Why EffectiV · The business case for air mixing
The coldest houris the most expensive one.
Better air mixing recovers a share of the heating, and heating follows the cold. The recovered energy is therefore concentrated in the coldest hours: the hours dynamic tariffs charge the most, the month’s demand charge is set and the gas burns hardest. A kilowatt-hour recovered then is worth more than its average price. This page does the arithmetic on your numbers, not ours.
One winter day, hour by hour
Heating load and the critical peak hours of Wisconsin Public Service’s rate
Hour
Outdoors
Price per kWh
vs the cheapest hour
Four tariffs
Four ways a kilowatt-hour gets priced.
What a recovered kilowatt-hour is worth depends on the hour it is recovered and on the tariff’s structure. Under a flat rate it follows the energy; under a dynamic tariff it follows the peak, and the peak is where heating concentrates.
01
Flat rate
One price all day. The recovered energy is worth the same at 3 a.m. and 7 a.m.
Savings follow the recovered energy and nothing else. This is the base case of the sketch below.
02
Critical peak pricing
Utilities call events on the coldest mornings and evenings. Wisconsin Public Service’s residential rate bills about $1.30/kWh in a critical peak hour against 7.3 ¢ off-peak, up to 50 hours a year; Hydro-Québec’s Rate Flex D about 46 ¢ against under 9 ¢, up to 120 hours a winter.
Event hours are the coldest mornings and evenings: exactly the hours when the heating load, and with it the recovered energy, is highest.
03
Time-of-use
Xcel Energy’s Colorado residential rate: about 10 ¢/kWh off-peak and 17 ¢ on-peak in winter, with the on-peak window on weekday evenings (5–9 p.m. since 2025). Ontario’s Ultra-Low Overnight plan runs from 3.9 ¢ overnight to 39.1 ¢ on weekday evenings.
The winter evening on-peak window coincides with the afternoon warm-up and the falling outdoor temperature. The share of the value in peak hours exceeds the share of the energy.
04
Demand charge
Most commercial tariffs bill the month’s highest 15-minute demand in kW. Lowering the heating demand in the coldest hour lowers the whole month’s charge.
A single quarter-hour sets the month’s demand charge, and in winter that quarter-hour is the coldest one. Lowering the heating demand then is paid back twelve times a year.
The design day
A design day, hour by hour.
One winter day in a heated building. The lime area is the heating load, which follows the outdoor temperature. The bright band on top is the heating a better air distribution recovers: you set that share yourself. The red hours are the tariff’s peak hours, when a kilowatt-hour costs the most, and the recovered energy that falls in them is drawn in red. Enter your building’s peak heating load and the tiles do the day’s arithmetic on your numbers.
Utilities call events on the coldest mornings and evenings. Wisconsin Public Service’s residential rate bills about $1.30/kWh in a critical peak hour against 7.3 ¢ off-peak, up to 50 hours a year; Hydro-Québec’s Rate Flex D about 46 ¢ against under 9 ¢, up to 120 hours a winter.
Heating recovered today
Saved today under this tariff
Of which during the peak hours
What a recovered kilowatt-hour is worth
Demand lowered in the coldest quarter-hour
Conceptual illustration only. It shows the principle, not a measurement: real temperatures, airflows and air quality vary from one room, system and building to the next. Model: a sinusoidal outdoor temperature around a design day, heating load proportional to the indoor–outdoor difference with a night setback and a morning warm-up. Prices are the published residential structures named above, used as examples of dynamic pricing; commercial contracts differ. The day’s figures use your peak load and your recovered share. For electric heating (resistance, heat pumps, dual-energy). With gas, the same hours are where the gas burns and the carbon is emitted.
The payback sketch
A payback sketch on your own numbers.
Nothing here is a claim. Enter your heating cost, the part of it that serves high-ceiling spaces, the share you expect better mixing to recover, and a carbon price. The sketch does the arithmetic, then draws the payback across the whole range of estimates. For a specific room, Verified quantifies the airflow and Ez terms by simulation.
Heating source
Grid
Heating energy recovered per year
Energy savings per year
Emissions avoided per year
Carbon value per year
Simple payback
Payback against the recovered share · the dot is your estimate; the curve covers 2 to 30 %
Your inputs, not a measurement or a promise. The arithmetic is transparent and contains no EffectiV figure. Real savings depend on your building, its equipment and its tariff. Simple payback = net project cost ÷ (energy savings + carbon value), at the average energy price: the peak and demand premiums above come on top. Published work on destratification in warm-air heated high-bay buildings reports savings in the order of 20 % of heating energy (Carbon Trust); your building’s number depends on its ceiling height, heaters, envelope and schedule.
