet are freezing but my head is boiling.” Just steady warmth.
What do you embed radiant pipes in?
This gets asked constantly — and most online answers are either vague or wildly overcomplicated. Here are the practical options we actually use:
- Concrete slab (most common in new builds): PEX is tied to mesh/rebar over insulation, then concrete is poured. The slab becomes thermal mass that stores and releases heat evenly. In many new builds, the premium isn’t “radiant vs not.” It’s doing the slab properly with insulation and good placement.
- Gypcrete (gypsum concrete): Often used on upper floors where weight matters. It self-levels nicely and adds mass, though standard concrete is typically better mass per dollar.
- Aluminum panel systems (dry install): PEX snaps into aluminum transfer plates/panels. Faster, no wet trades, good for renovations or certain upper floor assemblies — but design and spacing matter to avoid uneven floor feel.
- EPS panel systems (insulation + pipe holder): The panel positions tubing and provides insulation together, then you add a thin topping. Handy when you want speed and tidy layout.
Want the deeper version with design notes, zoning, and loop layout? See a detailed breakdown of how we design and install radiant floor systems.
In real houses, a high-efficiency boiler feeding low-temperature hydronic heat can reduce waste from duct losses, improve distribution, and avoid the on/off blasting you get with oversized forced-air systems in tight homes. The savings depend on design and fuel prices — but comfort gains are immediate, and efficiency gains are very common.
Air Source Heat Pumps — The Honest Assessment
A Strong Technology With Real Limitations in This Climate
Heat pumps have improved massively. Proper cold-climate units can perform well in Ontario, and they can be a great choice for homeowners who want to cut fossil fuel use. In moderate temperatures, they’re very efficient — that’s not marketing, that’s physics.
The honest catch is that efficiency drops as outdoor temperatures drop. Your heat pump works harder when it’s -15°C, -20°C, and below. That doesn’t mean “heat pumps don’t work here” — it means the design needs to account for Ontario’s cold hours and your backup strategy.
In many Simcoe County builds, the best heat pump setups are either: ducted heat pump systems with smart controls, or dual-fuel (heat pump for shoulder seasons + gas backup for deep cold). If you’re thinking heat pump + hydronic radiant, it can be done, but you want the design team to understand water temperature requirements and system integration.
Geothermal — The Premium Option
The Best Long-Term Performer. Not Always the Right Call.
Technically speaking, geothermal is hard to beat. Instead of pulling heat from cold outdoor air, it exchanges energy with the ground where temperatures are far more stable. That stability is why geothermal doesn’t “fall off a cliff” in deep cold the way air source systems can.
The issue isn’t performance. It’s upfront cost, site conditions, and complexity. In our region, the lot can make or break geothermal economics — rock, access, waterfront constraints, landscaping plans, and drilling logistics all matter.
The three common loop approaches (plain English)
- Horizontal loop (buried pipe): Pipe runs in trenches, typically 5–6 feet down. You need space (often a larger lot), and excavation is a real part of the budget.
- Vertical loop (drilled boreholes / “well-to-loop”): Works on smaller lots but tends to cost more because drilling is specialized. Depth and number of boreholes depend on load and geology.
- Lake/pond loop (where allowed and practical): Great when you have the right property and approvals — the water body becomes your heat exchanger. Not common, but it can be a nice option on the right site.
Geothermal pairs well with low-temperature hydronic radiant — often better than many air source setups — but it may include a water-to-water heat pump and additional components. Also, while some geothermal systems can contribute to domestic hot water (for example, through a desuperheater), you shouldn’t assume it replaces your full domestic hot water needs in every household.
If you want the direct comparison: geothermal vs air source heat pump in Ontario.
Forced Air — Why We Don’t Recommend It for ICF Homes
The Cheapest Option Upfront. The Worst Match for How ICF Performs.
Forced air is common because it’s familiar and it pencils nicely on a quote. It’s fast to install, most HVAC crews can do it in their sleep, and it can handle heating + cooling with one duct system.
The problem is comfort and fit. ICF homes are built to be stable, quiet, and even. Forced air tends to create stratification (hot up high, cooler down low), drafts, and noticeable cycling. And ductwork brings penetrations, chases, and compromises that you simply don’t need in many ICF designs.
If budget is truly tight and you need cooling, a properly designed duct system with good equipment is better than a messy “half system.” We just don’t pretend it delivers the same comfort as a well-designed radiant system in an ICF envelope.
The Cost Comparison Side by Side
What Each System Actually Costs in Simcoe County (Typical Ranges)
Costs vary by house size, zoning complexity, garage/driveway heat, fuel availability, and how “custom” the controls get. But homeowners deserve ranges that live in reality, not fantasy. Here’s how we explain it to clients at the budgeting stage.
| System | Typical installed range (Ontario ICF build) | What drives the number up |
|---|---|---|
| Combi boiler + hydronic radiant |
Often comparable to (or modestly above) a quality forced-air system once you factor:
boiler, manifolds, PEX loops, zoning, controls, and doing the slab properly.
