Plan network capacity with reliable heating calculations. Adjust temperatures, factors, and heat recovery assumptions easily. Export results for teams, bids, and design records fast.
| Input | Value | Unit |
|---|---|---|
| Indoor setpoint | 21 | °C |
| Outdoor design temp | -2 | °C |
| Supply / Return | 80 / 50 | °C |
| Ventilation flow | 120 | L/s |
| Heat recovery efficiency | 0.65 | – |
| Building volume | 1200 | m³ |
| Infiltration | 0.35 | ACH |
| Internal gains | 1500 | W |
| Diversity / Safety | 0.95 / 1.10 | – |
| Walls U × Area | 0.35 × 520 | W/m²·K × m² |
| Roof U × Area | 0.25 × 340 | W/m²·K × m² |
| Windows U × Area | 1.60 × 120 | W/m²·K × m² |
District heating sizing starts with agreed indoor setpoints and outdoor design temperatures. The calculator converts these into a design temperature difference that drives peak losses. In multi‑building systems, not every customer peaks simultaneously, so a diversity factor helps represent coincident demand. Selecting realistic coincidence prevents oversizing mains while protecting comfort on the coldest hours. Document assumptions with local climate records, because stakeholders often revisit criteria during procurement, commissioning, and future expansion formal planning cycles.
Envelope losses are modeled using the familiar U‑value times area approach. Separating walls, roof, floors, and glazing highlights where upgrades reduce capacity needs most. A small change in window U‑value can shift network peak, especially when glazing area is large. Use measured areas and conservative U‑values for early design, then refine with drawings and specifications.
Outdoor air introduces a continuous sensible load. The calculator estimates ventilation heat loss from airflow, air density, and specific heat, then reduces it using heat recovery efficiency. This makes heat recovery a powerful lever for district systems because it lowers both peak capacity and annual energy. If exhaust recovery is uncertain, test a low and high efficiency to bracket outcomes.
Infiltration is represented by air changes per hour and building volume, converted to a flow rate. Leaky buildings can dominate peak load even with decent insulation. A safety factor accounts for modeling uncertainty, wind effects, and future operational drift. Keep the safety factor transparent and aligned with your design standard, especially when the network serves critical occupancy.
Once design load is known, the tool computes mass flow from water specific heat and the selected supply‑return temperature difference. Higher water ΔT reduces required flow, helping smaller pipes and lower pumping energy, but may affect emitter performance. Use the reported flow as a starting point for pressure drop checks, control valve sizing, and substation heat exchanger selection.
UA is the overall heat loss factor in W/K. Multiply UA by the design temperature difference to estimate heat loss power before gains and factors. Lower UA means lower peak capacity and annual energy.
Use your project’s winter design temperature from local weather datasets or code guidance. For district systems, align the value across all connected buildings so the network peak is consistent and defensible.
No. This tool targets space‑heating load. Domestic hot water is usually added as a separate peak and annual component, often with diversity and storage considerations specific to occupancy and draw profiles.
Diversity reduces coincident peak across multiple customers. Safety increases capacity to cover uncertainty and operational drift. Apply them intentionally and document the basis, because they can change pipe sizing and plant selection.
It is a planning proxy using heating degree days and UA. It is useful for comparisons and early budgeting, but it cannot capture solar gains, schedules, controls, or intermittent operation. Use simulation or metered data for finals.
Enter representative design temperatures for peak conditions. If you operate multiple temperature levels, run scenarios and compare flows and loads. Lower temperature networks often need higher flow, but can reduce distribution losses and enable heat pumps.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.