Heat loss estimating, room-by-room surveying and radiator sizing. Please read and accept the following to continue.
These tools run entirely on your device. Everything you enter — projects, calculations and selections — stays in this device’s browser storage and is not sent to any server or third party. There is no account, no tracking and no analytics. Nothing is shared unless you choose to share it yourself by exporting a file, producing a report, or sending an email.
These tools assist competent persons in estimating heat loss and sizing heat emitters and generators. They are calculation aids only. They do not constitute engineering certification, a design, or a substitute for professional judgement, and do not by themselves satisfy any MCS, Building Regulations or other regulatory requirement.
Results depend on the information entered and the published data cited, and must be confirmed against current manufacturer data for the actual products installed. The user is responsible for checking all inputs and outputs, for working within their demonstrated scope of competence, and for compliance with current UK legislation, standards and manufacturers’ instructions. To the fullest extent permitted by law, the author accepts no liability for any error, omission, or any direct or indirect loss or damage arising from use of these tools or reliance on their output.
© 2026 Stephen Denney. All rights reserved. These tools may not be reproduced, redistributed, or modified without written permission. Sources (CIBSE, BSI, RdSAP, MCS and manufacturer data) are cited for reference only.
Heat loss estimating, room-by-room surveying and radiator sizing — on your phone.
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