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H1 Thermal Calculator

McNaughton Timber Windows and Doors demonstrate superior thermal efficiency. 


We have developed a BRANZ-approved H1 Thermal Calculator for timber joinery. Each window and door we manufacture is thermally modelled, providing a combined joinery house lot ‘R’ value to guide you on creating the most thermally efficient house.

thermal efficiency calculator

H1 Thermal Calculator is extremely useful in the following situations:​​


Houses where customers are wishing to maximise thermal performance.


Houses requiring increased window performance to offset lower thermal performance in other design elements (such as skylights, louvres, etc.).


Houses where windows/doors exceed 40% of the walls.


Non-Housing projects greater than 300m2.

Request Thermal Calculations for Your Project

We can provide specific individual thermal calculations (R Values) for each designed window/ door upon request. Should you require calculations at any stage of the design process, simply complete the form below and attach the architectural plans, and we will be happy to assist you with a comprehensive report.

Upload Architectural Plans

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