Estimate how much heat your rooms require.

Fill in the form below and click ‘Calculate’. This will show the minimum output requirement of the heater needed for the space you have specified.
Add other rooms to your list, for example ground floor or top floor rooms.
Click ‘view report’ to see our recommendation for the specific heater required.
Adding subsequent rooms
If you want to calculate for a number of rooms that are similar, but are perhaps on different floors for example – on the results page use the ‘COPY & AMEND’ feature to avoid having to input identical information again. If the room you wish to add is very different for example on a different site with different dimensions, then click the ADD ROOM button for a fresh start.

This calculator provides a guide to the heating requirements, for the details you input, based on the building regulations in force at the time the building was constructed.

The resulting calculations from this form should be treated as a guide and are not intended to replace a professionally prepared, detailed heat loss calculation.

Required fields are marked with an asterisk *.

Please see general notes for instructions.

Site details

Site name *

Room ID / number *

Construction

Please see construction notes.

Year built *

Temperatures

Inside temperature (°c) *

Outside temperature (°c) *

Dimensions

Floor area (㎡) *

Ceiling height (m) *

Areas

Please see area note.

Outside wall area including windows and
doors (㎡) *

Window and door area combined (㎡) *

For top floor rooms - Ceiling area including roof lights (leave as 0 if not a top floor room). (㎡) *

Roof light area (㎡) *

For ground floor rooms - Floor area (leave as 0 if not a ground floor room) (㎡) *

General notes

Internal heat transfer between spaces of different temperatures are not included.
A 10% margin is included on the final room heat loss.
Air changes rates have been assumed that will allow for a selected emitter to recover temperature should a window be opened for a short period.

Construction notes

Construction dates generally reflect Building Regulation U values however for simplicity some worst case allowances have been carrried forward.
2013 to Present U values are representative for commercial buildings and have been based on the domestic building allowance, assuming a reasonable whole build carbon balance was taken.
If an older building has been renovated please use the most recent date of renovation.

Area note

Only input areas for surfaces which have an external surface. For example, do not enter a floor when there is a room below; or a ceiling when there is a room above.