Calculator Inputs
Use the preset or enter your own heat loss coefficient. The page uses a single-column layout, while the form uses a responsive multi-column grid.
Example Data Table
These sample cases show how different envelope quality and temperature conditions affect radiant heat pump sizing and operating cost.
| Scenario | Area (m²) | ΔT (°C) | COP | Load (kW) | Daily Electric (kWh) | 30-Day Cost ($) |
|---|---|---|---|---|---|---|
| Well-insulated home | 120 | 19 | 3.8 | 4.53 | 11.93 | 64.43 |
| Large cold-climate zone | 180 | 24 | 3.2 | 11.12 | 41.71 | 225.23 |
| Mild climate retrofit | 90 | 14 | 4.2 | 1.84 | 3.50 | 18.91 |
Formula Used
The calculator estimates radiant heating demand from floor area, temperature difference, room height, system efficiency, and a design safety margin.
1) Base Heat Load
Base Heat Load (W) = Floor Area × Heat Loss Coefficient × Temperature Difference × Height Factor
2) Height Factor
Height Factor = Room Height ÷ 2.5
3) Adjusted Heating Load
Adjusted Load (W) = Base Heat Load × (1 + Design Margin) ÷ Efficiency Factor
4) Daily Thermal Energy
Daily Heat (kWh/day) = Required Heating Capacity (kW) × Runtime Hours
5) Daily Electric Use
Daily Electric Use (kWh/day) = Daily Heat ÷ COP
6) Period Cost
Period Cost = Electric Use for Selected Period × Electricity Rate
This approach is ideal for early-stage sizing, operating-cost screening, and comparing design assumptions. It does not replace a full room-by-room heating design.
How to Use This Calculator
- Enter the radiant floor area that needs heating.
- Set room height and choose an insulation preset.
- Review or edit the heat loss coefficient.
- Enter indoor and outdoor design temperatures.
- Input COP, efficiency, margin, runtime, and electricity rate.
- Set the number of heating days for your comparison period.
- Press the calculate button to show results above the form.
- Use the CSV or PDF buttons to save results.
Frequently Asked Questions
1) What does this calculator estimate?
It estimates radiant heating load, recommended installed capacity, daily electric use, selected-period energy demand, and operating cost using simplified engineering assumptions.
2) What is the heat loss coefficient?
It represents how strongly the building loses heat through the envelope. Better insulation usually means a lower coefficient and a smaller heat pump requirement.
3) Why does room height matter?
Taller rooms generally increase conditioned volume and heat loss. The calculator uses a simple height factor relative to a 2.5-meter reference room.
4) Why is COP important?
COP shows how much heat the system delivers for each unit of electricity consumed. A higher COP usually lowers daily and seasonal operating cost.
5) What does the design margin do?
The design margin adds safety capacity for uncertain conditions, intermittent setbacks, and envelope variations. Higher margin raises the recommended load and cost estimate.
6) Can this replace a full HVAC design?
No. It is best for planning and comparison. Final equipment selection should still consider zoning, loop temperatures, emitter spacing, ventilation, and local design standards.
7) Why does the chart rise at colder temperatures?
As outdoor temperature drops, the temperature difference across the building envelope grows. That increases heat loss and raises required heating capacity.
8) How should I choose heating days?
Use 30 days for a quick monthly estimate, or set a longer number for a seasonal comparison. Keep assumptions consistent when comparing multiple scenarios.