The pressure on builders is intensifying, meeting evolving energy codes, significantly reducing carbon footprints, and constructing net zero–ready homes all while remaining on schedule and within budget. These challenges were a key part of the discussions during a recent Building Knowledge Canada session in London, Ont., that I had the pleasure of attending, sparking a critical conversation on enhancing construction practices for better, more efficient homes.
“We can’t tax our way out of a housing crisis. With 36 per cent of a new home’s cost going to taxes, it’s no wonder affordability is out of reach. Smart policy changes can get shovels in the ground and homes into the market,” shares Patrick Marion, senior procurement and sustainability manager at Mattamy Homes. “The baker doesn’t bake bread to feed the world. The baker bakes bread to make money.”
Builders aren’t here to chase sustainability. They’re here to build homes profitably, quickly, and with fewer headaches. Air-to-water heat pump systems just happen to deliver on all of that and they decarbonize the home in the process.
Now, unfortunately, there is not a whole lot that those of us in the trades can do about the government’s choices on how they tax housing; short of making sure we vote and have our voices heard. We can help builders reduce their building costs and speed up their production times and overall productivity by utilizing hydronics.
Turning hydronics on its head
In the past, we have seen hydronics as being radiant floors, a boiler application, and requiring additional equipment for air conditioning, either an air-to-air central heat pump or a mini split.
Air-to-water heat pumps have turned this concept on its head and are a whole home packaged solution that can deliver heating, cooling, and domestic hot water in a packaged unit. Still relatively new to Canada, in Europe and Asia, they are light years ahead of us in deploying air-to-water technology because they have been deploying it for longer. Not only does an air-to-water heat pump speed up home productions and simplify the mechanical room, but it is also unique in that we can go as carbon neutral as we want on the emitters.
In my own home, I have a five-ton air-to-water heat pump and a traditional hydronic coil to heat the home. From an overall efficiency best case, my system will be at a COP of two.
During the Building Knowledge event, I had an opportunity to detail an air-to-water system design capable of operating efficiently at a supply temperature of just 95 F, delivering over 10 BTUs per watt at a coefficient of performance of three. Room-specific fan coil units, consuming only about 10 watts each, further decrease fan energy consumption dramatically down to 0.08 GJ per year compared to the traditional typical ducted systems with ECM air handlers.
From an operational carbon viewpoint, this efficiency alone achieves annual savings of approximately 200 kg carbon dioxide equivalents (CO2e) per home, exclusive of additional emissions avoided through eliminating combustion-based heating.
Operational carbon, which represents the total emissions generated from a home’s energy consumption over its lifespan is increasingly critical, explains Andrew Oding, vice president of Building Knowledge Canada. As Ontario’s electrical grid rapidly decarbonizes, the emissions intensity of buildings’ energy sources becomes pivotal. This is something that will affect every province and territory across the country. New net zero building standards will look at a variety of new key factors, including the operational carbon of the building and zoning options, which air-to-water is ideally positioned to do.
Streamlining construction
Beyond carbon savings, which was a new concept for me, an air-to-water hydronic heat pump can significantly streamline the construction process. Utilizing low-voltage terminal units connected with flexible PEX piping eliminates the need for bulky ductwork, reducing complexity in framing and installation. It simplifies coordination across trades, reducing overall installation time.
Incorporating thermal storage, whether a buffer tank or a phase-change material battery, enhances energy management through strategic load shifting. By capitalizing on Ontario’s ultra-low time-of-use electricity rates, homes can store thermal energy overnight for daytime heating needs. This method not only lowers energy costs but also supports grid stability, aligning perfectly with evolving utility incentive programs that encourage off-peak consumption and demand management.
This might seem like a crazy new concept, but we have been doing thermal storage since Roman times and the hypocaust systems. When we charge a slab with BTUs in a basement, that energy takes hours to dissipate. There is no benefit beyond comfort and energy savings with gas, although admittedly, those are big perks with an air-to-water heat pump. If we charge it off peak, we are also utilizing the ultra-low overnight rate and not only delivering comfort and energy savings, but we are also stabilizing the grid.
For builders, adopting air-to-water heat pump technology with low-temperature hydronics emitters can provide substantial productivity benefits — fewer involved trades, reduced callbacks, enhanced comfort consistency, and scalability for future electrification demands without added complexity. Builders who effectively leverage these technologies can reduce operational carbon emissions without sacrificing profitability, positioning themselves as industry leaders.
Ultimately, air-to-water heat pumps and low-temperature hydronic systems represent more than technological advances; they signify a shift towards constructing higher-quality, future-ready buildings that are both environmentally responsible and economically viable. Like with all systems, air-to-water is not the magic bullet for every application and there are just as many applications where a cold climate air-to-air heat pump is the best solution.