As the equinox passes and the summer season officially arrives, many of us will soon cast off our snug winter duvet in favour of something more lightweight – but what TOG do you use?
Comedian Rhod Gilbert delivered a famous rant about the seemingly arbitrary TOG system of measuring duvet warmth …4.5 for summer, 10.5 for winter… but what does it all mean?
In fact, the TOG unit was developed by the Manchester textile industry as a standard comparison of insulation and can be boiled down to SI units; The scale is 10 times larger than the thermal resistance or R-value so 1 TOG = 0.1 m²K/W.
Insulation relies on two things: conductivity and thickness.
Conductivity is a measure of how quickly heat can move through a material. For example, a cooking pot is designed to have a very conductive metal base but a handle which does not conduct heat rapidly into your hand. The expanded polystyrene in an has a conductivity of 0.031 W/m·K. Wood is 4 times more conductive, concrete 60 times and steel is a whopping 1600 times more conductive. This is why it is important to consider the impact of “thermal bridges” across your insulation layer; routes for heat to quickly leak out.
Resistivity
Turning conductivity upside down gives you resistivity – the resistance to the passage of heat. A thicker duvet has more TOGs or higher resistance to heat transfer, so a winter duvet can sustain more than double the temperature difference of a summer duvet.
The standard 162mm Innovaré can provide a TOG value of 53 and our thickest panel delivers a massive 100 TOG – the equivalent of 10 winter duvets! A lightweight structure also gives a very fast response to heating demand meaning a room will feel warmer quicker and reduce the overall heating period. No need to set your heating to come on 2 hours before you get up in winter.
Energy Bills
It is estimated that domestic heating accounts for a third of the country’s entire energy usage. Fuel poverty is a concern for over 2.5 million properties who spend at least 10% of the household income on energy. As we replace existing building stock and build new houses, care homes offices and schools, it is important that we are not creating a future energy debt legacy. Offsite manufacturing has the potential to fulfil the demand for simple efficient, simple buildings which are quick to build.
Sam Dawe, Technical Manager at Innovaré Systems
