The calculator estimates a revenue offset per kWh of electricity consumed. It is a starting point for a heating-cost assessment, not a quotation or a guaranteed saving.
What does the compute offset mean?
The Node consumes electricity to run SHA-256 computing hardware. In our model, that workload is Bitcoin mining. The expected mining proceeds, expressed in pence for each kWh consumed, are the compute offset.
Illustrative net electricity cost = electricity price − compute offset
Both figures must use the same basis: pence per kWh of electricity consumed.You still pay your electricity supplier. Computing proceeds are separate from that bill. The illustration does not mean your supplier sells electricity at the net figure, or that revenue is guaranteed.
The homepage calculator lets you change mining difficulty, Bitcoin's sterling price and hardware efficiency. The tariff comparison alongside it uses the site's stated fixed and smart-tariff assumptions; changing mining inputs does not forecast your future tariff.
Why the result changes
- Bitcoin price in pounds
- A lower BTC/GBP price reduces the sterling value of the same amount of Bitcoin earned.
- Network difficulty
- Higher difficulty means the same hardware is expected to earn less Bitcoin, with other inputs unchanged.
- Hardware efficiency, in J/TH
- This measures energy used per trillion hashes. A lower number means more computing work for the same electricity input.
- Block rewards and pool fees
- The model uses a rolling 144-block average reward, including transaction fees, and a 2% pool fee. These assumptions affect expected net proceeds.
The site checks market data every 24 hours; its calculator can fall back to saved defaults if live data is unavailable. Treat the displayed inputs as a scenario to inspect, not a forecast of the coming year.
Try a lower Bitcoin price and higher difficulty to see a less favourable outcome. For a separate zero-revenue comparison, use the electricity cost with no offset at all. That reveals how dependent the proposal is on mining proceeds.
A kWh consumed is not automatically a kWh delivered
An electricity meter records input energy. The heat that reaches the building depends on heat recovery, storage and distribution losses, auxiliary electricity use, and whether the generated heat is actually needed.
Net operating cost per useful kWh = net operating costs over a period ÷ useful heat delivered over that period
Use consistent costs, units and dates for every option being compared.Compute income changes the cost numerator. It does not multiply the heat output. A heat pump's COP describes a different physical process: moving heat from an outside source. See our thermal-storage guide for the distinction.
The homepage's smart-tariff illustration uses a historical Octopus Agile average for Southern Scotland, with specified morning and evening hours avoided. A building may not be able to follow that exact schedule. Its actual consumption-weighted tariff and useful heat delivery need their own assessment.
A tariff illustration and a measured result answer different questions
The GWhFI immersion-heating tariff demonstration reports consumption-weighted electricity prices for the displayed periods. It combines measured heater electricity use with Agile unit rates. This is an observed result for that installation and period, rather than the homepage's historical 16.6p/kWh scheduling illustration or a forecast for another property.
The dashboard's unit price does not include standing charges, equipment costs or maintenance, and it is not a cost per kWh of useful heat delivered. Establishing savings requires a fair comparison against an alternative operating schedule with the same hot-water needs. See how to read the demonstration before using it in a comparison.
Build the comparison around your property
Start with a full year of heating and hot-water demand where available. Use the same comfort requirements and time period for the existing system, a proposed Node system and other feasible alternatives.
- Include the full installation: hardware, storage, integration and any required building or electrical work.
- Include ongoing costs: electricity, maintenance, downtime and replacement assumptions. Keep tax treatment and any financing costs explicit.
- Treat standing charges consistently: distinguish charges you would pay anyway from those that would actually change.
- Show more than one scenario: compare expected conditions with lower compute proceeds, less favourable tariffs and reduced operating availability.
The headline illustration excludes hardware purchase, maintenance, downtime and tax. A useful feasibility draft makes those boundaries clear and explains who receives the computing proceeds and how their value is accounted for.
Send Heat21 your building details to discuss that assessment, or read how the heat-recovery system works before exploring the calculator.