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We were approached by the leadership team at Thermocill after they had independently proven their innovative window board concept with the University of Manchester and the University of Salford, but needed to take the huge leap from proof of concept to mass manufacture. Thermocill is an innovative window board that creates a wall of warm air in front of windows located above radiators. By directing the air from the radiator up and close to the glazing, it reduces both the amount of cold air entering the house and the amount of warm air leaking out via the windows.


We started the process by generating a number of possible options for manufacturing the unit. Given the need for the product to be fitted to a vast variety of window sizes and with varying sill thicknesses and depths, the unit needed to be highly adjustable by the installer. We settled on a design that used minimal plastic material but had the adjustability needed, as well as being interlocking so that multiple units can be installed side-by-side. The final design is produced via injection moulding and available in a recycled nylon with sustainable hemp fibres, which add to the strength as well as reducing the carbon footprint of the product.


After introducing Thermocill to our preferred injection moulding partner based here in the UK, the products are now in mass production and are being installed in homes all across the country. In these homes, Thermocill will be contributing to reduce the amount of energy required to heat a room by 14%, heating up a room up to 19% faster and saving an average 3-bedroom house around 10% in energy costs over the course of a year. It also reduces condensation on windows, which creates both a more comfortable and healthy environment for the occupants. The team are actively working with housing associations across the country to supply and fit Thermocill, in a bid to help meet the national net zero targets by 2050.

“The guys at npd were a total asset in bringing our product to life – they are an absolutely professional, technical and capable team.

Since the launch of Thermocill in October 2021, the product is gaining sales pace and is expected to become a household name within the energy saving product market!”

Keith Rimmer, CEO & Founder at Thermocill Limited

Credits and other information

Completed: 2021
Client: Thermocill Ltd
Product Team: Nathan Partington, Alex Hardisty & Chris Lester

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