Heating-system performance is often presented through laboratory testing, computer modelling or carefully controlled demonstrations.
Those tools are important, but homeowners, builders and heating professionals ultimately want to know something more practical:
How does the system perform in a real home, with real occupants, over an entire year?
This case study examines 12 months of actual FortisBC natural-gas billing data from a 242 m² (2,600 sq. ft.) family home in Victoria, British Columbia.
The home is occupied by a family of six and uses natural gas for:
Across all four of these loads, the home consumed just 38.5 gigajoules of natural gas over 12 months—equivalent to approximately 10,694 kWh.
That represents a measured natural-gas energy intensity of approximately 44 kWh/m² per year.
For a large, occupied family home with significant window area, the result demonstrates how low energy consumption and exceptional radiant comfort can work together.
The project is a detached 242 m² home located in Victoria on the southwest coast of British Columbia.
Its design includes large windows and open-concept living spaces—features that create an attractive, modern interior but can also increase heating demand compared with a smaller, more enclosed floor plan.
The home is occupied by six people, making the domestic hot-water load particularly relevant. Every shower, bath, load of dishes and other hot-water demand is included in the same annual natural-gas total as the heating system.
Natural gas is also used for cooking and the outdoor barbecue.
The recorded 38.5 GJ therefore does not represent space heating alone. It represents the combined annual gas consumption of the home’s principal gas-fired services.
The figures in this case study come from 12 consecutive months of FortisBC billing data.
This is important because the results reflect the way the home is genuinely occupied and operated. They include changing outdoor temperatures, thermostat adjustments, domestic hot-water use, cooking and day-to-day family life.
The recorded monthly gas consumption was:
Consumption followed the expected seasonal pattern. Gas use remained very low through the warmer months and increased as outdoor temperatures fell and the heating demand grew.
The lowest recorded month used only 0.3 GJ, while the peak month used 8.0 GJ.
This seasonal response indicates that the system was delivering energy when the building required heat rather than consuming it at a consistently elevated level throughout the year.
The home’s total annual gas consumption was 38.5 GJ, or approximately 10,694 kWh.
Dividing that annual consumption by the home’s 242 m² floor area produces a measured natural-gas intensity of approximately:
44 kWh/m² per year
This figure includes more than heating. It also includes domestic hot water for six occupants, gas cooking and barbecue use.
The actual portion used by the radiant heating system is therefore lower than the full 38.5 GJ total.
Without separate submeters, it is not possible to divide the utility bill precisely among space heating, domestic hot water, cooking and barbecue use. For that reason, this case study presents the complete measured gas total rather than attempting to assign an estimated amount to each load.
That makes the result both transparent and conservative.
Energy consumption varies between homes, so no comparison can be perfectly identical. Climate, airtightness, insulation, window area, occupant behaviour, thermostat settings, domestic hot-water demand and equipment efficiency all affect annual usage.
However, a 38.5 GJ annual total is notably low for a detached 242 m² home occupied by six people.
The comparison ranges used for homes of a similar size are:
Compared with the lower end of the high-efficiency forced-air range, the measured 38.5 GJ total is approximately 30% lower.
Compared with the upper end of that range, it is nearly 49% lower.
These comparisons are illustrative rather than controlled scientific tests. Nevertheless, the measured utility result places this home well below the conventional energy-consumption ranges commonly associated with detached homes of a similar size.
A radiant floor system delivers heat differently from a forced-air furnace.
Forced-air heating warms air and distributes it through ducts. The warm air rises, mixes with cooler room air and can create temperature differences between the floor, occupied area and ceiling.
Radiant floor heating uses the floor as a large, low-temperature heat-emitting surface.
Instead of introducing concentrated heat from a register, the system distributes warmth across the room from below. The floor, furniture and surrounding surfaces gradually absorb and release radiant energy.
This can provide several comfort benefits:
The purpose is not simply to make the floor feel warm. It is to create a stable indoor environment in which a large surface gently replaces the heat being lost by the building.
A room can feel comfortable even when its air temperature is slightly lower if the surrounding surfaces are warm.
This is one of the fundamental advantages of radiant heating.
Human comfort is influenced by both air temperature and mean radiant temperature—the average temperature of the surfaces surrounding the occupants. Cold walls, floors and windows can make a room feel uncomfortable even when the thermostat indicates an acceptable air temperature.
