Heat Loss Calculator

Follow the simple step-by-step process below to calculate the heat loss for any room in your house. We’ll even suggest some suitable radiators for you.

Stelrad Basic Heat Loss Programme

Use this heat loss calculator for a quick estimate of how much heat you need for your room or project.

The Stelrad basic heat loss calculator makes various assumptions based on your choices and may not take into account all factors relating to your particular requirements. If you require a more detailed calculation please use the advanced version of the programme at starsapp.co.uk. We accept no liability for any errors resulting from the estimates given. Calculations are based on Delta-T 50°C (Δ-T50°C) in accordance with BS EN 442. Your use of the Stelrad basic heat loss calculator is subject to these terms and conditions.

Additional terms and conditions:

Basic Heat loss Assumptions & Terms

The assumptions made in the basic heat loss programme are as follows:

  1. Interior walls are treated as party walls with an adjacent temperature of 10°C
  2. Interior walls have a u value of 1.5
  3. Interior walls include a single internal door measuring 1.98m x 0.76m and u value of 2.2
  4. A floor type other than “Heated Room” assumes an adjacent temperature of -3°C
  5. A ceiling type other than “Heated Room” assumes an adjacent temperature of -3°C
  6. External temperature is -3°C

Room Types:

  • Bathroom – Temperature: 22, Air Changes: 2
  • Bedroom – Temperature: 18, Air Changes: 1
  • Bedroom/En Suite – Temperature: 18, Air Changes: 2
  • Dining Room – Temperature: 21, Air Changes: 1.5
  • Hall – Temperature: 18, Air Changes: 1.5
  • Kitchen – Temperature: 18, Air Changes: 2
  • Kitchen/Diner – Temperature: 21, Air Changes: 2
  • Landing – Temperature: 18, Air Changes: 1.5
  • Living Room – Temperature: 21, Air Changes: 1.5
  • Study – Temperature: 21, Air Changes: 1.5
  • Utility Room – Temperature: 18, Air Changes: 2
  • WC – Temperature: 18, Air Changes: 2

Exterior Wall Types:

  • 220mm solid brick plastered – U Value: 2.10
  • 105mm solid brick plastered – U Value: 3.00
  • Brick cavity wall – U Value: 1.47
  • Insulated brick cavity wall – U Value: 0.50
  • Timber frame wall – U Value: 0.29

Glazing Types:

  • Wood/PVCu Single Glazed – U Value: 5.0
  • Wood/PVCu Double Glazed – U Value: 2.9
  • Low E Double Glazed - U Value: 1.7
  • Metal Frame Single Glazed – U Value: 5.8

Floor Types:

  • Heated room – U Value: 1.36, Adjacent Temperature: 21
  • Timber floor over ventilated air gap – U Value: 0.82, Adjacent Temperature: 10
  • Uninsulated solid floor on earth – U Value: 0.82, Adjacent Temperature: 10
  • Solid concrete floor – U Value: 1.6, Adjacent Temperature: 10

Ceiling Types:

  • Heated room – U Value: 1.62, Adjacent Temperature: 18
  • Insulated roof space – U Value: 0.71, Adjacent Temperature: -3
  • Uninsulated roof space – U Value: 2.30, Adjacent Temperature: -3
  • Insulated flat roof – U Value: 0.70, Adjacent Temperature: -3
  • Uninsulated flat roof – U Value: 2.19, Adjacent Temperature: -3

Exterior walls:

  • Room has 1 exterior wall – assume the exterior wall is the longer.
  • Room has 2 exterior walls – assumes the two exterior walls are at right angles.
  • Room has 3 exterior walls – assumes the exterior walls are two short and one long.

Images and descriptions

The physical dimensions of the Radiators stated on our Heat Loss Programmes are indicative only. Although we have made every effort to state accurate dimensions, we cannot guarantee that they will match those dimensions exactly. To the extent permitted by law, we accept no liability associated with such variations.

The images of the Radiators on our Heat Loss Programmes are for illustrative purposes only. Although we have made every effort to display the colours accurately, we cannot guarantee that your device's display of the colours will accurately reflect the colour of the Radiators these may vary slightly from those images. Radiators may show some colour variation. To the extent permitted by law, we accept no liability associated with such variations.

Your personal information

In the course of our dealings with you we will collect and process personal information about you. Further information on the manner in which we process personal information is set out in our Privacy Policy, a copy of which is available at www.stelrad.com.

Calls to our contact centre may be monitored and/or recorded for quality control and training purposes.
Contacting us and you.

If you have any questions, complaints or concerns please contact us by email at info@stelrad.com or by telephone on 01709 572 299.

Any formal legal notices should be sent to Stelrad Management Limited and our registered office is at 69-75 The Side, Newcastle Upon Tyne, Tyne & Wear, NE1 3JE.

Other important terms

We may update, vary and amend these assumptions and terms from time to time without prior notice. Each time you use the programmes, the assumptions used at that time will apply.