As TWL is to mimic the effects of the working environment on laborers, it is suggested the TWL-1S unit should be placed on the worksite where the majority of workers are located. For example, if there is no shade provided on the worksite, the TWL-1S should be exposed to sunlight as most workers are.
However, in order to prolong the machine life, you can place TWL-1S under sunlight while measuring. Before pushing the TWL button, please allow TWL-1S at least 10 minutes in the working environment to get balance. After the TWL level shows up, you can put it back to shade.