What the sketch leaves out
The average price is the floor.
The sketch counts energy at its average price. Five terms come on top, each with its own page.
01
The demand charge
The heating demand in the coldest hour sets the month’s demand charge. A mixed room asks for less in that hour, and the difference is billed every winter month.
02
Comfort, air quality and the people
Better mixing does more than even out the temperature: it brings the outdoor air into the breathing zone, so the indoor air quality improves with it. Both weigh on the people, and the people are the building’s largest cost. Absenteeism, lost concentration and the turnover that a cold, drafty or stuffy office drives are considerable costs; where payroll dwarfs the energy bill, they can exceed the energy saved.
03
The size of the heat pump
At electrification, the design-hour load sizes the heat pump, its backup and the electrical service. What mixing removes in that hour never has to be bought.
04
Outdoor air that reaches people
A higher Ez means less outdoor air to heat for the same breathing-zone ventilation (ASHRAE 62.1), which is avoided heat too.
05
Cooling savings
The sketch counts heating only. In summer, some rooms carry a warm pocket at the thermostat and the over-cooling that compensates for it; improved mixing removes it where it occurs, and a higher Ez lowers the outdoor air to cool. Usually smaller than the heating term, and on the same bill.
Money on the table
Incentives pay part of the fix; carbon raises the cost of the problem.
Incentives, carbon pricing and penalties enter the sketch through two sliders: the incentive on the project and the carbon price. Figures as of October 2026; check the current programs.
United States
utility programs
Utility and state efficiency programs continue after the federal 179D deduction ended for construction begun after June 30, 2026; amounts vary by utility and often cover custom measures.
Hydro-Québec
Efficient Solutions
Energy-efficiency measures in medium and large businesses can receive up to 75 % of eligible costs; up to 90 % for small businesses.
California–Québec
carbon price
Allowances on the joint cap-and-trade market sold for US$28.32 (C$39.64) per tonne at the November 2025 auction, a cost that flows into gas and fuel bills.
New York City
LL97 penalty
Above its annual limit, a building over 25,000 ft² pays US$268 per metric ton of CO₂e. For a building over the limit, every tonne avoided is worth that penalty.
Your number
How to get yours.
The sketch bounds the order of magnitude. Your building’s number comes from your room, your heaters and your tariff.
01
SelectiV
Compare diffusers at the same airflow in your room and see which ones deliver the heat to the occupied zone in heating.
SelectiV02
Verified
A CFD comparison of your design and a reference design, with the energy terms reported per ASHRAE 105 principles: numbers for your energy model and your incentive application.
Verified03
Tell us about your project
Ceiling height, heating source, tariff: our engineers will tell you what is worth measuring.
Tell us about your projectSources
The figures cited, and where they come from.
- 01Hydro-Québec, Rate Flex D and dynamic pricing
- 02Wisconsin Public Service, residential time-of-use / critical peak tariff (Schedule Rg-RR)
- 03Colorado Public Radio, Xcel Energy residential time-of-use rates (May 2025)
- 04Ontario Energy Board, electricity prices effective November 1, 2025
- 05Hydro-Québec, Winter peaks and grid capacity
- 06U.S. Energy Information Administration, Commercial Buildings Energy Consumption Survey 2018
- 07Natural Resources Canada, Energy Use in the Commercial/Institutional Sector (2019)
- 08U.S. EPA, GHG Emission Factors Hub (2024, 2025)
- 09Carbon Trust, destratification fans datasheet
- 10Hydro-Québec, Efficient Solutions Program
- 11U.S. Department of Energy, 179D Energy Efficient Commercial Buildings Tax Deduction
- 12Québec, joint auction results, November 19, 2025
- 13New York City, Local Law 97
- 14ASHRAE Standard 105-2021, Standard Methods of Determining, Expressing, and Comparing Building Energy Performance and Greenhouse Gas Emissions
Go further
The carbon, and the physics behind the page.
SelectiV · Verified
Designing a room? Start with the air.
Use SelectiV to lay out diffusers in 3D, or ask for a Verified CFD study to validate comfort, IAQ and energy before anything is installed.