Radiant floor heating raises the temperature of one of the room’s largest surfaces. This can improve perceived comfort without depending on high air temperatures or large temperature swings.
The system can therefore deliver a high level of comfort while operating steadily and efficiently.
High-mass radiant systems embedded in thick concrete can store substantial heat. That can be useful in some applications, but it can also create a slow response when the heating demand changes.
An in-joist Ultra-Fin system does not depend on heating a heavy concrete slab.
The system warms the joist cavity and transfers heat through the existing floor structure. With less thermal mass to heat, the system can respond more quickly to thermostat demand and changing outdoor conditions.
This is particularly valuable in Victoria’s coastal climate, where outdoor temperatures and solar gain may change considerably during the day.
A more responsive system can add heat when it is needed and reduce heat delivery when the room reaches its set temperature, helping minimize overheating and unnecessary energy use.
The home contains substantial areas of glazing.
Large windows can increase heat loss, particularly during cooler weather, and can create changes in room temperature as solar gain increases and decreases throughout the day.
Despite this architectural feature, the home’s annual measured natural-gas consumption remained only 38.5 GJ.
This suggests that a properly designed radiant system can serve modern, open-plan architecture without automatically resulting in excessive fuel consumption.
Good performance still depends on the complete building and mechanical design, including:
Radiant heating is not a substitute for a well-designed building envelope. The strongest results occur when the heating system and building are designed to work together.
Low-temperature hydronic heating can improve the operating conditions for a condensing boiler.
A condensing boiler achieves its highest efficiency when the returning water is cool enough for water vapour in the exhaust gases to condense. This allows the boiler to recover heat that would otherwise leave through the flue.
A properly designed radiant system can operate with lower water temperatures than many conventional radiator systems, particularly during milder weather.
Lower water temperatures can:
The annual utility data reflects the performance of the home as a complete system, not the radiant floor alone. However, the ability of radiant heating to work effectively at lower temperatures is an important part of achieving efficient hydronic performance.
The measured result should not be interpreted to mean that every radiant-heated home will automatically consume 38.5 GJ per year.
Performance depends on the design and operation of the entire building.
A successful hydronic radiant system requires:
Each room must be evaluated based on its size, exterior walls, windows, insulation, orientation and local design temperature.
The amount and location of the radiant heating must correspond to the room’s calculated demand.
Water temperature should be high enough to meet the heating requirement but no higher than necessary.
Each circuit must receive the flow required to deliver its designed output.
Rooms with different exposures, uses or solar gains should be controlled according to their individual requirements.
Heat should be directed toward the occupied space rather than lost into an unconditioned area below.
The complete system must be filled, purged, balanced, tested and adjusted before handover.
The performance measured in this home reflects the result of a properly designed and operating hydronic radiant system—not simply the presence of tubing beneath the floor.
Occupancy is an important part of the story.
Six people generally create more domestic hot-water demand than a smaller household. More showers, laundry, dishwashing and daily hot-water use increase the amount of natural gas consumed independently of space heating.
Cooking and barbecue use add further demand.
Because all of these uses are included within the measured 38.5 GJ annual total, the result provides a realistic picture of the home’s operation.
It is not an unoccupied demonstration home, a computer simulation or a heating-only estimate. It is an actively used family residence with a full range of everyday energy demands.
Good performance claims should be clear about the limits of the evidence.
This case study measures the natural gas delivered to one home over one year. It provides strong evidence of low real-world gas consumption in this specific installation.
It does not independently isolate:
This is therefore not a controlled comparison between two identical homes with different heating systems.
It is something more practical: a documented example showing that a large, six-person home with hydronic radiant heating can provide excellent comfort while recording very low annual natural-gas consumption.
The final numbers are straightforward:
Those figures move the conversation beyond theoretical output and laboratory conditions.
They show how a properly designed radiant heating system can perform in a real home, through changing seasons, while serving the everyday needs of a family of six.
Efficient heating should not require occupants to compromise on comfort.
This Western Canada home demonstrates that gentle radiant heat, quiet operation and even room temperatures can be achieved alongside exceptionally low measured natural-gas consumption.
The data is not a projection. It comes from 12 months of actual utility bills.
That is the performance that ultimately matters: not simply how a heating system performs on paper, but how it performs every day in the home it was designed to heat.