Best value when you keep the design clean and right-sized. |
Room-by-room thermostats, extra zones, heated garage, snow-melt, long loop runs, premium controls, complex floor assemblies. |
| Air source heat pump |
Wide range depending on ducted vs ductless, tonnage, backup heat strategy, and electrical service readiness.
Rebates can materially reduce net cost. |
Dual-fuel integration, electrical upgrades, multiple heads/zones, cold-weather backup, premium brand/spec. |
| Geothermal (ground source) |
Highest upfront cost because loops/drilling add a whole other scope.
Can be excellent for the right lot and long ownership horizon. |
Rock/drilling conditions, access constraints, number/depth of boreholes, loop design, added DHW components. |
| Forced air (gas furnace or ducted heat pump) |
Usually lowest upfront. Fastest install.
Often chosen for familiarity rather than long-term comfort. |
Duct complexity, bulkheads/chases, high-end zoning, better filtration/HRV integration, premium equipment. |
Common Questions About Heating Systems for ICF Homes in Ontario
What is the best heating system for an ICF home in Ontario? +
For most new ICF homes in Ontario, we recommend a high-efficiency combination boiler feeding hydronic radiant floor heat. It matches how ICF homes behave (steady, stable temperatures), it’s quiet, comfortable, and it’s a straightforward system to service long-term. Geothermal can be the best long-term performer on the right lot with the right budget, and heat pumps are a solid option when designed properly — but for the typical Simcoe County custom build, combi + radiant is the most consistent winner.
Can you use a heat pump with radiant floor heating in an ICF home? +
Yes, but the design matters. Radiant floors typically want lower, steady water temperatures. Some air source heat pumps struggle to efficiently deliver the required water temperatures in deep cold without backup. Geothermal tends to pair more naturally with low-temperature hydronic radiant. The key is designing the heat source and distribution system together — not picking one and hoping the other “just works.”
How much does radiant floor heating cost in Ontario? +
The installed cost depends on the number of zones, floor assemblies, and whether you’re heating extras like a garage or shop. In many new builds, the “radiant cost” is best understood as a system package: boiler + manifolds + PEX + controls + doing the slab properly with insulation. The good news is that in a well-designed new build, radiant often lands closer to “comparable” with a high-quality forced-air setup than people expect — especially when you value comfort and long-term operating stability.
What is a combination boiler and how does it work with radiant heat? +
A combination (“combi”) boiler is a compact wall-hung unit that provides both space heating and domestic hot water. For radiant heat, it supplies warm water to a manifold that distributes flow to the PEX loops in your floors. For hot water, it heats on demand — meaning no big tank and no standby losses. It’s one of the cleanest, simplest mechanical-room setups you can put in a new Ontario home.
Does radiant floor heating save money compared to a furnace? +
Often, yes — but the bigger “win” is comfort. Radiant systems can reduce waste from duct losses and can run steady at lower temperatures. In tight ICF homes, forced-air systems are commonly oversized, which leads to short-cycling and less efficient operation. If you right-size and design it properly, radiant plus a high-efficiency boiler can be a very efficient way to heat an ICF home, and it tends to keep homeowners happier year after year.
Is geothermal worth it for an ICF home in Simcoe County? +
Geothermal can be fantastic, but it’s site-dependent. If your lot and budget support it — and you plan to own the home long enough to justify the premium — it can deliver very stable efficiency even in deep cold. The challenge is upfront cost and installation complexity (drilling, loops, access, geology). For many ICF homes, the heating load is already low enough that geothermal’s payback stretches out unless the conditions are ideal.
What do you embed radiant floor pipes in? +
Most commonly: a concrete slab in new construction. Other options include gypcrete (often on upper floors), aluminum transfer panel systems (dry install), and EPS panel systems that combine insulation and pipe positioning. The “best” choice depends on your floor structure, weight limits, desired response time, and construction sequencing. If you want the practical details: in-floor heating installation.
Let’s Design the Right System for Your Build
The heating system decision needs to happen early — ideally before the slab is poured and before mechanical rough-ins lock you into a path. The “right” answer depends on your heat loss, fuel availability (gas vs propane), your lot, your budget, and how you plan to live in the home.
If you want a quick ballpark, start here: our cost calculator. If you want the correct answer for your plans and lot, reach out and we’ll talk it through like builders do — clearly, directly, and without trying to sell you a science project you didn’t ask for.
Related reading: Heat Loss Calculations • Geothermal vs Air Source Heat Pump
